parser.rs

// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use core::prelude::*;

use abi;
use abi::AbiSet;
use ast::{Sigil, BorrowedSigil, ManagedSigil, OwnedSigil};
use ast::{CallSugar, NoSugar, DoSugar, ForSugar};
use ast::{TyBareFn, TyClosure};
use ast::{RegionTyParamBound, TraitTyParamBound};
use ast::{provided, public, purity};
use ast::{_mod, add, arg, arm, attribute, bind_by_ref, bind_infer};
use ast::{bitand, bitor, bitxor, blk};
use ast::{blk_check_mode, box};
use ast::{crate, crate_cfg, decl, decl_item};
use ast::{decl_local, default_blk, deref, div, enum_def, explicit_self};
use ast::{expr, expr_, expr_addr_of, expr_match, expr_again};
use ast::{expr_assign, expr_assign_op, expr_binary, expr_block};
use ast::{expr_break, expr_call, expr_cast, expr_copy, expr_do_body};
use ast::{expr_field, expr_fn_block, expr_if, expr_index};
use ast::{expr_lit, expr_log, expr_loop, expr_loop_body, expr_mac};
use ast::{expr_method_call, expr_paren, expr_path, expr_repeat};
use ast::{expr_ret, expr_self, expr_struct, expr_tup, expr_unary};
use ast::{expr_vec, expr_vstore, expr_vstore_mut_box};
use ast::{expr_vstore_slice, expr_vstore_box};
use ast::{expr_vstore_mut_slice, expr_while, extern_fn, field, fn_decl};
use ast::{expr_vstore_uniq, Onceness, Once, Many};
use ast::{foreign_item, foreign_item_const, foreign_item_fn, foreign_mod};
use ast::{ident, impure_fn, inherited, item, item_, item_const};
use ast::{item_enum, item_fn, item_foreign_mod, item_impl};
use ast::{item_mac, item_mod, item_struct, item_trait, item_ty, lit, lit_};
use ast::{lit_bool, lit_float, lit_float_unsuffixed, lit_int};
use ast::{lit_int_unsuffixed, lit_nil, lit_str, lit_uint, local, m_const};
use ast::{m_imm, m_mutbl, mac_, mac_invoc_tt, matcher, match_nonterminal};
use ast::{match_seq, match_tok, method, mt, mul, mutability};
use ast::{named_field, neg, node_id, noreturn, not, pat, pat_box, pat_enum};
use ast::{pat_ident, pat_lit, pat_range, pat_region, pat_struct};
use ast::{pat_tup, pat_uniq, pat_wild, private};
use ast::{rem, required};
use ast::{ret_style, return_val, shl, shr, stmt, stmt_decl};
use ast::{stmt_expr, stmt_semi, stmt_mac, struct_def, struct_field};
use ast::{struct_variant_kind, subtract};
use ast::{sty_box, sty_region, sty_static, sty_uniq, sty_value};
use ast::{token_tree, trait_method, trait_ref, tt_delim, tt_seq, tt_tok};
use ast::{tt_nonterminal, tuple_variant_kind, Ty, ty_, ty_bot, ty_box};
use ast::{ty_field, ty_fixed_length_vec, ty_closure, ty_bare_fn};
use ast::{ty_infer, ty_method};
use ast::{ty_nil, TyParam, TyParamBound, ty_path, ty_ptr, ty_rptr};
use ast::{ty_tup, ty_u32, ty_uniq, ty_vec, uniq};
use ast::{unnamed_field, unsafe_blk, unsafe_fn, view_item};
use ast::{view_item_, view_item_extern_mod, view_item_use};
use ast::{view_path, view_path_glob, view_path_list, view_path_simple};
use ast::visibility;
use ast;
use ast_util::{as_prec, ident_to_path, operator_prec};
use ast_util;
use codemap::{span, BytePos, spanned, mk_sp};
use codemap;
use parse::attr::parser_attr;
use parse::classify;
use parse::common::{seq_sep_none};
use parse::common::{seq_sep_trailing_disallowed, seq_sep_trailing_allowed};
use parse::lexer::reader;
use parse::lexer::TokenAndSpan;
use parse::obsolete::{ObsoleteClassTraits};
use parse::obsolete::{ObsoleteLet, ObsoleteFieldTerminator};
use parse::obsolete::{ObsoleteMoveInit, ObsoleteBinaryMove, ObsoleteSwap};
use parse::obsolete::{ObsoleteSyntax, ObsoleteLowerCaseKindBounds};
use parse::obsolete::{ObsoleteUnsafeBlock, ObsoleteImplSyntax};
use parse::obsolete::{ObsoleteTraitBoundSeparator, ObsoleteMutOwnedPointer};
use parse::obsolete::{ObsoleteMutVector, ObsoleteImplVisibility};
use parse::obsolete::{ObsoleteRecordType, ObsoleteRecordPattern};
use parse::obsolete::{ObsoletePostFnTySigil};
use parse::obsolete::{ObsoleteBareFnType, ObsoleteNewtypeEnum};
use parse::obsolete::ObsoleteMode;
use parse::obsolete::{ObsoleteLifetimeNotation, ObsoleteConstManagedPointer};
use parse::obsolete::{ObsoletePurity, ObsoleteStaticMethod};
use parse::obsolete::{ObsoleteConstItem, ObsoleteFixedLengthVectorType};
use parse::obsolete::{ObsoleteNamedExternModule, ObsoleteMultipleLocalDecl};
use parse::token::{can_begin_expr, get_ident_interner, ident_to_str, is_ident, is_ident_or_path};
use parse::token::{is_plain_ident, INTERPOLATED, keywords, special_idents, token_to_binop};
use parse::token;
use parse::{new_sub_parser_from_file, next_node_id, ParseSess};
use opt_vec;
use opt_vec::OptVec;

use core::either::Either;
use core::either;
use core::hashmap::HashSet;
use core::vec;

#[deriving(Eq)]
enum restriction {
    UNRESTRICTED,
    RESTRICT_STMT_EXPR,
    RESTRICT_NO_BAR_OP,
    RESTRICT_NO_BAR_OR_DOUBLEBAR_OP,
}

type arg_or_capture_item = Either<arg, ()>;
type item_info = (ident, item_, Option<~[attribute]>);

pub enum item_or_view_item {
    // indicates a failure to parse any kind of item:
    iovi_none,
    iovi_item(@item),
    iovi_foreign_item(@foreign_item),
    iovi_view_item(@view_item)
}

#[deriving(Eq)]
enum view_item_parse_mode {
    VIEW_ITEMS_AND_ITEMS_ALLOWED,
    FOREIGN_ITEMS_ALLOWED,
    IMPORTS_AND_ITEMS_ALLOWED
}

/* The expr situation is not as complex as I thought it would be.
The important thing is to make sure that lookahead doesn't balk
at INTERPOLATED tokens */
macro_rules! maybe_whole_expr (
    ($p:expr) => (
        match *($p).token {
            INTERPOLATED(token::nt_expr(e)) => {
                $p.bump();
                return e;
            }
            INTERPOLATED(token::nt_path(pt)) => {
                $p.bump();
                return $p.mk_expr(
                    ($p).span.lo,
                    ($p).span.hi,
                    expr_path(pt)
                );
            }
            _ => ()
        }
    )
)

macro_rules! maybe_whole (
    ($p:expr, $constructor:ident) => (
        match copy *($p).token {
            INTERPOLATED(token::$constructor(x)) => {
                $p.bump();
                return x;
            }
            _ => ()
       }
    );
    (deref $p:expr, $constructor:ident) => (
        match copy *($p).token {
            INTERPOLATED(token::$constructor(x)) => {
                $p.bump();
                return copy *x;
            }
            _ => ()
        }
    );
    (Some $p:expr, $constructor:ident) => (
        match copy *($p).token {
            INTERPOLATED(token::$constructor(x)) => {
                $p.bump();
                return Some(x);
            }
            _ => ()
        }
    );
    (iovi $p:expr, $constructor:ident) => (
        match copy *($p).token {
            INTERPOLATED(token::$constructor(x)) => {
                $p.bump();
                return iovi_item(x);
            }
            _ => ()
        }
    );
    (pair_empty $p:expr, $constructor:ident) => (
        match copy *($p).token {
            INTERPOLATED(token::$constructor(x)) => {
                $p.bump();
                return (~[], x);
            }
            _ => ()
        }
    )
)


fn maybe_append(lhs: ~[attribute], rhs: Option<~[attribute]>)
             -> ~[attribute] {
    match rhs {
        None => lhs,
        Some(ref attrs) => vec::append(lhs, (*attrs))
    }
}


struct ParsedItemsAndViewItems {
    attrs_remaining: ~[attribute],
    view_items: ~[@view_item],
    items: ~[@item],
    foreign_items: ~[@foreign_item]
}

/* ident is handled by common.rs */

pub fn Parser(sess: @mut ParseSess,
              cfg: ast::crate_cfg,
              rdr: @reader)
           -> Parser {
    let tok0 = copy rdr.next_token();
    let interner = get_ident_interner();

    Parser {
        reader: rdr,
        interner: interner,
        sess: sess,
        cfg: cfg,
        token: @mut copy tok0.tok,
        span: @mut copy tok0.sp,
        last_span: @mut copy tok0.sp,
        buffer: @mut ([copy tok0, .. 4]),
        buffer_start: @mut 0,
        buffer_end: @mut 0,
        tokens_consumed: @mut 0,
        restriction: @mut UNRESTRICTED,
        quote_depth: @mut 0,
        obsolete_set: @mut HashSet::new(),
        mod_path_stack: @mut ~[],
    }
}

// ooh, nasty mutable fields everywhere....
pub struct Parser {
    sess: @mut ParseSess,
    cfg: crate_cfg,
    // the current token:
    token: @mut token::Token,
    // the span of the current token:
    span: @mut span,
    // the span of the prior token:
    last_span: @mut span,
    buffer: @mut [TokenAndSpan, ..4],
    buffer_start: @mut int,
    buffer_end: @mut int,
    tokens_consumed: @mut uint,
    restriction: @mut restriction,
    quote_depth: @mut uint, // not (yet) related to the quasiquoter
    reader: @reader,
    interner: @token::ident_interner,
    /// The set of seen errors about obsolete syntax. Used to suppress
    /// extra detail when the same error is seen twice
    obsolete_set: @mut HashSet<ObsoleteSyntax>,
    /// Used to determine the path to externally loaded source files
    mod_path_stack: @mut ~[@str],

}

#[unsafe_destructor]
impl Drop for Parser {
    /* do not copy the parser; its state is tied to outside state */
    fn finalize(&self) {}
}

impl Parser {
    // advance the parser by one token
    pub fn bump(&self) {
        *self.last_span = copy *self.span;
        let next = if *self.buffer_start == *self.buffer_end {
            self.reader.next_token()
        } else {
            let next = copy self.buffer[*self.buffer_start];
            *self.buffer_start = (*self.buffer_start + 1) & 3;
            next
        };
        *self.token = copy next.tok;
        *self.span = copy next.sp;
        *self.tokens_consumed += 1u;
    }
    // EFFECT: replace the current token and span with the given one
    pub fn replace_token(&self,
                         next: token::Token,
                         lo: BytePos,
                         hi: BytePos) {
        *self.token = next;
        *self.span = mk_sp(lo, hi);
    }
    pub fn buffer_length(&self) -> int {
        if *self.buffer_start <= *self.buffer_end {
            return *self.buffer_end - *self.buffer_start;
        }
        return (4 - *self.buffer_start) + *self.buffer_end;
    }
    pub fn look_ahead(&self, distance: uint) -> token::Token {
        let dist = distance as int;
        while self.buffer_length() < dist {
            self.buffer[*self.buffer_end] = self.reader.next_token();
            *self.buffer_end = (*self.buffer_end + 1) & 3;
        }
        return copy self.buffer[(*self.buffer_start + dist - 1) & 3].tok;
    }
    pub fn fatal(&self, m: &str) -> ! {
        self.sess.span_diagnostic.span_fatal(*copy self.span, m)
    }
    pub fn span_fatal(&self, sp: span, m: &str) -> ! {
        self.sess.span_diagnostic.span_fatal(sp, m)
    }
    pub fn span_note(&self, sp: span, m: &str) {
        self.sess.span_diagnostic.span_note(sp, m)
    }
    pub fn bug(&self, m: &str) -> ! {
        self.sess.span_diagnostic.span_bug(*copy self.span, m)
    }
    pub fn warn(&self, m: &str) {
        self.sess.span_diagnostic.span_warn(*copy self.span, m)
    }
    pub fn span_err(&self, sp: span, m: &str) {
        self.sess.span_diagnostic.span_err(sp, m)
    }
    pub fn abort_if_errors(&self) {
        self.sess.span_diagnostic.handler().abort_if_errors();
    }
    pub fn get_id(&self) -> node_id { next_node_id(self.sess) }

    pub fn id_to_str(&self, id: ident) -> @str {
        get_ident_interner().get(id.name)
    }

    // is this one of the keywords that signals a closure type?
    pub fn token_is_closure_keyword(&self, tok: &token::Token) -> bool {
        token::is_keyword(keywords::Pure, tok) ||
            token::is_keyword(keywords::Unsafe, tok) ||
            token::is_keyword(keywords::Once, tok) ||
            token::is_keyword(keywords::Fn, tok)
    }

    pub fn token_is_lifetime(&self, tok: &token::Token) -> bool {
        match *tok {
            token::LIFETIME(*) => true,
            _ => false,
        }
    }

    pub fn get_lifetime(&self, tok: &token::Token) -> ast::ident {
        match *tok {
            token::LIFETIME(ref ident) => copy *ident,
            _ => self.bug("not a lifetime"),
        }
    }

    // parse a ty_bare_fun type:
    pub fn parse_ty_bare_fn(&self) -> ty_ {
        /*

        extern "ABI" [pure|unsafe] fn <'lt> (S) -> T
               ^~~~^ ^~~~~~~~~~~~^    ^~~~^ ^~^    ^
                 |     |                |    |     |
                 |     |                |    |   Return type
                 |     |                |  Argument types
                 |     |            Lifetimes
                 |     |
                 |   Purity
                ABI

        */

        let opt_abis = self.parse_opt_abis();
        let abis = opt_abis.get_or_default(AbiSet::Rust());
        let purity = self.parse_unsafety();
        self.expect_keyword(keywords::Fn);
        let (decl, lifetimes) = self.parse_ty_fn_decl();
        return ty_bare_fn(@TyBareFn {
            abis: abis,
            purity: purity,
            lifetimes: lifetimes,
            decl: decl
        });
    }

    // parse a ty_closure type
    pub fn parse_ty_closure(&self,
                            sigil: ast::Sigil,
                            region: Option<@ast::Lifetime>)
                            -> ty_ {
        /*

        (&|~|@) ['r] [pure|unsafe] [once] fn [:Bounds] <'lt> (S) -> T
        ^~~~~~^ ^~~^ ^~~~~~~~~~~~^ ^~~~~^    ^~~~~~~~^ ^~~~^ ^~^    ^
           |     |     |             |           |       |    |     |
           |     |     |             |           |       |    |   Return type
           |     |     |             |           |       |  Argument types
           |     |     |             |           |   Lifetimes
           |     |     |             |       Closure bounds
           |     |     |          Once-ness (a.k.a., affine)
           |     |   Purity
           | Lifetime bound
        Allocation type

        */

        // At this point, the allocation type and lifetime bound have been
        // parsed.

        let purity = self.parse_unsafety();
        let onceness = parse_onceness(self);
        self.expect_keyword(keywords::Fn);
        let bounds = self.parse_optional_ty_param_bounds();

        if self.parse_fn_ty_sigil().is_some() {
            self.obsolete(*self.span, ObsoletePostFnTySigil);
        }

        let (decl, lifetimes) = self.parse_ty_fn_decl();

        return ty_closure(@TyClosure {
            sigil: sigil,
            region: region,
            purity: purity,
            onceness: onceness,
            bounds: bounds,
            decl: decl,
            lifetimes: lifetimes,
        });

        fn parse_onceness(this: &Parser) -> Onceness {
            if this.eat_keyword(keywords::Once) {
                Once
            } else {
                Many
            }
        }
    }

    // looks like this should be called parse_unsafety
    pub fn parse_unsafety(&self) -> purity {
        if self.eat_keyword(keywords::Pure) {
            self.obsolete(*self.last_span, ObsoletePurity);
            return impure_fn;
        } else if self.eat_keyword(keywords::Unsafe) {
            return unsafe_fn;
        } else {
            return impure_fn;
        }
    }

    // parse a function type (following the 'fn')
    pub fn parse_ty_fn_decl(&self) -> (fn_decl, OptVec<ast::Lifetime>) {
        /*

        (fn) <'lt> (S) -> T
             ^~~~^ ^~^    ^
               |    |     |
               |    |   Return type
               |  Argument types
           Lifetimes

        */
        let lifetimes = if self.eat(&token::LT) {
            let lifetimes = self.parse_lifetimes();
            self.expect_gt();
            lifetimes
        } else {
            opt_vec::Empty
        };

        let inputs = self.parse_unspanned_seq(
            &token::LPAREN,
            &token::RPAREN,
            seq_sep_trailing_disallowed(token::COMMA),
            |p| p.parse_arg_general(false)
        );
        let (ret_style, ret_ty) = self.parse_ret_ty();
        let decl = ast::fn_decl {
            inputs: inputs,
            output: ret_ty,
            cf: ret_style
        };
        (decl, lifetimes)
    }

