icuSources/common/unicode/ucnv_cb.h

   1 /*
   2 **********************************************************************
   3 *   Copyright (C) 2000-2001, International Business Machines
   4 *   Corporation and others.  All Rights Reserved.
   5 **********************************************************************
   6  *  ucnv_cb.h:
   7  *  External APIs for the ICU's codeset conversion library
   8  *  Helena Shih
   9  *
  10  * Modification History:
  11  *
  12  *   Date        Name        Description
  13  */
  14
  15 /**
  16  * \file
  17  * \brief C UConverter functions to aid the writers of callbacks
  18  *
  19  * <h2> Callback API for UConverter </h2>
  20  *
  21  * These functions are provided here for the convenience of the callback
  22  * writer. If you are just looking for callback functions to use, please
  23  * see ucnv_err.h.  DO NOT call these functions directly when you are
  24  * working with converters, unless your code has been called as a callback
  25  * via ucnv_setFromUCallback or ucnv_setToUCallback !!
  26  *
  27  * A note about error codes and overflow.  Unlike other ICU functions,
  28  * these functions do not expect the error status to be U_ZERO_ERROR.
  29  * Callbacks must be much more careful about their error codes.
  30  * The error codes used here are in/out parameters, which should be passed
  31  * back in the callback's error parameter.
  32  *
  33  * For example, if you call ucnv_cbfromUWriteBytes to write data out
  34  * to the output codepage, it may return U_BUFFER_OVERFLOW_ERROR if
  35  * the data did not fit in the target. But this isn't a failing error,
  36  * in fact, ucnv_cbfromUWriteBytes may be called AGAIN with the error
  37  * status still U_BUFFER_OVERFLOW_ERROR to attempt to write further bytes,
  38  * which will also go into the internal overflow buffers.
  39  *
  40  * Concerning offsets, the 'offset' parameters here are relative to the start
  41  * of SOURCE.  For example, Suppose the string "ABCD" was being converted
  42  * from Unicode into a codepage which doesn't have a mapping for 'B'.
  43  * 'A' will be written out correctly, but
  44  * The FromU Callback will be called on an unassigned character for 'B'.
  45  * At this point, this is the state of the world:
  46  *    Target:    A [..]     [points after A]
  47  *    Source:  A B [C] D    [points to C - B has been consumed]
  48  *             0 1  2  3
  49  *    codePoint = "B"       [the unassigned codepoint]
  50  *
  51  * Now, suppose a callback wants to write the substitution character '?' to
  52  * the target. It calls ucnv_cbFromUWriteBytes() to write the ?.
  53  * It should pass ZERO as the offset, because the offset as far as the
  54  * callback is concerned is relative to the SOURCE pointer [which points
  55  * before 'C'.]  If the callback goes into the args and consumes 'C' also,
  56  * it would call FromUWriteBytes with an offset of 1 (and advance the source
  57  * pointer).
  58  *
  59  */
  60
  61 #ifndef UCNV_CB_H
  62 #define UCNV_CB_H
  63
  64 #include "unicode/utypes.h"
  65 #include "unicode/ucnv.h"
  66 #include "unicode/ucnv_err.h"
  67
  68 /**
  69  * ONLY used by FromU callback functions.
  70  * Writes out the specified byte output bytes to the target byte buffer or to converter internal buffers.
  71  *
  72  * @param args callback fromUnicode arguments
  73  * @param source source bytes to write
  74  * @param length length of bytes to write
  75  * @param offsetIndex the relative offset index from callback.
  76  * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG>
  77  * be returned to the user, because it means that not all data could be written into the target buffer, and some is
  78  * in the converter error buffer.
  79  * @see ucnv_cbFromUWriteSub
  80  * @stable ICU 2.0
  81  */
  82 U_CAPI void U_EXPORT2
  83 ucnv_cbFromUWriteBytes (UConverterFromUnicodeArgs *args,
  84                         const char* source,
  85                         int32_t length,
  86                         int32_t offsetIndex,
  87                         UErrorCode * err);
  88
  89 /**
  90  * ONLY used by FromU callback functions.
  91  * This function will write out the correct substitution character sequence
  92  * to the target.
  93  *
  94  * @param args callback fromUnicode arguments
  95  * @param offsetIndex the relative offset index from the current source pointer to be used
  96  * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG>
  97  * be returned to the user, because it means that not all data could be written into the target buffer, and some is
  98  * in the converter error buffer.
  99  * @see ucnv_cbFromUWriteBytes
 100  * @stable ICU 2.0
 101  */
 102 U_CAPI void U_EXPORT2
 103 ucnv_cbFromUWriteSub (UConverterFromUnicodeArgs *args,
 104                       int32_t offsetIndex,
 105                       UErrorCode * err);
 106
 107 /**
 108  * ONLY used by fromU callback functions.
 109  * This function will write out the error character(s) to the target UChar buffer.
 110  *
 111  * @param args callback fromUnicode arguments
 112  * @param source pointer to pointer to first UChar to write [on exit: 1 after last UChar processed]
 113  * @param sourceLimit pointer after last UChar to write
 114  * @param offsetIndex the relative offset index from callback which will be set
 115  * @param err error status <TT>U_BUFFER_OVERFLOW</TT>
 116  * @see ucnv_cbToUWriteSub
 117  * @stable ICU 2.0
 118  */
 119 U_CAPI void U_EXPORT2 ucnv_cbFromUWriteUChars(UConverterFromUnicodeArgs *args,
 120                              const UChar** source,
 121                              const UChar*  sourceLimit,
 122                              int32_t offsetIndex,
 123                              UErrorCode * err);
 124
 125 /**
 126  * ONLY used by ToU callback functions.
 127  *  This function will write out the specified characters to the target
 128  * UChar buffer.
 129  *
 130  * @param args callback toUnicode arguments
 131  * @param source source string to write
 132  * @param length the length of source string
 133  * @param offsetIndex the relative offset index which will be written.
 134  * @param err error status <TT>U_BUFFER_OVERFLOW</TT>
 135  * @see ucnv_cbToUWriteSub
 136  * @stable ICU 2.0
 137  */
 138 U_CAPI void U_EXPORT2 ucnv_cbToUWriteUChars (UConverterToUnicodeArgs *args,
 139                                              const UChar* source,
 140                                              int32_t length,
 141                                              int32_t offsetIndex,
 142                                              UErrorCode * err);
 143
 144 /**
 145  * ONLY used by ToU  callback functions.
 146  * This function will write out the Unicode substitution character (U+FFFD).
 147  *
 148  * @param args callback fromUnicode arguments
 149  * @param offsetIndex the relative offset index from callback.
 150  * @param err error status <TT>U_BUFFER_OVERFLOW</TT>
 151  * @see ucnv_cbToUWriteUChars
 152  * @stable ICU 2.0
 153  */
 154 U_CAPI void U_EXPORT2 ucnv_cbToUWriteSub (UConverterToUnicodeArgs *args,
 155                        int32_t offsetIndex,
 156                        UErrorCode * err);
 157 #endif