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29 //
30 // Author: Sanjay Ghemawat
31 //
32 // A string like object that points into another piece of memory.
33 // Useful for providing an interface that allows clients to easily
34 // pass in either a "const char*" or a "string".
35 //
36 // Arghh!  I wish C++ literals were automatically of type "string".
37 
38 #ifndef _PCRE_STRINGPIECE_H
39 #define _PCRE_STRINGPIECE_H
40 
41 #include <cstring>
42 #include <string>
43 #include <iosfwd>    // for ostream forward-declaration
44 
45 #if 0
46 #define HAVE_TYPE_TRAITS
47 #include <type_traits.h>
48 #elif 0
49 #define HAVE_TYPE_TRAITS
50 #include <bits/type_traits.h>
51 #endif
52 
53 #include <pcre.h>
54 
55 using std::memcmp;
56 using std::strlen;
57 using std::string;
58 
59 namespace pcrecpp {
60 
61 class PCRECPP_EXP_DEFN StringPiece {
62  private:
63   const char*   ptr_;
64   int           length_;
65 
66  public:
67   // We provide non-explicit singleton constructors so users can pass
68   // in a "const char*" or a "string" wherever a "StringPiece" is
69   // expected.
StringPiece()70   StringPiece()
71     : ptr_(NULL), length_(0) { }
StringPiece(const char * str)72   StringPiece(const char* str)
73     : ptr_(str), length_(static_cast<int>(strlen(ptr_))) { }
StringPiece(const unsigned char * str)74   StringPiece(const unsigned char* str)
75     : ptr_(reinterpret_cast<const char*>(str)),
76       length_(static_cast<int>(strlen(ptr_))) { }
StringPiece(const string & str)77   StringPiece(const string& str)
78     : ptr_(str.data()), length_(static_cast<int>(str.size())) { }
StringPiece(const char * offset,int len)79   StringPiece(const char* offset, int len)
80     : ptr_(offset), length_(len) { }
81 
82   // data() may return a pointer to a buffer with embedded NULs, and the
83   // returned buffer may or may not be null terminated.  Therefore it is
84   // typically a mistake to pass data() to a routine that expects a NUL
85   // terminated string.  Use "as_string().c_str()" if you really need to do
86   // this.  Or better yet, change your routine so it does not rely on NUL
87   // termination.
data()88   const char* data() const { return ptr_; }
size()89   int size() const { return length_; }
empty()90   bool empty() const { return length_ == 0; }
91 
clear()92   void clear() { ptr_ = NULL; length_ = 0; }
set(const char * buffer,int len)93   void set(const char* buffer, int len) { ptr_ = buffer; length_ = len; }
set(const char * str)94   void set(const char* str) {
95     ptr_ = str;
96     length_ = static_cast<int>(strlen(str));
97   }
set(const void * buffer,int len)98   void set(const void* buffer, int len) {
99     ptr_ = reinterpret_cast<const char*>(buffer);
100     length_ = len;
101   }
102 
103   char operator[](int i) const { return ptr_[i]; }
104 
remove_prefix(int n)105   void remove_prefix(int n) {
106     ptr_ += n;
107     length_ -= n;
108   }
109 
remove_suffix(int n)110   void remove_suffix(int n) {
111     length_ -= n;
112   }
113 
114   bool operator==(const StringPiece& x) const {
115     return ((length_ == x.length_) &&
116             (memcmp(ptr_, x.ptr_, length_) == 0));
117   }
118   bool operator!=(const StringPiece& x) const {
119     return !(*this == x);
120   }
121 
122 #define STRINGPIECE_BINARY_PREDICATE(cmp,auxcmp)                             \
123   bool operator cmp (const StringPiece& x) const {                           \
124     int r = memcmp(ptr_, x.ptr_, length_ < x.length_ ? length_ : x.length_); \
125     return ((r auxcmp 0) || ((r == 0) && (length_ cmp x.length_)));          \
126   }
127   STRINGPIECE_BINARY_PREDICATE(<,  <);
128   STRINGPIECE_BINARY_PREDICATE(<=, <);
129   STRINGPIECE_BINARY_PREDICATE(>=, >);
130   STRINGPIECE_BINARY_PREDICATE(>,  >);
131 #undef STRINGPIECE_BINARY_PREDICATE
132 
compare(const StringPiece & x)133   int compare(const StringPiece& x) const {
134     int r = memcmp(ptr_, x.ptr_, length_ < x.length_ ? length_ : x.length_);
135     if (r == 0) {
136       if (length_ < x.length_) r = -1;
137       else if (length_ > x.length_) r = +1;
138     }
139     return r;
140   }
141 
as_string()142   string as_string() const {
143     return string(data(), size());
144   }
145 
CopyToString(string * target)146   void CopyToString(string* target) const {
147     target->assign(ptr_, length_);
148   }
149 
150   // Does "this" start with "x"
starts_with(const StringPiece & x)151   bool starts_with(const StringPiece& x) const {
152     return ((length_ >= x.length_) && (memcmp(ptr_, x.ptr_, x.length_) == 0));
153   }
154 };
155 
156 }   // namespace pcrecpp
157 
158 // ------------------------------------------------------------------
159 // Functions used to create STL containers that use StringPiece
160 //  Remember that a StringPiece's lifetime had better be less than
161 //  that of the underlying string or char*.  If it is not, then you
162 //  cannot safely store a StringPiece into an STL container
163 // ------------------------------------------------------------------
164 
165 #ifdef HAVE_TYPE_TRAITS
166 // This makes vector<StringPiece> really fast for some STL implementations
167 template<> struct __type_traits<pcrecpp::StringPiece> {
168   typedef __true_type    has_trivial_default_constructor;
169   typedef __true_type    has_trivial_copy_constructor;
170   typedef __true_type    has_trivial_assignment_operator;
171   typedef __true_type    has_trivial_destructor;
172   typedef __true_type    is_POD_type;
173 };
174 #endif
175 
176 // allow StringPiece to be logged
177 PCRECPP_EXP_DECL std::ostream& operator<<(std::ostream& o,
178                                           const pcrecpp::StringPiece& piece);
179 
180 #endif /* _PCRE_STRINGPIECE_H */
181