    // parse the methods in a trait declaration
    pub fn parse_trait_methods(&self) -> ~[trait_method] {
        do self.parse_unspanned_seq(
            &token::LBRACE,
            &token::RBRACE,
            seq_sep_none()
        ) |p| {
            let attrs = p.parse_outer_attributes();
            let lo = p.span.lo;

            let vis = p.parse_visibility();
            let pur = p.parse_fn_purity();
            // NB: at the moment, trait methods are public by default; this
            // could change.
            let ident = p.parse_ident();

            let generics = p.parse_generics();

            let (explicit_self, d) = do self.parse_fn_decl_with_self() |p| {
                // This is somewhat dubious; We don't want to allow argument
                // names to be left off if there is a definition...
                either::Left(p.parse_arg_general(false))
            };

            let hi = p.last_span.hi;
            debug!("parse_trait_methods(): trait method signature ends in \
                    `%s`",
                   self.this_token_to_str());
            match *p.token {
              token::SEMI => {
                p.bump();
                debug!("parse_trait_methods(): parsing required method");
                // NB: at the moment, visibility annotations on required
                // methods are ignored; this could change.
                required(ty_method {
                    ident: ident,
                    attrs: attrs,
                    purity: pur,
                    decl: d,
                    generics: generics,
                    explicit_self: explicit_self,
                    id: p.get_id(),
                    span: mk_sp(lo, hi)
                })
              }
              token::LBRACE => {
                debug!("parse_trait_methods(): parsing provided method");
                let (inner_attrs, body) =
                    p.parse_inner_attrs_and_block();
                let attrs = vec::append(attrs, inner_attrs);
                provided(@ast::method {
                    ident: ident,
                    attrs: attrs,
                    generics: generics,
                    explicit_self: explicit_self,
                    purity: pur,
                    decl: d,
                    body: body,
                    id: p.get_id(),
                    span: mk_sp(lo, hi),
                    self_id: p.get_id(),
                    vis: vis,
                })
              }

              _ => {
                    p.fatal(
                        fmt!(
                            "expected `;` or `}` but found `%s`",
                            self.this_token_to_str()
                        )
                    );
                }
            }
        }
    }

    // parse a possibly mutable type
    pub fn parse_mt(&self) -> mt {
        let mutbl = self.parse_mutability();
        let t = self.parse_ty(false);
        mt { ty: t, mutbl: mutbl }
    }

    // parse [mut/const/imm] ID : TY
    // now used only by obsolete record syntax parser...
    pub fn parse_ty_field(&self) -> ty_field {
        let lo = self.span.lo;
        let mutbl = self.parse_mutability();
        let id = self.parse_ident();
        self.expect(&token::COLON);
        let ty = self.parse_ty(false);
        spanned(
            lo,
            ty.span.hi,
            ast::ty_field_ {
                ident: id,
                mt: ast::mt { ty: ty, mutbl: mutbl },
            }
        )
    }

    // parse optional return type [ -> TY ] in function decl
    pub fn parse_ret_ty(&self) -> (ret_style, @Ty) {
        return if self.eat(&token::RARROW) {
            let lo = self.span.lo;
            if self.eat(&token::NOT) {
                (
                    noreturn,
                    @Ty {
                        id: self.get_id(),
                        node: ty_bot,
                        span: mk_sp(lo, self.last_span.hi)
                    }
                )
            } else {
                (return_val, self.parse_ty(false))
            }
        } else {
            let pos = self.span.lo;
            (
                return_val,
                @Ty {
                    id: self.get_id(),
                    node: ty_nil,
                    span: mk_sp(pos, pos),
                }
            )
        }
    }

    // parse a type.
    // Useless second parameter for compatibility with quasiquote macros.
    // Bleh!
    pub fn parse_ty(&self, _: bool) -> @Ty {
        maybe_whole!(self, nt_ty);

        let lo = self.span.lo;

        let t = if *self.token == token::LPAREN {
            self.bump();
            if *self.token == token::RPAREN {
                self.bump();
                ty_nil
            } else {
                // (t) is a parenthesized ty
                // (t,) is the type of a tuple with only one field,
                // of type t
                let mut ts = ~[self.parse_ty(false)];
                let mut one_tuple = false;
                while *self.token == token::COMMA {
                    self.bump();
                    if *self.token != token::RPAREN {
                        ts.push(self.parse_ty(false));
                    }
                    else {
                        one_tuple = true;
                    }
                }
                let t = if ts.len() == 1 && !one_tuple {
                    copy ts[0].node
                } else {
                    ty_tup(ts)
                };
                self.expect(&token::RPAREN);
                t
            }
        } else if *self.token == token::AT {
            // MANAGED POINTER
            self.bump();
            self.parse_box_or_uniq_pointee(ManagedSigil, ty_box)
        } else if *self.token == token::TILDE {
            // OWNED POINTER
            self.bump();
            self.parse_box_or_uniq_pointee(OwnedSigil, ty_uniq)
        } else if *self.token == token::BINOP(token::STAR) {
            // STAR POINTER (bare pointer?)
            self.bump();
            ty_ptr(self.parse_mt())
        } else if *self.token == token::LBRACE {
            // STRUCTURAL RECORD (remove?)
            let elems = self.parse_unspanned_seq(
                &token::LBRACE,
                &token::RBRACE,
                seq_sep_trailing_allowed(token::COMMA),
                |p| p.parse_ty_field()
            );
            if elems.len() == 0 {
                self.unexpected_last(&token::RBRACE);
            }
            self.obsolete(*self.last_span, ObsoleteRecordType);
            ty_nil
        } else if *self.token == token::LBRACKET {
            // VECTOR
            self.expect(&token::LBRACKET);
            let mt = self.parse_mt();
            if mt.mutbl == m_mutbl {    // `m_const` too after snapshot
                self.obsolete(*self.last_span, ObsoleteMutVector);
            }

            // Parse the `, ..e` in `[ int, ..e ]`
            // where `e` is a const expression
            let t = match self.maybe_parse_fixed_vstore() {
                None => ty_vec(mt),
                Some(suffix) => ty_fixed_length_vec(mt, suffix)
            };
            self.expect(&token::RBRACKET);
            t
        } else if *self.token == token::BINOP(token::AND) {
            // BORROWED POINTER
            self.bump();
            self.parse_borrowed_pointee()
        } else if self.eat_keyword(keywords::Extern) {
            // EXTERN FUNCTION
            self.parse_ty_bare_fn()
        } else if self.token_is_closure_keyword(&copy *self.token) {
            // CLOSURE
            let result = self.parse_ty_closure(ast::BorrowedSigil, None);
            self.obsolete(*self.last_span, ObsoleteBareFnType);
            result
        } else if *self.token == token::MOD_SEP
            || is_ident_or_path(self.token) {
            // NAMED TYPE
            let path = self.parse_path_with_tps(false);
            ty_path(path, self.get_id())
        } else {
            self.fatal(fmt!("expected type, found token %?",
                            *self.token));
        };

        let sp = mk_sp(lo, self.last_span.hi);
        @Ty {id: self.get_id(), node: t, span: sp}
    }

    // parse the type following a @ or a ~
    pub fn parse_box_or_uniq_pointee(&self,
                                     sigil: ast::Sigil,
                                     ctor: &fn(v: mt) -> ty_) -> ty_ {
        // @'foo fn() or @foo/fn() or @fn() are parsed directly as fn types:
        match *self.token {
            token::LIFETIME(*) => {
                let lifetime = @self.parse_lifetime();
                self.bump();
                return self.parse_ty_closure(sigil, Some(lifetime));
            }

            token::IDENT(*) => {
                if self.look_ahead(1u) == token::BINOP(token::SLASH) &&
                    self.token_is_closure_keyword(&self.look_ahead(2u))
                {
                    let lifetime = @self.parse_lifetime();
                    self.obsolete(*self.last_span, ObsoleteLifetimeNotation);
                    return self.parse_ty_closure(sigil, Some(lifetime));
                } else if self.token_is_closure_keyword(&copy *self.token) {
                    return self.parse_ty_closure(sigil, None);
                }
            }
            _ => {}
        }

        // other things are parsed as @ + a type.  Note that constructs like
        // @[] and @str will be resolved during typeck to slices and so forth,
        // rather than boxed ptrs.  But the special casing of str/vec is not
        // reflected in the AST type.
        let mt = self.parse_mt();

        if mt.mutbl != m_imm && sigil == OwnedSigil {
            self.obsolete(*self.last_span, ObsoleteMutOwnedPointer);
        }
        if mt.mutbl == m_const && sigil == ManagedSigil {
            self.obsolete(*self.last_span, ObsoleteConstManagedPointer);
        }

        ctor(mt)
    }

    pub fn parse_borrowed_pointee(&self) -> ty_ {
        // look for `&'lt` or `&'foo ` and interpret `foo` as the region name:
        let opt_lifetime = self.parse_opt_lifetime();

        if self.token_is_closure_keyword(&copy *self.token) {
            return self.parse_ty_closure(BorrowedSigil, opt_lifetime);
        }

        let mt = self.parse_mt();
        return ty_rptr(opt_lifetime, mt);
    }

    // parse an optional, obsolete argument mode.
    pub fn parse_arg_mode(&self) {
        if self.eat(&token::BINOP(token::MINUS)) {
            self.obsolete(*self.span, ObsoleteMode);
        } else if self.eat(&token::ANDAND) {
            self.obsolete(*self.span, ObsoleteMode);
        } else if self.eat(&token::BINOP(token::PLUS)) {
            if self.eat(&token::BINOP(token::PLUS)) {
                self.obsolete(*self.span, ObsoleteMode);
            } else {
                self.obsolete(*self.span, ObsoleteMode);
            }
        } else {
            // Ignore.
        }
    }

    pub fn is_named_argument(&self) -> bool {
        let offset = if *self.token == token::BINOP(token::AND) {
            1
        } else if *self.token == token::BINOP(token::MINUS) {
            1
        } else if *self.token == token::ANDAND {
            1
        } else if *self.token == token::BINOP(token::PLUS) {
            if self.look_ahead(1) == token::BINOP(token::PLUS) {
                2
            } else {
                1
            }
        } else { 0 };
        if offset == 0 {
            is_plain_ident(&*self.token)
                && self.look_ahead(1) == token::COLON
        } else {
            is_plain_ident(&self.look_ahead(offset))
                && self.look_ahead(offset + 1) == token::COLON
        }
    }

    // This version of parse arg doesn't necessarily require
    // identifier names.
    pub fn parse_arg_general(&self, require_name: bool) -> arg {
        let mut is_mutbl = false;
        let pat = if require_name || self.is_named_argument() {
            self.parse_arg_mode();
            is_mutbl = self.eat_keyword(keywords::Mut);
            let pat = self.parse_pat();
            self.expect(&token::COLON);
            pat
        } else {
            ast_util::ident_to_pat(self.get_id(),
                                   *self.last_span,
                                   special_idents::invalid)
        };

        let t = self.parse_ty(false);

        ast::arg {
            is_mutbl: is_mutbl,
            ty: t,
            pat: pat,
            id: self.get_id(),
        }
    }

    // parse a single function argument
    pub fn parse_arg(&self) -> arg_or_capture_item {
        either::Left(self.parse_arg_general(true))
    }

    // parse an argument in a lambda header e.g. |arg, arg|
    pub fn parse_fn_block_arg(&self) -> arg_or_capture_item {
        self.parse_arg_mode();
        let is_mutbl = self.eat_keyword(keywords::Mut);
        let pat = self.parse_pat();
        let t = if self.eat(&token::COLON) {
            self.parse_ty(false)
        } else {
            @Ty {
                id: self.get_id(),
                node: ty_infer,
                span: mk_sp(self.span.lo, self.span.hi),
            }
        };
        either::Left(ast::arg {
            is_mutbl: is_mutbl,
            ty: t,
            pat: pat,
            id: self.get_id()
        })
    }

    pub fn maybe_parse_fixed_vstore(&self) -> Option<@ast::expr> {
        if self.eat(&token::BINOP(token::STAR)) {
            self.obsolete(*self.last_span, ObsoleteFixedLengthVectorType);
            Some(self.parse_expr())
        } else if *self.token == token::COMMA &&
                self.look_ahead(1) == token::DOTDOT {
            self.bump();
            self.bump();
            Some(self.parse_expr())
        } else {
            None
        }
    }

    // matches token_lit = LIT_INT | ...
    pub fn lit_from_token(&self, tok: &token::Token) -> lit_ {
        match *tok {
            token::LIT_INT(i, it) => lit_int(i, it),
            token::LIT_UINT(u, ut) => lit_uint(u, ut),
            token::LIT_INT_UNSUFFIXED(i) => lit_int_unsuffixed(i),
            token::LIT_FLOAT(s, ft) => lit_float(self.id_to_str(s), ft),
            token::LIT_FLOAT_UNSUFFIXED(s) =>
                lit_float_unsuffixed(self.id_to_str(s)),
            token::LIT_STR(s) => lit_str(self.id_to_str(s)),
            token::LPAREN => { self.expect(&token::RPAREN); lit_nil },
            _ => { self.unexpected_last(tok); }
        }
    }

    // matches lit = true | false | token_lit
    pub fn parse_lit(&self) -> lit {
        let lo = self.span.lo;
        let lit = if self.eat_keyword(keywords::True) {
            lit_bool(true)
        } else if self.eat_keyword(keywords::False) {
            lit_bool(false)
        } else {
            // XXX: This is a really bad copy!
            let tok = copy *self.token;
            self.bump();
            self.lit_from_token(&tok)
        };
        codemap::spanned { node: lit, span: mk_sp(lo, self.last_span.hi) }
    }

    // matches '-' lit | lit
    pub fn parse_literal_maybe_minus(&self) -> @expr {
        let minus_lo = self.span.lo;
        let minus_present = self.eat(&token::BINOP(token::MINUS));

        let lo = self.span.lo;
        let literal = @self.parse_lit();
        let hi = self.span.hi;
        let expr = self.mk_expr(lo, hi, expr_lit(literal));

        if minus_present {
            let minus_hi = self.span.hi;
            self.mk_expr(minus_lo, minus_hi, self.mk_unary(neg, expr))
        } else {
            expr
        }
    }

    // parse a path into a vector of idents, whether the path starts
    // with ::, and a span.
    pub fn parse_path(&self) -> (~[ast::ident],bool,span) {
        let lo = self.span.lo;
        let is_global = self.eat(&token::MOD_SEP);
        let (ids,span{lo:_,hi,expn_info}) = self.parse_path_non_global();
        (ids,is_global,span{lo:lo,hi:hi,expn_info:expn_info})
    }

    // parse a path beginning with an identifier into a vector of idents and a span
    pub fn parse_path_non_global(&self) -> (~[ast::ident],span) {
        let lo = self.span.lo;
        let mut ids = ~[];
        // must be at least one to begin:
        ids.push(self.parse_ident());
        loop {
            match *self.token {
                token::MOD_SEP => {
                    match self.look_ahead(1) {
                        token::IDENT(*) => {
                            self.bump();
                            ids.push(self.parse_ident());
                        }
                        _ => break
                    }
                }
                _ => break
            }
        }
        (ids, mk_sp(lo, self.last_span.hi))
    }

    // parse a path that doesn't have type parameters attached
    pub fn parse_path_without_tps(&self) -> @ast::Path {
        maybe_whole!(self, nt_path);
        let (ids,is_global,sp) = self.parse_path();
        @ast::Path { span: sp,
                     global: is_global,
                     idents: ids,
                     rp: None,
                     types: ~[] }
    }

    // parse a path optionally with type parameters. If 'colons'
    // is true, then type parameters must be preceded by colons,
    // as in a::t::<t1,t2>
    pub fn parse_path_with_tps(&self, colons: bool) -> @ast::Path {
        debug!("parse_path_with_tps(colons=%b)", colons);

        maybe_whole!(self, nt_path);
        let lo = self.span.lo;
        let path = self.parse_path_without_tps();
        if colons && !self.eat(&token::MOD_SEP) {
            return path;
        }

        // Parse the (obsolete) trailing region parameter, if any, which will
        // be written "foo/&x"
        let rp_slash = {
            if *self.token == token::BINOP(token::SLASH)
                && self.look_ahead(1u) == token::BINOP(token::AND)
            {
                self.bump(); self.bump();
                self.obsolete(*self.last_span, ObsoleteLifetimeNotation);
                match *self.token {
                    token::IDENT(sid, _) => {
                        let span = copy self.span;
                        self.bump();
                        Some(@ast::Lifetime {
                            id: self.get_id(),
                            span: *span,
                            ident: sid
                        })
                    }
                    _ => {
                        self.fatal(fmt!("Expected a lifetime name"));
                    }
                }
            } else {
                None
            }
        };

        // Parse any lifetime or type parameters which may appear:
        let (lifetimes, tps) = self.parse_generic_values();
        let hi = self.span.lo;

        let rp = match (&rp_slash, &lifetimes) {
            (&Some(_), _) => rp_slash,
            (&None, v) => {
                if v.len() == 0 {
                    None
                } else if v.len() == 1 {
                    Some(@*v.get(0))
                } else {
                    self.fatal(fmt!("Expected at most one \
                                     lifetime name (for now)"));
                }
            }
        };

        @ast::Path { span: mk_sp(lo, hi),
                     rp: rp,
                     types: tps,
                     .. copy *path }
    }

    /// parses 0 or 1 lifetime
    pub fn parse_opt_lifetime(&self) -> Option<@ast::Lifetime> {
        match *self.token {
            token::LIFETIME(*) => {
                Some(@self.parse_lifetime())
            }

            // Also accept the (obsolete) syntax `foo/`
            token::IDENT(*) => {
                if self.look_ahead(1u) == token::BINOP(token::SLASH) {
                    self.obsolete(*self.last_span, ObsoleteLifetimeNotation);
                    Some(@self.parse_lifetime())
                } else {
                    None
                }
            }

