1//===-- LibCxxSliceArray.cpp-----------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "LibCxx.h"
10
11#include "lldb/Core/ValueObject.h"
12#include "lldb/DataFormatters/FormattersHelpers.h"
13#include <optional>
14
15using namespace lldb;
16using namespace lldb_private;
17using namespace lldb_private::formatters;
18
19namespace lldb_private {
20namespace formatters {
21
22bool LibcxxStdSliceArraySummaryProvider(ValueObject &valobj, Stream &stream,
23 const TypeSummaryOptions &options) {
24 ValueObjectSP obj = valobj.GetNonSyntheticValue();
25 if (!obj)
26 return false;
27
28 ValueObjectSP ptr_sp = obj->GetChildMemberWithName(name: "__size_");
29 if (!ptr_sp)
30 return false;
31 const size_t size = ptr_sp->GetValueAsUnsigned(fail_value: 0);
32
33 ptr_sp = obj->GetChildMemberWithName(name: "__stride_");
34 if (!ptr_sp)
35 return false;
36 const size_t stride = ptr_sp->GetValueAsUnsigned(fail_value: 0);
37
38 stream.Printf(format: "stride=%zu size=%zu", stride, size);
39
40 return true;
41}
42
43/// Data formatter for libc++'s std::slice_array.
44///
45/// A slice_array is created by using:
46/// operator[](std::slice slicearr);
47/// and std::slice is created by:
48/// slice(std::size_t start, std::size_t size, std::size_t stride);
49/// The std::slice_array has the following members:
50/// - __vp_ points to std::valarray::__begin_ + @a start
51/// - __size_ is @a size
52/// - __stride_is @a stride
53class LibcxxStdSliceArraySyntheticFrontEnd : public SyntheticChildrenFrontEnd {
54public:
55 LibcxxStdSliceArraySyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
56
57 ~LibcxxStdSliceArraySyntheticFrontEnd() override;
58
59 llvm::Expected<uint32_t> CalculateNumChildren() override;
60
61 lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override;
62
63 lldb::ChildCacheState Update() override;
64
65 bool MightHaveChildren() override;
66
67 size_t GetIndexOfChildWithName(ConstString name) override;
68
69private:
70 /// A non-owning pointer to slice_array.__vp_.
71 ValueObject *m_start = nullptr;
72 /// slice_array.__size_.
73 size_t m_size = 0;
74 /// slice_array.__stride_.
75 size_t m_stride = 0;
76 /// The type of slice_array's template argument T.
77 CompilerType m_element_type;
78 /// The sizeof slice_array's template argument T.
79 uint32_t m_element_size = 0;
80};
81
82} // namespace formatters
83} // namespace lldb_private
84
85lldb_private::formatters::LibcxxStdSliceArraySyntheticFrontEnd::
86 LibcxxStdSliceArraySyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
87 : SyntheticChildrenFrontEnd(*valobj_sp), m_element_type() {
88 if (valobj_sp)
89 Update();
90}
91
92lldb_private::formatters::LibcxxStdSliceArraySyntheticFrontEnd::
93 ~LibcxxStdSliceArraySyntheticFrontEnd() {
94 // these need to stay around because they are child objects who will follow
95 // their parent's life cycle
96 // delete m_start;
97}
98
99llvm::Expected<uint32_t> lldb_private::formatters::
100 LibcxxStdSliceArraySyntheticFrontEnd::CalculateNumChildren() {
101 return m_size;
102}
103
104lldb::ValueObjectSP
105lldb_private::formatters::LibcxxStdSliceArraySyntheticFrontEnd::GetChildAtIndex(
106 uint32_t idx) {
107 if (!m_start)
108 return lldb::ValueObjectSP();
109
110 uint64_t offset = idx * m_stride * m_element_size;
111 offset = offset + m_start->GetValueAsUnsigned(fail_value: 0);
112 StreamString name;
113 name.Printf(format: "[%" PRIu64 "]", (uint64_t)idx);
114 return CreateValueObjectFromAddress(name: name.GetString(), address: offset,
115 exe_ctx: m_backend.GetExecutionContextRef(),
116 type: m_element_type);
117}
118
119lldb::ChildCacheState
120lldb_private::formatters::LibcxxStdSliceArraySyntheticFrontEnd::Update() {
121 m_start = nullptr;
122
123 CompilerType type = m_backend.GetCompilerType();
124 if (type.GetNumTemplateArguments() == 0)
125 return ChildCacheState::eRefetch;
126
127 m_element_type = type.GetTypeTemplateArgument(idx: 0);
128 if (std::optional<uint64_t> size = m_element_type.GetByteSize(exe_scope: nullptr))
129 m_element_size = *size;
130
131 if (m_element_size == 0)
132 return ChildCacheState::eRefetch;
133
134 ValueObjectSP start = m_backend.GetChildMemberWithName(name: "__vp_");
135 ValueObjectSP size = m_backend.GetChildMemberWithName(name: "__size_");
136 ValueObjectSP stride = m_backend.GetChildMemberWithName(name: "__stride_");
137
138 if (!start || !size || !stride)
139 return ChildCacheState::eRefetch;
140
141 m_start = start.get();
142 m_size = size->GetValueAsUnsigned(fail_value: 0);
143 m_stride = stride->GetValueAsUnsigned(fail_value: 0);
144
145 return ChildCacheState::eRefetch;
146}
147
148bool lldb_private::formatters::LibcxxStdSliceArraySyntheticFrontEnd::
149 MightHaveChildren() {
150 return true;
151}
152
153size_t lldb_private::formatters::LibcxxStdSliceArraySyntheticFrontEnd::
154 GetIndexOfChildWithName(ConstString name) {
155 if (!m_start)
156 return std::numeric_limits<size_t>::max();
157 return ExtractIndexFromString(item_name: name.GetCString());
158}
159
160lldb_private::SyntheticChildrenFrontEnd *
161lldb_private::formatters::LibcxxStdSliceArraySyntheticFrontEndCreator(
162 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
163 if (!valobj_sp)
164 return nullptr;
165 return new LibcxxStdSliceArraySyntheticFrontEnd(valobj_sp);
166}
167

source code of lldb/source/Plugins/Language/CPlusPlus/LibCxxSliceArray.cpp