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bytestream.h
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00001 // Copyright (C) 2009-2010, International Business Machines
00002 // Corporation and others. All Rights Reserved.
00003 //
00004 // Copyright 2007 Google Inc. All Rights Reserved.
00005 // Author: sanjay@google.com (Sanjay Ghemawat)
00006 //
00007 // Abstract interface that consumes a sequence of bytes (ByteSink).
00008 //
00009 // Used so that we can write a single piece of code that can operate
00010 // on a variety of output string types.
00011 //
00012 // Various implementations of this interface are provided:
00013 //   ByteSink:
00014 //      CheckedArrayByteSink    Write to a flat array, with bounds checking
00015 //      StringByteSink          Write to an STL string
00016 
00017 // This code is a contribution of Google code, and the style used here is
00018 // a compromise between the original Google code and the ICU coding guidelines.
00019 // For example, data types are ICU-ified (size_t,int->int32_t),
00020 // and API comments doxygen-ified, but function names and behavior are
00021 // as in the original, if possible.
00022 // Assertion-style error handling, not available in ICU, was changed to
00023 // parameter "pinning" similar to UnicodeString.
00024 //
00025 // In addition, this is only a partial port of the original Google code,
00026 // limited to what was needed so far. The (nearly) complete original code
00027 // is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
00028 // (see ICU ticket 6765, r25517).
00029 
00030 #ifndef __BYTESTREAM_H__
00031 #define __BYTESTREAM_H__
00032 
00038 #include "unicode/utypes.h"
00039 #include "unicode/uobject.h"
00040 #include "unicode/std_string.h"
00041 
00042 U_NAMESPACE_BEGIN
00043 
00048 class U_COMMON_API ByteSink : public UMemory {
00049 public:
00054   ByteSink() { }
00059   virtual ~ByteSink() { }
00060 
00067   virtual void Append(const char* bytes, int32_t n) = 0;
00068 
00111   virtual char* GetAppendBuffer(int32_t min_capacity,
00112                                 int32_t desired_capacity_hint,
00113                                 char* scratch, int32_t scratch_capacity,
00114                                 int32_t* result_capacity);
00115 
00124   virtual void Flush();
00125 
00126 private:
00127   ByteSink(const ByteSink &); // copy constructor not implemented
00128   ByteSink &operator=(const ByteSink &); // assignment operator not implemented
00129 };
00130 
00131 // -------------------------------------------------------------
00132 // Some standard implementations
00133 
00143 class U_COMMON_API CheckedArrayByteSink : public ByteSink {
00144 public:
00151   CheckedArrayByteSink(char* outbuf, int32_t capacity);
00160   virtual CheckedArrayByteSink& Reset();
00167   virtual void Append(const char* bytes, int32_t n);
00182   virtual char* GetAppendBuffer(int32_t min_capacity,
00183                                 int32_t desired_capacity_hint,
00184                                 char* scratch, int32_t scratch_capacity,
00185                                 int32_t* result_capacity);
00191   int32_t NumberOfBytesWritten() const { return size_; }
00198   UBool Overflowed() const { return overflowed_; }
00206   int32_t NumberOfBytesAppended() const { return appended_; }
00207 private:
00208   char* outbuf_;
00209   const int32_t capacity_;
00210   int32_t size_;
00211   int32_t appended_;
00212   UBool overflowed_;
00213   CheckedArrayByteSink(); 
00214   CheckedArrayByteSink(const CheckedArrayByteSink &); 
00215   CheckedArrayByteSink &operator=(const CheckedArrayByteSink &); 
00216 };
00217 
00218 #if U_HAVE_STD_STRING
00219 
00225 template<typename StringClass>
00226 class StringByteSink : public ByteSink {
00227  public:
00233   StringByteSink(StringClass* dest) : dest_(dest) { }
00240   virtual void Append(const char* data, int32_t n) { dest_->append(data, n); }
00241  private:
00242   StringClass* dest_;
00243   StringByteSink(); 
00244   StringByteSink(const StringByteSink &); 
00245   StringByteSink &operator=(const StringByteSink &); 
00246 };
00247 
00248 #endif
00249 
00250 U_NAMESPACE_END
00251 
00252 #endif  // __BYTESTREAM_H__
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