            _ => {
                None
            }
        }
    }

    /// Parses a single lifetime
    // matches lifetime = ( LIFETIME ) | ( IDENT / )
    pub fn parse_lifetime(&self) -> ast::Lifetime {
        match *self.token {
            token::LIFETIME(i) => {
                let span = copy self.span;
                self.bump();
                return ast::Lifetime {
                    id: self.get_id(),
                    span: *span,
                    ident: i
                };
            }

            // Also accept the (obsolete) syntax `foo/`
            token::IDENT(i, _) => {
                let span = copy self.span;
                self.bump();
                self.expect(&token::BINOP(token::SLASH));
                self.obsolete(*self.last_span, ObsoleteLifetimeNotation);
                return ast::Lifetime {
                    id: self.get_id(),
                    span: *span,
                    ident: i
                };
            }

            _ => {
                self.fatal(fmt!("Expected a lifetime name"));
            }
        }
    }

    // matches lifetimes = ( lifetime ) | ( lifetime , lifetimes )
    // actually, it matches the empty one too, but putting that in there
    // messes up the grammar....
    pub fn parse_lifetimes(&self) -> OptVec<ast::Lifetime> {
        /*!
         *
         * Parses zero or more comma separated lifetimes.
         * Expects each lifetime to be followed by either
         * a comma or `>`.  Used when parsing type parameter
         * lists, where we expect something like `<'a, 'b, T>`.
         */

        let mut res = opt_vec::Empty;
        loop {
            match *self.token {
                token::LIFETIME(_) => {
                    res.push(self.parse_lifetime());
                }
                _ => {
                    return res;
                }
            }

            match *self.token {
                token::COMMA => { self.bump();}
                token::GT => { return res; }
                token::BINOP(token::SHR) => { return res; }
                _ => {
                    self.fatal(fmt!("expected `,` or `>` after lifetime name, got: %?",
                                    *self.token));
                }
            }
        }
    }

    pub fn token_is_mutability(&self, tok: &token::Token) -> bool {
        token::is_keyword(keywords::Mut, tok) ||
        token::is_keyword(keywords::Const, tok)
    }

    // parse mutability declaration (mut/const/imm)
    pub fn parse_mutability(&self) -> mutability {
        if self.eat_keyword(keywords::Mut) {
            m_mutbl
        } else if self.eat_keyword(keywords::Const) {
            m_const
        } else {
            m_imm
        }
    }

    // parse ident COLON expr
    pub fn parse_field(&self) -> field {
        let lo = self.span.lo;
        let i = self.parse_ident();
        self.expect(&token::COLON);
        let e = self.parse_expr();
        spanned(lo, e.span.hi, ast::field_ {
            ident: i,
            expr: e
        })
    }

    pub fn mk_expr(&self, lo: BytePos, hi: BytePos, node: expr_) -> @expr {
        @expr {
            id: self.get_id(),
            node: node,
            span: mk_sp(lo, hi),
        }
    }

    pub fn mk_unary(&self, unop: ast::unop, expr: @expr) -> ast::expr_ {
        expr_unary(self.get_id(), unop, expr)
    }

    pub fn mk_binary(&self, binop: ast::binop, lhs: @expr, rhs: @expr) -> ast::expr_ {
        expr_binary(self.get_id(), binop, lhs, rhs)
    }

    pub fn mk_call(&self, f: @expr, args: ~[@expr], sugar: CallSugar) -> ast::expr_ {
        expr_call(f, args, sugar)
    }

    pub fn mk_method_call(&self,
                      rcvr: @expr,
                      ident: ident,
                      tps: ~[@Ty],
                      args: ~[@expr],
                      sugar: CallSugar) -> ast::expr_ {
        expr_method_call(self.get_id(), rcvr, ident, tps, args, sugar)
    }

    pub fn mk_index(&self, expr: @expr, idx: @expr) -> ast::expr_ {
        expr_index(self.get_id(), expr, idx)
    }

    pub fn mk_field(&self, expr: @expr, ident: ident, tys: ~[@Ty]) -> ast::expr_ {
        expr_field(expr, ident, tys)
    }

    pub fn mk_assign_op(&self, binop: ast::binop, lhs: @expr, rhs: @expr) -> ast::expr_ {
        expr_assign_op(self.get_id(), binop, lhs, rhs)
    }

    pub fn mk_mac_expr(&self, lo: BytePos, hi: BytePos, m: mac_) -> @expr {
        @expr {
            id: self.get_id(),
            node: expr_mac(codemap::spanned {node: m, span: mk_sp(lo, hi)}),
            span: mk_sp(lo, hi),
        }
    }

    pub fn mk_lit_u32(&self, i: u32) -> @expr {
        let span = self.span;
        let lv_lit = @codemap::spanned {
            node: lit_uint(i as u64, ty_u32),
            span: *span
        };

        @expr {
            id: self.get_id(),
            node: expr_lit(lv_lit),
            span: *span,
        }
    }

    // at the bottom (top?) of the precedence hierarchy,
    // parse things like parenthesized exprs,
    // macros, return, etc.
    pub fn parse_bottom_expr(&self) -> @expr {
        maybe_whole_expr!(self);

        let lo = self.span.lo;
        let mut hi = self.span.hi;

        let ex: expr_;

        if *self.token == token::LPAREN {
            self.bump();
            // (e) is parenthesized e
            // (e,) is a tuple with only one field, e
            let mut trailing_comma = false;
            if *self.token == token::RPAREN {
                hi = self.span.hi;
                self.bump();
                let lit = @spanned(lo, hi, lit_nil);
                return self.mk_expr(lo, hi, expr_lit(lit));
            }
            let mut es = ~[self.parse_expr()];
            while *self.token == token::COMMA {
                self.bump();
                if *self.token != token::RPAREN {
                    es.push(self.parse_expr());
                }
                else {
                    trailing_comma = true;
                }
            }
            hi = self.span.hi;
            self.expect(&token::RPAREN);

            return if es.len() == 1 && !trailing_comma {
                self.mk_expr(lo, self.span.hi, expr_paren(es[0]))
            }
            else {
                self.mk_expr(lo, hi, expr_tup(es))
            }
        } else if *self.token == token::LBRACE {
            self.bump();
            let blk = self.parse_block_tail(lo, default_blk);
            return self.mk_expr(blk.span.lo, blk.span.hi,
                                 expr_block(blk));
        } else if token::is_bar(&*self.token) {
            return self.parse_lambda_expr();
        } else if self.eat_keyword(keywords::Self) {
            ex = expr_self;
            hi = self.span.hi;
        } else if self.eat_keyword(keywords::If) {
            return self.parse_if_expr();
        } else if self.eat_keyword(keywords::For) {
            return self.parse_sugary_call_expr(~"for", ForSugar,
                                               expr_loop_body);
        } else if self.eat_keyword(keywords::Do) {
            return self.parse_sugary_call_expr(~"do", DoSugar,
                                               expr_do_body);
        } else if self.eat_keyword(keywords::While) {
            return self.parse_while_expr();
        } else if self.token_is_lifetime(&*self.token) {
            let lifetime = self.get_lifetime(&*self.token);
            self.bump();
            self.expect(&token::COLON);
            self.expect_keyword(keywords::Loop);
            return self.parse_loop_expr(Some(lifetime));
        } else if self.eat_keyword(keywords::Loop) {
            return self.parse_loop_expr(None);
        } else if self.eat_keyword(keywords::Match) {
            return self.parse_match_expr();
        } else if self.eat_keyword(keywords::Unsafe) {
            return self.parse_block_expr(lo, unsafe_blk);
        } else if *self.token == token::LBRACKET {
            self.bump();
            let mutbl = self.parse_mutability();
            if mutbl == m_mutbl || mutbl == m_const {
                self.obsolete(*self.last_span, ObsoleteMutVector);
            }

            if *self.token == token::RBRACKET {
                // Empty vector.
                self.bump();
                ex = expr_vec(~[], mutbl);
            } else {
                // Nonempty vector.
                let first_expr = self.parse_expr();
                if *self.token == token::COMMA &&
                        self.look_ahead(1) == token::DOTDOT {
                    // Repeating vector syntax: [ 0, ..512 ]
                    self.bump();
                    self.bump();
                    let count = self.parse_expr();
                    self.expect(&token::RBRACKET);
                    ex = expr_repeat(first_expr, count, mutbl);
                } else if *self.token == token::COMMA {
                    // Vector with two or more elements.
                    self.bump();
                    let remaining_exprs = self.parse_seq_to_end(
                        &token::RBRACKET,
                        seq_sep_trailing_allowed(token::COMMA),
                        |p| p.parse_expr()
                    );
                    ex = expr_vec(~[first_expr] + remaining_exprs, mutbl);
                } else {
                    // Vector with one element.
                    self.expect(&token::RBRACKET);
                    ex = expr_vec(~[first_expr], mutbl);
                }
            }
            hi = self.last_span.hi;
        } else if self.eat_keyword(keywords::__Log) {
            // LOG expression
            self.expect(&token::LPAREN);
            let lvl = self.parse_expr();
            self.expect(&token::COMMA);
            let e = self.parse_expr();
            ex = expr_log(lvl, e);
            hi = self.span.hi;
            self.expect(&token::RPAREN);
        } else if self.eat_keyword(keywords::Return) {
            // RETURN expression
            if can_begin_expr(&*self.token) {
                let e = self.parse_expr();
                hi = e.span.hi;
                ex = expr_ret(Some(e));
            } else { ex = expr_ret(None); }
        } else if self.eat_keyword(keywords::Break) {
            // BREAK expression
            if self.token_is_lifetime(&*self.token) {
                let lifetime = self.get_lifetime(&*self.token);
                self.bump();
                ex = expr_break(Some(lifetime));
            } else {
                ex = expr_break(None);
            }
            hi = self.span.hi;
        } else if self.eat_keyword(keywords::Copy) {
            // COPY expression
            let e = self.parse_expr();
            ex = expr_copy(e);
            hi = e.span.hi;
        } else if *self.token == token::MOD_SEP ||
                is_ident(&*self.token) && !self.is_keyword(keywords::True) &&
                !self.is_keyword(keywords::False) {
            let pth = self.parse_path_with_tps(true);

            // `!`, as an operator, is prefix, so we know this isn't that
            if *self.token == token::NOT {
                // MACRO INVOCATION expression
                self.bump();
                match *self.token {
                    token::LPAREN | token::LBRACE => {}
                    _ => self.fatal("expected open delimiter")
                };

                let ket = token::flip_delimiter(&*self.token);
                let tts = self.parse_unspanned_seq(
                    &copy *self.token,
                    &ket,
                    seq_sep_none(),
                    |p| p.parse_token_tree()
                );
                let hi = self.span.hi;

                return self.mk_mac_expr(lo, hi, mac_invoc_tt(pth, tts));
            } else if *self.token == token::LBRACE {
                // This might be a struct literal.
                if self.looking_at_record_literal() {
                    // It's a struct literal.
                    self.bump();
                    let mut fields = ~[];
                    let mut base = None;

                    fields.push(self.parse_field());
                    while *self.token != token::RBRACE {
                        if self.try_parse_obsolete_with() {
                            break;
                        }

                        self.expect(&token::COMMA);

                        if self.eat(&token::DOTDOT) {
                            base = Some(self.parse_expr());
                            break;
                        }

                        if *self.token == token::RBRACE {
                            // Accept an optional trailing comma.
                            break;
                        }
                        fields.push(self.parse_field());
                    }

                    hi = pth.span.hi;
                    self.expect(&token::RBRACE);
                    ex = expr_struct(pth, fields, base);
                    return self.mk_expr(lo, hi, ex);
                }
            }

            hi = pth.span.hi;
            ex = expr_path(pth);
        } else {
            // other literal expression
            let lit = self.parse_lit();
            hi = lit.span.hi;
            ex = expr_lit(@lit);
        }

        return self.mk_expr(lo, hi, ex);
    }

    // parse a block or unsafe block
    pub fn parse_block_expr(&self, lo: BytePos, blk_mode: blk_check_mode)
                            -> @expr {
        self.expect(&token::LBRACE);
        let blk = self.parse_block_tail(lo, blk_mode);
        return self.mk_expr(blk.span.lo, blk.span.hi, expr_block(blk));
    }

    // parse a.b or a(13) or a[4] or just a
    pub fn parse_dot_or_call_expr(&self) -> @expr {
        let b = self.parse_bottom_expr();
        self.parse_dot_or_call_expr_with(b)
    }

    pub fn parse_dot_or_call_expr_with(&self, e0: @expr) -> @expr {
        let mut e = e0;
        let lo = e.span.lo;
        let mut hi;
        loop {
            // expr.f
            if self.eat(&token::DOT) {
                match *self.token {
                  token::IDENT(i, _) => {
                    hi = self.span.hi;
                    self.bump();
                    let (_, tys) = if self.eat(&token::MOD_SEP) {
                        self.expect(&token::LT);
                        self.parse_generic_values_after_lt()
                    } else {
                        (opt_vec::Empty, ~[])
                    };

                    // expr.f() method call
                    match *self.token {
                        token::LPAREN => {
                            let es = self.parse_unspanned_seq(
                                &token::LPAREN,
                                &token::RPAREN,
                                seq_sep_trailing_disallowed(token::COMMA),
                                |p| p.parse_expr()
                            );
                            hi = self.span.hi;

                            let nd = self.mk_method_call(e, i, tys, es, NoSugar);
                            e = self.mk_expr(lo, hi, nd);
                        }
                        _ => {
                            e = self.mk_expr(lo, hi, self.mk_field(e, i, tys));
                        }
                    }
                  }
                  _ => self.unexpected()
                }
                loop;
            }
            if self.expr_is_complete(e) { break; }
            match *self.token {
              // expr(...)
              token::LPAREN => {
                let es = self.parse_unspanned_seq(
                    &token::LPAREN,
                    &token::RPAREN,
                    seq_sep_trailing_disallowed(token::COMMA),
                    |p| p.parse_expr()
                );
                hi = self.span.hi;

                let nd = self.mk_call(e, es, NoSugar);
                e = self.mk_expr(lo, hi, nd);
              }

              // expr[...]
              token::LBRACKET => {
                self.bump();
                let ix = self.parse_expr();
                hi = ix.span.hi;
                self.expect(&token::RBRACKET);
                e = self.mk_expr(lo, hi, self.mk_index(e, ix));
              }

              _ => return e
            }
        }
        return e;
    }

    // parse an optional separator followed by a kleene-style
    // repetition token (+ or *).
    pub fn parse_sep_and_zerok(&self) -> (Option<token::Token>, bool) {
        if *self.token == token::BINOP(token::STAR)
            || *self.token == token::BINOP(token::PLUS) {
            let zerok = *self.token == token::BINOP(token::STAR);
            self.bump();
            (None, zerok)
        } else {
            let sep = copy *self.token;
            self.bump();
            if *self.token == token::BINOP(token::STAR)
                || *self.token == token::BINOP(token::PLUS) {
                let zerok = *self.token == token::BINOP(token::STAR);
                self.bump();
                (Some(sep), zerok)
            } else {
                self.fatal("expected `*` or `+`");
            }
        }
    }

    // parse a single token tree from the input.
    pub fn parse_token_tree(&self) -> token_tree {
        maybe_whole!(deref self, nt_tt);

        // this is the fall-through for the 'match' below.
        // invariants: the current token is not a left-delimiter,
        // not an EOF, and not the desired right-delimiter (if
        // it were, parse_seq_to_before_end would have prevented
        // reaching this point.
        fn parse_non_delim_tt_tok(p: &Parser) -> token_tree {
            maybe_whole!(deref p, nt_tt);
            match *p.token {
              token::RPAREN | token::RBRACE | token::RBRACKET
              => {
                p.fatal(
                    fmt!(
                        "incorrect close delimiter: `%s`",
                        p.this_token_to_str()
                    )
                );
              }
              /* we ought to allow different depths of unquotation */
              token::DOLLAR if *p.quote_depth > 0u => {
                p.bump();
                let sp = *p.span;

                if *p.token == token::LPAREN {
                    let seq = p.parse_seq(
                        &token::LPAREN,
                        &token::RPAREN,
                        seq_sep_none(),
                        |p| p.parse_token_tree()
                    );
                    let (s, z) = p.parse_sep_and_zerok();
                    let seq = match seq {
                        spanned { node, _ } => node,
                    };
                    tt_seq(
                        mk_sp(sp.lo, p.span.hi),
                        seq,
                        s,
                        z
                    )
                } else {
                    tt_nonterminal(sp, p.parse_ident())
                }
              }
              _ => {
                  parse_any_tt_tok(p)
              }
            }
        }

        // turn the next token into a tt_tok:
        fn parse_any_tt_tok(p: &Parser) -> token_tree{
            let res = tt_tok(*p.span, copy *p.token);
            p.bump();
            res
        }

        match *self.token {
            token::EOF => {
                self.fatal("file ended with unbalanced delimiters");
            }
            token::LPAREN | token::LBRACE | token::LBRACKET => {
                let close_delim = token::flip_delimiter(&*self.token);
                tt_delim(
                    vec::append(
                        // the open delimiter:
                        ~[parse_any_tt_tok(self)],
                        vec::append(
                            self.parse_seq_to_before_end(
                                &close_delim,
                                seq_sep_none(),
                                |p| p.parse_token_tree()
                            ),
                            // the close delimiter:
                            [parse_any_tt_tok(self)]
                        )
                    )
                )
            }
            _ => parse_non_delim_tt_tok(self)
        }
    }

