/* ******************************************************************************* * Copyright (C) 2011-2012, International Business Machines * Corporation and others. All Rights Reserved. ******************************************************************************* * file name: appendable.h * encoding: US-ASCII * tab size: 8 (not used) * indentation:4 * * created on: 2010dec07 * created by: Markus W. Scherer */ #ifndef __APPENDABLE_H__ #define __APPENDABLE_H__ /** * \file * \brief C++ API: Appendable class: Sink for Unicode code points and 16-bit code units (UChars). */ #include "unicode/utypes.h" #include "unicode/uobject.h" U_NAMESPACE_BEGIN class UnicodeString; /** * Base class for objects to which Unicode characters and strings can be appended. * Combines elements of Java Appendable and ICU4C ByteSink. * * This class can be used in APIs where it does not matter whether the actual destination is * a UnicodeString, a UChar[] array, a UnicodeSet, or any other object * that receives and processes characters and/or strings. * * Implementation classes must implement at least appendCodeUnit(UChar). * The base class provides default implementations for the other methods. * * The methods do not take UErrorCode parameters. * If an error occurs (e.g., out-of-memory), * in addition to returning FALSE from failing operations, * the implementation must prevent unexpected behavior (e.g., crashes) * from further calls and should make the error condition available separately * (e.g., store a UErrorCode, make/keep a UnicodeString bogus). * @stable ICU 4.8 */ class U_COMMON_API Appendable : public UObject { public: /** * Destructor. * @stable ICU 4.8 */ ~Appendable(); /** * Appends a 16-bit code unit. * @param c code unit * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool appendCodeUnit(UChar c) = 0; /** * Appends a code point. * The default implementation calls appendCodeUnit(UChar) once or twice. * @param c code point 0..0x10ffff * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool appendCodePoint(UChar32 c); /** * Appends a string. * The default implementation calls appendCodeUnit(UChar) for each code unit. * @param s string, must not be NULL if length!=0 * @param length string length, or -1 if NUL-terminated * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool appendString(const UChar *s, int32_t length); /** * Tells the object that the caller is going to append roughly * appendCapacity UChars. A subclass might use this to pre-allocate * a larger buffer if necessary. * The default implementation does nothing. (It always returns TRUE.) * @param appendCapacity estimated number of UChars that will be appended * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool reserveAppendCapacity(int32_t appendCapacity); /** * Returns a writable buffer for appending and writes the buffer's capacity to * *resultCapacity. Guarantees *resultCapacity>=minCapacity. * May return a pointer to the caller-owned scratch buffer which must have * scratchCapacity>=minCapacity. * The returned buffer is only valid until the next operation * on this Appendable. * * After writing at most *resultCapacity UChars, call appendString() with the * pointer returned from this function and the number of UChars written. * Many appendString() implementations will avoid copying UChars if this function * returned an internal buffer. * * Partial usage example: * \code * int32_t capacity; * UChar* buffer = app.getAppendBuffer(..., &capacity); * ... Write n UChars into buffer, with n <= capacity. * app.appendString(buffer, n); * \endcode * In many implementations, that call to append will avoid copying UChars. * * If the Appendable allocates or reallocates an internal buffer, it should use * the desiredCapacityHint if appropriate. * If a caller cannot provide a reasonable guess at the desired capacity, * it should pass desiredCapacityHint=0. * * If a non-scratch buffer is returned, the caller may only pass * a prefix to it to appendString(). * That is, it is not correct to pass an interior pointer to appendString(). * * The default implementation always returns the scratch buffer. * * @param minCapacity required minimum capacity of the returned buffer; * must be non-negative * @param desiredCapacityHint desired capacity of the returned buffer; * must be non-negative * @param scratch default caller-owned buffer * @param scratchCapacity capacity of the scratch buffer * @param resultCapacity pointer to an integer which will be set to the * capacity of the returned buffer * @return a buffer with *resultCapacity>=minCapacity * @stable ICU 4.8 */ virtual UChar *getAppendBuffer(int32_t minCapacity, int32_t desiredCapacityHint, UChar *scratch, int32_t scratchCapacity, int32_t *resultCapacity); private: // No ICU "poor man's RTTI" for this class nor its subclasses. virtual UClassID getDynamicClassID() const; }; /** * An Appendable implementation which writes to a UnicodeString. * * This class is not intended for public subclassing. * @stable ICU 4.8 */ class U_COMMON_API UnicodeStringAppendable : public Appendable { public: /** * Aliases the UnicodeString (keeps its reference) for writing. * @param s The UnicodeString to which this Appendable will write. * @stable ICU 4.8 */ explicit UnicodeStringAppendable(UnicodeString &s) : str(s) {} /** * Destructor. * @stable ICU 4.8 */ ~UnicodeStringAppendable(); /** * Appends a 16-bit code unit to the string. * @param c code unit * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool appendCodeUnit(UChar c); /** * Appends a code point to the string. * @param c code point 0..0x10ffff * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool appendCodePoint(UChar32 c); /** * Appends a string to the UnicodeString. * @param s string, must not be NULL if length!=0 * @param length string length, or -1 if NUL-terminated * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool appendString(const UChar *s, int32_t length); /** * Tells the UnicodeString that the caller is going to append roughly * appendCapacity UChars. * @param appendCapacity estimated number of UChars that will be appended * @return TRUE if the operation succeeded * @stable ICU 4.8 */ virtual UBool reserveAppendCapacity(int32_t appendCapacity); /** * Returns a writable buffer for appending and writes the buffer's capacity to * *resultCapacity. Guarantees *resultCapacity>=minCapacity. * May return a pointer to the caller-owned scratch buffer which must have * scratchCapacity>=minCapacity. * The returned buffer is only valid until the next write operation * on the UnicodeString. * * For details see Appendable::getAppendBuffer(). * * @param minCapacity required minimum capacity of the returned buffer; * must be non-negative * @param desiredCapacityHint desired capacity of the returned buffer; * must be non-negative * @param scratch default caller-owned buffer * @param scratchCapacity capacity of the scratch buffer * @param resultCapacity pointer to an integer which will be set to the * capacity of the returned buffer * @return a buffer with *resultCapacity>=minCapacity * @stable ICU 4.8 */ virtual UChar *getAppendBuffer(int32_t minCapacity, int32_t desiredCapacityHint, UChar *scratch, int32_t scratchCapacity, int32_t *resultCapacity); private: UnicodeString &str; }; U_NAMESPACE_END #endif // __APPENDABLE_H__