← Back
Editing: ucnv_cb.h
// © 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ********************************************************************** * Copyright (C) 2000-2004, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * ucnv_cb.h: * External APIs for the ICU's codeset conversion library * Helena Shih * * Modification History: * * Date Name Description */ /** * \file * \brief C API: UConverter functions to aid the writers of callbacks * * <h2> Callback API for UConverter </h2> * * These functions are provided here for the convenience of the callback * writer. If you are just looking for callback functions to use, please * see ucnv_err.h. DO NOT call these functions directly when you are * working with converters, unless your code has been called as a callback * via ucnv_setFromUCallback or ucnv_setToUCallback !! * * A note about error codes and overflow. Unlike other ICU functions, * these functions do not expect the error status to be U_ZERO_ERROR. * Callbacks must be much more careful about their error codes. * The error codes used here are in/out parameters, which should be passed * back in the callback's error parameter. * * For example, if you call ucnv_cbfromUWriteBytes to write data out * to the output codepage, it may return U_BUFFER_OVERFLOW_ERROR if * the data did not fit in the target. But this isn't a failing error, * in fact, ucnv_cbfromUWriteBytes may be called AGAIN with the error * status still U_BUFFER_OVERFLOW_ERROR to attempt to write further bytes, * which will also go into the internal overflow buffers. * * Concerning offsets, the 'offset' parameters here are relative to the start * of SOURCE. For example, Suppose the string "ABCD" was being converted * from Unicode into a codepage which doesn't have a mapping for 'B'. * 'A' will be written out correctly, but * The FromU Callback will be called on an unassigned character for 'B'. * At this point, this is the state of the world: * Target: A [..] [points after A] * Source: A B [C] D [points to C - B has been consumed] * 0 1 2 3 * codePoint = "B" [the unassigned codepoint] * * Now, suppose a callback wants to write the substitution character '?' to * the target. It calls ucnv_cbFromUWriteBytes() to write the ?. * It should pass ZERO as the offset, because the offset as far as the * callback is concerned is relative to the SOURCE pointer [which points * before 'C'.] If the callback goes into the args and consumes 'C' also, * it would call FromUWriteBytes with an offset of 1 (and advance the source * pointer). * */ #ifndef UCNV_CB_H #define UCNV_CB_H #include "unicode/utypes.h" #if !UCONFIG_NO_CONVERSION #include "unicode/ucnv.h" #include "unicode/ucnv_err.h" /** * ONLY used by FromU callback functions. * Writes out the specified byte output bytes to the target byte buffer or to converter internal buffers. * * @param args callback fromUnicode arguments * @param source source bytes to write * @param length length of bytes to write * @param offsetIndex the relative offset index from callback. * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG> * be returned to the user, because it means that not all data could be written into the target buffer, and some is * in the converter error buffer. * @see ucnv_cbFromUWriteSub * @stable ICU 2.0 */ U_CAPI void U_EXPORT2 ucnv_cbFromUWriteBytes (UConverterFromUnicodeArgs *args, const char* source, int32_t length, int32_t offsetIndex, UErrorCode * err); /** * ONLY used by FromU callback functions. * This function will write out the correct substitution character sequence * to the target. * * @param args callback fromUnicode arguments * @param offsetIndex the relative offset index from the current source pointer to be used * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG> * be returned to the user, because it means that not all data could be written into the target buffer, and some is * in the converter error buffer. * @see ucnv_cbFromUWriteBytes * @stable ICU 2.0 */ U_CAPI void U_EXPORT2 ucnv_cbFromUWriteSub (UConverterFromUnicodeArgs *args, int32_t offsetIndex, UErrorCode * err); /** * ONLY used by fromU callback functions. * This function will write out the error character(s) to the target UChar buffer. * * @param args callback fromUnicode arguments * @param source pointer to pointer to first UChar to write [on exit: 1 after last UChar processed] * @param sourceLimit pointer after last UChar to write * @param offsetIndex the relative offset index from callback which will be set * @param err error status <TT>U_BUFFER_OVERFLOW</TT> * @see ucnv_cbToUWriteSub * @stable ICU 2.0 */ U_CAPI void U_EXPORT2 ucnv_cbFromUWriteUChars(UConverterFromUnicodeArgs *args, const UChar** source, const UChar* sourceLimit, int32_t offsetIndex, UErrorCode * err); /** * ONLY used by ToU callback functions. * This function will write out the specified characters to the target * UChar buffer. * * @param args callback toUnicode arguments * @param source source string to write * @param length the length of source string * @param offsetIndex the relative offset index which will be written. * @param err error status <TT>U_BUFFER_OVERFLOW</TT> * @see ucnv_cbToUWriteSub * @stable ICU 2.0 */ U_CAPI void U_EXPORT2 ucnv_cbToUWriteUChars (UConverterToUnicodeArgs *args, const UChar* source, int32_t length, int32_t offsetIndex, UErrorCode * err); /** * ONLY used by ToU callback functions. * This function will write out the Unicode substitution character (U+FFFD). * * @param args callback fromUnicode arguments * @param offsetIndex the relative offset index from callback. * @param err error status <TT>U_BUFFER_OVERFLOW</TT> * @see ucnv_cbToUWriteUChars * @stable ICU 2.0 */ U_CAPI void U_EXPORT2 ucnv_cbToUWriteSub (UConverterToUnicodeArgs *args, int32_t offsetIndex, UErrorCode * err); #endif #endif
Save File
Cancel