clang 10.0.0git

ComparisonCategories.h
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1 //===- ComparisonCategories.h - Three Way Comparison Data -------*- C++ -*-===//
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 // This file defines the Comparison Category enum and data types, which
10 // store the types and expressions needed to support operator<=>
11 //
12 //===----------------------------------------------------------------------===//
13
14 #ifndef LLVM_CLANG_AST_COMPARISONCATEGORIES_H
15 #define LLVM_CLANG_AST_COMPARISONCATEGORIES_H
16
17 #include "clang/Basic/LLVM.h"
18 #include "llvm/ADT/APSInt.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include <array>
21 #include <cassert>
22
23 namespace llvm {
24 class StringRef;
25 class APSInt;
26 }
27
28 namespace clang {
29
30 class ASTContext;
31 class VarDecl;
32 class CXXRecordDecl;
33 class Sema;
34 class QualType;
35 class NamespaceDecl;
36
37 /// An enumeration representing the different comparison categories
38 /// types.
39 ///
40 /// C++2a [cmp.categories.pre] The types weak_equality, strong_equality,
41 /// partial_ordering, weak_ordering, and strong_ordering are collectively
42 /// termed the comparison category types.
43 enum class ComparisonCategoryType : unsigned char {
44 PartialOrdering,
45 WeakOrdering,
46 StrongOrdering,
47 First = PartialOrdering,
48 Last = StrongOrdering
49 };
50
51 /// Determine the common comparison type, as defined in C++2a
52 /// [class.spaceship]p4.
53 inline ComparisonCategoryType commonComparisonType(ComparisonCategoryType A,
54 ComparisonCategoryType B) {
55 return A < B ? A : B;
56 }
57
58 /// Get the comparison category that should be used when comparing values of
59 /// type \c T.
60 Optional<ComparisonCategoryType> getComparisonCategoryForBuiltinCmp(QualType T);
61
62 /// An enumeration representing the possible results of a three-way
63 /// comparison. These values map onto instances of comparison category types
64 /// defined in the standard library. e.g. 'std::strong_ordering::less'.
65 enum class ComparisonCategoryResult : unsigned char {
66 Equal,
67 Equivalent,
68 Less,
69 Greater,
70 Unordered,
71 Last = Unordered
72 };
73
74 class ComparisonCategoryInfo {
75 friend class ComparisonCategories;
76 friend class Sema;
77
78 public:
79 ComparisonCategoryInfo(const ASTContext &Ctx, CXXRecordDecl *RD,
80 ComparisonCategoryType Kind)
81 : Ctx(Ctx), Record(RD), Kind(Kind) {}
82
83 struct ValueInfo {
84 ComparisonCategoryResult Kind;
85 VarDecl *VD;
86
87 ValueInfo(ComparisonCategoryResult Kind, VarDecl *VD)
88 : Kind(Kind), VD(VD) {}
89
90 /// True iff we've successfully evaluated the variable as a constant
91 /// expression and extracted its integer value.
92 bool hasValidIntValue() const;
93
94 /// Get the constant integer value used by this variable to represent
95 /// the comparison category result type.
96 llvm::APSInt getIntValue() const;
97 };
98 private:
99 const ASTContext &Ctx;
100
101 /// A map containing the comparison category result decls from the
102 /// standard library. The key is a value of ComparisonCategoryResult.
103 mutable llvm::SmallVector<
104 ValueInfo, static_cast<unsigned>(ComparisonCategoryResult::Last) + 1>
105 Objects;
106
107 /// Lookup the ValueInfo struct for the specified ValueKind. If the
108 /// VarDecl for the value cannot be found, nullptr is returned.
109 ///
110 /// If the ValueInfo does not have a valid integer value the variable
111 /// is evaluated as a constant expression to determine that value.
112 ValueInfo *lookupValueInfo(ComparisonCategoryResult ValueKind) const;
113
114 public:
115 /// The declaration for the comparison category type from the
116 /// standard library.
117 // FIXME: Make this const
118 CXXRecordDecl *Record = nullptr;
119
120 /// The Kind of the comparison category type
121 ComparisonCategoryType Kind;
122
123 public:
124 QualType getType() const;
125
126 const ValueInfo *getValueInfo(ComparisonCategoryResult ValueKind) const {
127 ValueInfo *Info = lookupValueInfo(ValueKind);
128 assert(Info &&
129 "comparison category does not contain the specified result kind");
130 assert(Info->hasValidIntValue() &&
131 "couldn't determine the integer constant for this value");
132 return Info;
133 }
134
135 /// True iff the comparison is "strong". i.e. it checks equality and
136 /// not equivalence.
