1 // © 2016 and later: Unicode, Inc. and others. 2 // License & terms of use: http://www.unicode.org/copyright.html 3 /* 4 ********************************************************************** 5 * Copyright (C) 2000-2004, International Business Machines 6 * Corporation and others. All Rights Reserved. 7 ********************************************************************** 8 * ucnv_cb.h: 9 * External APIs for the ICU's codeset conversion library 10 * Helena Shih 11 * 12 * Modification History: 13 * 14 * Date Name Description 15 */ 16 17 /** 18 * \file 19 * \brief C UConverter functions to aid the writers of callbacks 20 * 21 * <h2> Callback API for UConverter </h2> 22 * 23 * These functions are provided here for the convenience of the callback 24 * writer. If you are just looking for callback functions to use, please 25 * see ucnv_err.h. DO NOT call these functions directly when you are 26 * working with converters, unless your code has been called as a callback 27 * via ucnv_setFromUCallback or ucnv_setToUCallback !! 28 * 29 * A note about error codes and overflow. Unlike other ICU functions, 30 * these functions do not expect the error status to be U_ZERO_ERROR. 31 * Callbacks must be much more careful about their error codes. 32 * The error codes used here are in/out parameters, which should be passed 33 * back in the callback's error parameter. 34 * 35 * For example, if you call ucnv_cbfromUWriteBytes to write data out 36 * to the output codepage, it may return U_BUFFER_OVERFLOW_ERROR if 37 * the data did not fit in the target. But this isn't a failing error, 38 * in fact, ucnv_cbfromUWriteBytes may be called AGAIN with the error 39 * status still U_BUFFER_OVERFLOW_ERROR to attempt to write further bytes, 40 * which will also go into the internal overflow buffers. 41 * 42 * Concerning offsets, the 'offset' parameters here are relative to the start 43 * of SOURCE. For example, Suppose the string "ABCD" was being converted 44 * from Unicode into a codepage which doesn't have a mapping for 'B'. 45 * 'A' will be written out correctly, but 46 * The FromU Callback will be called on an unassigned character for 'B'. 47 * At this point, this is the state of the world: 48 * Target: A [..] [points after A] 49 * Source: A B [C] D [points to C - B has been consumed] 50 * 0 1 2 3 51 * codePoint = "B" [the unassigned codepoint] 52 * 53 * Now, suppose a callback wants to write the substitution character '?' to 54 * the target. It calls ucnv_cbFromUWriteBytes() to write the ?. 55 * It should pass ZERO as the offset, because the offset as far as the 56 * callback is concerned is relative to the SOURCE pointer [which points 57 * before 'C'.] If the callback goes into the args and consumes 'C' also, 58 * it would call FromUWriteBytes with an offset of 1 (and advance the source 59 * pointer). 60 * 61 */ 62 63 #ifndef UCNV_CB_H 64 #define UCNV_CB_H 65 66 #include "unicode/utypes.h" 67 68 #if !UCONFIG_NO_CONVERSION 69 70 #include "unicode/ucnv.h" 71 #include "unicode/ucnv_err.h" 72 73 /** 74 * ONLY used by FromU callback functions. 75 * Writes out the specified byte output bytes to the target byte buffer or to converter internal buffers. 76 * 77 * @param args callback fromUnicode arguments 78 * @param source source bytes to write 79 * @param length length of bytes to write 80 * @param offsetIndex the relative offset index from callback. 81 * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG> 82 * be returned to the user, because it means that not all data could be written into the target buffer, and some is 83 * in the converter error buffer. 84 * @see ucnv_cbFromUWriteSub 85 * @stable ICU 2.0 86 */ 87 U_CAPI void U_EXPORT2 88 ucnv_cbFromUWriteBytes (UConverterFromUnicodeArgs *args, 89 const char* source, 90 int32_t length, 91 int32_t offsetIndex, 92 UErrorCode * err); 93 94 /** 95 * ONLY used by FromU callback functions. 96 * This function will write out the correct substitution character sequence 97 * to the target. 98 * 99 * @param args callback fromUnicode arguments 100 * @param offsetIndex the relative offset index from the current source pointer to be used 101 * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG> 102 * be returned to the user, because it means that not all data could be written into the target buffer, and some is 103 * in the converter error buffer. 104 * @see ucnv_cbFromUWriteBytes 105 * @stable ICU 2.0 106 */ 107 U_CAPI void U_EXPORT2 108 ucnv_cbFromUWriteSub (UConverterFromUnicodeArgs *args, 109 int32_t offsetIndex, 110 UErrorCode * err); 111 112 /** 113 * ONLY used by fromU callback functions. 114 * This function will write out the error character(s) to the target UChar buffer. 115 * 116 * @param args callback fromUnicode arguments 117 * @param source pointer to pointer to first UChar to write [on exit: 1 after last UChar processed] 118 * @param sourceLimit pointer after last UChar to write 119 * @param offsetIndex the relative offset index from callback which will be set 120 * @param err error status <TT>U_BUFFER_OVERFLOW</TT> 121 * @see ucnv_cbToUWriteSub 122 * @stable ICU 2.0 123 */ 124 U_CAPI void U_EXPORT2 ucnv_cbFromUWriteUChars(UConverterFromUnicodeArgs *args, 125 const UChar** source, 126 const UChar* sourceLimit, 127 int32_t offsetIndex, 128 UErrorCode * err); 129 130 /** 131 * ONLY used by ToU callback functions. 132 * This function will write out the specified characters to the target 133 * UChar buffer. 134 * 135 * @param args callback toUnicode arguments 136 * @param source source string to write 137 * @param length the length of source string 138 * @param offsetIndex the relative offset index which will be written. 139 * @param err error status <TT>U_BUFFER_OVERFLOW</TT> 140 * @see ucnv_cbToUWriteSub 141 * @stable ICU 2.0 142 */ 143 U_CAPI void U_EXPORT2 ucnv_cbToUWriteUChars (UConverterToUnicodeArgs *args, 144 const UChar* source, 145 int32_t length, 146 int32_t offsetIndex, 147 UErrorCode * err); 148 149 /** 150 * ONLY used by ToU callback functions. 151 * This function will write out the Unicode substitution character (U+FFFD). 152 * 153 * @param args callback fromUnicode arguments 154 * @param offsetIndex the relative offset index from callback. 155 * @param err error status <TT>U_BUFFER_OVERFLOW</TT> 156 * @see ucnv_cbToUWriteUChars 157 * @stable ICU 2.0 158 */ 159 U_CAPI void U_EXPORT2 ucnv_cbToUWriteSub (UConverterToUnicodeArgs *args, 160 int32_t offsetIndex, 161 UErrorCode * err); 162 #endif 163 164 #endif 165