lldb_providers.py

import sys

from lldb import (
    SBData,
    SBError,
    SBValue,
    eBasicTypeLong,
    eBasicTypeUnsignedLong,
    eBasicTypeUnsignedChar,
)

# from lldb.formatters import Logger

####################################################################################################
# This file contains two kinds of pretty-printers: summary and synthetic.
#
# Important classes from LLDB module:
#   SBValue: the value of a variable, a register, or an expression
#   SBType:  the data type; each SBValue has a corresponding SBType
#
# Summary provider is a function with the type `(SBValue, dict) -> str`.
#   The first parameter is the object encapsulating the actual variable being displayed;
#   The second parameter is an internal support parameter used by LLDB, and you should not touch it.
#
# Synthetic children is the way to provide a children-based representation of the object's value.
# Synthetic provider is a class that implements the following interface:
#
#     class SyntheticChildrenProvider:
#         def __init__(self, SBValue, dict)
#         def num_children(self)
#         def get_child_index(self, str)
#         def get_child_at_index(self, int)
#         def update(self)
#         def has_children(self)
#         def get_value(self)
#
#
# You can find more information and examples here:
#   1. https://lldb.llvm.org/varformats.html
#   2. https://lldb.llvm.org/use/python-reference.html
#   3. https://github.com/llvm/llvm-project/blob/llvmorg-8.0.1/lldb/www/python_reference/lldb.formatters.cpp-pysrc.html
#   4. https://github.com/llvm-mirror/lldb/tree/master/examples/summaries/cocoa
####################################################################################################

PY3 = sys.version_info[0] == 3


class LLDBOpaque:
    """
    An marker type for use in type hints to denote LLDB bookkeeping variables. Values marked with
    this type should never be used except when passing as an argument to an LLDB function.
    """


class ValueBuilder:
    def __init__(self, valobj: SBValue):
        self.valobj = valobj
        process = valobj.GetProcess()
        self.endianness = process.GetByteOrder()
        self.pointer_size = process.GetAddressByteSize()

    def from_int(self, name: str, value: int) -> SBValue:
        type = self.valobj.GetType().GetBasicType(eBasicTypeLong)
        data = SBData.CreateDataFromSInt64Array(
            self.endianness, self.pointer_size, [value]
        )
        return self.valobj.CreateValueFromData(name, data, type)

    def from_uint(self, name: str, value: int) -> SBValue:
        type = self.valobj.GetType().GetBasicType(eBasicTypeUnsignedLong)
        data = SBData.CreateDataFromUInt64Array(
            self.endianness, self.pointer_size, [value]
        )
        return self.valobj.CreateValueFromData(name, data, type)


def unwrap_unique_or_non_null(unique_or_nonnull: SBValue) -> SBValue:
    # BACKCOMPAT: rust 1.32
    # https://github.com/rust-lang/rust/commit/7a0911528058e87d22ea305695f4047572c5e067
    # BACKCOMPAT: rust 1.60
    # https://github.com/rust-lang/rust/commit/2a91eeac1a2d27dd3de1bf55515d765da20fd86f
    ptr = unique_or_nonnull.GetChildMemberWithName("pointer")
    return ptr if ptr.TypeIsPointerType() else ptr.GetChildAtIndex(0)


class DefaultSyntheticProvider:
    def __init__(self, valobj: SBValue, _dict: LLDBOpaque):
        # logger = Logger.Logger()
        # logger >> "Default synthetic provider for " + str(valobj.GetName())
        self.valobj = valobj

    def num_children(self) -> int:
        return self.valobj.GetNumChildren()

    def get_child_index(self, name: str) -> int:
        return self.valobj.GetIndexOfChildWithName(name)

    def get_child_at_index(self, index: int) -> SBValue:
        return self.valobj.GetChildAtIndex(index)

    def update(self):
        pass

    def has_children(self) -> bool:
        return self.valobj.MightHaveChildren()