137 bool isStrong() const {
138 using CCK = ComparisonCategoryType;
139 return Kind == CCK::StrongOrdering;
140 }
141
142 /// True iff the comparison is not totally ordered.
143 bool isPartial() const {
144 using CCK = ComparisonCategoryType;
145 return Kind == CCK::PartialOrdering;
146 }
147
148 /// Converts the specified result kind into the the correct result kind
149 /// for this category. Specifically it lowers strong equality results to
150 /// weak equivalence if needed.
151 ComparisonCategoryResult makeWeakResult(ComparisonCategoryResult Res) const {
152 using CCR = ComparisonCategoryResult;
153 if (!isStrong() && Res == CCR::Equal)
154 return CCR::Equivalent;
155 return Res;
156 }
157
158 const ValueInfo *getEqualOrEquiv() const {
159 return getValueInfo(makeWeakResult(ComparisonCategoryResult::Equal));
160 }
161 const ValueInfo *getLess() const {
162 return getValueInfo(ComparisonCategoryResult::Less);
163 }
164 const ValueInfo *getGreater() const {
165 return getValueInfo(ComparisonCategoryResult::Greater);
166 }
167 const ValueInfo *getUnordered() const {
168 assert(isPartial());
169 return getValueInfo(ComparisonCategoryResult::Unordered);
170 }
171 };
172
173 class ComparisonCategories {
174 public:
175 static StringRef getCategoryString(ComparisonCategoryType Kind);
176 static StringRef getResultString(ComparisonCategoryResult Kind);
177
178 /// Return the list of results which are valid for the specified
179 /// comparison category type.
180 static std::vector<ComparisonCategoryResult>
181 getPossibleResultsForType(ComparisonCategoryType Type);
182
183 /// Return the comparison category information for the category
184 /// specified by 'Kind'.
185 const ComparisonCategoryInfo &getInfo(ComparisonCategoryType Kind) const {
186 const ComparisonCategoryInfo *Result = lookupInfo(Kind);
187 assert(Result != nullptr &&
188 "information for specified comparison category has not been built");
189 return *Result;
190 }
191
192 /// Return the comparison category information as specified by
193 /// `getCategoryForType(Ty)`. If the information is not already cached,
194 /// the declaration is looked up and a cache entry is created.
195 /// NOTE: Lookup is expected to succeed. Use lookupInfo if failure is
196 /// possible.
197 const ComparisonCategoryInfo &getInfoForType(QualType Ty) const;
198
199 public:
200 /// Return the cached comparison category information for the
201 /// specified 'Kind'. If no cache entry is present the comparison category
202 /// type is looked up. If lookup fails nullptr is returned. Otherwise, a
203 /// new cache entry is created and returned
204 const ComparisonCategoryInfo *lookupInfo(ComparisonCategoryType Kind) const;
205
206 ComparisonCategoryInfo *lookupInfo(ComparisonCategoryType Kind) {
207 const auto &This = *this;
208 return const_cast<ComparisonCategoryInfo *>(This.lookupInfo(Kind));
209 }
210
211 const ComparisonCategoryInfo *lookupInfoForType(QualType Ty) const;
212
213 private:
214 friend class ASTContext;
215
216 explicit ComparisonCategories(const ASTContext &Ctx) : Ctx(Ctx) {}
217
218 const ASTContext &Ctx;
219
220 /// A map from the ComparisonCategoryType (represented as 'char') to the
221 /// cached information for the specified category.
222 mutable llvm::DenseMap<char, ComparisonCategoryInfo> Data;
223 mutable NamespaceDecl *StdNS = nullptr;
224 };
225
226 } // namespace clang
227
228 #endif
clang::ComparisonCategoryInfo
Definition: ComparisonCategories.h:74
clang::ComparisonCategoryInfo::ValueInfo
Definition: ComparisonCategories.h:83
clang::QualType
A (possibly-)qualified type.
Definition: Type.h:654
llvm
Specialize PointerLikeTypeTraits to allow LazyGenerationalUpdatePtr to be placed into a PointerUnion...
Definition: Dominators.h:30
clang::ComparisonCategoryResult::Equal
clang::ComparisonCategoryResult::Greater
clang::ComparisonCategoryInfo::Kind
ComparisonCategoryType Kind
The Kind of the comparison category type.
Definition: ComparisonCategories.h:121
clang::Type
The base class of the type hierarchy.
Definition: Type.h:1450
clang::NamespaceDecl
Represent a C++ namespace.
Definition: Decl.h:497
clang::VarDecl
Represents a variable declaration or definition.
