????
Your IP : 3.143.5.248
// Copyright (C) 2009, International Business Machines
// Corporation and others. All Rights Reserved.
//
// Copyright 2001 and onwards Google Inc.
// Author: Sanjay Ghemawat
// This code is a contribution of Google code, and the style used here is
// a compromise between the original Google code and the ICU coding guidelines.
// For example, data types are ICU-ified (size_t,int->int32_t),
// and API comments doxygen-ified, but function names and behavior are
// as in the original, if possible.
// Assertion-style error handling, not available in ICU, was changed to
// parameter "pinning" similar to UnicodeString.
//
// In addition, this is only a partial port of the original Google code,
// limited to what was needed so far. The (nearly) complete original code
// is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
// (see ICU ticket 6765, r25517).
#ifndef __STRINGPIECE_H__
#define __STRINGPIECE_H__
/**
* \file
* \brief C++ API: StringPiece: Read-only byte string wrapper class.
*/
#include "unicode/utypes.h"
#include "unicode/uobject.h"
#include "unicode/std_string.h"
// Arghh! I wish C++ literals were "string".
U_NAMESPACE_BEGIN
/**
* A string-like object that points to a sized piece of memory.
*
* We provide non-explicit singleton constructors so users can pass
* in a "const char*" or a "string" wherever a "StringPiece" is
* expected.
*
* Functions or methods may use const StringPiece& parameters to accept either
* a "const char*" or a "string" value that will be implicitly converted to
* a StringPiece.
*
* Systematic usage of StringPiece is encouraged as it will reduce unnecessary
* conversions from "const char*" to "string" and back again.
*
* @draft ICU 4.2
*/
class U_COMMON_API StringPiece : public UMemory {
private:
const char* ptr_;
int32_t length_;
public:
/**
* Default constructor, creates an empty StringPiece.
* @draft ICU 4.2
*/
StringPiece() : ptr_(NULL), length_(0) { }
/**
* Constructs from a NUL-terminated const char * pointer.
* @param str a NUL-terminated const char * pointer
* @draft ICU 4.2
*/
StringPiece(const char* str);
#if U_HAVE_STD_STRING
/**
* Constructs from a std::string.
* @draft ICU 4.2
*/
StringPiece(const U_STD_NSQ string& str)
: ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { }
#endif
/**
* Constructs from a const char * pointer and a specified length.
* @param offset a const char * pointer (need not be terminated)
* @param len the length of the string; must be non-negative
* @draft ICU 4.2
*/
StringPiece(const char* offset, int32_t len) : ptr_(offset), length_(len) { }
/**
* Substring of another StringPiece.
* @param x the other StringPiece
* @param pos start position in x; must be non-negative and <= x.length().
* @draft ICU 4.2
*/
StringPiece(const StringPiece& x, int32_t pos);
/**
* Substring of another StringPiece.
* @param x the other StringPiece
* @param pos start position in x; must be non-negative and <= x.length().
* @param len length of the substring;
* must be non-negative and will be pinned to at most x.length() - pos.
* @draft ICU 4.2
*/
StringPiece(const StringPiece& x, int32_t pos, int32_t len);
/**
* Returns the string pointer. May be NULL if it is empty.
*
* 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.
* @return the string pointer
* @draft ICU 4.2
*/
const char* data() const { return ptr_; }
/**
* Returns the string length. Same as length().
* @return the string length
* @draft ICU 4.2
*/
int32_t size() const { return length_; }
/**
* Returns the string length. Same as size().
* @return the string length
* @draft ICU 4.2
*/
int32_t length() const { return length_; }
/**
* Returns whether the string is empty.
* @return TRUE if the string is empty
* @draft ICU 4.2
*/
UBool empty() const { return length_ == 0; }
/**
* Sets to an empty string.
* @draft ICU 4.2
*/
void clear() { ptr_ = NULL; length_ = 0; }
/**
* Removes the first n string units.
* @param n prefix length, must be non-negative and <=length()
* @draft ICU 4.2
*/
void remove_prefix(int32_t n) {
if (n >= 0) {
if (n > length_) {
n = length_;
}
ptr_ += n;
length_ -= n;
}
}
/**
* Removes the last n string units.
* @param n suffix length, must be non-negative and <=length()
* @draft ICU 4.2
*/
void remove_suffix(int32_t n) {
if (n >= 0) {
if (n <= length_) {
length_ -= n;
} else {
length_ = 0;
}
}
}
/**
* Maximum integer, used as a default value for substring methods.
* @draft ICU 4.2
*/
static const int32_t npos = 0x7fffffff;
/**
* Returns a substring of this StringPiece.
* @param pos start position; must be non-negative and <= length().
* @param len length of the substring;
* must be non-negative and will be pinned to at most length() - pos.
* @return the substring StringPiece
* @draft ICU 4.2
*/
StringPiece substr(int32_t pos, int32_t len = npos) const {
return StringPiece(*this, pos, len);
}
};
U_NAMESPACE_END
#endif // __STRINGPIECE_H__