class EmptySyntheticProvider:
    def __init__(self, valobj: SBValue, _dict: LLDBOpaque):
        # logger = Logger.Logger()
        # logger >> "[EmptySyntheticProvider] for " + str(valobj.GetName())
        self.valobj = valobj

    def num_children(self) -> int:
        return 0

    def get_child_index(self, name: str) -> int:
        return -1

    def get_child_at_index(self, index: int) -> SBValue:
        return None

    def update(self):
        pass

    def has_children(self) -> bool:
        return False


def SizeSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    return "size=" + str(valobj.GetNumChildren())


def vec_to_string(vec: SBValue) -> str:
    length = vec.GetNumChildren()
    chars = [vec.GetChildAtIndex(i).GetValueAsUnsigned() for i in range(length)]
    return (
        bytes(chars).decode(errors="replace")
        if PY3
        else "".join(chr(char) for char in chars)
    )


def StdStringSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    # logger = Logger.Logger()
    # logger >> "[StdStringSummaryProvider] for " + str(valobj.GetName())
    vec = valobj.GetChildAtIndex(0)
    return '"%s"' % vec_to_string(vec)


def StdOsStringSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    # logger = Logger.Logger()
    # logger >> "[StdOsStringSummaryProvider] for " + str(valobj.GetName())
    buf = valobj.GetChildAtIndex(0).GetChildAtIndex(0)
    is_windows = "Wtf8Buf" in buf.type.name
    vec = buf.GetChildAtIndex(0) if is_windows else buf
    return '"%s"' % vec_to_string(vec)


def StdStrSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    # logger = Logger.Logger()
    # logger >> "[StdStrSummaryProvider] for " + str(valobj.GetName())

    # the code below assumes non-synthetic value, this makes sure the assumption holds
    valobj = valobj.GetNonSyntheticValue()

    length = valobj.GetChildMemberWithName("length").GetValueAsUnsigned()
    if length == 0:
        return '""'

    data_ptr = valobj.GetChildMemberWithName("data_ptr")

    start = data_ptr.GetValueAsUnsigned()
    error = SBError()
    process = data_ptr.GetProcess()
    data = process.ReadMemory(start, length, error)
    data = data.decode(encoding="UTF-8") if PY3 else data
    return '"%s"' % data


def StdPathBufSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    # logger = Logger.Logger()
    # logger >> "[StdPathBufSummaryProvider] for " + str(valobj.GetName())
    return StdOsStringSummaryProvider(valobj.GetChildMemberWithName("inner"), _dict)


def StdPathSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    # logger = Logger.Logger()
    # logger >> "[StdPathSummaryProvider] for " + str(valobj.GetName())
    length = valobj.GetChildMemberWithName("length").GetValueAsUnsigned()
    if length == 0:
        return '""'

    data_ptr = valobj.GetChildMemberWithName("data_ptr")

    start = data_ptr.GetValueAsUnsigned()
    error = SBError()
    process = data_ptr.GetProcess()
    data = process.ReadMemory(start, length, error)
    if PY3:
        try:
            data = data.decode(encoding="UTF-8")
        except UnicodeDecodeError:
            return "%r" % data
    return '"%s"' % data


class StructSyntheticProvider:
    """Pretty-printer for structs and struct enum variants"""

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque, is_variant: bool = False):
        # logger = Logger.Logger()
        self.valobj = valobj
        self.is_variant = is_variant
        self.type = valobj.GetType()
        self.fields = {}

        if is_variant:
            self.fields_count = self.type.GetNumberOfFields() - 1
            real_fields = self.type.fields[1:]
        else:
            self.fields_count = self.type.GetNumberOfFields()
            real_fields = self.type.fields

        for number, field in enumerate(real_fields):
            self.fields[field.name] = number

    def num_children(self) -> int:
        return self.fields_count

    def get_child_index(self, name: str) -> int:
        return self.fields.get(name, -1)

    def get_child_at_index(self, index: int) -> SBValue:
        if self.is_variant:
            field = self.type.GetFieldAtIndex(index + 1)
        else:
            field = self.type.GetFieldAtIndex(index)
        return self.valobj.GetChildMemberWithName(field.name)

    def update(self):
        # type: () -> None
        pass

    def has_children(self) -> bool:
        return True


class ClangEncodedEnumProvider:
    """Pretty-printer for 'clang-encoded' enums support implemented in LLDB"""

