1 //===--- StringView.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 // FIXME: Use std::string_view instead when we support C++17. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_DEMANGLE_STRINGVIEW_H 14 #define LLVM_DEMANGLE_STRINGVIEW_H 15 16 #include "DemangleConfig.h" 17 #include <algorithm> 18 #include <cassert> 19 #include <cstring> 20 21 DEMANGLE_NAMESPACE_BEGIN 22 23 class StringView { 24 const char *First; 25 const char *Last; 26 27 public: 28 static const size_t npos = ~size_t(0); 29 30 template <size_t N> StringView(const char (& Str)[N])31 StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {} StringView(const char * First_,const char * Last_)32 StringView(const char *First_, const char *Last_) 33 : First(First_), Last(Last_) {} StringView(const char * First_,size_t Len)34 StringView(const char *First_, size_t Len) 35 : First(First_), Last(First_ + Len) {} StringView(const char * Str)36 StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {} StringView()37 StringView() : First(nullptr), Last(nullptr) {} 38 39 StringView substr(size_t Pos, size_t Len = npos) const { 40 assert(Pos <= size()); 41 return StringView(begin() + Pos, std::min(Len, size() - Pos)); 42 } 43 44 size_t find(char C, size_t From = 0) const { 45 size_t FindBegin = std::min(From, size()); 46 // Avoid calling memchr with nullptr. 47 if (FindBegin < size()) { 48 // Just forward to memchr, which is faster than a hand-rolled loop. 49 if (const void *P = ::memchr(First + FindBegin, C, size() - FindBegin)) 50 return size_t(static_cast<const char *>(P) - First); 51 } 52 return npos; 53 } 54 55 StringView dropFront(size_t N = 1) const { 56 if (N >= size()) 57 N = size(); 58 return StringView(First + N, Last); 59 } 60 61 StringView dropBack(size_t N = 1) const { 62 if (N >= size()) 63 N = size(); 64 return StringView(First, Last - N); 65 } 66 front()67 char front() const { 68 assert(!empty()); 69 return *begin(); 70 } 71 back()72 char back() const { 73 assert(!empty()); 74 return *(end() - 1); 75 } 76 popFront()77 char popFront() { 78 assert(!empty()); 79 return *First++; 80 } 81 consumeFront(char C)82 bool consumeFront(char C) { 83 if (!startsWith(C)) 84 return false; 85 *this = dropFront(1); 86 return true; 87 } 88 consumeFront(StringView S)89 bool consumeFront(StringView S) { 90 if (!startsWith(S)) 91 return false; 92 *this = dropFront(S.size()); 93 return true; 94 } 95 startsWith(char C)96 bool startsWith(char C) const { return !empty() && *begin() == C; } 97 startsWith(StringView Str)98 bool startsWith(StringView Str) const { 99 if (Str.size() > size()) 100 return false; 101 return std::equal(Str.begin(), Str.end(), begin()); 102 } 103 104 const char &operator[](size_t Idx) const { return *(begin() + Idx); } 105 begin()106 const char *begin() const { return First; } end()107 const char *end() const { return Last; } size()108 size_t size() const { return static_cast<size_t>(Last - First); } empty()109 bool empty() const { return First == Last; } 110 }; 111 112 inline bool operator==(const StringView &LHS, const StringView &RHS) { 113 return LHS.size() == RHS.size() && 114 std::equal(LHS.begin(), LHS.end(), RHS.begin()); 115 } 116 117 DEMANGLE_NAMESPACE_END 118 119 #endif 120