1 // Copyright 2001-2010 The RE2 Authors. All Rights Reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // A string-like object that points to a sized piece of memory. 6 // 7 // Functions or methods may use const StringPiece& parameters to accept either 8 // a "const char*" or a "string" value that will be implicitly converted to 9 // a StringPiece. The implicit conversion means that it is often appropriate 10 // to include this .h file in other files rather than forward-declaring 11 // StringPiece as would be appropriate for most other Google classes. 12 // 13 // Systematic usage of StringPiece is encouraged as it will reduce unnecessary 14 // conversions from "const char*" to "string" and back again. 15 // 16 // 17 // Arghh! I wish C++ literals were "string". 18 19 #ifndef STRINGS_STRINGPIECE_H__ 20 #define STRINGS_STRINGPIECE_H__ 21 22 #include <string.h> 23 #include <cstddef> 24 #include <iosfwd> 25 #include <string> 26 #ifdef WIN32 27 #include <algorithm> 28 #endif 29 30 namespace re2 { 31 32 class StringPiece { 33 private: 34 const char* ptr_; 35 int length_; 36 37 public: 38 // We provide non-explicit singleton constructors so users can pass 39 // in a "const char*" or a "string" wherever a "StringPiece" is 40 // expected. 41 StringPiece() : ptr_(NULL), length_(0) { } 42 StringPiece(const char* str) 43 : ptr_(str), length_((str == NULL) ? 0 : static_cast<int>(strlen(str))) { } 44 StringPiece(const std::string& str) 45 : ptr_(str.data()), length_(static_cast<int>(str.size())) { } 46 StringPiece(const char* offset, int len) : ptr_(offset), length_(len) { } 47 48 // data() may return a pointer to a buffer with embedded NULs, and the 49 // returned buffer may or may not be null terminated. Therefore it is 50 // typically a mistake to pass data() to a routine that expects a NUL 51 // terminated string. 52 const char* data() const { return ptr_; } 53 int size() const { return length_; } 54 int length() const { return length_; } 55 bool empty() const { return length_ == 0; } 56 57 void clear() { ptr_ = NULL; length_ = 0; } 58 void set(const char* data, int len) { ptr_ = data; length_ = len; } 59 void set(const char* str) { 60 ptr_ = str; 61 if (str != NULL) 62 length_ = static_cast<int>(strlen(str)); 63 else 64 length_ = 0; 65 } 66 void set(const void* data, int len) { 67 ptr_ = reinterpret_cast<const char*>(data); 68 length_ = len; 69 } 70 71 char operator[](int i) const { return ptr_[i]; } 72 73 void remove_prefix(int n) { 74 ptr_ += n; 75 length_ -= n; 76 } 77 78 void remove_suffix(int n) { 79 length_ -= n; 80 } 81 82 int compare(const StringPiece& x) const { 83 int r = memcmp(ptr_, x.ptr_, std::min(length_, x.length_)); 84 if (r == 0) { 85 if (length_ < x.length_) r = -1; 86 else if (length_ > x.length_) r = +1; 87 } 88 return r; 89 } 90 91 std::string as_string() const { 92 return std::string(data(), size()); 93 } 94 // We also define ToString() here, since many other string-like 95 // interfaces name the routine that converts to a C++ string 96 // "ToString", and it's confusing to have the method that does that 97 // for a StringPiece be called "as_string()". We also leave the 98 // "as_string()" method defined here for existing code. 99 std::string ToString() const { 100 return std::string(data(), size()); 101 } 102 103 void CopyToString(std::string* target) const; 104 void AppendToString(std::string* target) const; 105 106 // Does "this" start with "x" 107 bool starts_with(const StringPiece& x) const { 108 return ((length_ >= x.length_) && 109 (memcmp(ptr_, x.ptr_, x.length_) == 0)); 110 } 111 112 // Does "this" end with "x" 113 bool ends_with(const StringPiece& x) const { 114 return ((length_ >= x.length_) && 115 (memcmp(ptr_ + (length_-x.length_), x.ptr_, x.length_) == 0)); 116 } 117 118 // standard STL container boilerplate 119 typedef char value_type; 120 typedef const char* pointer; 121 typedef const char& reference; 122 typedef const char& const_reference; 123 typedef size_t size_type; 124 typedef ptrdiff_t difference_type; 125 static const size_type npos; 126 typedef const char* const_iterator; 127 typedef const char* iterator; 128 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 129 typedef std::reverse_iterator<iterator> reverse_iterator; 130 iterator begin() const { return ptr_; } 131 iterator end() const { return ptr_ + length_; } 132 const_reverse_iterator rbegin() const { 133 return const_reverse_iterator(ptr_ + length_); 134 } 135 const_reverse_iterator rend() const { 136 return const_reverse_iterator(ptr_); 137 } 138 // STLS says return size_type, but Google says return int 139 int max_size() const { return length_; } 140 int capacity() const { return length_; } 141 142 int copy(char* buf, size_type n, size_type pos = 0) const; 143 144 int find(const StringPiece& s, size_type pos = 0) const; 145 int find(char c, size_type pos = 0) const; 146 int rfind(const StringPiece& s, size_type pos = npos) const; 147 int rfind(char c, size_type pos = npos) const; 148 149 StringPiece substr(size_type pos, size_type n = npos) const; 150 151 static bool _equal(const StringPiece&, const StringPiece&); 152 }; 153 154 inline bool operator==(const StringPiece& x, const StringPiece& y) { 155 return StringPiece::_equal(x, y); 156 } 157 158 inline bool operator!=(const StringPiece& x, const StringPiece& y) { 159 return !(x == y); 160 } 161 162 inline bool operator<(const StringPiece& x, const StringPiece& y) { 163 const int r = memcmp(x.data(), y.data(), 164 std::min(x.size(), y.size())); 165 return ((r < 0) || ((r == 0) && (x.size() < y.size()))); 166 } 167 168 inline bool operator>(const StringPiece& x, const StringPiece& y) { 169 return y < x; 170 } 171 172 inline bool operator<=(const StringPiece& x, const StringPiece& y) { 173 return !(x > y); 174 } 175 176 inline bool operator>=(const StringPiece& x, const StringPiece& y) { 177 return !(x < y); 178 } 179 180 } // namespace re2 181 182 // allow StringPiece to be logged 183 extern std::ostream& operator<<(std::ostream& o, const re2::StringPiece& piece); 184 185 #endif // STRINGS_STRINGPIECE_H__ 186