    // parse a stream of tokens into a list of token_trees,
    // up to EOF.
    pub fn parse_all_token_trees(&self) -> ~[token_tree] {
        let mut tts = ~[];
        while *self.token != token::EOF {
            tts.push(self.parse_token_tree());
        }
        tts
    }

    pub fn parse_matchers(&self) -> ~[matcher] {
        // unification of matchers and token_trees would vastly improve
        // the interpolation of matchers
        maybe_whole!(self, nt_matchers);
        let name_idx = @mut 0u;
        match *self.token {
            token::LBRACE | token::LPAREN | token::LBRACKET => {
                self.parse_matcher_subseq(
                    name_idx,
                    copy *self.token,
                    // tjc: not sure why we need a copy
                    token::flip_delimiter(self.token)
                )
            }
            _ => self.fatal("expected open delimiter")
        }
    }


    // This goofy function is necessary to correctly match parens in matchers.
    // Otherwise, `$( ( )` would be a valid matcher, and `$( () )` would be
    // invalid. It's similar to common::parse_seq.
    pub fn parse_matcher_subseq(&self,
                                name_idx: @mut uint,
                                bra: token::Token,
                                ket: token::Token)
                                -> ~[matcher] {
        let mut ret_val = ~[];
        let mut lparens = 0u;

        self.expect(&bra);

        while *self.token != ket || lparens > 0u {
            if *self.token == token::LPAREN { lparens += 1u; }
            if *self.token == token::RPAREN { lparens -= 1u; }
            ret_val.push(self.parse_matcher(name_idx));
        }

        self.bump();

        return ret_val;
    }

    pub fn parse_matcher(&self, name_idx: @mut uint) -> matcher {
        let lo = self.span.lo;

        let m = if *self.token == token::DOLLAR {
            self.bump();
            if *self.token == token::LPAREN {
                let name_idx_lo = *name_idx;
                let ms = self.parse_matcher_subseq(
                    name_idx,
                    token::LPAREN,
                    token::RPAREN
                );
                if ms.len() == 0u {
                    self.fatal("repetition body must be nonempty");
                }
                let (sep, zerok) = self.parse_sep_and_zerok();
                match_seq(ms, sep, zerok, name_idx_lo, *name_idx)
            } else {
                let bound_to = self.parse_ident();
                self.expect(&token::COLON);
                let nt_name = self.parse_ident();
                let m = match_nonterminal(bound_to, nt_name, *name_idx);
                *name_idx += 1u;
                m
            }
        } else {
            let m = match_tok(copy *self.token);
            self.bump();
            m
        };

        return spanned(lo, self.span.hi, m);
    }

    // parse a prefix-operator expr
    pub fn parse_prefix_expr(&self) -> @expr {
        let lo = self.span.lo;
        let hi;

        let ex;
        match *self.token {
          token::NOT => {
            self.bump();
            let e = self.parse_prefix_expr();
            hi = e.span.hi;
            ex = self.mk_unary(not, e);
          }
          token::BINOP(b) => {
            match b {
              token::MINUS => {
                self.bump();
                let e = self.parse_prefix_expr();
                hi = e.span.hi;
                ex = self.mk_unary(neg, e);
              }
              token::STAR => {
                self.bump();
                let e = self.parse_prefix_expr();
                hi = e.span.hi;
                ex = self.mk_unary(deref, e);
              }
              token::AND => {
                self.bump();
                let _lt = self.parse_opt_lifetime();
                let m = self.parse_mutability();
                let e = self.parse_prefix_expr();
                hi = e.span.hi;
                // HACK: turn &[...] into a &-evec
                ex = match e.node {
                  expr_vec(*) | expr_lit(@codemap::spanned {
                    node: lit_str(_), span: _
                  })
                  if m == m_imm => {
                    expr_vstore(e, expr_vstore_slice)
                  }
                  expr_vec(*) if m == m_mutbl => {
                    expr_vstore(e, expr_vstore_mut_slice)
                  }
                  _ => expr_addr_of(m, e)
                };
              }
              _ => return self.parse_dot_or_call_expr()
            }
          }
          token::AT => {
            self.bump();
            let m = self.parse_mutability();
            if m == m_const {
                self.obsolete(*self.last_span, ObsoleteConstManagedPointer);
            }

            let e = self.parse_prefix_expr();
            hi = e.span.hi;
            // HACK: turn @[...] into a @-evec
            ex = match e.node {
              expr_vec(*) | expr_repeat(*) if m == m_mutbl =>
                expr_vstore(e, expr_vstore_mut_box),
              expr_vec(*) |
              expr_lit(@codemap::spanned { node: lit_str(_), span: _}) |
              expr_repeat(*) if m == m_imm => expr_vstore(e, expr_vstore_box),
              _ => self.mk_unary(box(m), e)
            };
          }
          token::TILDE => {
            self.bump();
            let m = self.parse_mutability();
            if m != m_imm {
                self.obsolete(*self.last_span, ObsoleteMutOwnedPointer);
            }

            let e = self.parse_prefix_expr();
            hi = e.span.hi;
            // HACK: turn ~[...] into a ~-evec
            ex = match e.node {
              expr_vec(*) |
              expr_lit(@codemap::spanned { node: lit_str(_), span: _}) |
              expr_repeat(*)
              if m == m_imm => expr_vstore(e, expr_vstore_uniq),
              _ => self.mk_unary(uniq(m), e)
            };
          }
          _ => return self.parse_dot_or_call_expr()
        }
        return self.mk_expr(lo, hi, ex);
    }

    // parse an expression of binops
    pub fn parse_binops(&self) -> @expr {
        self.parse_more_binops(self.parse_prefix_expr(), 0)
    }

    // parse an expression of binops of at least min_prec precedence
    pub fn parse_more_binops(&self, lhs: @expr, min_prec: uint) -> @expr {
        if self.expr_is_complete(lhs) { return lhs; }
        let peeked = copy *self.token;
        if peeked == token::BINOP(token::OR) &&
            (*self.restriction == RESTRICT_NO_BAR_OP ||
             *self.restriction == RESTRICT_NO_BAR_OR_DOUBLEBAR_OP) {
            lhs
        } else if peeked == token::OROR &&
            *self.restriction == RESTRICT_NO_BAR_OR_DOUBLEBAR_OP {
            lhs
        } else {
            let cur_opt = token_to_binop(peeked);
            match cur_opt {
                Some(cur_op) => {
                    let cur_prec = operator_prec(cur_op);
                    if cur_prec > min_prec {
                        self.bump();
                        let expr = self.parse_prefix_expr();
                        let rhs = self.parse_more_binops(expr, cur_prec);
                        let bin = self.mk_expr(lhs.span.lo, rhs.span.hi,
                                               self.mk_binary(cur_op, lhs, rhs));
                        self.parse_more_binops(bin, min_prec)
                    } else {
                        lhs
                    }
                }
                None => {
                    if as_prec > min_prec && self.eat_keyword(keywords::As) {
                        let rhs = self.parse_ty(true);
                        let _as = self.mk_expr(lhs.span.lo,
                                               rhs.span.hi,
                                               expr_cast(lhs, rhs));
                        self.parse_more_binops(_as, min_prec)
                    } else {
                        lhs
                    }
                }
            }
        }
    }

    // parse an assignment expression....
    // actually, this seems to be the main entry point for
    // parsing an arbitrary expression.
    pub fn parse_assign_expr(&self) -> @expr {
        let lo = self.span.lo;
        let lhs = self.parse_binops();
        match *self.token {
          token::EQ => {
              self.bump();
              let rhs = self.parse_expr();
              self.mk_expr(lo, rhs.span.hi, expr_assign(lhs, rhs))
          }
          token::BINOPEQ(op) => {
              self.bump();
              let rhs = self.parse_expr();
              let aop;
              match op {
                  token::PLUS => aop = add,
                  token::MINUS => aop = subtract,
                  token::STAR => aop = mul,
                  token::SLASH => aop = div,
                  token::PERCENT => aop = rem,
                  token::CARET => aop = bitxor,
                  token::AND => aop = bitand,
                  token::OR => aop = bitor,
                  token::SHL => aop = shl,
                  token::SHR => aop = shr
              }
              self.mk_expr(lo, rhs.span.hi,
                           self.mk_assign_op(aop, lhs, rhs))
          }
          token::LARROW => {
              self.obsolete(*self.span, ObsoleteBinaryMove);
              // Bogus value (but it's an error)
              self.bump(); // <-
              self.bump(); // rhs
              self.bump(); // ;
              self.mk_expr(lo, self.span.hi,
                           expr_break(None))
          }
          token::DARROW => {
            self.obsolete(*self.span, ObsoleteSwap);
            self.bump();
            // Ignore what we get, this is an error anyway
            self.parse_expr();
            self.mk_expr(lo, self.span.hi, expr_break(None))
          }
          _ => {
              lhs
          }
        }
    }

    // parse an 'if' expression ('if' token already eaten)
    pub fn parse_if_expr(&self) -> @expr {
        let lo = self.last_span.lo;
        let cond = self.parse_expr();
        let thn = self.parse_block();
        let mut els: Option<@expr> = None;
        let mut hi = thn.span.hi;
        if self.eat_keyword(keywords::Else) {
            let elexpr = self.parse_else_expr();
            els = Some(elexpr);
            hi = elexpr.span.hi;
        }
        self.mk_expr(lo, hi, expr_if(cond, thn, els))
    }

    // `|args| { ... }` or `{ ...}` like in `do` expressions
    pub fn parse_lambda_block_expr(&self) -> @expr {
        self.parse_lambda_expr_(
            || {
                match *self.token {
                  token::BINOP(token::OR) | token::OROR => {
                    self.parse_fn_block_decl()
                  }
                  _ => {
                    // No argument list - `do foo {`
                      ast::fn_decl {
                          inputs: ~[],
                          output: @Ty {
                              id: self.get_id(),
                              node: ty_infer,
                              span: *self.span
                          },
                          cf: return_val
                      }
                  }
                }
            },
            || {
                let blk = self.parse_block();
                self.mk_expr(blk.span.lo, blk.span.hi, expr_block(blk))
            })
    }

    // `|args| expr`
    pub fn parse_lambda_expr(&self) -> @expr {
        self.parse_lambda_expr_(|| self.parse_fn_block_decl(),
                                || self.parse_expr())
    }

    // parse something of the form |args| expr
    // this is used both in parsing a lambda expr
    // and in parsing a block expr as e.g. in for...
    pub fn parse_lambda_expr_(&self,
                              parse_decl: &fn() -> fn_decl,
                              parse_body: &fn() -> @expr)
                              -> @expr {
        let lo = self.last_span.lo;
        let decl = parse_decl();
        let body = parse_body();
        let fakeblock = ast::blk_ {
            view_items: ~[],
            stmts: ~[],
            expr: Some(body),
            id: self.get_id(),
            rules: default_blk,
        };
        let fakeblock = spanned(body.span.lo, body.span.hi,
                                fakeblock);
        return self.mk_expr(lo, body.span.hi,
                            expr_fn_block(decl, fakeblock));
    }

    pub fn parse_else_expr(&self) -> @expr {
        if self.eat_keyword(keywords::If) {
            return self.parse_if_expr();
        } else {
            let blk = self.parse_block();
            return self.mk_expr(blk.span.lo, blk.span.hi, expr_block(blk));
        }
    }

    // parse a 'for' or 'do'.
    // the 'for' and 'do' expressions parse as calls, but look like
    // function calls followed by a closure expression.
    pub fn parse_sugary_call_expr(&self,
                                  keyword: ~str,
                                  sugar: CallSugar,
                                  ctor: &fn(v: @expr) -> expr_)
                                  -> @expr {
        let lo = self.last_span;
        // Parse the callee `foo` in
        //    for foo || {
        //    for foo.bar || {
        // etc, or the portion of the call expression before the lambda in
        //    for foo() || {
        // or
        //    for foo.bar(a) || {
        // Turn on the restriction to stop at | or || so we can parse
        // them as the lambda arguments
        let e = self.parse_expr_res(RESTRICT_NO_BAR_OR_DOUBLEBAR_OP);
        match e.node {
            expr_call(f, ref args, NoSugar) => {
                let block = self.parse_lambda_block_expr();
                let last_arg = self.mk_expr(block.span.lo, block.span.hi,
                                            ctor(block));
                let args = vec::append(copy *args, [last_arg]);
                self.mk_expr(lo.lo, block.span.hi, expr_call(f, args, sugar))
            }
            expr_method_call(_, f, i, ref tps, ref args, NoSugar) => {
                let block = self.parse_lambda_block_expr();
                let last_arg = self.mk_expr(block.span.lo, block.span.hi,
                                            ctor(block));
                let args = vec::append(copy *args, [last_arg]);
                self.mk_expr(lo.lo, block.span.hi,
                             self.mk_method_call(f, i, copy *tps, args, sugar))
            }
            expr_field(f, i, ref tps) => {
                let block = self.parse_lambda_block_expr();
                let last_arg = self.mk_expr(block.span.lo, block.span.hi,
                                            ctor(block));
                self.mk_expr(lo.lo, block.span.hi,
                             self.mk_method_call(f, i, copy *tps, ~[last_arg], sugar))
            }
            expr_path(*) | expr_call(*) | expr_method_call(*) |
                expr_paren(*) => {
                let block = self.parse_lambda_block_expr();
                let last_arg = self.mk_expr(block.span.lo, block.span.hi,
                                            ctor(block));
                self.mk_expr(
                    lo.lo,
                    last_arg.span.hi,
                    self.mk_call(e, ~[last_arg], sugar))
            }
            _ => {
                // There may be other types of expressions that can
                // represent the callee in `for` and `do` expressions
                // but they aren't represented by tests
                debug!("sugary call on %?", e.node);
                self.span_fatal(
                    *lo,
                    fmt!("`%s` must be followed by a block call", keyword));
            }
        }
    }

    pub fn parse_while_expr(&self) -> @expr {
        let lo = self.last_span.lo;
        let cond = self.parse_expr();
        let body = self.parse_block();
        let hi = body.span.hi;
        return self.mk_expr(lo, hi, expr_while(cond, body));
    }

    pub fn parse_loop_expr(&self, opt_ident: Option<ast::ident>) -> @expr {
        // loop headers look like 'loop {' or 'loop unsafe {'
        let is_loop_header =
            *self.token == token::LBRACE
            || (is_ident(&*self.token)
                && self.look_ahead(1) == token::LBRACE);

        if is_loop_header {
            // This is a loop body
            let lo = self.last_span.lo;
            let body = self.parse_block();
            let hi = body.span.hi;
            return self.mk_expr(lo, hi, expr_loop(body, opt_ident));
        } else {
            // This is a 'continue' expression
            if opt_ident.is_some() {
                self.span_err(*self.last_span,
                              "a label may not be used with a `loop` expression");
            }

            let lo = self.span.lo;
            let ex = if self.token_is_lifetime(&*self.token) {
                let lifetime = self.get_lifetime(&*self.token);
                self.bump();
                expr_again(Some(lifetime))
            } else {
                expr_again(None)
            };
            let hi = self.span.hi;
            return self.mk_expr(lo, hi, ex);
        }
    }

    // For distingishing between record literals and blocks
    fn looking_at_record_literal(&self) -> bool {
        let lookahead = self.look_ahead(1);
        *self.token == token::LBRACE &&
            (token::is_keyword(keywords::Mut, &lookahead) ||
             (is_plain_ident(&lookahead) &&
              self.look_ahead(2) == token::COLON))
    }

    fn parse_match_expr(&self) -> @expr {
        let lo = self.last_span.lo;
        let discriminant = self.parse_expr();
        self.expect(&token::LBRACE);
        let mut arms: ~[arm] = ~[];
        while *self.token != token::RBRACE {
            let pats = self.parse_pats();
            let mut guard = None;
            if self.eat_keyword(keywords::If) { guard = Some(self.parse_expr()); }
            self.expect(&token::FAT_ARROW);
            let expr = self.parse_expr_res(RESTRICT_STMT_EXPR);

            let require_comma =
                !classify::expr_is_simple_block(expr)
                && *self.token != token::RBRACE;

            if require_comma {
                self.expect(&token::COMMA);
            } else {
                self.eat(&token::COMMA);
            }

            let blk = codemap::spanned {
                node: ast::blk_ {
                    view_items: ~[],
                    stmts: ~[],
                    expr: Some(expr),
                    id: self.get_id(),
                    rules: default_blk,
                },
                span: expr.span,
            };

            arms.push(ast::arm { pats: pats, guard: guard, body: blk });
        }
        let hi = self.span.hi;
        self.bump();
        return self.mk_expr(lo, hi, expr_match(discriminant, arms));
    }

    // parse an expression
    pub fn parse_expr(&self) -> @expr {
        return self.parse_expr_res(UNRESTRICTED);
    }

    // parse an expression, subject to the given restriction
    fn parse_expr_res(&self, r: restriction) -> @expr {
        let old = *self.restriction;
        *self.restriction = r;
        let e = self.parse_assign_expr();
        *self.restriction = old;
        return e;
    }

    // parse the RHS of a local variable declaration (e.g. '= 14;')
    fn parse_initializer(&self) -> Option<@expr> {
        match *self.token {
          token::EQ => {
            self.bump();
            return Some(self.parse_expr());
          }
          token::LARROW => {
              self.obsolete(*self.span, ObsoleteMoveInit);
              self.bump();
              self.bump();
              return None;
          }
          _ => {
            return None;
          }
        }
    }