    DISCRIMINANT_MEMBER_NAME = "$discr$"
    VALUE_MEMBER_NAME = "value"

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque):
        self.valobj = valobj
        self.update()

    def has_children(self) -> bool:
        return True

    def num_children(self) -> int:
        if self.is_default:
            return 1
        return 2

    def get_child_index(self, name: str) -> int:
        if name == ClangEncodedEnumProvider.VALUE_MEMBER_NAME:
            return 0
        if name == ClangEncodedEnumProvider.DISCRIMINANT_MEMBER_NAME:
            return 1
        return -1

    def get_child_at_index(self, index: int) -> SBValue:
        if index == 0:
            return self.variant.GetChildMemberWithName(
                ClangEncodedEnumProvider.VALUE_MEMBER_NAME
            )
        if index == 1:
            return self.variant.GetChildMemberWithName(
                ClangEncodedEnumProvider.DISCRIMINANT_MEMBER_NAME
            )

    def update(self):
        all_variants = self.valobj.GetChildAtIndex(0)
        index = self._getCurrentVariantIndex(all_variants)
        self.variant = all_variants.GetChildAtIndex(index)
        self.is_default = (
            self.variant.GetIndexOfChildWithName(
                ClangEncodedEnumProvider.DISCRIMINANT_MEMBER_NAME
            )
            == -1
        )

    def _getCurrentVariantIndex(self, all_variants: SBValue) -> int:
        default_index = 0
        for i in range(all_variants.GetNumChildren()):
            variant = all_variants.GetChildAtIndex(i)
            discr = variant.GetChildMemberWithName(
                ClangEncodedEnumProvider.DISCRIMINANT_MEMBER_NAME
            )
            if discr.IsValid():
                discr_unsigned_value = discr.GetValueAsUnsigned()
                if variant.GetName() == f"$variant${discr_unsigned_value}":
                    return i
            else:
                default_index = i
        return default_index


class TupleSyntheticProvider:
    """Pretty-printer for tuples and tuple enum variants"""

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque, is_variant: bool = False):
        # logger = Logger.Logger()
        self.valobj = valobj
        self.is_variant = is_variant
        self.type = valobj.GetType()

        if is_variant:
            self.size = self.type.GetNumberOfFields() - 1
        else:
            self.size = self.type.GetNumberOfFields()

    def num_children(self) -> int:
        return self.size

    def get_child_index(self, name: str) -> int:
        if name.isdigit():
            return int(name)
        else:
            return -1

    def get_child_at_index(self, index: int) -> SBValue:
        if self.is_variant:
            field = self.type.GetFieldAtIndex(index + 1)
        else:
            field = self.type.GetFieldAtIndex(index)
        element = self.valobj.GetChildMemberWithName(field.name)
        return self.valobj.CreateValueFromData(
            str(index), element.GetData(), element.GetType()
        )

    def update(self):
        pass

    def has_children(self) -> bool:
        return True


class StdVecSyntheticProvider:
    """Pretty-printer for alloc::vec::Vec<T>

    struct Vec<T> { buf: RawVec<T>, len: usize }
    rust 1.75: struct RawVec<T> { ptr: Unique<T>, cap: usize, ... }
    rust 1.76: struct RawVec<T> { ptr: Unique<T>, cap: Cap(usize), ... }
    rust 1.31.1: struct Unique<T: ?Sized> { pointer: NonZero<*const T>, ... }
    rust 1.33.0: struct Unique<T: ?Sized> { pointer: *const T, ... }
    rust 1.62.0: struct Unique<T: ?Sized> { pointer: NonNull<T>, ... }
    struct NonZero<T>(T)
    struct NonNull<T> { pointer: *const T }
    """

