1 //===-- GenericOptional.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 "Generic.h"
10 #include "LibCxx.h"
11 #include "LibStdcpp.h"
12 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
13 #include "lldb/DataFormatters/FormattersHelpers.h"
14 #include "lldb/Target/Target.h"
15
16 using namespace lldb;
17 using namespace lldb_private;
18
GenericOptionalSummaryProvider(ValueObject & valobj,Stream & stream,const TypeSummaryOptions & options)19 bool lldb_private::formatters::GenericOptionalSummaryProvider(
20 ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
21 stream.Printf(" Has Value=%s ",
22 valobj.GetNumChildren() == 0 ? "false" : "true");
23
24 return true;
25 }
26
27 // Synthetic Children Provider
28 namespace {
29
30 class GenericOptionalFrontend : public SyntheticChildrenFrontEnd {
31 public:
32 enum class StdLib {
33 LibCxx,
34 LibStdcpp,
35 };
36
37 GenericOptionalFrontend(ValueObject &valobj, StdLib stdlib);
38
GetIndexOfChildWithName(ConstString name)39 size_t GetIndexOfChildWithName(ConstString name) override {
40 return formatters::ExtractIndexFromString(name.GetCString());
41 }
42
MightHaveChildren()43 bool MightHaveChildren() override { return true; }
CalculateNumChildren()44 size_t CalculateNumChildren() override { return m_has_value ? 1U : 0U; }
45
46 ValueObjectSP GetChildAtIndex(size_t idx) override;
47 bool Update() override;
48
49 private:
50 bool m_has_value = false;
51 StdLib m_stdlib;
52 };
53
54 } // namespace
55
GenericOptionalFrontend(ValueObject & valobj,StdLib stdlib)56 GenericOptionalFrontend::GenericOptionalFrontend(ValueObject &valobj,
57 StdLib stdlib)
58 : SyntheticChildrenFrontEnd(valobj), m_stdlib(stdlib) {
59 if (auto target_sp = m_backend.GetTargetSP()) {
60 Update();
61 }
62 }
63
Update()64 bool GenericOptionalFrontend::Update() {
65 ValueObjectSP engaged_sp;
66
67 if (m_stdlib == StdLib::LibCxx)
68 engaged_sp = m_backend.GetChildMemberWithName("__engaged_");
69 else if (m_stdlib == StdLib::LibStdcpp)
70 engaged_sp = m_backend.GetChildMemberWithName("_M_payload")
71 ->GetChildMemberWithName("_M_engaged");
72
73 if (!engaged_sp)
74 return false;
75
76 // _M_engaged/__engaged is a bool flag and is true if the optional contains a
77 // value. Converting it to unsigned gives us a size of 1 if it contains a
78 // value and 0 if not.
79 m_has_value = engaged_sp->GetValueAsUnsigned(0) != 0;
80
81 return false;
82 }
83
GetChildAtIndex(size_t _idx)84 ValueObjectSP GenericOptionalFrontend::GetChildAtIndex(size_t _idx) {
85 if (!m_has_value)
86 return ValueObjectSP();
87
88 ValueObjectSP val_sp;
89
90 if (m_stdlib == StdLib::LibCxx)
91 // __val_ contains the underlying value of an optional if it has one.
92 // Currently because it is part of an anonymous union
93 // GetChildMemberWithName() does not peer through and find it unless we are
94 // at the parent itself. We can obtain the parent through __engaged_.
95 val_sp = m_backend.GetChildMemberWithName("__engaged_")
96 ->GetParent()
97 ->GetChildAtIndex(0)
98 ->GetChildMemberWithName("__val_");
99 else if (m_stdlib == StdLib::LibStdcpp) {
100 val_sp = m_backend.GetChildMemberWithName("_M_payload")
101 ->GetChildMemberWithName("_M_payload");
102
103 // In some implementations, _M_value contains the underlying value of an
104 // optional, and in other versions, it's in the payload member.
105 ValueObjectSP candidate = val_sp->GetChildMemberWithName("_M_value");
106 if (candidate)
107 val_sp = candidate;
108 }
109
110 if (!val_sp)
111 return ValueObjectSP();
112
113 CompilerType holder_type = val_sp->GetCompilerType();
114
115 if (!holder_type)
116 return ValueObjectSP();
117
118 return val_sp->Clone(ConstString("Value"));
119 }
120
121 SyntheticChildrenFrontEnd *
LibStdcppOptionalSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)122 formatters::LibStdcppOptionalSyntheticFrontEndCreator(
123 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
124 if (valobj_sp)
125 return new GenericOptionalFrontend(
126 *valobj_sp, GenericOptionalFrontend::StdLib::LibStdcpp);
127 return nullptr;
128 }
129
LibcxxOptionalSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)130 SyntheticChildrenFrontEnd *formatters::LibcxxOptionalSyntheticFrontEndCreator(
131 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
132 if (valobj_sp)
133 return new GenericOptionalFrontend(*valobj_sp,
134 GenericOptionalFrontend::StdLib::LibCxx);
135 return nullptr;
136 }
137