1/*
2**********************************************************************
3*   Copyright (C) 2000-2004, 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
66#if !UCONFIG_NO_CONVERSION
67
68#include "unicode/ucnv.h"
69#include "unicode/ucnv_err.h"
70
71/**
72 * ONLY used by FromU callback functions.
73 * Writes out the specified byte output bytes to the target byte buffer or to converter internal buffers.
74 *
75 * @param args callback fromUnicode arguments
76 * @param source source bytes to write
77 * @param length length of bytes to write
78 * @param offsetIndex the relative offset index from callback.
79 * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG>
80 * be returned to the user, because it means that not all data could be written into the target buffer, and some is
81 * in the converter error buffer.
82 * @see ucnv_cbFromUWriteSub
83 * @stable ICU 2.0
84 */
85U_STABLE void U_EXPORT2
86ucnv_cbFromUWriteBytes (UConverterFromUnicodeArgs *args,
87                        const char* source,
88                        int32_t length,
89                        int32_t offsetIndex,
90                        UErrorCode * err);
91
92/**
93 * ONLY used by FromU callback functions.
94 * This function will write out the correct substitution character sequence
95 * to the target.
96 *
97 * @param args callback fromUnicode arguments
98 * @param offsetIndex the relative offset index from the current source pointer to be used
99 * @param err error status. If <TT>U_BUFFER_OVERFLOW</TT> is returned, then U_BUFFER_OVERFLOW <STRONG>must</STRONG>
100 * be returned to the user, because it means that not all data could be written into the target buffer, and some is
101 * in the converter error buffer.
102 * @see ucnv_cbFromUWriteBytes
103 * @stable ICU 2.0
104 */
105U_STABLE void U_EXPORT2
106ucnv_cbFromUWriteSub (UConverterFromUnicodeArgs *args,
107                      int32_t offsetIndex,
108                      UErrorCode * err);
109
110/**
111 * ONLY used by fromU callback functions.
112 * This function will write out the error character(s) to the target UChar buffer.
113 *
114 * @param args callback fromUnicode arguments
115 * @param source pointer to pointer to first UChar to write [on exit: 1 after last UChar processed]
116 * @param sourceLimit pointer after last UChar to write
117 * @param offsetIndex the relative offset index from callback which will be set
118 * @param err error status <TT>U_BUFFER_OVERFLOW</TT>
119 * @see ucnv_cbToUWriteSub
120 * @stable ICU 2.0
121 */
122U_STABLE void U_EXPORT2 ucnv_cbFromUWriteUChars(UConverterFromUnicodeArgs *args,
123                             const UChar** source,
124                             const UChar*  sourceLimit,
125                             int32_t offsetIndex,
126                             UErrorCode * err);
127
128/**
129 * ONLY used by ToU callback functions.
130 *  This function will write out the specified characters to the target
131 * UChar buffer.
132 *
133 * @param args callback toUnicode arguments
134 * @param source source string to write
135 * @param length the length of source string
136 * @param offsetIndex the relative offset index which will be written.
137 * @param err error status <TT>U_BUFFER_OVERFLOW</TT>
138 * @see ucnv_cbToUWriteSub
139 * @stable ICU 2.0
140 */
141U_STABLE void U_EXPORT2 ucnv_cbToUWriteUChars (UConverterToUnicodeArgs *args,
142                                             const UChar* source,
143                                             int32_t length,
144                                             int32_t offsetIndex,
145                                             UErrorCode * err);
146
147/**
148 * ONLY used by ToU  callback functions.
149 * This function will write out the Unicode substitution character (U+FFFD).
150 *
151 * @param args callback fromUnicode arguments
152 * @param offsetIndex the relative offset index from callback.
153 * @param err error status <TT>U_BUFFER_OVERFLOW</TT>
154 * @see ucnv_cbToUWriteUChars
155 * @stable ICU 2.0
156 */
157U_STABLE void U_EXPORT2 ucnv_cbToUWriteSub (UConverterToUnicodeArgs *args,
158                       int32_t offsetIndex,
159                       UErrorCode * err);
160#endif
161
162#endif
163