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque):
        # logger = Logger.Logger()
        # logger >> "[StdVecSyntheticProvider] for " + str(valobj.GetName())
        self.valobj = valobj
        self.update()

    def num_children(self) -> int:
        return self.length

    def get_child_index(self, name: str) -> int:
        index = name.lstrip("[").rstrip("]")
        if index.isdigit():
            return int(index)
        else:
            return -1

    def get_child_at_index(self, index: int) -> SBValue:
        start = self.data_ptr.GetValueAsUnsigned()
        address = start + index * self.element_type_size
        element = self.data_ptr.CreateValueFromAddress(
            "[%s]" % index, address, self.element_type
        )
        return element

    def update(self):
        self.length = self.valobj.GetChildMemberWithName("len").GetValueAsUnsigned()
        self.buf = self.valobj.GetChildMemberWithName("buf").GetChildMemberWithName(
            "inner"
        )

        self.data_ptr = unwrap_unique_or_non_null(
            self.buf.GetChildMemberWithName("ptr")
        )

        self.element_type = self.valobj.GetType().GetTemplateArgumentType(0)
        self.element_type_size = self.element_type.GetByteSize()

    def has_children(self) -> bool:
        return True


class StdSliceSyntheticProvider:
    def __init__(self, valobj: SBValue, _dict: LLDBOpaque):
        self.valobj = valobj
        self.update()

    def num_children(self) -> int:
        return self.length

    def get_child_index(self, name: str) -> int:
        index = name.lstrip("[").rstrip("]")
        if index.isdigit():
            return int(index)
        else:
            return -1

    def get_child_at_index(self, index: int) -> SBValue:
        start = self.data_ptr.GetValueAsUnsigned()
        address = start + index * self.element_type_size
        element = self.data_ptr.CreateValueFromAddress(
            "[%s]" % index, address, self.element_type
        )
        return element

    def update(self):
        self.length = self.valobj.GetChildMemberWithName("length").GetValueAsUnsigned()
        self.data_ptr = self.valobj.GetChildMemberWithName("data_ptr")

        self.element_type = self.data_ptr.GetType().GetPointeeType()
        self.element_type_size = self.element_type.GetByteSize()

    def has_children(self) -> bool:
        return True


class StdVecDequeSyntheticProvider:
    """Pretty-printer for alloc::collections::vec_deque::VecDeque<T>

    struct VecDeque<T> { head: usize, len: usize, buf: RawVec<T> }
    """

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque):
        # logger = Logger.Logger()
        # logger >> "[StdVecDequeSyntheticProvider] for " + str(valobj.GetName())
        self.valobj = valobj
        self.update()

    def num_children(self) -> int:
        return self.size

    def get_child_index(self, name: str) -> int:
        index = name.lstrip("[").rstrip("]")
        if index.isdigit() and int(index) < self.size:
            return int(index)
        else:
            return -1

    def get_child_at_index(self, index: int) -> SBValue:
        start = self.data_ptr.GetValueAsUnsigned()
        address = start + ((index + self.head) % self.cap) * self.element_type_size
        element = self.data_ptr.CreateValueFromAddress(
            "[%s]" % index, address, self.element_type
        )
        return element

    def update(self):
        self.head = self.valobj.GetChildMemberWithName("head").GetValueAsUnsigned()
        self.size = self.valobj.GetChildMemberWithName("len").GetValueAsUnsigned()
        self.buf = self.valobj.GetChildMemberWithName("buf").GetChildMemberWithName(
            "inner"
        )
        cap = self.buf.GetChildMemberWithName("cap")
        if cap.GetType().num_fields == 1:
            cap = cap.GetChildAtIndex(0)
        self.cap = cap.GetValueAsUnsigned()

        self.data_ptr = unwrap_unique_or_non_null(
            self.buf.GetChildMemberWithName("ptr")
        )

        self.element_type = self.valobj.GetType().GetTemplateArgumentType(0)
        self.element_type_size = self.element_type.GetByteSize()

    def has_children(self) -> bool:
        return True


# BACKCOMPAT: rust 1.35
class StdOldHashMapSyntheticProvider:
    """Pretty-printer for std::collections::hash::map::HashMap<K, V, S>

    struct HashMap<K, V, S> {..., table: RawTable<K, V>, ... }
    struct RawTable<K, V> { capacity_mask: usize, size: usize, hashes: TaggedHashUintPtr, ... }
    """

