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 return HashValue < Sym.HashValue;
43 }
44
45 // The stored hash is truncated to RawSize bytes.
46 // This trades off memory against the number of symbols we can handle.
47 constexpr static size_t RawSize = 8;
48 llvm::StringRef raw() const;
49 static SymbolID fromRaw(llvm::StringRef);
50
51 // Returns a hex encoded string.
52 std::string str() const;
53 static llvm::Expected<SymbolID> fromStr(llvm::StringRef);
54
isNull()55 bool isNull() const { return *this == SymbolID(); }
56 explicit operator bool() const { return !isNull(); }
57
58 private:
59 std::array<uint8_t, RawSize> HashValue{};
60 };
61
hash_value(const SymbolID & ID)62 inline llvm::hash_code hash_value(const SymbolID &ID) {
63 // We already have a good hash, just return the first bytes.
64 static_assert(sizeof(size_t) <= SymbolID::RawSize,
65 "size_t longer than SHA1!");
66 size_t Result;
67 memcpy(&Result, ID.raw().data(), sizeof(size_t));
68 return llvm::hash_code(Result);
69 }
70
71 // Write SymbolID into the given stream. SymbolID is encoded as ID.str().
72 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const SymbolID &ID);
73
74 } // namespace clangd
75 } // namespace clang
76
77 namespace llvm {
78 // Support SymbolIDs as DenseMap keys.
79 template <> struct DenseMapInfo<clang::clangd::SymbolID> {
80 static inline clang::clangd::SymbolID getEmptyKey() {
81 static clang::clangd::SymbolID EmptyKey("EMPTYKEY");
82 return EmptyKey;
83 }
84 static inline clang::clangd::SymbolID getTombstoneKey() {
85 static clang::clangd::SymbolID TombstoneKey("TOMBSTONEKEY");
86 return TombstoneKey;
87 }
88 static unsigned getHashValue(const clang::clangd::SymbolID &Sym) {
89 return hash_value(Sym);
90 }
91 static bool isEqual(const clang::clangd::SymbolID &LHS,
92 const clang::clangd::SymbolID &RHS) {
93 return LHS == RHS;
94 }
95 };
96 } // namespace llvm
97
98 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
99