clang-tools  16.0.0git
SymbolID.h
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1 //===--- SymbolID.h ----------------------------------------------*- 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 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
10 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
11 
12 #include "llvm/ADT/Hashing.h"
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/Support/Error.h"
15 #include "llvm/Support/raw_ostream.h"
16 #include <array>
17 #include <cstddef>
18 #include <cstdint>
19 #include <string>
20 
21 namespace clang {
22 namespace clangd {
23 
24 // The class identifies a particular C++ symbol (class, function, method, etc).
25 //
26 // As USRs (Unified Symbol Resolution) could be large, especially for functions
27 // with long type arguments, SymbolID is using truncated SHA1(USR) values to
28 // guarantee the uniqueness of symbols while using a relatively small amount of
29 // memory (vs storing USRs directly).
30 //
31 // SymbolID can be used as key in the symbol indexes to lookup the symbol.
32 class SymbolID {
33 public:
34  SymbolID() = default;
35  explicit SymbolID(llvm::StringRef USR);
36 
37  bool operator==(const SymbolID &Sym) const {
38  return HashValue == Sym.HashValue;
39  }
40  bool operator!=(const SymbolID &Sym) const { return !(*this == Sym); }
41  bool operator<(const SymbolID &Sym) const {
42  // Avoid lexicographic compare which requires swapping bytes or even memcmp!
43  return llvm::bit_cast<IntTy>(HashValue) <
44  llvm::bit_cast<IntTy>(Sym.HashValue);
45  }
46 
47  // The stored hash is truncated to RawSize bytes.
48  // This trades off memory against the number of symbols we can handle.
49  constexpr static size_t RawSize = 8;
50  llvm::StringRef raw() const;
51  static SymbolID fromRaw(llvm::StringRef);
52 
53  // Returns a hex encoded string.
54  std::string str() const;
55  static llvm::Expected<SymbolID> fromStr(llvm::StringRef);
56 
57  bool isNull() const { return *this == SymbolID(); }
58  explicit operator bool() const { return !isNull(); }
59 
60 private:
61  using IntTy = uint64_t;
62  static_assert(sizeof(IntTy) == RawSize);
63  std::array<uint8_t, RawSize> HashValue{};
64 };
65 
66 inline llvm::hash_code hash_value(const SymbolID &ID) {
67  // We already have a good hash, just return the first bytes.
68  static_assert(sizeof(size_t) <= SymbolID::RawSize,
69  "size_t longer than SHA1!");
70  size_t Result;
71  memcpy(&Result, ID.raw().data(), sizeof(size_t));
72  return llvm::hash_code(Result);
73 }
74 
75 // Write SymbolID into the given stream. SymbolID is encoded as ID.str().
76 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const SymbolID &ID);
77 
78 } // namespace clangd
79 } // namespace clang
80 
81 namespace llvm {
82 // Support SymbolIDs as DenseMap keys.
83 template <> struct DenseMapInfo<clang::clangd::SymbolID> {
85  static clang::clangd::SymbolID EmptyKey("EMPTYKEY");
86  return EmptyKey;
87  }
89  static clang::clangd::SymbolID TombstoneKey("TOMBSTONEKEY");
90  return TombstoneKey;
91  }
92  static unsigned getHashValue(const clang::clangd::SymbolID &Sym) {
93  return hash_value(Sym);
94  }
95  static bool isEqual(const clang::clangd::SymbolID &LHS,
96  const clang::clangd::SymbolID &RHS) {
97  return LHS == RHS;
98  }
99 };
100 } // namespace llvm
101 
102 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
llvm
Some operations such as code completion produce a set of candidates.
Definition: YAMLGenerator.cpp:31
USR
std::string USR
Definition: SymbolInfoTests.cpp:25
llvm::DenseMapInfo< clang::clangd::SymbolID >::isEqual
static bool isEqual(const clang::clangd::SymbolID &LHS, const clang::clangd::SymbolID &RHS)
Definition: SymbolID.h:95
clang::clangd::SymbolID::operator<
bool operator<(const SymbolID &Sym) const
Definition: SymbolID.h:41
llvm::DenseMapInfo< clang::clangd::SymbolID >::getHashValue
static unsigned getHashValue(const clang::clangd::SymbolID &Sym)
Definition: SymbolID.h:92
clang::clangd::hash_value
llvm::hash_code hash_value(const SymbolID &ID)
Definition: SymbolID.h:66
llvm::DenseMapInfo< clang::clangd::SymbolID >::getEmptyKey
static clang::clangd::SymbolID getEmptyKey()
Definition: SymbolID.h:84
clang::clangd::SymbolID::isNull
bool isNull() const
Definition: SymbolID.h:57
clang::clangd::SymbolID::RawSize
constexpr static size_t RawSize
Definition: SymbolID.h:49
clang::doc::SymbolID
std::array< uint8_t, 20 > SymbolID
Definition: Representation.h:31
clang::clangd::SymbolID::str
std::string str() const
Definition: SymbolID.cpp:34
clang::clangd::SymbolID::operator==
bool operator==(const SymbolID &Sym) const
Definition: SymbolID.h:37
clang::clangd::operator<<
llvm::raw_ostream & operator<<(llvm::raw_ostream &OS, const CodeCompletion &C)
Definition: CodeComplete.cpp:2217
llvm::DenseMapInfo< clang::clangd::SymbolID >::getTombstoneKey
static clang::clangd::SymbolID getTombstoneKey()
Definition: SymbolID.h:88
ID
static char ID
Definition: Logger.cpp:74
clang::clangd::SymbolID::fromRaw
static SymbolID fromRaw(llvm::StringRef)
Definition: SymbolID.cpp:27
clang::clangd::SymbolID::fromStr
static llvm::Expected< SymbolID > fromStr(llvm::StringRef)
Definition: SymbolID.cpp:36
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
OS
llvm::raw_string_ostream OS
Definition: TraceTests.cpp:160
clang::clangd::SymbolID::SymbolID
SymbolID()=default
clang::clangd::SymbolID::operator!=
bool operator!=(const SymbolID &Sym) const
Definition: SymbolID.h:40
clang::clangd::SymbolID::raw
llvm::StringRef raw() const
Definition: SymbolID.cpp:22
clang::clangd::SymbolID
Definition: SymbolID.h:32