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque, show_values: bool = True):
        self.valobj = valobj
        self.show_values = show_values
        self.update()

    def num_children(self) -> int:
        return self.size

    def get_child_index(self, name: str) -> int:
        index = name.lstrip("[").rstrip("]")
        if index.isdigit():
            return int(index)
        else:
            return -1

    def get_child_at_index(self, index: int) -> SBValue:
        # logger = Logger.Logger()
        start = self.data_ptr.GetValueAsUnsigned() & ~1

        # See `libstd/collections/hash/table.rs:raw_bucket_at
        hashes = self.hash_uint_size * self.capacity
        align = self.pair_type_size
        # See `libcore/alloc.rs:padding_needed_for`
        len_rounded_up = (
            (
                (((hashes + align) % self.modulo - 1) % self.modulo)
                & ~((align - 1) % self.modulo)
            )
            % self.modulo
            - hashes
        ) % self.modulo
        # len_rounded_up = ((hashes + align - 1) & ~(align - 1)) - hashes

        pairs_offset = hashes + len_rounded_up
        pairs_start = start + pairs_offset

        table_index = self.valid_indices[index]
        idx = table_index & self.capacity_mask
        address = pairs_start + idx * self.pair_type_size
        element = self.data_ptr.CreateValueFromAddress(
            "[%s]" % index, address, self.pair_type
        )
        if self.show_values:
            return element
        else:
            key = element.GetChildAtIndex(0)
            return self.valobj.CreateValueFromData(
                "[%s]" % index, key.GetData(), key.GetType()
            )

    def update(self):
        # logger = Logger.Logger()

        self.table = self.valobj.GetChildMemberWithName("table")  # type: SBValue
        self.size = self.table.GetChildMemberWithName("size").GetValueAsUnsigned()
        self.hashes = self.table.GetChildMemberWithName("hashes")
        self.hash_uint_type = self.hashes.GetType()
        self.hash_uint_size = self.hashes.GetType().GetByteSize()
        self.modulo = 2**self.hash_uint_size
        self.data_ptr = self.hashes.GetChildAtIndex(0).GetChildAtIndex(0)

        self.capacity_mask = self.table.GetChildMemberWithName(
            "capacity_mask"
        ).GetValueAsUnsigned()
        self.capacity = (self.capacity_mask + 1) % self.modulo

        marker = self.table.GetChildMemberWithName("marker").GetType()  # type: SBType
        self.pair_type = marker.template_args[0]
        self.pair_type_size = self.pair_type.GetByteSize()

        self.valid_indices = []
        for idx in range(self.capacity):
            address = self.data_ptr.GetValueAsUnsigned() + idx * self.hash_uint_size
            hash_uint = self.data_ptr.CreateValueFromAddress(
                "[%s]" % idx, address, self.hash_uint_type
            )
            hash_ptr = hash_uint.GetChildAtIndex(0).GetChildAtIndex(0)
            if hash_ptr.GetValueAsUnsigned() != 0:
                self.valid_indices.append(idx)

        # logger >> "Valid indices: {}".format(str(self.valid_indices))

    def has_children(self) -> bool:
        return True


class StdHashMapSyntheticProvider:
    """Pretty-printer for hashbrown's HashMap"""