    // parse patterns, separated by '|' s
    fn parse_pats(&self) -> ~[@pat] {
        let mut pats = ~[];
        loop {
            pats.push(self.parse_pat());
            if *self.token == token::BINOP(token::OR) { self.bump(); }
            else { return pats; }
        };
    }

    fn parse_pat_vec_elements(
        &self,
    ) -> (~[@pat], Option<@pat>, ~[@pat]) {
        let mut before = ~[];
        let mut slice = None;
        let mut after = ~[];
        let mut first = true;
        let mut before_slice = true;

        while *self.token != token::RBRACKET {
            if first { first = false; }
            else { self.expect(&token::COMMA); }

            let mut is_slice = false;
            if before_slice {
                if *self.token == token::DOTDOT {
                    self.bump();
                    is_slice = true;
                    before_slice = false;
                }
            }

            let subpat = self.parse_pat();
            if is_slice {
                match subpat {
                    @ast::pat { node: pat_wild, _ } => (),
                    @ast::pat { node: pat_ident(_, _, _), _ } => (),
                    @ast::pat { span, _ } => self.span_fatal(
                        span, "expected an identifier or `_`"
                    )
                }
                slice = Some(subpat);
            } else {
                if before_slice {
                    before.push(subpat);
                } else {
                    after.push(subpat);
                }
            }
        }

        (before, slice, after)
    }

    // parse the fields of a struct-like pattern
    fn parse_pat_fields(&self) -> (~[ast::field_pat], bool) {
        let mut fields = ~[];
        let mut etc = false;
        let mut first = true;
        while *self.token != token::RBRACE {
            if first { first = false; }
            else { self.expect(&token::COMMA); }

            if *self.token == token::UNDERSCORE {
                self.bump();
                if *self.token != token::RBRACE {
                    self.fatal(
                        fmt!(
                            "expected `}`, found `%s`",
                            self.this_token_to_str()
                        )
                    );
                }
                etc = true;
                break;
            }

            let lo1 = self.last_span.lo;
            let fieldname = self.parse_ident();
            let hi1 = self.last_span.lo;
            let fieldpath = ast_util::ident_to_path(mk_sp(lo1, hi1),
                                                    fieldname);
            let subpat;
            if *self.token == token::COLON {
                self.bump();
                subpat = self.parse_pat();
            } else {
                subpat = @ast::pat {
                    id: self.get_id(),
                    node: pat_ident(bind_infer, fieldpath, None),
                    span: *self.last_span
                };
            }
            fields.push(ast::field_pat { ident: fieldname, pat: subpat });
        }
        return (fields, etc);
    }

    // parse a pattern.
    pub fn parse_pat(&self) -> @pat {
        maybe_whole!(self, nt_pat);

        let lo = self.span.lo;
        let mut hi = self.span.hi;
        let pat;
        match /*bad*/ copy *self.token {
            // parse _
          token::UNDERSCORE => { self.bump(); pat = pat_wild; }
            // parse @pat
          token::AT => {
            self.bump();
            let sub = self.parse_pat();
            hi = sub.span.hi;
            // HACK: parse @"..." as a literal of a vstore @str
            pat = match sub.node {
              pat_lit(e@@expr {
                node: expr_lit(@codemap::spanned {
                    node: lit_str(_),
                    span: _}), _
              }) => {
                let vst = @expr {
                    id: self.get_id(),
                    node: expr_vstore(e, expr_vstore_box),
                    span: mk_sp(lo, hi),
                };
                pat_lit(vst)
              }
              _ => pat_box(sub)
            };
          }
          token::TILDE => {
            // parse ~pat
            self.bump();
            let sub = self.parse_pat();
            hi = sub.span.hi;
            // HACK: parse ~"..." as a literal of a vstore ~str
            pat = match sub.node {
              pat_lit(e@@expr {
                node: expr_lit(@codemap::spanned {
                    node: lit_str(_),
                    span: _}), _
              }) => {
                let vst = @expr {
                    id: self.get_id(),
                    node: expr_vstore(e, expr_vstore_uniq),
                    span: mk_sp(lo, hi),
                };
                pat_lit(vst)
              }
              _ => pat_uniq(sub)
            };
          }
          token::BINOP(token::AND) => {
              // parse &pat
              let lo = self.span.lo;
              self.bump();
              let sub = self.parse_pat();
              hi = sub.span.hi;
              // HACK: parse &"..." as a literal of a borrowed str
              pat = match sub.node {
                  pat_lit(e@@expr {
                      node: expr_lit(@codemap::spanned {
                            node: lit_str(_), span: _}), _
                  }) => {
                      let vst = @expr {
                          id: self.get_id(),
                          node: expr_vstore(e, expr_vstore_slice),
                          span: mk_sp(lo, hi)
                      };
                      pat_lit(vst)
                  }
              _ => pat_region(sub)
              };
          }
          token::LBRACE => {
            self.bump();
            let (_, _) = self.parse_pat_fields();
            hi = self.span.hi;
            self.bump();
            self.obsolete(*self.span, ObsoleteRecordPattern);
            pat = pat_wild;
          }
          token::LPAREN => {
            // parse (pat,pat,pat,...) as tuple
            self.bump();
            if *self.token == token::RPAREN {
                hi = self.span.hi;
                self.bump();
                let lit = @codemap::spanned {
                    node: lit_nil,
                    span: mk_sp(lo, hi)};
                let expr = self.mk_expr(lo, hi, expr_lit(lit));
                pat = pat_lit(expr);
            } else {
                let mut fields = ~[self.parse_pat()];
                if self.look_ahead(1) != token::RPAREN {
                    while *self.token == token::COMMA {
                        self.bump();
                        fields.push(self.parse_pat());
                    }
                }
                if fields.len() == 1 { self.expect(&token::COMMA); }
                hi = self.span.hi;
                self.expect(&token::RPAREN);
                pat = pat_tup(fields);
            }
          }
          token::LBRACKET => {
            // parse [pat,pat,...] as vector pattern
            self.bump();
            let (before, slice, after) =
                self.parse_pat_vec_elements();
            hi = self.span.hi;
            self.expect(&token::RBRACKET);
            pat = ast::pat_vec(before, slice, after);
          }
          ref tok => {
            if !is_ident_or_path(tok)
                || self.is_keyword(keywords::True)
                || self.is_keyword(keywords::False)
            {
                // Parse an expression pattern or exp .. exp.
                //
                // These expressions are limited to literals (possibly
                // preceded by unary-minus) or identifiers.
                let val = self.parse_literal_maybe_minus();
                if self.eat(&token::DOTDOT) {
                    let end = if is_ident_or_path(tok) {
                        let path = self.parse_path_with_tps(true);
                        let hi = self.span.hi;
                        self.mk_expr(lo, hi, expr_path(path))
                    } else {
                        self.parse_literal_maybe_minus()
                    };
                    pat = pat_range(val, end);
                } else {
                    pat = pat_lit(val);
                }
            } else if self.eat_keyword(keywords::Ref) {
                // parse ref pat
                let mutbl = self.parse_mutability();
                pat = self.parse_pat_ident(bind_by_ref(mutbl));
            } else if self.eat_keyword(keywords::Copy) {
                // parse copy pat
                self.warn("copy keyword in patterns no longer has any effect, \
                           remove it");
                pat = self.parse_pat_ident(bind_infer);
            } else {
                let can_be_enum_or_struct;
                match self.look_ahead(1) {
                    token::LPAREN | token::LBRACKET | token::LT |
                    token::LBRACE | token::MOD_SEP =>
                        can_be_enum_or_struct = true,
                    _ =>
                        can_be_enum_or_struct = false
                }

                if self.look_ahead(1) == token::DOTDOT {
                    let start = self.parse_expr_res(RESTRICT_NO_BAR_OP);
                    self.eat(&token::DOTDOT);
                    let end = self.parse_expr_res(RESTRICT_NO_BAR_OP);
                    pat = pat_range(start, end);
                }
                else if is_plain_ident(&*self.token) && !can_be_enum_or_struct {
                    let name = self.parse_path_without_tps();
                    let sub;
                    if self.eat(&token::AT) {
                        // parse foo @ pat
                        sub = Some(self.parse_pat());
                    } else {
                        // or just foo
                        sub = None;
                    }
                    pat = pat_ident(bind_infer, name, sub);
                } else {
                    // parse an enum pat
                    let enum_path = self.parse_path_with_tps(true);
                    match *self.token {
                        token::LBRACE => {
                            self.bump();
                            let (fields, etc) =
                                self.parse_pat_fields();
                            self.bump();
                            pat = pat_struct(enum_path, fields, etc);
                        }
                        _ => {
                            let mut args: ~[@pat] = ~[];
                            match *self.token {
                              token::LPAREN => match self.look_ahead(1u) {
                                token::BINOP(token::STAR) => {
                                    // This is a "top constructor only" pat
                                      self.bump(); self.bump();
                                      self.expect(&token::RPAREN);
                                      pat = pat_enum(enum_path, None);
                                  }
                                _ => {
                                    args = self.parse_unspanned_seq(
                                        &token::LPAREN,
                                        &token::RPAREN,
                                        seq_sep_trailing_disallowed(
                                            token::COMMA
                                        ),
                                        |p| p.parse_pat()
                                    );
                                    pat = pat_enum(enum_path, Some(args));
                                  }
                              },
                              _ => {
                                  if enum_path.idents.len()==1u {
                                      // it could still be either an enum
                                      // or an identifier pattern, resolve
                                      // will sort it out:
                                      pat = pat_ident(bind_infer,
                                                      enum_path,
                                                      None);
                                  } else {
                                      pat = pat_enum(enum_path, Some(args));
                                  }
                              }
                            }
                        }
                    }
                }
            }
            hi = self.last_span.hi;
          }
        }
        @ast::pat { id: self.get_id(), node: pat, span: mk_sp(lo, hi) }
    }

    // parse ident or ident @ pat
    // used by the copy foo and ref foo patterns to give a good
    // error message when parsing mistakes like ref foo(a,b)
    fn parse_pat_ident(&self,
                       binding_mode: ast::binding_mode)
                       -> ast::pat_ {
        if !is_plain_ident(&*self.token) {
            self.span_fatal(*self.last_span,
                            "expected identifier, found path");
        }
        // why a path here, and not just an identifier?
        let name = self.parse_path_without_tps();
        let sub = if self.eat(&token::AT) {
            Some(self.parse_pat())
        } else {
            None
        };

        // just to be friendly, if they write something like
        //   ref Some(i)
        // we end up here with ( as the current token.  This shortly
        // leads to a parse error.  Note that if there is no explicit
        // binding mode then we do not end up here, because the lookahead
        // will direct us over to parse_enum_variant()
        if *self.token == token::LPAREN {
            self.span_fatal(
                *self.last_span,
                "expected identifier, found enum pattern");
        }

        pat_ident(binding_mode, name, sub)
    }

    // parse a local variable declaration
    fn parse_local(&self, is_mutbl: bool) -> @local {
        let lo = self.span.lo;
        let pat = self.parse_pat();
        let mut ty = @Ty {
            id: self.get_id(),
            node: ty_infer,
            span: mk_sp(lo, lo),
        };
        if self.eat(&token::COLON) { ty = self.parse_ty(false); }
        let init = self.parse_initializer();
        @spanned(
            lo,
            self.last_span.hi,
            ast::local_ {
                is_mutbl: is_mutbl,
                ty: ty,
                pat: pat,
                init: init,
                id: self.get_id(),
            }
        )
    }

    // parse a "let" stmt
    fn parse_let(&self) -> @decl {
        let is_mutbl = self.eat_keyword(keywords::Mut);
        let lo = self.span.lo;
        let local = self.parse_local(is_mutbl);
        while self.eat(&token::COMMA) {
            let _ = self.parse_local(is_mutbl);
            self.obsolete(*self.span, ObsoleteMultipleLocalDecl);
        }
        return @spanned(lo, self.last_span.hi, decl_local(local));
    }

    // parse a structure field
    fn parse_name_and_ty(&self,
                         pr: visibility,
                         attrs: ~[attribute]) -> @struct_field {
        let lo = self.span.lo;
        if !is_plain_ident(&*self.token) {
            self.fatal("expected ident");
        }
        let name = self.parse_ident();
        self.expect(&token::COLON);
        let ty = self.parse_ty(false);
        @spanned(lo, self.last_span.hi, ast::struct_field_ {
            kind: named_field(name, pr),
            id: self.get_id(),
            ty: ty,
            attrs: attrs,
        })
    }

    // parse a statement. may include decl.
    // precondition: any attributes are parsed already
    pub fn parse_stmt(&self, item_attrs: ~[attribute]) -> @stmt {
        maybe_whole!(self, nt_stmt);

        fn check_expected_item(p: &Parser, current_attrs: &[attribute]) {
            // If we have attributes then we should have an item
            if !current_attrs.is_empty() {
                p.span_err(*p.last_span,
                           "expected item after attributes");
            }
        }

        let lo = self.span.lo;
        if self.is_keyword(keywords::Let) {
            check_expected_item(self, item_attrs);
            self.expect_keyword(keywords::Let);
            let decl = self.parse_let();
            return @spanned(lo, decl.span.hi, stmt_decl(decl, self.get_id()));
        } else if is_ident(&*self.token)
            && !token::is_any_keyword(self.token)
            && self.look_ahead(1) == token::NOT {
            // parse a macro invocation. Looks like there's serious
            // overlap here; if this clause doesn't catch it (and it
            // won't, for brace-delimited macros) it will fall through
            // to the macro clause of parse_item_or_view_item. This
            // could use some cleanup, it appears to me.

            // whoops! I now have a guess: I'm guessing the "parens-only"
            // rule here is deliberate, to allow macro users to use parens
            // for things that should be parsed as stmt_mac, and braces
            // for things that should expand into items. Tricky, and
            // somewhat awkward... and probably undocumented. Of course,
            // I could just be wrong.

            check_expected_item(self, item_attrs);

            // Potential trouble: if we allow macros with paths instead of
            // idents, we'd need to look ahead past the whole path here...
            let pth = self.parse_path_without_tps();
            self.bump();

            let id = if *self.token == token::LPAREN {
                token::special_idents::invalid // no special identifier
            } else {
                self.parse_ident()
            };

            let tts = self.parse_unspanned_seq(
                &token::LPAREN,
                &token::RPAREN,
                seq_sep_none(),
                |p| p.parse_token_tree()
            );
            let hi = self.span.hi;

            if id == token::special_idents::invalid {
                return @spanned(lo, hi, stmt_mac(
                    spanned(lo, hi, mac_invoc_tt(pth, tts)), false));
            } else {
                // if it has a special ident, it's definitely an item
                return @spanned(lo, hi, stmt_decl(
                    @spanned(lo, hi, decl_item(
                        self.mk_item(
                            lo, hi, id /*id is good here*/,
                            item_mac(spanned(lo, hi, mac_invoc_tt(pth, tts))),
                            inherited, ~[/*no attrs*/]))),
                    self.get_id()));
            }

        } else {
            match self.parse_item_or_view_item(/*bad*/ copy item_attrs,
                                                           false) {
                iovi_item(i) => {
                    let hi = i.span.hi;
                    let decl = @spanned(lo, hi, decl_item(i));
                    return @spanned(lo, hi, stmt_decl(decl, self.get_id()));
                }
                iovi_view_item(vi) => {
                    self.span_fatal(vi.span,
                                    "view items must be declared at the top of the block");
                }
                iovi_foreign_item(_) => {
                    self.fatal("foreign items are not allowed here");
                }
                iovi_none() => { /* fallthrough */ }
            }

            check_expected_item(self, item_attrs);

            // Remainder are line-expr stmts.
            let e = self.parse_expr_res(RESTRICT_STMT_EXPR);
            return @spanned(lo, e.span.hi, stmt_expr(e, self.get_id()));
        }
    }

    // is this expression a successfully-parsed statement?
    fn expr_is_complete(&self, e: @expr) -> bool {
        return *self.restriction == RESTRICT_STMT_EXPR &&
            !classify::expr_requires_semi_to_be_stmt(e);
    }

    // parse a block. No inner attrs are allowed.
    pub fn parse_block(&self) -> blk {
        maybe_whole!(self, nt_block);

        let lo = self.span.lo;
        if self.eat_keyword(keywords::Unsafe) {
            self.obsolete(copy *self.span, ObsoleteUnsafeBlock);
        }
        self.expect(&token::LBRACE);

        return self.parse_block_tail_(lo, default_blk, ~[]);
    }

    // parse a block. Inner attrs are allowed.
    fn parse_inner_attrs_and_block(&self)
        -> (~[attribute], blk) {

        maybe_whole!(pair_empty self, nt_block);

        let lo = self.span.lo;
        if self.eat_keyword(keywords::Unsafe) {
            self.obsolete(copy *self.span, ObsoleteUnsafeBlock);
        }
        self.expect(&token::LBRACE);
        let (inner, next) = self.parse_inner_attrs_and_next();

        (inner, self.parse_block_tail_(lo, default_blk, next))
    }

    // Precondition: already parsed the '{' or '#{'
    // I guess that also means "already parsed the 'impure'" if
    // necessary, and this should take a qualifier.
    // some blocks start with "#{"...
    fn parse_block_tail(&self, lo: BytePos, s: blk_check_mode) -> blk {
        self.parse_block_tail_(lo, s, ~[])
    }

    // parse the rest of a block expression or function body
    fn parse_block_tail_(&self, lo: BytePos, s: blk_check_mode,
                         first_item_attrs: ~[attribute]) -> blk {
        let mut stmts = ~[];
        let mut expr = None;

