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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.
StringPiece()38   StringPiece() : ptr_(NULL), length_(0) { }
StringPiece(const char * str)39   StringPiece(const char* str)
40     : ptr_(str), length_((str == NULL) ? 0 : static_cast<int>(strlen(str))) { }
StringPiece(const std::string & str)41   StringPiece(const std::string& str)
42     : ptr_(str.data()), length_(static_cast<int>(str.size())) { }
StringPiece(const char * offset,int len)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.
data()49   const char* data() const { return ptr_; }
size()50   int size() const { return length_; }
length()51   int length() const { return length_; }
empty()52   bool empty() const { return length_ == 0; }
53 
clear()54   void clear() { ptr_ = NULL; length_ = 0; }
set(const char * data,int len)55   void set(const char* data, int len) { ptr_ = data; length_ = len; }
set(const char * str)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   }
set(const void * data,int len)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 
remove_prefix(int n)70   void remove_prefix(int n) {
71     ptr_ += n;
72     length_ -= n;
73   }
74 
remove_suffix(int n)75   void remove_suffix(int n) {
76     length_ -= n;
77   }
78 
compare(const StringPiece & x)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 
as_string()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.
ToString()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"
starts_with(const StringPiece & 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"
ends_with(const StringPiece & 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;
begin()127   iterator begin() const { return ptr_; }
end()128   iterator end() const { return ptr_ + length_; }
rbegin()129   const_reverse_iterator rbegin() const {
130     return const_reverse_iterator(ptr_ + length_);
131   }
rend()132   const_reverse_iterator rend() const {
133     return const_reverse_iterator(ptr_);
134   }
135   // STLS says return size_type, but Google says return int
max_size()136   int max_size() const { return length_; }
capacity()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