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque, show_values: bool = True):
        self.valobj = valobj
        self.show_values = show_values
        self.update()

    def num_children(self) -> int:
        return self.size

    def get_child_index(self, name: str) -> int:
        index = name.lstrip("[").rstrip("]")
        if index.isdigit():
            return int(index)
        else:
            return -1

    def get_child_at_index(self, index: int) -> SBValue:
        pairs_start = self.data_ptr.GetValueAsUnsigned()
        idx = self.valid_indices[index]
        if self.new_layout:
            idx = -(idx + 1)
        address = pairs_start + idx * self.pair_type_size
        element = self.data_ptr.CreateValueFromAddress(
            "[%s]" % index, address, self.pair_type
        )
        if self.show_values:
            return element
        else:
            key = element.GetChildAtIndex(0)
            return self.valobj.CreateValueFromData(
                "[%s]" % index, key.GetData(), key.GetType()
            )

    def update(self):
        table = self.table()
        inner_table = table.GetChildMemberWithName("table")

        capacity = (
            inner_table.GetChildMemberWithName("bucket_mask").GetValueAsUnsigned() + 1
        )
        ctrl = inner_table.GetChildMemberWithName("ctrl").GetChildAtIndex(0)

        self.size = inner_table.GetChildMemberWithName("items").GetValueAsUnsigned()
        self.pair_type = table.type.template_args[0]
        if self.pair_type.IsTypedefType():
            self.pair_type = self.pair_type.GetTypedefedType()
        self.pair_type_size = self.pair_type.GetByteSize()

        self.new_layout = not inner_table.GetChildMemberWithName("data").IsValid()
        if self.new_layout:
            self.data_ptr = ctrl.Cast(self.pair_type.GetPointerType())
        else:
            self.data_ptr = inner_table.GetChildMemberWithName("data").GetChildAtIndex(
                0
            )

        u8_type = self.valobj.GetTarget().GetBasicType(eBasicTypeUnsignedChar)
        u8_type_size = (
            self.valobj.GetTarget().GetBasicType(eBasicTypeUnsignedChar).GetByteSize()
        )

        self.valid_indices = []
        for idx in range(capacity):
            address = ctrl.GetValueAsUnsigned() + idx * u8_type_size
            value = ctrl.CreateValueFromAddress(
                "ctrl[%s]" % idx, address, u8_type
            ).GetValueAsUnsigned()
            is_present = value & 128 == 0
            if is_present:
                self.valid_indices.append(idx)

    def table(self) -> SBValue:
        if self.show_values:
            hashbrown_hashmap = self.valobj.GetChildMemberWithName("base")
        else:
            # BACKCOMPAT: rust 1.47
            # HashSet wraps either std HashMap or hashbrown::HashSet, which both
            # wrap hashbrown::HashMap, so either way we "unwrap" twice.
            hashbrown_hashmap = self.valobj.GetChildAtIndex(0).GetChildAtIndex(0)
        return hashbrown_hashmap.GetChildMemberWithName("table")

    def has_children(self) -> bool:
        return True


def StdRcSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    strong = valobj.GetChildMemberWithName("strong").GetValueAsUnsigned()
    weak = valobj.GetChildMemberWithName("weak").GetValueAsUnsigned()
    return "strong={}, weak={}".format(strong, weak)


class StdRcSyntheticProvider:
    """Pretty-printer for alloc::rc::Rc<T> and alloc::sync::Arc<T>

    struct Rc<T> { ptr: NonNull<RcInner<T>>, ... }
    rust 1.31.1: struct NonNull<T> { pointer: NonZero<*const T> }
    rust 1.33.0: struct NonNull<T> { pointer: *const T }
    struct NonZero<T>(T)
    struct RcInner<T> { strong: Cell<usize>, weak: Cell<usize>, value: T }
    struct Cell<T> { value: UnsafeCell<T> }
    struct UnsafeCell<T> { value: T }

    struct Arc<T> { ptr: NonNull<ArcInner<T>>, ... }
    struct ArcInner<T> { strong: atomic::AtomicUsize, weak: atomic::AtomicUsize, data: T }
    struct AtomicUsize { v: UnsafeCell<usize> }
    """