        // wouldn't it be more uniform to parse view items only, here?
        let ParsedItemsAndViewItems {
            attrs_remaining: attrs_remaining,
            view_items: view_items,
            items: items,
            _
        } = self.parse_items_and_view_items(first_item_attrs,
                                            false, false);

        for items.each |item| {
            let decl = @spanned(item.span.lo, item.span.hi, decl_item(*item));
            stmts.push(@spanned(item.span.lo, item.span.hi,
                                stmt_decl(decl, self.get_id())));
        }

        let mut attributes_box = attrs_remaining;

        while (*self.token != token::RBRACE) {
            // parsing items even when they're not allowed lets us give
            // better error messages and recover more gracefully.
            attributes_box.push_all(self.parse_outer_attributes());
            match *self.token {
                token::SEMI => {
                    if !attributes_box.is_empty() {
                        self.span_err(*self.last_span, "expected item after attributes");
                        attributes_box = ~[];
                    }
                    self.bump(); // empty
                }
                token::RBRACE => {
                    // fall through and out.
                }
                _ => {
                    let stmt = self.parse_stmt(attributes_box);
                    attributes_box = ~[];
                    match stmt.node {
                        stmt_expr(e, stmt_id) => {
                            // expression without semicolon
                            match copy *self.token {
                                token::SEMI => {
                                    self.bump();
                                    stmts.push(@codemap::spanned {
                                        node: stmt_semi(e, stmt_id),
                                        .. copy *stmt});
                                }
                                token::RBRACE => {
                                    expr = Some(e);
                                }
                                t => {
                                    if classify::stmt_ends_with_semi(stmt) {
                                        self.fatal(
                                            fmt!(
                                                "expected `;` or `}` after \
                                                 expression but found `%s`",
                                                self.token_to_str(&t)
                                            )
                                        );
                                    }
                                    stmts.push(stmt);
                                }
                            }
                        }
                        stmt_mac(ref m, _) => {
                            // statement macro; might be an expr
                            match *self.token {
                                token::SEMI => {
                                    self.bump();
                                    stmts.push(@codemap::spanned {
                                        node: stmt_mac(copy *m, true),
                                        .. copy *stmt});
                                }
                                token::RBRACE => {
                                    // if a block ends in `m!(arg)` without
                                    // a `;`, it must be an expr
                                    expr = Some(
                                        self.mk_mac_expr(stmt.span.lo,
                                                         stmt.span.hi,
                                                         copy m.node));
                                }
                                _ => { stmts.push(stmt); }
                            }
                        }
                        _ => { // all other kinds of statements:
                            stmts.push(stmt);

                            if classify::stmt_ends_with_semi(stmt) {
                                self.expect(&token::SEMI);
                            }
                        }
                    }
                }
            }
        }

        if !attributes_box.is_empty() {
            self.span_err(*self.last_span, "expected item after attributes");
        }

        let hi = self.span.hi;
        self.bump();
        let bloc = ast::blk_ {
            view_items: view_items,
            stmts: stmts,
            expr: expr,
            id: self.get_id(),
            rules: s,
        };
        spanned(lo, hi, bloc)
    }

    fn mk_ty_path(&self, i: ident) -> @Ty {
        @Ty {
            id: self.get_id(),
            node: ty_path(
                ident_to_path(*self.last_span, i),
                self.get_id()),
            span: *self.last_span,
        }
    }

    fn parse_optional_purity(&self) -> ast::purity {
        if self.eat_keyword(keywords::Pure) {
            self.obsolete(*self.last_span, ObsoletePurity);
            ast::impure_fn
        } else if self.eat_keyword(keywords::Unsafe) {
            ast::unsafe_fn
        } else {
            ast::impure_fn
        }
    }

    fn parse_optional_onceness(&self) -> ast::Onceness {
        if self.eat_keyword(keywords::Once) { ast::Once } else { ast::Many }
    }

    // matches optbounds = ( ( : ( boundseq )? )? )
    // where   boundseq  = ( bound + boundseq ) | bound
    // and     bound     = 'static | ty
    fn parse_optional_ty_param_bounds(&self) -> OptVec<TyParamBound> {
        if !self.eat(&token::COLON) {
            return opt_vec::Empty;
        }

        let mut result = opt_vec::Empty;
        loop {
            match *self.token {
                token::LIFETIME(lifetime) => {
                    if "static" == self.id_to_str(lifetime) {
                        result.push(RegionTyParamBound);
                    } else {
                        self.span_err(*self.span,
                                      "`'static` is the only permissible region bound here");
                    }
                    self.bump();
                }
                token::MOD_SEP | token::IDENT(*) => {
                    let obsolete_bound = match *self.token {
                        token::MOD_SEP => false,
                        token::IDENT(sid, _) => {
                            match self.id_to_str(sid).as_slice() {
                                "send" |
                                "copy" |
                                "const" |
                                "owned" => {
                                    self.obsolete(
                                        *self.span,
                                        ObsoleteLowerCaseKindBounds);
                                    self.bump();
                                    true
                                }
                                _ => false
                            }
                        }
                        _ => fail!()
                    };

                    if !obsolete_bound {
                        let tref = self.parse_trait_ref();
                        result.push(TraitTyParamBound(tref));
                    }
                }
                _ => break,
            }

            if self.eat(&token::BINOP(token::PLUS)) {
                loop;
            }

            if is_ident_or_path(self.token) {
                self.obsolete(*self.span,
                              ObsoleteTraitBoundSeparator);
            }
        }

        return result;
    }

    // matches typaram = IDENT optbounds
    fn parse_ty_param(&self) -> TyParam {
        let ident = self.parse_ident();
        let bounds = @self.parse_optional_ty_param_bounds();
        ast::TyParam { ident: ident, id: self.get_id(), bounds: bounds }
    }

    // parse a set of optional generic type parameter declarations
    // matches generics = ( ) | ( < > ) | ( < typaramseq ( , )? > ) | ( < lifetimes ( , )? > )
    //                  | ( < lifetimes , typaramseq ( , )? > )
    // where   typaramseq = ( typaram ) | ( typaram , typaramseq )
    pub fn parse_generics(&self) -> ast::Generics {
        if self.eat(&token::LT) {
            let lifetimes = self.parse_lifetimes();
            let ty_params = self.parse_seq_to_gt(
                Some(token::COMMA),
                |p| p.parse_ty_param());
            ast::Generics { lifetimes: lifetimes, ty_params: ty_params }
        } else {
            ast_util::empty_generics()
        }
    }

    // parse a generic use site
    fn parse_generic_values(
        &self) -> (OptVec<ast::Lifetime>, ~[@Ty])
    {
        if !self.eat(&token::LT) {
            (opt_vec::Empty, ~[])
        } else {
            self.parse_generic_values_after_lt()
        }
    }

    fn parse_generic_values_after_lt(
        &self) -> (OptVec<ast::Lifetime>, ~[@Ty])
    {
        let lifetimes = self.parse_lifetimes();
        let result = self.parse_seq_to_gt(
            Some(token::COMMA),
            |p| p.parse_ty(false));
        (lifetimes, opt_vec::take_vec(result))
    }

    // parse the argument list and result type of a function declaration
    pub fn parse_fn_decl(&self) -> fn_decl {
        let args_or_capture_items: ~[arg_or_capture_item] =
            self.parse_unspanned_seq(
                &token::LPAREN,
                &token::RPAREN,
                seq_sep_trailing_disallowed(token::COMMA),
                |p| p.parse_arg()
            );

        let inputs = either::lefts(args_or_capture_items);

        let (ret_style, ret_ty) = self.parse_ret_ty();
        ast::fn_decl {
            inputs: inputs,
            output: ret_ty,
            cf: ret_style,
        }
    }

    fn is_self_ident(&self) -> bool {
        match *self.token {
          token::IDENT(id, false) if id == special_idents::self_
            => true,
          _ => false
        }
    }

    fn expect_self_ident(&self) {
        if !self.is_self_ident() {
            self.fatal(
                fmt!(
                    "expected `self` but found `%s`",
                    self.this_token_to_str()
                )
            );
        }
        self.bump();
    }

    // parse the argument list and result type of a function
    // that may have a self type.
    fn parse_fn_decl_with_self(
        &self,
        parse_arg_fn:
        &fn(&Parser) -> arg_or_capture_item
    ) -> (explicit_self, fn_decl) {
        fn maybe_parse_explicit_self(
            cnstr: &fn(v: mutability) -> ast::explicit_self_,
            p: &Parser
        ) -> ast::explicit_self_ {
            // We need to make sure it isn't a mode or a type
            if token::is_keyword(keywords::Self, &p.look_ahead(1)) ||
                ((token::is_keyword(keywords::Const, &p.look_ahead(1)) ||
                  token::is_keyword(keywords::Mut, &p.look_ahead(1))) &&
                 token::is_keyword(keywords::Self, &p.look_ahead(2))) {

                p.bump();
                let mutability = p.parse_mutability();
                p.expect_self_ident();
                cnstr(mutability)
            } else {
                sty_static
            }
        }

        fn maybe_parse_borrowed_explicit_self(this: &Parser) -> ast::explicit_self_ {
            // The following things are possible to see here:
            //
            //     fn(&self)
            //     fn(&mut self)
            //     fn(&'lt self)
            //     fn(&'lt mut self)
            //
            // We already know that the current token is `&`.

            if (token::is_keyword(keywords::Self, &this.look_ahead(1))) {
                this.bump();
                this.expect_self_ident();
                sty_region(None, m_imm)
            } else if (this.token_is_mutability(&this.look_ahead(1)) &&
                       token::is_keyword(keywords::Self, &this.look_ahead(2))) {
                this.bump();
                let mutability = this.parse_mutability();
                this.expect_self_ident();
                sty_region(None, mutability)
            } else if (this.token_is_lifetime(&this.look_ahead(1)) &&
                       token::is_keyword(keywords::Self, &this.look_ahead(2))) {
                this.bump();
                let lifetime = @this.parse_lifetime();
                this.expect_self_ident();
                sty_region(Some(lifetime), m_imm)
            } else if (this.token_is_lifetime(&this.look_ahead(1)) &&
                       this.token_is_mutability(&this.look_ahead(2)) &&
                       token::is_keyword(keywords::Self, &this.look_ahead(3))) {
                this.bump();
                let lifetime = @this.parse_lifetime();
                let mutability = this.parse_mutability();
                this.expect_self_ident();
                sty_region(Some(lifetime), mutability)
            } else {
                sty_static
            }
        }

        self.expect(&token::LPAREN);

        // A bit of complexity and lookahead is needed here in order to be
        // backwards compatible.
        let lo = self.span.lo;
        let explicit_self = match *self.token {
          token::BINOP(token::AND) => {
            maybe_parse_borrowed_explicit_self(self)
          }
          token::AT => {
            maybe_parse_explicit_self(sty_box, self)
          }
          token::TILDE => {
            maybe_parse_explicit_self(sty_uniq, self)
          }
          token::IDENT(*) if self.is_self_ident() => {
            self.bump();
            sty_value
          }
          _ => {
            sty_static
          }
        };

        // If we parsed a self type, expect a comma before the argument list.
        let args_or_capture_items;
        if explicit_self != sty_static {
            match *self.token {
                token::COMMA => {
                    self.bump();
                    let sep = seq_sep_trailing_disallowed(token::COMMA);
                    args_or_capture_items = self.parse_seq_to_before_end(
                        &token::RPAREN,
                        sep,
                        parse_arg_fn
                    );
                }
                token::RPAREN => {
                    args_or_capture_items = ~[];
                }
                _ => {
                    self.fatal(
                        fmt!(
                            "expected `,` or `)`, found `%s`",
                            self.this_token_to_str()
                        )
                    );
                }
            }
        } else {
            let sep = seq_sep_trailing_disallowed(token::COMMA);
            args_or_capture_items = self.parse_seq_to_before_end(
                &token::RPAREN,
                sep,
                parse_arg_fn
            );
        }

        self.expect(&token::RPAREN);

        let hi = self.span.hi;

        let inputs = either::lefts(args_or_capture_items);
        let (ret_style, ret_ty) = self.parse_ret_ty();

        let fn_decl = ast::fn_decl {
            inputs: inputs,
            output: ret_ty,
            cf: ret_style
        };

        (spanned(lo, hi, explicit_self), fn_decl)
    }

    // parse the |arg, arg| header on a lambda
    fn parse_fn_block_decl(&self) -> fn_decl {
        let inputs_captures = {
            if self.eat(&token::OROR) {
                ~[]
            } else {
                self.parse_unspanned_seq(
                    &token::BINOP(token::OR),
                    &token::BINOP(token::OR),
                    seq_sep_trailing_disallowed(token::COMMA),
                    |p| p.parse_fn_block_arg()
                )
            }
        };
        let output = if self.eat(&token::RARROW) {
            self.parse_ty(false)
        } else {
            @Ty { id: self.get_id(), node: ty_infer, span: *self.span }
        };

        ast::fn_decl {
            inputs: either::lefts(inputs_captures),
            output: output,
            cf: return_val,
        }
    }

    // parse the name and optional generic types of a function header.
    fn parse_fn_header(&self) -> (ident, ast::Generics) {
        let id = self.parse_ident();
        let generics = self.parse_generics();
        (id, generics)
    }

    fn mk_item(&self, lo: BytePos, hi: BytePos, ident: ident,
               node: item_, vis: visibility,
               attrs: ~[attribute]) -> @item {
        @ast::item { ident: ident,
                     attrs: attrs,
                     id: self.get_id(),
                     node: node,
                     vis: vis,
                     span: mk_sp(lo, hi) }
    }

    // parse an item-position function declaration.
    fn parse_item_fn(&self, purity: purity, abis: AbiSet) -> item_info {
        let (ident, generics) = self.parse_fn_header();
        let decl = self.parse_fn_decl();
        let (inner_attrs, body) = self.parse_inner_attrs_and_block();
        (ident,
         item_fn(decl, purity, abis, generics, body),
         Some(inner_attrs))
    }

    // parse a method in a trait impl
    fn parse_method(&self) -> @method {
        let attrs = self.parse_outer_attributes();
        let lo = self.span.lo;

        let visa = self.parse_visibility();
        let pur = self.parse_fn_purity();
        let ident = self.parse_ident();
        let generics = self.parse_generics();
        let (explicit_self, decl) = do self.parse_fn_decl_with_self() |p| {
            p.parse_arg()
        };

        let (inner_attrs, body) = self.parse_inner_attrs_and_block();
        let hi = body.span.hi;
        let attrs = vec::append(attrs, inner_attrs);
        @ast::method {
            ident: ident,
            attrs: attrs,
            generics: generics,
            explicit_self: explicit_self,
            purity: pur,
            decl: decl,
            body: body,
            id: self.get_id(),
            span: mk_sp(lo, hi),
            self_id: self.get_id(),
            vis: visa,
        }
    }

    // parse trait Foo { ... }
    fn parse_item_trait(&self) -> item_info {
        let ident = self.parse_ident();
        self.parse_region_param();
        let tps = self.parse_generics();

        // Parse traits, if necessary.
        let traits;
        if *self.token == token::COLON {
            self.bump();
            traits = self.parse_trait_ref_list(&token::LBRACE);
        } else {
            traits = ~[];
        }

        let meths = self.parse_trait_methods();
        (ident, item_trait(tps, traits, meths), None)
    }

    // Parses two variants (with the region/type params always optional):
    //    impl<T> Foo { ... }
    //    impl<T> ToStr for ~[T] { ... }
    fn parse_item_impl(&self, visibility: ast::visibility) -> item_info {
        // First, parse type parameters if necessary.
        let generics = self.parse_generics();

        // This is a new-style impl declaration.
        // XXX: clownshoes
        let ident = special_idents::clownshoes_extensions;

        // Special case: if the next identifier that follows is '(', don't
        // allow this to be parsed as a trait.
        let could_be_trait = *self.token != token::LPAREN;

        // Parse the trait.
        let mut ty = self.parse_ty(false);

        // Parse traits, if necessary.
        let opt_trait = if could_be_trait && self.eat_keyword(keywords::For) {
            // New-style trait. Reinterpret the type as a trait.
            let opt_trait_ref = match ty.node {
                ty_path(path, node_id) => {
                    Some(@trait_ref {
                        path: path,
                        ref_id: node_id
                    })
                }
                _ => {
                    self.span_err(*self.span, "not a trait");
                    None
                }
            };

            ty = self.parse_ty(false);
            opt_trait_ref
        } else if self.eat(&token::COLON) {
            self.obsolete(copy *self.span, ObsoleteImplSyntax);
            Some(self.parse_trait_ref())
        } else {
            None
        };

        // Do not allow visibility to be specified.
        if visibility != ast::inherited {
            self.obsolete(*self.span, ObsoleteImplVisibility);
        }

        let mut meths = ~[];
        if !self.eat(&token::SEMI) {
            self.expect(&token::LBRACE);
            while !self.eat(&token::RBRACE) {
                meths.push(self.parse_method());
            }
        }

        (ident, item_impl(generics, opt_trait, ty, meths), None)
    }

    // parse a::B<~str,int>
    fn parse_trait_ref(&self) -> @trait_ref {
        @ast::trait_ref {
            path: self.parse_path_with_tps(false),
            ref_id: self.get_id(),
        }
    }

    // parse B + C<~str,int> + D
    fn parse_trait_ref_list(&self, ket: &token::Token) -> ~[@trait_ref] {
        self.parse_seq_to_before_end(
            ket,
            seq_sep_trailing_disallowed(token::BINOP(token::PLUS)),
            |p| p.parse_trait_ref()
        )
    }

