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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
* Copyright (C) 2015, International Business Machines Corporation and
* others. All Rights Reserved.
******************************************************************************
*
* File unistrappender.h
******************************************************************************
*/
#ifndef __UNISTRAPPENDER_H__
#define __UNISTRAPPENDER_H__
#include "unicode/unistr.h"
#include "unicode/uobject.h"
#include "unicode/utf16.h"
#include "unicode/utypes.h"
#include "cmemory.h"
U_NAMESPACE_BEGIN
/**
* An optimization for the slowness of calling UnicodeString::append()
* one character at a time in a loop. It stores appends in a buffer while
* never actually calling append on the unicode string unless the buffer
* fills up or is flushed.
*
* proper usage:
* {
* UnicodeStringAppender appender(astring);
* for (int32_t i = 0; i < 100; ++i) {
* appender.append((char16_t) i);
* }
* // appender flushed automatically when it goes out of scope.
* }
*/
class UnicodeStringAppender : public UMemory {
public:
/**
* dest is the UnicodeString being appended to. It must always
* exist while this instance exists.
*/
UnicodeStringAppender(UnicodeString &dest) : fDest(&dest), fIdx(0) { }
inline void append(char16_t x) {
if (fIdx == UPRV_LENGTHOF(fBuffer)) {
fDest->append(fBuffer, 0, fIdx);
fIdx = 0;
}
fBuffer[fIdx++] = x;
}
inline void append(UChar32 x) {
if (fIdx >= UPRV_LENGTHOF(fBuffer) - 1) {
fDest->append(fBuffer, 0, fIdx);
fIdx = 0;
}
U16_APPEND_UNSAFE(fBuffer, fIdx, x);
}
/**
* Ensures that all appended characters have been written out to dest.
*/
inline void flush() {
if (fIdx) {
fDest->append(fBuffer, 0, fIdx);
}
fIdx = 0;
}
/**
* flush the buffer when we go out of scope.
*/
~UnicodeStringAppender() {
flush();
}
private:
UnicodeString *fDest;
int32_t fIdx;
char16_t fBuffer[32];
UnicodeStringAppender(const UnicodeStringAppender &other);
UnicodeStringAppender &operator=(const UnicodeStringAppender &other);
};
U_NAMESPACE_END
#endif
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