235 lines
8.4 KiB
C++
235 lines
8.4 KiB
C++
// © 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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/*
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*******************************************************************************
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* Copyright (C) 2011-2012, International Business Machines
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* Corporation and others. All Rights Reserved.
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*******************************************************************************
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* file name: appendable.h
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* encoding: UTF-8
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 2010dec07
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* created by: Markus W. Scherer
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*/
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#ifndef __APPENDABLE_H__
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#define __APPENDABLE_H__
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/**
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* \file
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* \brief C++ API: Appendable class: Sink for Unicode code points and 16-bit code units (char16_ts).
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*/
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#include "unicode/utypes.h"
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#include "unicode/uobject.h"
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U_NAMESPACE_BEGIN
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class UnicodeString;
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/**
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* Base class for objects to which Unicode characters and strings can be appended.
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* Combines elements of Java Appendable and ICU4C ByteSink.
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*
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* This class can be used in APIs where it does not matter whether the actual destination is
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* a UnicodeString, a char16_t[] array, a UnicodeSet, or any other object
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* that receives and processes characters and/or strings.
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*
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* Implementation classes must implement at least appendCodeUnit(char16_t).
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* The base class provides default implementations for the other methods.
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*
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* The methods do not take UErrorCode parameters.
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* If an error occurs (e.g., out-of-memory),
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* in addition to returning FALSE from failing operations,
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* the implementation must prevent unexpected behavior (e.g., crashes)
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* from further calls and should make the error condition available separately
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* (e.g., store a UErrorCode, make/keep a UnicodeString bogus).
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* @stable ICU 4.8
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*/
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class U_COMMON_API Appendable : public UObject {
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public:
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/**
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* Destructor.
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* @stable ICU 4.8
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*/
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~Appendable();
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/**
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* Appends a 16-bit code unit.
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* @param c code unit
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool appendCodeUnit(char16_t c) = 0;
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/**
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* Appends a code point.
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* The default implementation calls appendCodeUnit(char16_t) once or twice.
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* @param c code point 0..0x10ffff
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool appendCodePoint(UChar32 c);
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/**
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* Appends a string.
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* The default implementation calls appendCodeUnit(char16_t) for each code unit.
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* @param s string, must not be NULL if length!=0
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* @param length string length, or -1 if NUL-terminated
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool appendString(const char16_t *s, int32_t length);
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/**
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* Tells the object that the caller is going to append roughly
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* appendCapacity char16_ts. A subclass might use this to pre-allocate
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* a larger buffer if necessary.
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* The default implementation does nothing. (It always returns TRUE.)
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* @param appendCapacity estimated number of char16_ts that will be appended
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool reserveAppendCapacity(int32_t appendCapacity);
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/**
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* Returns a writable buffer for appending and writes the buffer's capacity to
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* *resultCapacity. Guarantees *resultCapacity>=minCapacity.
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* May return a pointer to the caller-owned scratch buffer which must have
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* scratchCapacity>=minCapacity.
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* The returned buffer is only valid until the next operation
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* on this Appendable.
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*
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* After writing at most *resultCapacity char16_ts, call appendString() with the
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* pointer returned from this function and the number of char16_ts written.
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* Many appendString() implementations will avoid copying char16_ts if this function
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* returned an internal buffer.
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*
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* Partial usage example:
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* \code
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* int32_t capacity;
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* char16_t* buffer = app.getAppendBuffer(..., &capacity);
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* ... Write n char16_ts into buffer, with n <= capacity.
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* app.appendString(buffer, n);
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* \endcode
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* In many implementations, that call to append will avoid copying char16_ts.
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*
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* If the Appendable allocates or reallocates an internal buffer, it should use
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* the desiredCapacityHint if appropriate.
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* If a caller cannot provide a reasonable guess at the desired capacity,
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* it should pass desiredCapacityHint=0.
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*
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* If a non-scratch buffer is returned, the caller may only pass
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* a prefix to it to appendString().
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* That is, it is not correct to pass an interior pointer to appendString().
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*
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* The default implementation always returns the scratch buffer.
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*
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* @param minCapacity required minimum capacity of the returned buffer;
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* must be non-negative
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* @param desiredCapacityHint desired capacity of the returned buffer;
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* must be non-negative
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* @param scratch default caller-owned buffer
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* @param scratchCapacity capacity of the scratch buffer
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* @param resultCapacity pointer to an integer which will be set to the
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* capacity of the returned buffer
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* @return a buffer with *resultCapacity>=minCapacity
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* @stable ICU 4.8
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*/
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virtual char16_t *getAppendBuffer(int32_t minCapacity,
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int32_t desiredCapacityHint,
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char16_t *scratch, int32_t scratchCapacity,
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int32_t *resultCapacity);
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};
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/**
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* An Appendable implementation which writes to a UnicodeString.
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*
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* This class is not intended for public subclassing.
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* @stable ICU 4.8
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*/
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class U_COMMON_API UnicodeStringAppendable : public Appendable {
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public:
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/**
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* Aliases the UnicodeString (keeps its reference) for writing.
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* @param s The UnicodeString to which this Appendable will write.
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* @stable ICU 4.8
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*/
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explicit UnicodeStringAppendable(UnicodeString &s) : str(s) {}
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/**
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* Destructor.
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* @stable ICU 4.8
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*/
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~UnicodeStringAppendable();
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/**
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* Appends a 16-bit code unit to the string.
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* @param c code unit
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool appendCodeUnit(char16_t c);
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/**
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* Appends a code point to the string.
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* @param c code point 0..0x10ffff
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool appendCodePoint(UChar32 c);
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/**
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* Appends a string to the UnicodeString.
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* @param s string, must not be NULL if length!=0
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* @param length string length, or -1 if NUL-terminated
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool appendString(const char16_t *s, int32_t length);
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/**
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* Tells the UnicodeString that the caller is going to append roughly
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* appendCapacity char16_ts.
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* @param appendCapacity estimated number of char16_ts that will be appended
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* @return TRUE if the operation succeeded
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* @stable ICU 4.8
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*/
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virtual UBool reserveAppendCapacity(int32_t appendCapacity);
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/**
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* Returns a writable buffer for appending and writes the buffer's capacity to
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* *resultCapacity. Guarantees *resultCapacity>=minCapacity.
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* May return a pointer to the caller-owned scratch buffer which must have
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* scratchCapacity>=minCapacity.
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* The returned buffer is only valid until the next write operation
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* on the UnicodeString.
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*
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* For details see Appendable::getAppendBuffer().
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*
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* @param minCapacity required minimum capacity of the returned buffer;
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* must be non-negative
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* @param desiredCapacityHint desired capacity of the returned buffer;
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* must be non-negative
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* @param scratch default caller-owned buffer
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* @param scratchCapacity capacity of the scratch buffer
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* @param resultCapacity pointer to an integer which will be set to the
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* capacity of the returned buffer
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* @return a buffer with *resultCapacity>=minCapacity
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* @stable ICU 4.8
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*/
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virtual char16_t *getAppendBuffer(int32_t minCapacity,
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int32_t desiredCapacityHint,
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char16_t *scratch, int32_t scratchCapacity,
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int32_t *resultCapacity);
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private:
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UnicodeString &str;
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};
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U_NAMESPACE_END
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#endif // __APPENDABLE_H__
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