    // parse struct Foo { ... }
    fn parse_item_struct(&self) -> item_info {
        let class_name = self.parse_ident();
        self.parse_region_param();
        let generics = self.parse_generics();
        if self.eat(&token::COLON) {
            self.obsolete(copy *self.span, ObsoleteClassTraits);
            let _ = self.parse_trait_ref_list(&token::LBRACE);
        }

        let mut fields: ~[@struct_field];
        let is_tuple_like;

        if self.eat(&token::LBRACE) {
            // It's a record-like struct.
            is_tuple_like = false;
            fields = ~[];
            while *self.token != token::RBRACE {
                for self.parse_struct_decl_field().each |struct_field| {
                    fields.push(*struct_field)
                }
            }
            if fields.len() == 0 {
                self.fatal(fmt!("Unit-like struct should be written as `struct %s;`",
                                get_ident_interner().get(class_name.name)));
            }
            self.bump();
        } else if *self.token == token::LPAREN {
            // It's a tuple-like struct.
            is_tuple_like = true;
            fields = do self.parse_unspanned_seq(
                &token::LPAREN,
                &token::RPAREN,
                seq_sep_trailing_allowed(token::COMMA)
            ) |p| {
                let attrs = self.parse_outer_attributes();
                let lo = p.span.lo;
                let struct_field_ = ast::struct_field_ {
                    kind: unnamed_field,
                    id: self.get_id(),
                    ty: p.parse_ty(false),
                    attrs: attrs,
                };
                @spanned(lo, p.span.hi, struct_field_)
            };
            self.expect(&token::SEMI);
        } else if self.eat(&token::SEMI) {
            // It's a unit-like struct.
            is_tuple_like = true;
            fields = ~[];
        } else {
            self.fatal(
                fmt!(
                    "expected `{`, `(`, or `;` after struct name \
                    but found `%s`",
                    self.this_token_to_str()
                )
            );
        }

        let _ = self.get_id();  // XXX: Workaround for crazy bug.
        let new_id = self.get_id();
        (class_name,
         item_struct(@ast::struct_def {
             fields: fields,
             ctor_id: if is_tuple_like { Some(new_id) } else { None }
         }, generics),
         None)
    }

    fn token_is_pound_or_doc_comment(&self, tok: token::Token) -> bool {
        match tok {
            token::POUND | token::DOC_COMMENT(_) => true,
            _ => false
        }
    }

    // parse a structure field declaration
    pub fn parse_single_struct_field(&self,
                                     vis: visibility,
                                     attrs: ~[attribute])
                                     -> @struct_field {
        if self.eat_obsolete_ident("let") {
            self.obsolete(*self.last_span, ObsoleteLet);
        }

        let a_var = self.parse_name_and_ty(vis, attrs);
        match *self.token {
            token::SEMI => {
                self.obsolete(copy *self.span, ObsoleteFieldTerminator);
                self.bump();
            }
            token::COMMA => {
                self.bump();
            }
            token::RBRACE => {}
            _ => {
                self.span_fatal(
                    copy *self.span,
                    fmt!(
                        "expected `,`, or '}' but found `%s`",
                        self.this_token_to_str()
                    )
                );
            }
        }
        a_var
    }

    // parse an element of a struct definition
    fn parse_struct_decl_field(&self) -> ~[@struct_field] {

        let attrs = self.parse_outer_attributes();

        if self.try_parse_obsolete_priv_section(attrs) {
            return ~[];
        }

        if self.eat_keyword(keywords::Priv) {
            return ~[self.parse_single_struct_field(private, attrs)]
        }

        if self.eat_keyword(keywords::Pub) {
           return ~[self.parse_single_struct_field(public, attrs)];
        }

        if self.try_parse_obsolete_struct_ctor() {
            return ~[];
        }

        return ~[self.parse_single_struct_field(inherited, attrs)];
    }

    // parse visiility: PUB, PRIV, or nothing
    fn parse_visibility(&self) -> visibility {
        if self.eat_keyword(keywords::Pub) { public }
        else if self.eat_keyword(keywords::Priv) { private }
        else { inherited }
    }

    fn parse_staticness(&self) -> bool {
        if self.eat_keyword(keywords::Static) {
            self.obsolete(*self.last_span, ObsoleteStaticMethod);
            true
        } else {
            false
        }
    }

    // given a termination token and a vector of already-parsed
    // attributes (of length 0 or 1), parse all of the items in a module
    fn parse_mod_items(&self, term: token::Token,
                       first_item_attrs: ~[attribute]) -> _mod {
        // parse all of the items up to closing or an attribute.
        // view items are legal here.
        let ParsedItemsAndViewItems {
            attrs_remaining: attrs_remaining,
            view_items: view_items,
            items: starting_items,
            _
        } = self.parse_items_and_view_items(first_item_attrs,
                                            true, true);
        let mut items: ~[@item] = starting_items;
        let attrs_remaining_len = attrs_remaining.len();

        // don't think this other loop is even necessary....

        let mut first = true;
        while *self.token != term {
            let mut attrs = self.parse_outer_attributes();
            if first {
                attrs = attrs_remaining + attrs;
                first = false;
            }
            debug!("parse_mod_items: parse_item_or_view_item(attrs=%?)",
                   attrs);
            match self.parse_item_or_view_item(
                /*bad*/ copy attrs,
                true // macros allowed
            ) {
              iovi_item(item) => items.push(item),
              iovi_view_item(view_item) => {
                self.span_fatal(view_item.span, "view items must be  declared at the top of the \
                                                 module");
              }
              _ => {
                self.fatal(
                    fmt!(
                        "expected item but found `%s`",
                        self.this_token_to_str()
                    )
                );
              }
            }
            debug!("parse_mod_items: attrs=%?", attrs);
        }

        if first && attrs_remaining_len > 0u {
            // We parsed attributes for the first item but didn't find it
            self.span_err(*self.last_span, "expected item after attributes");
        }

        ast::_mod { view_items: view_items, items: items }
    }

    fn parse_item_const(&self) -> item_info {
        let id = self.parse_ident();
        self.expect(&token::COLON);
        let ty = self.parse_ty(false);
        self.expect(&token::EQ);
        let e = self.parse_expr();
        self.expect(&token::SEMI);
        (id, item_const(ty, e), None)
    }

    // parse a mod { ...}  item
    fn parse_item_mod(&self, outer_attrs: ~[ast::attribute]) -> item_info {
        let id_span = *self.span;
        let id = self.parse_ident();
        if *self.token == token::SEMI {
            self.bump();
            // This mod is in an external file. Let's go get it!
            let (m, attrs) = self.eval_src_mod(id, outer_attrs, id_span);
            (id, m, Some(attrs))
        } else {
            self.push_mod_path(id, outer_attrs);
            self.expect(&token::LBRACE);
            let (inner, next) = self.parse_inner_attrs_and_next();
            let m = self.parse_mod_items(token::RBRACE, next);
            self.expect(&token::RBRACE);
            self.pop_mod_path();
            (id, item_mod(m), Some(inner))
        }
    }

    fn push_mod_path(&self, id: ident, attrs: ~[ast::attribute]) {
        let default_path = token::interner_get(id.name);
        let file_path = match ::attr::first_attr_value_str_by_name(
            attrs, "path") {

            Some(d) => d,
            None => default_path
        };
        self.mod_path_stack.push(file_path)
    }

    fn pop_mod_path(&self) {
        self.mod_path_stack.pop();
    }

    // read a module from a source file.
    fn eval_src_mod(&self, id: ast::ident,
                    outer_attrs: ~[ast::attribute],
                    id_sp: span) -> (ast::item_, ~[ast::attribute]) {

        let prefix = Path(self.sess.cm.span_to_filename(*self.span));
        let prefix = prefix.dir_path();
        let mod_path_stack = &*self.mod_path_stack;
        let mod_path = Path(".").push_many(*mod_path_stack);
        let default_path = token::interner_get(id.name).to_owned() + ".rs";
        let file_path = match ::attr::first_attr_value_str_by_name(
            outer_attrs, "path") {
            Some(d) => {
                let path = Path(d);
                if !path.is_absolute {
                    mod_path.push(d)
                } else {
                    path
                }
            }
            None => mod_path.push(default_path)
        };

        self.eval_src_mod_from_path(prefix, file_path,
                                    outer_attrs, id_sp)
    }

    fn eval_src_mod_from_path(&self, prefix: Path, path: Path,
                              outer_attrs: ~[ast::attribute],
                              id_sp: span
                             ) -> (ast::item_, ~[ast::attribute]) {

        let full_path = if path.is_absolute {
            path
        } else {
            prefix.push_many(path.components)
        };
        let full_path = full_path.normalize();
        let p0 =
            new_sub_parser_from_file(self.sess, copy self.cfg,
                                     &full_path, id_sp);
        let (inner, next) = p0.parse_inner_attrs_and_next();
        let mod_attrs = vec::append(outer_attrs, inner);
        let first_item_outer_attrs = next;
        let m0 = p0.parse_mod_items(token::EOF, first_item_outer_attrs);
        return (ast::item_mod(m0), mod_attrs);

        fn cdir_path_opt(default: @str, attrs: ~[ast::attribute]) -> @str {
            match ::attr::first_attr_value_str_by_name(attrs, "path") {
                Some(d) => d,
                None => default
            }
        }
    }

    // parse a function declaration from a foreign module
    fn parse_item_foreign_fn(&self,  attrs: ~[attribute]) -> @foreign_item {
        let lo = self.span.lo;
        let vis = self.parse_visibility();
        let purity = self.parse_fn_purity();
        let (ident, generics) = self.parse_fn_header();
        let decl = self.parse_fn_decl();
        let hi = self.span.hi;
        self.expect(&token::SEMI);
        @ast::foreign_item { ident: ident,
                             attrs: attrs,
                             node: foreign_item_fn(decl, purity, generics),
                             id: self.get_id(),
                             span: mk_sp(lo, hi),
                             vis: vis }
    }

    // parse a const definition from a foreign module
    fn parse_item_foreign_const(&self, vis: ast::visibility,
                                attrs: ~[attribute]) -> @foreign_item {
        let lo = self.span.lo;

        // XXX: Obsolete; remove after snap.
        if self.eat_keyword(keywords::Const) {
            self.obsolete(*self.last_span, ObsoleteConstItem);
        } else {
            self.expect_keyword(keywords::Static);
        }

        let ident = self.parse_ident();
        self.expect(&token::COLON);
        let ty = self.parse_ty(false);
        let hi = self.span.hi;
        self.expect(&token::SEMI);
        @ast::foreign_item { ident: ident,
                             attrs: attrs,
                             node: foreign_item_const(ty),
                             id: self.get_id(),
                             span: mk_sp(lo, hi),
                             vis: vis }
    }

    // parse safe/unsafe and fn
    fn parse_fn_purity(&self) -> purity {
        if self.eat_keyword(keywords::Fn) { impure_fn }
        else if self.eat_keyword(keywords::Pure) {
            self.obsolete(*self.last_span, ObsoletePurity);
            self.expect_keyword(keywords::Fn);
            // NB: We parse this as impure for bootstrapping purposes.
            impure_fn
        } else if self.eat_keyword(keywords::Unsafe) {
            self.expect_keyword(keywords::Fn);
            unsafe_fn
        }
        else { self.unexpected(); }
    }


    // at this point, this is essentially a wrapper for
    // parse_foreign_items.
    fn parse_foreign_mod_items(&self,
                               sort: ast::foreign_mod_sort,
                               abis: AbiSet,
                               first_item_attrs: ~[attribute])
                               -> foreign_mod {
        let ParsedItemsAndViewItems {
            attrs_remaining: attrs_remaining,
            view_items: view_items,
            items: _,
            foreign_items: foreign_items
        } = self.parse_foreign_items(first_item_attrs, true);
        if (! attrs_remaining.is_empty()) {
            self.span_err(*self.last_span,
                          "expected item after attributes");
        }
        assert!(*self.token == token::RBRACE);
        ast::foreign_mod {
            sort: sort,
            abis: abis,
            view_items: view_items,
            items: foreign_items
        }
    }

    // parse extern foo; or extern mod foo { ... } or extern { ... }
    fn parse_item_foreign_mod(&self,
                              lo: BytePos,
                              opt_abis: Option<AbiSet>,
                              visibility: visibility,
                              attrs: ~[attribute],
                              items_allowed: bool)
                              -> item_or_view_item {
        let mut must_be_named_mod = false;
        if self.is_keyword(keywords::Mod) {
            must_be_named_mod = true;
            self.expect_keyword(keywords::Mod);
        } else if *self.token != token::LBRACE {
            self.span_fatal(
                copy *self.span,
                fmt!(
                    "expected `{` or `mod` but found `%s`",
                    self.this_token_to_str()
                )
            );
        }

        let (sort, ident) = match *self.token {
            token::IDENT(*) => (ast::named, self.parse_ident()),
            _ => {
                if must_be_named_mod {
                    self.span_fatal(
                        copy *self.span,
                        fmt!(
                            "expected foreign module name but found `%s`",
                            self.this_token_to_str()
                        )
                    );
                }

                (ast::anonymous,
                 special_idents::clownshoes_foreign_mod)
            }
        };

        // extern mod foo { ... } or extern { ... }
        if items_allowed && self.eat(&token::LBRACE) {
            // `extern mod foo { ... }` is obsolete.
            if sort == ast::named {
                self.obsolete(*self.last_span, ObsoleteNamedExternModule);
            }

            let abis = opt_abis.get_or_default(AbiSet::C());

            let (inner, next) = self.parse_inner_attrs_and_next();
            let m = self.parse_foreign_mod_items(sort, abis, next);
            self.expect(&token::RBRACE);

            return iovi_item(self.mk_item(lo, self.last_span.hi, ident,
                                          item_foreign_mod(m), visibility,
                                          maybe_append(/*bad*/ copy attrs,
                                                       Some(inner))));
        }

        if opt_abis.is_some() {
            self.span_err(*self.span, "an ABI may not be specified here");
        }

        // extern mod foo;
        let metadata = self.parse_optional_meta();
        self.expect(&token::SEMI);
        iovi_view_item(@ast::view_item {
            node: view_item_extern_mod(ident, metadata, self.get_id()),
            attrs: copy attrs,
            vis: visibility,
            span: mk_sp(lo, self.last_span.hi)
        })
    }

    // parse type Foo = Bar;
    fn parse_item_type(&self) -> item_info {
        let ident = self.parse_ident();
        self.parse_region_param();
        let tps = self.parse_generics();
        self.expect(&token::EQ);
        let ty = self.parse_ty(false);
        self.expect(&token::SEMI);
        (ident, item_ty(ty, tps), None)
    }

    // parse obsolete region parameter
    fn parse_region_param(&self) {
        if self.eat(&token::BINOP(token::SLASH)) {
            self.obsolete(*self.last_span, ObsoleteLifetimeNotation);
            self.expect(&token::BINOP(token::AND));
        }
    }

    // parse a structure-like enum variant definition
    // this should probably be renamed or refactored...
    fn parse_struct_def(&self) -> @struct_def {
        let mut fields: ~[@struct_field] = ~[];
        while *self.token != token::RBRACE {
            for self.parse_struct_decl_field().each |struct_field| {
                fields.push(*struct_field);
            }
        }
        self.bump();

        return @ast::struct_def {
            fields: fields,
            ctor_id: None
        };
    }

    // parse the part of an "enum" decl following the '{'
    fn parse_enum_def(&self, _generics: &ast::Generics) -> enum_def {
        let mut variants = ~[];
        let mut all_nullary = true;
        let mut have_disr = false;
        while *self.token != token::RBRACE {
            let variant_attrs = self.parse_outer_attributes();
            let vlo = self.span.lo;

            let vis = self.parse_visibility();

            let ident;
            let kind;
            let mut args = ~[];
            let mut disr_expr = None;
            ident = self.parse_ident();
            if self.eat(&token::LBRACE) {
                // Parse a struct variant.
                all_nullary = false;
                kind = struct_variant_kind(self.parse_struct_def());
            } else if *self.token == token::LPAREN {
                all_nullary = false;
                let arg_tys = self.parse_unspanned_seq(
                    &token::LPAREN,
                    &token::RPAREN,
                    seq_sep_trailing_disallowed(token::COMMA),
                    |p| p.parse_ty(false)
                );
                for arg_tys.each |ty| {
                    args.push(ast::variant_arg {
                        ty: *ty,
                        id: self.get_id(),
                    });
                }
                kind = tuple_variant_kind(args);
            } else if self.eat(&token::EQ) {
                have_disr = true;
                disr_expr = Some(self.parse_expr());
                kind = tuple_variant_kind(args);
            } else {
                kind = tuple_variant_kind(~[]);
            }

            let vr = ast::variant_ {
                name: ident,
                attrs: variant_attrs,
                kind: kind,
                id: self.get_id(),
                disr_expr: disr_expr,
                vis: vis,
            };
            variants.push(spanned(vlo, self.last_span.hi, vr));

            if !self.eat(&token::COMMA) { break; }
        }
        self.expect(&token::RBRACE);
        if (have_disr && !all_nullary) {
            self.fatal("discriminator values can only be used with a c-like \
                        enum");
        }

        ast::enum_def { variants: variants }
    }

    // parse an "enum" declaration
    fn parse_item_enum(&self) -> item_info {
        let id = self.parse_ident();
        self.parse_region_param();
        let generics = self.parse_generics();
        // Newtype syntax
        if *self.token == token::EQ {
            // enum x = ty;
            self.bump();
            let ty = self.parse_ty(false);
            self.expect(&token::SEMI);
            let variant = spanned(ty.span.lo, ty.span.hi, ast::variant_ {
                name: id,
                attrs: ~[],
                kind: tuple_variant_kind(
                    ~[ast::variant_arg {ty: ty, id: self.get_id()}]
                ),
                id: self.get_id(),
                disr_expr: None,
                vis: public,
            });

            self.obsolete(*self.last_span, ObsoleteNewtypeEnum);

            return (
                id,
                item_enum(
                    ast::enum_def { variants: ~[variant] },
                    generics),
                None
            );
        }
        // enum X { ... }
        self.expect(&token::LBRACE);

        let enum_definition = self.parse_enum_def(&generics);
        (id, item_enum(enum_definition, generics), None)
    }

    fn parse_fn_ty_sigil(&self) -> Option<Sigil> {
        match *self.token {
            token::AT => {
                self.bump();
                Some(ManagedSigil)
            }
            token::TILDE => {
                self.bump();
                Some(OwnedSigil)
            }
            token::BINOP(token::AND) => {
                self.bump();
                Some(BorrowedSigil)
            }
            _ => {
                None
            }
        }
    }

    fn fn_expr_lookahead(&self, tok: token::Token) -> bool {
        match tok {
          token::LPAREN | token::AT | token::TILDE | token::BINOP(_) => true,
          _ => false
        }
    }