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque, is_atomic: bool = False):
        self.valobj = valobj

        self.ptr = unwrap_unique_or_non_null(self.valobj.GetChildMemberWithName("ptr"))

        self.value = self.ptr.GetChildMemberWithName("data" if is_atomic else "value")

        self.strong = (
            self.ptr.GetChildMemberWithName("strong")
            .GetChildAtIndex(0)
            .GetChildMemberWithName("value")
        )
        self.weak = (
            self.ptr.GetChildMemberWithName("weak")
            .GetChildAtIndex(0)
            .GetChildMemberWithName("value")
        )

        self.value_builder = ValueBuilder(valobj)

        self.update()

    def num_children(self) -> int:
        # Actually there are 3 children, but only the `value` should be shown as a child
        return 1

    def get_child_index(self, name: str) -> int:
        if name == "value":
            return 0
        if name == "strong":
            return 1
        if name == "weak":
            return 2
        return -1

    def get_child_at_index(self, index: int) -> SBValue:
        if index == 0:
            return self.value
        if index == 1:
            return self.value_builder.from_uint("strong", self.strong_count)
        if index == 2:
            return self.value_builder.from_uint("weak", self.weak_count)

        return None

    def update(self):
        self.strong_count = self.strong.GetValueAsUnsigned()
        self.weak_count = self.weak.GetValueAsUnsigned() - 1

    def has_children(self) -> bool:
        return True


class StdCellSyntheticProvider:
    """Pretty-printer for std::cell::Cell"""

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque):
        self.valobj = valobj
        self.value = valobj.GetChildMemberWithName("value").GetChildAtIndex(0)

    def num_children(self) -> int:
        return 1

    def get_child_index(self, name: str) -> int:
        if name == "value":
            return 0
        return -1

    def get_child_at_index(self, index: int) -> SBValue:
        if index == 0:
            return self.value
        return None

    def update(self):
        pass

    def has_children(self) -> bool:
        return True


def StdRefSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    borrow = valobj.GetChildMemberWithName("borrow").GetValueAsSigned()
    return (
        "borrow={}".format(borrow) if borrow >= 0 else "borrow_mut={}".format(-borrow)
    )


class StdRefSyntheticProvider:
    """Pretty-printer for std::cell::Ref, std::cell::RefMut, and std::cell::RefCell"""

    def __init__(self, valobj: SBValue, _dict: LLDBOpaque, is_cell: bool = False):
        self.valobj = valobj

        borrow = valobj.GetChildMemberWithName("borrow")
        value = valobj.GetChildMemberWithName("value")
        if is_cell:
            self.borrow = borrow.GetChildMemberWithName("value").GetChildMemberWithName(
                "value"
            )
            self.value = value.GetChildMemberWithName("value")
        else:
            self.borrow = (
                borrow.GetChildMemberWithName("borrow")
                .GetChildMemberWithName("value")
                .GetChildMemberWithName("value")
            )
            self.value = value.Dereference()

        self.value_builder = ValueBuilder(valobj)

        self.update()

    def num_children(self) -> int:
        # Actually there are 2 children, but only the `value` should be shown as a child
        return 1

    def get_child_index(self, name: str) -> int:
        if name == "value":
            return 0
        if name == "borrow":
            return 1
        return -1

    def get_child_at_index(self, index: int) -> SBValue:
        if index == 0:
            return self.value
        if index == 1:
            return self.value_builder.from_int("borrow", self.borrow_count)
        return None

    def update(self):
        self.borrow_count = self.borrow.GetValueAsSigned()

    def has_children(self) -> bool:
        return True


def StdNonZeroNumberSummaryProvider(valobj: SBValue, _dict: LLDBOpaque) -> str:
    inner = valobj.GetChildAtIndex(0)
    inner_inner = inner.GetChildAtIndex(0)

    # FIXME: Avoid printing as character literal,
    #        see https://github.com/llvm/llvm-project/issues/65076.
    if inner_inner.GetTypeName() in ["char", "unsigned char"]:
        return str(inner_inner.GetValueAsSigned())
    else:
        return inner_inner.GetValue()