Definition: Decl.h:820
clang::interp::This
bool This(InterpState &S, CodePtr OpPC)
Definition: Interp.h:827
clang::ComparisonCategoryResult::Equivalent
clang::ComparisonCategoryType::PartialOrdering
clang::ASTContext
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:168
llvm::Optional
Definition: LLVM.h:37
clang::ComparisonCategoryInfo::ValueInfo::VD
VarDecl * VD
Definition: ComparisonCategories.h:85
clang::ComparisonCategoryResult
ComparisonCategoryResult
An enumeration representing the possible results of a three-way comparison.
Definition: ComparisonCategories.h:65
clang::ComparisonCategoryInfo::isPartial
bool isPartial() const
True iff the comparison is not totally ordered.
Definition: ComparisonCategories.h:143
LLVM.h
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
clang::ComparisonCategoryType::First
clang::ComparisonCategoryResult::Less
clang::ComparisonCategoryInfo::getValueInfo
const ValueInfo * getValueInfo(ComparisonCategoryResult ValueKind) const
Definition: ComparisonCategories.h:126
clang::ComparisonCategoryType::StrongOrdering
clang::Sema
Sema - This implements semantic analysis and AST building for C.
Definition: Sema.h:336
clang::ComparisonCategoryType::Last
clang::ComparisonCategoryType::WeakOrdering
clang::ComparisonCategoryInfo::ValueInfo::hasValidIntValue
bool hasValidIntValue() const
True iff we&#39;ve successfully evaluated the variable as a constant expression and extracted its integer...
Definition: ComparisonCategories.cpp:42
clang::ComparisonCategories
Definition: ComparisonCategories.h:173
clang::ComparisonCategoryInfo::getGreater
const ValueInfo * getGreater() const
Definition: ComparisonCategories.h:164
Kind
Kind
Definition: ChrootChecker.cpp:29
APSInt
llvm::APSInt APSInt
Definition: ByteCodeEmitter.cpp:18
clang::ComparisonCategoryInfo::getLess
const ValueInfo * getLess() const
Definition: ComparisonCategories.h:161
llvm::SmallVector
Definition: LLVM.h:35
clang::getComparisonCategoryForBuiltinCmp
Optional< ComparisonCategoryType > getComparisonCategoryForBuiltinCmp(QualType T)
Get the comparison category that should be used when comparing values of type T.
Definition: ComparisonCategories.cpp:23
clang::ComparisonCategories::lookupInfo
ComparisonCategoryInfo * lookupInfo(ComparisonCategoryType Kind)
Definition: ComparisonCategories.h:206
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:21
clang::ComparisonCategoryInfo::ComparisonCategoryInfo
ComparisonCategoryInfo(const ASTContext &Ctx, CXXRecordDecl *RD, ComparisonCategoryType Kind)
Definition: ComparisonCategories.h:79
clang::CXXRecordDecl
Represents a C++ struct/union/class.
Definition: DeclCXX.h:253
clang::ComparisonCategoryInfo::isStrong
bool isStrong() const
True iff the comparison is "strong".
Definition: ComparisonCategories.h:137
clang::ComparisonCategoryResult::Unordered
clang::ComparisonCategoryInfo::getEqualOrEquiv
const ValueInfo * getEqualOrEquiv() const
Definition: ComparisonCategories.h:158
clang::ComparisonCategories::getInfo
const ComparisonCategoryInfo & getInfo(ComparisonCategoryType Kind) const
Return the comparison category information for the category specified by &#39;Kind&#39;.
Definition: ComparisonCategories.h:185
clang::ComparisonCategoryInfo::ValueInfo::ValueInfo
ValueInfo(ComparisonCategoryResult Kind, VarDecl *VD)
Definition: ComparisonCategories.h:87
clang::ComparisonCategoryType
ComparisonCategoryType
An enumeration representing the different comparison categories types.
Definition: ComparisonCategories.h:43
clang::ComparisonCategoryInfo::getUnordered
const ValueInfo * getUnordered() const
Definition: ComparisonCategories.h:167
clang::commonComparisonType
ComparisonCategoryType commonComparisonType(ComparisonCategoryType A, ComparisonCategoryType B)
Determine the common comparison type, as defined in C++2a [class.spaceship]p4.
Definition: ComparisonCategories.h:53
clang::ComparisonCategoryInfo::ValueInfo::Kind
ComparisonCategoryResult Kind
Definition: ComparisonCategories.h:84
clang::ComparisonCategoryInfo::makeWeakResult
ComparisonCategoryResult makeWeakResult(ComparisonCategoryResult Res) const
Converts the specified result kind into the the correct result kind for this category.
Definition: ComparisonCategories.h:151