    // parse a string as an ABI spec on an extern type or module
    fn parse_opt_abis(&self) -> Option<AbiSet> {
        match *self.token {
            token::LIT_STR(s) => {
                self.bump();
                let the_string = ident_to_str(&s);
                let mut abis = AbiSet::empty();
                for the_string.word_iter().advance |word| {
                    match abi::lookup(word) {
                        Some(abi) => {
                            if abis.contains(abi) {
                                self.span_err(
                                    *self.span,
                                    fmt!("ABI `%s` appears twice",
                                         word));
                            } else {
                                abis.add(abi);
                            }
                        }

                        None => {
                            self.span_err(
                                *self.span,
                                fmt!("illegal ABI: \
                                      expected one of [%s], \
                                      found `%s`",
                                     abi::all_names().connect(", "),
                                     word));
                        }
                    }
                }
                Some(abis)
            }

            _ => {
                None
            }
        }
    }

    // parse one of the items or view items allowed by the
    // flags; on failure, return iovi_none.
    // NB: this function no longer parses the items inside an
    // extern mod.
    fn parse_item_or_view_item(
        &self,
        attrs: ~[attribute],
        macros_allowed: bool
    ) -> item_or_view_item {
        maybe_whole!(iovi self, nt_item);
        let lo = self.span.lo;

        let visibility = self.parse_visibility();

        // must be a view item:
        if self.eat_keyword(keywords::Use) {
            // USE ITEM (iovi_view_item)
            let view_item = self.parse_use();
            self.expect(&token::SEMI);
            return iovi_view_item(@ast::view_item {
                node: view_item,
                attrs: attrs,
                vis: visibility,
                span: mk_sp(lo, self.last_span.hi)
            });
        }
        // either a view item or an item:
        if self.eat_keyword(keywords::Extern) {
            let opt_abis = self.parse_opt_abis();

            if self.eat_keyword(keywords::Fn) {
                // EXTERN FUNCTION ITEM
                let abis = opt_abis.get_or_default(AbiSet::C());
                let (ident, item_, extra_attrs) =
                    self.parse_item_fn(extern_fn, abis);
                return iovi_item(self.mk_item(lo, self.last_span.hi, ident,
                                              item_, visibility,
                                              maybe_append(attrs,
                                                           extra_attrs)));
            } else  {
                // EXTERN MODULE ITEM (iovi_view_item)
                return self.parse_item_foreign_mod(lo, opt_abis, visibility, attrs,
                                                   true);
            }
        }
        // the rest are all guaranteed to be items:
        if (self.is_keyword(keywords::Const) ||
            (self.is_keyword(keywords::Static) &&
             !token::is_keyword(keywords::Fn, &self.look_ahead(1)))) {
            // CONST / STATIC ITEM
            if self.is_keyword(keywords::Const) {
                self.obsolete(*self.span, ObsoleteConstItem);
            }
            self.bump();
            let (ident, item_, extra_attrs) = self.parse_item_const();
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.is_keyword(keywords::Fn) &&
            !self.fn_expr_lookahead(self.look_ahead(1u)) {
            // FUNCTION ITEM
            self.bump();
            let (ident, item_, extra_attrs) =
                self.parse_item_fn(impure_fn, AbiSet::Rust());
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.eat_keyword(keywords::Pure) {
            // PURE FUNCTION ITEM (obsolete)
            self.obsolete(*self.last_span, ObsoletePurity);
            self.expect_keyword(keywords::Fn);
            let (ident, item_, extra_attrs) =
                self.parse_item_fn(impure_fn, AbiSet::Rust());
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.is_keyword(keywords::Unsafe)
            && self.look_ahead(1u) != token::LBRACE {
            // UNSAFE FUNCTION ITEM
            self.bump();
            self.expect_keyword(keywords::Fn);
            let (ident, item_, extra_attrs) =
                self.parse_item_fn(unsafe_fn, AbiSet::Rust());
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.eat_keyword(keywords::Mod) {
            // MODULE ITEM
            let (ident, item_, extra_attrs) =
                self.parse_item_mod(/*bad*/ copy attrs);
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.eat_keyword(keywords::Type) {
            // TYPE ITEM
            let (ident, item_, extra_attrs) = self.parse_item_type();
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.eat_keyword(keywords::Enum) {
            // ENUM ITEM
            let (ident, item_, extra_attrs) = self.parse_item_enum();
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.eat_keyword(keywords::Trait) {
            // TRAIT ITEM
            let (ident, item_, extra_attrs) = self.parse_item_trait();
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.eat_keyword(keywords::Impl) {
            // IMPL ITEM
            let (ident, item_, extra_attrs) =
                self.parse_item_impl(visibility);
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        if self.eat_keyword(keywords::Struct) {
            // STRUCT ITEM
            let (ident, item_, extra_attrs) = self.parse_item_struct();
            return iovi_item(self.mk_item(lo, self.last_span.hi, ident, item_,
                                          visibility,
                                          maybe_append(attrs, extra_attrs)));
        }
        self.parse_macro_use_or_failure(attrs,macros_allowed,lo,visibility)
    }

    // parse a foreign item; on failure, return iovi_none.
    fn parse_foreign_item(
        &self,
        attrs: ~[attribute],
        macros_allowed: bool
    ) -> item_or_view_item {
        maybe_whole!(iovi self, nt_item);
        let lo = self.span.lo;

        let visibility = self.parse_visibility();

        if (self.is_keyword(keywords::Const) || self.is_keyword(keywords::Static)) {
            // FOREIGN CONST ITEM
            let item = self.parse_item_foreign_const(visibility, attrs);
            return iovi_foreign_item(item);
        }
        if (self.is_keyword(keywords::Fn) || self.is_keyword(keywords::Pure) ||
                self.is_keyword(keywords::Unsafe)) {
            // FOREIGN FUNCTION ITEM
            let item = self.parse_item_foreign_fn(attrs);
            return iovi_foreign_item(item);
        }
        self.parse_macro_use_or_failure(attrs,macros_allowed,lo,visibility)
    }

    // this is the fall-through for parsing items.
    fn parse_macro_use_or_failure(
        &self,
        attrs: ~[attribute],
        macros_allowed: bool,
        lo : BytePos,
        visibility : visibility
    ) -> item_or_view_item {
        if macros_allowed && !token::is_any_keyword(self.token)
                && self.look_ahead(1) == token::NOT
                && (is_plain_ident(&self.look_ahead(2))
                    || self.look_ahead(2) == token::LPAREN
                    || self.look_ahead(2) == token::LBRACE) {
            // MACRO INVOCATION ITEM
            if attrs.len() > 0 {
                self.fatal("attrs on macros are not yet supported");
            }

            // item macro.
            let pth = self.parse_path_without_tps();
            self.expect(&token::NOT);

            // a 'special' identifier (like what `macro_rules!` uses)
            // is optional. We should eventually unify invoc syntax
            // and remove this.
            let id = if is_plain_ident(&*self.token) {
                self.parse_ident()
            } else {
                token::special_idents::invalid // no special identifier
            };
            // eat a matched-delimiter token tree:
            let tts = match *self.token {
                token::LPAREN | token::LBRACE => {
                    let ket = token::flip_delimiter(&*self.token);
                    self.parse_unspanned_seq(
                        &copy *self.token,
                        &ket,
                        seq_sep_none(),
                        |p| p.parse_token_tree()
                    )
                }
                _ => self.fatal("expected open delimiter")
            };
            // single-variant-enum... :
            let m = ast::mac_invoc_tt(pth, tts);
            let m: ast::mac = codemap::spanned { node: m,
                                             span: mk_sp(self.span.lo,
                                                         self.span.hi) };
            let item_ = item_mac(m);
            return iovi_item(self.mk_item(lo, self.last_span.hi, id, item_,
                                          visibility, attrs));
        }

        // FAILURE TO PARSE ITEM
        if visibility != inherited {
            let mut s = ~"unmatched visibility `";
            s += if visibility == public { "pub" } else { "priv" };
            s += "`";
            self.span_fatal(*self.last_span, s);
        }
        return iovi_none;
    }

    pub fn parse_item(&self, attrs: ~[attribute]) -> Option<@ast::item> {
        match self.parse_item_or_view_item(attrs, true) {
            iovi_none =>
                None,
            iovi_view_item(_) =>
                self.fatal("view items are not allowed here"),
            iovi_foreign_item(_) =>
                self.fatal("foreign items are not allowed here"),
            iovi_item(item) =>
                Some(item)
        }
    }

    // parse, e.g., "use a::b::{z,y}"
    fn parse_use(&self) -> view_item_ {
        return view_item_use(self.parse_view_paths());
    }


    // matches view_path : MOD? IDENT EQ non_global_path
    // | MOD? non_global_path MOD_SEP LBRACE RBRACE
    // | MOD? non_global_path MOD_SEP LBRACE ident_seq RBRACE
    // | MOD? non_global_path MOD_SEP STAR
    // | MOD? non_global_path
    fn parse_view_path(&self) -> @view_path {
        let lo = self.span.lo;

        let first_ident = self.parse_ident();
        let mut path = ~[first_ident];
        debug!("parsed view_path: %s", self.id_to_str(first_ident));
        match *self.token {
          token::EQ => {
            // x = foo::bar
            self.bump();
            path = ~[self.parse_ident()];
            while *self.token == token::MOD_SEP {
                self.bump();
                let id = self.parse_ident();
                path.push(id);
            }
            let path = @ast::Path { span: mk_sp(lo, self.span.hi),
                                    global: false,
                                    idents: path,
                                    rp: None,
                                    types: ~[] };
            return @spanned(lo, self.span.hi,
                            view_path_simple(first_ident,
                                             path,
                                             self.get_id()));
          }

          token::MOD_SEP => {
            // foo::bar or foo::{a,b,c} or foo::*
            while *self.token == token::MOD_SEP {
                self.bump();

                match *self.token {
                  token::IDENT(i, _) => {
                    self.bump();
                    path.push(i);
                  }

                  // foo::bar::{a,b,c}
                  token::LBRACE => {
                    let idents = self.parse_unspanned_seq(
                        &token::LBRACE,
                        &token::RBRACE,
                        seq_sep_trailing_allowed(token::COMMA),
                        |p| p.parse_path_list_ident()
                    );
                    let path = @ast::Path { span: mk_sp(lo, self.span.hi),
                                            global: false,
                                            idents: path,
                                            rp: None,
                                            types: ~[] };
                    return @spanned(lo, self.span.hi,
                                 view_path_list(path, idents, self.get_id()));
                  }

                  // foo::bar::*
                  token::BINOP(token::STAR) => {
                    self.bump();
                    let path = @ast::Path { span: mk_sp(lo, self.span.hi),
                                            global: false,
                                            idents: path,
                                            rp: None,
                                            types: ~[] };
                    return @spanned(lo, self.span.hi,
                                    view_path_glob(path, self.get_id()));
                  }

                  _ => break
                }
            }
          }
          _ => ()
        }
        let last = path[path.len() - 1u];
        let path = @ast::Path { span: mk_sp(lo, self.span.hi),
                                global: false,
                                idents: path,
                                rp: None,
                                types: ~[] };
        return @spanned(lo,
                        self.last_span.hi,
                        view_path_simple(last, path, self.get_id()));
    }

    // matches view_paths = view_path | view_path , view_paths
    fn parse_view_paths(&self) -> ~[@view_path] {
        let mut vp = ~[self.parse_view_path()];
        while *self.token == token::COMMA {
            self.bump();
            vp.push(self.parse_view_path());
        }
        return vp;
    }

    fn is_view_item(&self) -> bool {
        let tok;
        let next_tok;
        if !self.is_keyword(keywords::Pub) && !self.is_keyword(keywords::Priv) {
            tok = copy *self.token;
            next_tok = self.look_ahead(1);
        } else {
            tok = self.look_ahead(1);
            next_tok = self.look_ahead(2);
        };
        token::is_keyword(keywords::Use, &tok)
            || (token::is_keyword(keywords::Extern, &tok) &&
                token::is_keyword(keywords::Mod, &next_tok))
    }

    // parse a view item.
    fn parse_view_item(
        &self,
        attrs: ~[attribute],
        vis: visibility
    ) -> @view_item {
        let lo = self.span.lo;
        let node = if self.eat_keyword(keywords::Use) {
            self.parse_use()
        } else if self.eat_keyword(keywords::Extern) {
            self.expect_keyword(keywords::Mod);
            let ident = self.parse_ident();
            let metadata = self.parse_optional_meta();
            view_item_extern_mod(ident, metadata, self.get_id())
        } else {
            self.bug("expected view item");
        };
        self.expect(&token::SEMI);
        @ast::view_item { node: node,
                          attrs: attrs,
                          vis: vis,
                          span: mk_sp(lo, self.last_span.hi) }
    }

    // Parses a sequence of items. Stops when it finds program
    // text that can't be parsed as an item
    // - mod_items uses extern_mod_allowed = true
    // - block_tail_ uses extern_mod_allowed = false
    fn parse_items_and_view_items(&self,
                                  first_item_attrs: ~[attribute],
                                  mut extern_mod_allowed: bool,
                                  macros_allowed: bool)
                                  -> ParsedItemsAndViewItems {
        let mut attrs = vec::append(first_item_attrs,
                                    self.parse_outer_attributes());
        // First, parse view items.
        let mut (view_items, items) = (~[], ~[]);
        let mut done = false;
        // I think this code would probably read better as a single
        // loop with a mutable three-state-variable (for extern mods,
        // view items, and regular items) ... except that because
        // of macros, I'd like to delay that entire check until later.
        loop {
            match self.parse_item_or_view_item(/*bad*/ copy attrs,
                                                           macros_allowed) {
                iovi_none => {
                    done = true;
                    break;
                }
                iovi_view_item(view_item) => {
                    match view_item.node {
                        view_item_use(*) => {
                            // `extern mod` must precede `use`.
                            extern_mod_allowed = false;
                        }
                        view_item_extern_mod(*)
                        if !extern_mod_allowed => {
                            self.span_err(view_item.span,
                                          "\"extern mod\" declarations are not allowed here");
                        }
                        view_item_extern_mod(*) => {}
                    }
                    view_items.push(view_item);
                }
                iovi_item(item) => {
                    items.push(item);
                    attrs = self.parse_outer_attributes();
                    break;
                }
                iovi_foreign_item(_) => {
                    fail!();
                }
            }
            attrs = self.parse_outer_attributes();
        }

        // Next, parse items.
        if !done {
            loop {
                match self.parse_item_or_view_item(/*bad*/ copy attrs,
                                                   macros_allowed) {
                    iovi_none => break,
                    iovi_view_item(view_item) => {
                        self.span_err(view_item.span,
                                      "`use` and `extern mod` declarations must precede items");
                    }
                    iovi_item(item) => {
                        items.push(item)
                    }
                    iovi_foreign_item(_) => {
                        fail!();
                    }
                }
                attrs = self.parse_outer_attributes();
            }
        }

        ParsedItemsAndViewItems {
            attrs_remaining: attrs,
            view_items: view_items,
            items: items,
            foreign_items: ~[]
        }
    }

    // Parses a sequence of foreign items. Stops when it finds program
    // text that can't be parsed as an item
    fn parse_foreign_items(&self, first_item_attrs: ~[attribute],
                           macros_allowed: bool)
        -> ParsedItemsAndViewItems {
        let mut attrs = vec::append(first_item_attrs,
                                    self.parse_outer_attributes());
        let mut foreign_items = ~[];
        loop {
            match self.parse_foreign_item(/*bad*/ copy attrs, macros_allowed) {
                iovi_none => {
                    if *self.token == token::RBRACE {
                        break
                    }
                    self.unexpected();
                },
                iovi_view_item(view_item) => {
                    // I think this can't occur:
                    self.span_err(view_item.span,
                                  "`use` and `extern mod` declarations must precede items");
                }
                iovi_item(item) => {
                    // FIXME #5668: this will occur for a macro invocation:
                    self.span_fatal(item.span, "macros cannot expand to foreign items");
                }
                iovi_foreign_item(foreign_item) => {
                    foreign_items.push(foreign_item);
                }
            }
            attrs = self.parse_outer_attributes();
        }

        ParsedItemsAndViewItems {
            attrs_remaining: attrs,
            view_items: ~[],
            items: ~[],
            foreign_items: foreign_items
        }
    }

    // Parses a source module as a crate. This is the main
    // entry point for the parser.
    pub fn parse_crate_mod(&self) -> @crate {
        let lo = self.span.lo;
        // parse the crate's inner attrs, maybe (oops) one
        // of the attrs of an item:
        let (inner, next) = self.parse_inner_attrs_and_next();
        let first_item_outer_attrs = next;
        // parse the items inside the crate:
        let m = self.parse_mod_items(token::EOF, first_item_outer_attrs);
        @spanned(lo, self.span.lo,
                 ast::crate_ { module: m,
                               attrs: inner,
                               config: copy self.cfg })
    }

    pub fn parse_str(&self) -> @str {
        match *self.token {
            token::LIT_STR(s) => {
                self.bump();
                ident_to_str(&s)
            }
            _ =>  self.fatal("expected string literal")
        }
    }
}