✏ 编辑: pcre_stringpiece.h

// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met:
//
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//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
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// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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//
// Author: Sanjay Ghemawat
//
// A string like object that points into another piece of memory.
// Useful for providing an interface that allows clients to easily
// pass in either a "const char*" or a "string".
//
// Arghh!  I wish C++ literals were automatically of type "string".

#ifndef _PCRE_STRINGPIECE_H
#define _PCRE_STRINGPIECE_H

#include <cstring>
#include <string>
#include <iosfwd>    // for ostream forward-declaration

#if 0
#define HAVE_TYPE_TRAITS
#include <type_traits.h>
#elif 0
#define HAVE_TYPE_TRAITS
#include <bits/type_traits.h>
#endif

#include <pcre.h>

using std::memcmp;
using std::strlen;
using std::string;

namespace pcrecpp {

class PCRECPP_EXP_DEFN StringPiece {
 private:
  const char*   ptr_;
  int           length_;

public:
  // We provide non-explicit singleton constructors so users can pass
  // in a "const char*" or a "string" wherever a "StringPiece" is
  // expected.
  StringPiece()
    : ptr_(NULL), length_(0) { }
  StringPiece(const char* str)
    : ptr_(str), length_(static_cast<int>(strlen(ptr_))) { }
  StringPiece(const unsigned char* str)
    : ptr_(reinterpret_cast<const char*>(str)),
      length_(static_cast<int>(strlen(ptr_))) { }
  StringPiece(const string& str)
    : ptr_(str.data()), length_(static_cast<int>(str.size())) { }
  StringPiece(const char* offset, int len)
    : ptr_(offset), length_(len) { }

// data() may return a pointer to a buffer with embedded NULs, and the
  // returned buffer may or may not be null terminated.  Therefore it is
  // typically a mistake to pass data() to a routine that expects a NUL
  // terminated string.  Use "as_string().c_str()" if you really need to do
  // this.  Or better yet, change your routine so it does not rely on NUL
  // termination.
  const char* data() const { return ptr_; }
  int size() const { return length_; }
  bool empty() const { return length_ == 0; }

void clear() { ptr_ = NULL; length_ = 0; }
  void set(const char* buffer, int len) { ptr_ = buffer; length_ = len; }
  void set(const char* str) {
    ptr_ = str;
    length_ = static_cast<int>(strlen(str));
  }
  void set(const void* buffer, int len) {
    ptr_ = reinterpret_cast<const char*>(buffer);
    length_ = len;
  }

char operator[](int i) const { return ptr_[i]; }

void remove_prefix(int n) {
    ptr_ += n;
    length_ -= n;
  }

void remove_suffix(int n) {
    length_ -= n;
  }

bool operator==(const StringPiece& x) const {
    return ((length_ == x.length_) &&
            (memcmp(ptr_, x.ptr_, length_) == 0));
  }
  bool operator!=(const StringPiece& x) const {
    return !(*this == x);
  }

#define STRINGPIECE_BINARY_PREDICATE(cmp,auxcmp)                             \
  bool operator cmp (const StringPiece& x) const {                           \
    int r = memcmp(ptr_, x.ptr_, length_ < x.length_ ? length_ : x.length_); \
    return ((r auxcmp 0) || ((r == 0) && (length_ cmp x.length_)));          \
  }
  STRINGPIECE_BINARY_PREDICATE(<,  <);
  STRINGPIECE_BINARY_PREDICATE(<=, <);
  STRINGPIECE_BINARY_PREDICATE(>=, >);
  STRINGPIECE_BINARY_PREDICATE(>,  >);
#undef STRINGPIECE_BINARY_PREDICATE

int compare(const StringPiece& x) const {
    int r = memcmp(ptr_, x.ptr_, length_ < x.length_ ? length_ : x.length_);
    if (r == 0) {
      if (length_ < x.length_) r = -1;
      else if (length_ > x.length_) r = +1;
    }
    return r;
  }

string as_string() const {
    return string(data(), size());
  }

void CopyToString(string* target) const {
    target->assign(ptr_, length_);
  }

// Does "this" start with "x"
  bool starts_with(const StringPiece& x) const {
    return ((length_ >= x.length_) && (memcmp(ptr_, x.ptr_, x.length_) == 0));
  }
};

}   // namespace pcrecpp

// ------------------------------------------------------------------
// Functions used to create STL containers that use StringPiece
//  Remember that a StringPiece's lifetime had better be less than
//  that of the underlying string or char*.  If it is not, then you
//  cannot safely store a StringPiece into an STL container
// ------------------------------------------------------------------

#ifdef HAVE_TYPE_TRAITS
// This makes vector<StringPiece> really fast for some STL implementations
template<> struct __type_traits<pcrecpp::StringPiece> {
  typedef __true_type    has_trivial_default_constructor;
  typedef __true_type    has_trivial_copy_constructor;
  typedef __true_type    has_trivial_assignment_operator;
  typedef __true_type    has_trivial_destructor;
  typedef __true_type    is_POD_type;
};
#endif

// allow StringPiece to be logged
std::ostream& operator<<(std::ostream& o, const pcrecpp::StringPiece& piece);

#endif /* _PCRE_STRINGPIECE_H */

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