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 // Copyright (C) 2009-2013, 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.

  *

  * @stable ICU 4.2

  */

 class U_COMMON_API StringPiece : public UMemory {

  private:

   const char*   ptr_;

   int32_t       length_;

  public:

   /**

    * Default constructor, creates an empty StringPiece.

    * @stable ICU 4.2

    */

   StringPiece() : ptr_(NULL), length_(0) { }

   /**

    * Constructs from a NUL-terminated const char * pointer.

    * @param str a NUL-terminated const char * pointer

    * @stable ICU 4.2

    */

   StringPiece(const char* str);

 #if U_HAVE_STD_STRING

   /**

    * Constructs from a std::string.

    * @stable ICU 4.2

    */

   StringPiece(const std::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

    * @stable 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().

    * @stable 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.

    * @stable 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

    * @stable ICU 4.2

    */

   const char* data() const { return ptr_; }

   /**

    * Returns the string length. Same as length().

    * @return the string length

    * @stable ICU 4.2

    */

   int32_t size() const { return length_; }

   /**

    * Returns the string length. Same as size().

    * @return the string length

    * @stable ICU 4.2

    */

   int32_t length() const { return length_; }

   /**

    * Returns whether the string is empty.

    * @return TRUE if the string is empty

    * @stable ICU 4.2

    */

   UBool empty() const { return length_ == 0; }

   /**

    * Sets to an empty string.

    * @stable ICU 4.2

    */

   void clear() { ptr_ = NULL; length_ = 0; }

   /**

    * Reset the stringpiece to refer to new data.

    * @param xdata pointer the new string data.  Need not be nul terminated.

    * @param len the length of the new data

    * @stable ICU 4.8

    */

   void set(const char* xdata, int32_t len) { ptr_ = xdata; length_ = len; }

   /**

    * Reset the stringpiece to refer to new data.

    * @param str a pointer to a NUL-terminated string. 

    * @stable ICU 4.8

    */

   void set(const char* str);

   /**

    * Removes the first n string units.

    * @param n prefix length, must be non-negative and <=length()

    * @stable 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()

    * @stable 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.

    * @stable 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

    * @stable ICU 4.2

    */

   StringPiece substr(int32_t pos, int32_t len = npos) const {

     return StringPiece(*this, pos, len);

   }

 };

 /**

  * Global operator == for StringPiece

  * @param x The first StringPiece to compare.

  * @param y The second StringPiece to compare.

  * @return TRUE if the string data is equal

  * @stable ICU 4.8

  */

 U_EXPORT UBool U_EXPORT2 

 operator==(const StringPiece& x, const StringPiece& y);

 /**

  * Global operator != for StringPiece

  * @param x The first StringPiece to compare.

  * @param y The second StringPiece to compare.

  * @return TRUE if the string data is not equal

  * @stable ICU 4.8

  */

 inline UBool operator!=(const StringPiece& x, const StringPiece& y) {

   return !(x == y);

 }

 U_NAMESPACE_END

 #endif  // __STRINGPIECE_H__