89 lines
2.3 KiB
C++
89 lines
2.3 KiB
C++
/*
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******************************************************************************
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* Copyright (C) 2015, International Business Machines Corporation and
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* others. All Rights Reserved.
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******************************************************************************
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*
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* File unistrappender.h
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******************************************************************************
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*/
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#ifndef __UNISTRAPPENDER_H__
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#define __UNISTRAPPENDER_H__
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#include "unicode/unistr.h"
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#include "unicode/uobject.h"
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#include "unicode/utf16.h"
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#include "unicode/utypes.h"
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#include "cmemory.h"
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U_NAMESPACE_BEGIN
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/**
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* An optimization for the slowness of calling UnicodeString::append()
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* one character at a time in a loop. It stores appends in a buffer while
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* never actually calling append on the unicode string unless the buffer
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* fills up or is flushed.
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*
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* proper usage:
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* {
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* UnicodeStringAppender appender(astring);
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* for (int32_t i = 0; i < 100; ++i) {
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* appender.append((UChar) i);
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* }
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* // appender flushed automatically when it goes out of scope.
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* }
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*/
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class UnicodeStringAppender : public UMemory {
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public:
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/**
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* dest is the UnicodeString being appended to. It must always
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* exist while this instance exists.
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*/
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UnicodeStringAppender(UnicodeString &dest) : fDest(&dest), fIdx(0) { }
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inline void append(UChar x) {
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if (fIdx == UPRV_LENGTHOF(fBuffer)) {
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fDest->append(fBuffer, 0, fIdx);
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fIdx = 0;
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}
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fBuffer[fIdx++] = x;
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}
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inline void append(UChar32 x) {
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if (fIdx >= UPRV_LENGTHOF(fBuffer) - 1) {
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fDest->append(fBuffer, 0, fIdx);
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fIdx = 0;
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}
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U16_APPEND_UNSAFE(fBuffer, fIdx, x);
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}
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/**
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* Ensures that all appended characters have been written out to dest.
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*/
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inline void flush() {
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if (fIdx) {
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fDest->append(fBuffer, 0, fIdx);
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}
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fIdx = 0;
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}
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/**
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* flush the buffer when we go out of scope.
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*/
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~UnicodeStringAppender() {
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flush();
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}
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private:
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UnicodeString *fDest;
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int32_t fIdx;
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UChar fBuffer[32];
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UnicodeStringAppender(const UnicodeStringAppender &other);
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UnicodeStringAppender &operator=(const UnicodeStringAppender &other);
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};
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U_NAMESPACE_END
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#endif
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