TextCharBuffer.h

//========================================================================================
// 
// $File$
// 
// Owner: Nat McCully
// 
// $Author$
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// $DateTime$
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// Copyright 1997-2010 Adobe Systems Incorporated. All rights reserved.
// 
// NOTICE: Adobe permits you to use, modify, and distribute this file in accordance 
// with the terms of the Adobe license agreement accompanying it. If you have received
// this file from a source other than Adobe, then your use, modification, or 
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//========================================================================================

#ifndef __TextCharBuffer__
#define __TextCharBuffer__


#include "WideString.h"


inline bool IsHighSurrogate(UTF16TextChar c)
{ return (c >= kTextChar_HighSurrogateStart && c <= kTextChar_HighSurrogateEnd); }

inline bool IsLowSurrogate(UTF16TextChar c)
{ return (c >= kTextChar_LowSurrogateStart && c <= kTextChar_LowSurrogateEnd); }

inline UTF32TextChar BuildUTF32Char(UTF16TextChar hi, UTF16TextChar low)
{ return ((hi - 0xD800) * 0x400 + (low - 0xDC00) + 0x10000); }



class TextCharBuffer
{
 public:
 TextCharBuffer(WideString::const_iterator b, WideString::const_iterator e) :fBegin(b.PtrAt()), fEnd(e.PtrAt())
 { fCharCount = e - b; }
 TextCharBuffer(const TextCharBuffer& o) :fBegin(o.fBegin), fEnd(o.fEnd), fCharCount(o.fCharCount)
 {}
 explicit TextCharBuffer(const WideString& s) :fBegin(s.begin_raw()), fEnd(s.end_raw()), fCharCount(s.Length())
 {}
 TextCharBuffer(const UTF16TextChar *begin, const UTF16TextChar *end, int32 charCount)
 :fBegin(begin), fEnd(end), fCharCount(charCount)
 {}

 UTF32TextChar First() const
 { return !IsHighSurrogate(*fBegin) ? *fBegin : BuildUTF32Char(fBegin[0], fBegin[1]); }

 const UTF16TextChar* begin_raw() const
 { return fBegin; }
 const UTF16TextChar* end_raw() const
 { return fEnd; }

 int32 CharCount() const
 { return fCharCount; }

 void RemoveFirst()
 { --fCharCount;
 if (!IsHighSurrogate(*fBegin))
 ++fBegin; // not high surrogate
 else
 fBegin += 2; }

 void RemoveLast()
 { --fCharCount;
 --fEnd;
 if (IsLowSurrogate(*fEnd))
 --fEnd; } // was low surrogate

 private:
 TextCharBuffer() :fBegin(nil), fEnd(nil), fCharCount(0)
 {}

 const UTF16TextChar *fBegin;
 const UTF16TextChar *fEnd;
 int32 fCharCount;
};


#endif
 // __TextCharBuffer__