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 27 namespace re2 { 28 29 class StringPiece { 30 private: 31 const char* ptr_; 32 int length_; 33 34 public: 35 // We provide non-explicit singleton constructors so users can pass 36 // in a "const char*" or a "string" wherever a "StringPiece" is 37 // expected. 38 StringPiece() : ptr_(NULL), length_(0) { } 39 StringPiece(const char* str) 40 : ptr_(str), length_((str == NULL) ? 0 : static_cast<int>(strlen(str))) { } 41 StringPiece(const std::string& str) 42 : ptr_(str.data()), length_(static_cast<int>(str.size())) { } 43 StringPiece(const char* offset, int len) : ptr_(offset), length_(len) { } 44 45 // data() may return a pointer to a buffer with embedded NULs, and the 46 // returned buffer may or may not be null terminated. Therefore it is 47 // typically a mistake to pass data() to a routine that expects a NUL 48 // terminated string. 49 const char* data() const { return ptr_; } 50 int size() const { return length_; } 51 int length() const { return length_; } 52 bool empty() const { return length_ == 0; } 53 54 void clear() { ptr_ = NULL; length_ = 0; } 55 void set(const char* data, int len) { ptr_ = data; length_ = len; } 56 void set(const char* str) { 57 ptr_ = str; 58 if (str != NULL) 59 length_ = static_cast<int>(strlen(str)); 60 else 61 length_ = 0; 62 } 63 void set(const void* data, int len) { 64 ptr_ = reinterpret_cast<const char*>(data); 65 length_ = len; 66 } 67 68 char operator[](int i) const { return ptr_[i]; } 69 70 void remove_prefix(int n) { 71 ptr_ += n; 72 length_ -= n; 73 } 74 75 void remove_suffix(int n) { 76 length_ -= n; 77 } 78 79 int compare(const StringPiece& x) const { 80 int r = memcmp(ptr_, x.ptr_, std::min(length_, x.length_)); 81 if (r == 0) { 82 if (length_ < x.length_) r = -1; 83 else if (length_ > x.length_) r = +1; 84 } 85 return r; 86 } 87 88 std::string as_string() const { 89 return std::string(data(), size()); 90 } 91 // We also define ToString() here, since many other string-like 92 // interfaces name the routine that converts to a C++ string 93 // "ToString", and it's confusing to have the method that does that 94 // for a StringPiece be called "as_string()". We also leave the 95 // "as_string()" method defined here for existing code. 96 std::string ToString() const { 97 return std::string(data(), size()); 98 } 99 100 void CopyToString(std::string* target) const; 101 void AppendToString(std::string* target) const; 102 103 // Does "this" start with "x" 104 bool starts_with(const StringPiece& x) const { 105 return ((length_ >= x.length_) && 106 (memcmp(ptr_, x.ptr_, x.length_) == 0)); 107 } 108 109 // Does "this" end with "x" 110 bool ends_with(const StringPiece& x) const { 111 return ((length_ >= x.length_) && 112 (memcmp(ptr_ + (length_-x.length_), x.ptr_, x.length_) == 0)); 113 } 114 115 // standard STL container boilerplate 116 typedef char value_type; 117 typedef const char* pointer; 118 typedef const char& reference; 119 typedef const char& const_reference; 120 typedef size_t size_type; 121 typedef ptrdiff_t difference_type; 122 static const size_type npos; 123 typedef const char* const_iterator; 124 typedef const char* iterator; 125 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 126 typedef std::reverse_iterator<iterator> reverse_iterator; 127 iterator begin() const { return ptr_; } 128 iterator end() const { return ptr_ + length_; } 129 const_reverse_iterator rbegin() const { 130 return const_reverse_iterator(ptr_ + length_); 131 } 132 const_reverse_iterator rend() const { 133 return const_reverse_iterator(ptr_); 134 } 135 // STLS says return size_type, but Google says return int 136 int max_size() const { return length_; } 137 int capacity() const { return length_; } 138 139 int copy(char* buf, size_type n, size_type pos = 0) const; 140 141 int find(const StringPiece& s, size_type pos = 0) const; 142 int find(char c, size_type pos = 0) const; 143 int rfind(const StringPiece& s, size_type pos = npos) const; 144 int rfind(char c, size_type pos = npos) const; 145 146 StringPiece substr(size_type pos, size_type n = npos) const; 147 148 static bool _equal(const StringPiece&, const StringPiece&); 149 }; 150 151 inline bool operator==(const StringPiece& x, const StringPiece& y) { 152 return StringPiece::_equal(x, y); 153 } 154 155 inline bool operator!=(const StringPiece& x, const StringPiece& y) { 156 return !(x == y); 157 } 158 159 inline bool operator<(const StringPiece& x, const StringPiece& y) { 160 const int r = memcmp(x.data(), y.data(), 161 std::min(x.size(), y.size())); 162 return ((r < 0) || ((r == 0) && (x.size() < y.size()))); 163 } 164 165 inline bool operator>(const StringPiece& x, const StringPiece& y) { 166 return y < x; 167 } 168 169 inline bool operator<=(const StringPiece& x, const StringPiece& y) { 170 return !(x > y); 171 } 172 173 inline bool operator>=(const StringPiece& x, const StringPiece& y) { 174 return !(x < y); 175 } 176 177 } // namespace re2 178 179 // allow StringPiece to be logged 180 extern std::ostream& operator<<(std::ostream& o, const re2::StringPiece& piece); 181 182 #endif // STRINGS_STRINGPIECE_H__ 183
