1/*
2******************************************************************************
3*
4* © 2016 and later: Unicode, Inc. and others.
5* License & terms of use: http://www.unicode.org/copyright.html
6*
7******************************************************************************
8* file name: ubiditransform.h
9* encoding: UTF-8
10* tab size: 8 (not used)
11* indentation:4
12*
13* created on: 2016jul24
14* created by: Lina Kemmel
15*
16*/
17
18#ifndef UBIDITRANSFORM_H
19#define UBIDITRANSFORM_H
20
21#include "unicode/utypes.h"
22#include "unicode/ubidi.h"
23#include "unicode/uchar.h"
24#include "unicode/localpointer.h"
25
26/**
27 * \file
28 * \brief Bidi Transformations
29 */
30
31/**
32 * `UBiDiOrder` indicates the order of text.
33 *
34 * This bidi transformation engine supports all possible combinations (4 in
35 * total) of input and output text order:
36 *
37 * - <logical input, visual output>: unless the output direction is RTL, this
38 * corresponds to a normal operation of the Bidi algorithm as described in the
39 * Unicode Technical Report and implemented by `UBiDi` when the
40 * reordering mode is set to `UBIDI_REORDER_DEFAULT`. Visual RTL
41 * mode is not supported by `UBiDi` and is accomplished through
42 * reversing a visual LTR string,
43 *
44 * - <visual input, logical output>: unless the input direction is RTL, this
45 * corresponds to an "inverse bidi algorithm" in `UBiDi` with the
46 * reordering mode set to `UBIDI_REORDER_INVERSE_LIKE_DIRECT`.
47 * Visual RTL mode is not not supported by `UBiDi` and is
48 * accomplished through reversing a visual LTR string,
49 *
50 * - <logical input, logical output>: if the input and output base directions
51 * mismatch, this corresponds to the `UBiDi` implementation with the
52 * reordering mode set to `UBIDI_REORDER_RUNS_ONLY`; and if the
53 * input and output base directions are identical, the transformation engine
54 * will only handle character mirroring and Arabic shaping operations without
55 * reordering,
56 *
57 * - <visual input, visual output>: this reordering mode is not supported by
58 * the `UBiDi` engine; it implies character mirroring, Arabic
59 * shaping, and - if the input/output base directions mismatch - string
60 * reverse operations.
61 * @see ubidi_setInverse
62 * @see ubidi_setReorderingMode
63 * @see UBIDI_REORDER_DEFAULT
64 * @see UBIDI_REORDER_INVERSE_LIKE_DIRECT
65 * @see UBIDI_REORDER_RUNS_ONLY
66 * @stable ICU 58
67 */
68typedef enum {
69 /** 0: Constant indicating a logical order.
70 * This is the default for input text.
71 * @stable ICU 58
72 */
73 UBIDI_LOGICAL = 0,
74 /** 1: Constant indicating a visual order.
75 * This is a default for output text.
76 * @stable ICU 58
77 */
78 UBIDI_VISUAL
79} UBiDiOrder;
80
81/**
82 * <code>UBiDiMirroring</code> indicates whether or not characters with the
83 * "mirrored" property in RTL runs should be replaced with their mirror-image
84 * counterparts.
85 * @see UBIDI_DO_MIRRORING
86 * @see ubidi_setReorderingOptions
87 * @see ubidi_writeReordered
88 * @see ubidi_writeReverse
89 * @stable ICU 58
90 */
91typedef enum {
92 /** 0: Constant indicating that character mirroring should not be
93 * performed.
94 * This is the default.
95 * @stable ICU 58
96 */
97 UBIDI_MIRRORING_OFF = 0,
98 /** 1: Constant indicating that character mirroring should be performed.
99 * This corresponds to calling <code>ubidi_writeReordered</code> or
100 * <code>ubidi_writeReverse</code> with the
101 * <code>UBIDI_DO_MIRRORING</code> option bit set.
102 * @stable ICU 58
103 */
104 UBIDI_MIRRORING_ON
105} UBiDiMirroring;
106
107/**
108 * Forward declaration of the <code>UBiDiTransform</code> structure that stores
109 * information used by the layout transformation engine.
110 * @stable ICU 58
111 */
112typedef struct UBiDiTransform UBiDiTransform;
113
114/**
115 * Performs transformation of text from the bidi layout defined by the input
116 * ordering scheme to the bidi layout defined by the output ordering scheme,
117 * and applies character mirroring and Arabic shaping operations.<p>
118 * In terms of <code>UBiDi</code>, such a transformation implies:
119 * <ul>
120 * <li>calling <code>ubidi_setReorderingMode</code> as needed (when the
121 * reordering mode is other than normal),</li>
122 * <li>calling <code>ubidi_setInverse</code> as needed (when text should be
123 * transformed from a visual to a logical form),</li>
124 * <li>resolving embedding levels of each character in the input text by
125 * calling <code>ubidi_setPara</code>,</li>
126 * <li>reordering the characters based on the computed embedding levels, also
127 * performing character mirroring as needed, and streaming the result to the
128 * output, by calling <code>ubidi_writeReordered</code>,</li>
129 * <li>performing Arabic digit and letter shaping on the output text by calling
130 * <code>u_shapeArabic</code>.</li>
131 * </ul>
132 * An "ordering scheme" encompasses the base direction and the order of text,
133 * and these characteristics must be defined by the caller for both input and
134 * output explicitly .<p>
135 * There are 36 possible combinations of <input, output> ordering schemes,
136 * which are partially supported by <code>UBiDi</code> already. Examples of the
137 * currently supported combinations:
138 * <ul>
139 * <li><Logical LTR, Visual LTR>: this is equivalent to calling
140 * <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_LTR</code>,</li>
141 * <li><Logical RTL, Visual LTR>: this is equivalent to calling
142 * <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_RTL</code>,</li>
143 * <li><Logical Default ("Auto") LTR, Visual LTR>: this is equivalent to
144 * calling <code>ubidi_setPara</code> with
145 * <code>paraLevel == UBIDI_DEFAULT_LTR</code>,</li>
146 * <li><Logical Default ("Auto") RTL, Visual LTR>: this is equivalent to
147 * calling <code>ubidi_setPara</code> with
148 * <code>paraLevel == UBIDI_DEFAULT_RTL</code>,</li>
149 * <li><Visual LTR, Logical LTR>: this is equivalent to
150 * calling <code>ubidi_setInverse(UBiDi*, TRUE)</code> and then
151 * <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_LTR</code>,</li>
152 * <li><Visual LTR, Logical RTL>: this is equivalent to
153 * calling <code>ubidi_setInverse(UBiDi*, TRUE)</code> and then
154 * <code>ubidi_setPara</code> with <code>paraLevel == UBIDI_RTL</code>.</li>
155 * </ul>
156 * All combinations that involve the Visual RTL scheme are unsupported by
157 * <code>UBiDi</code>, for instance:
158 * <ul>
159 * <li><Logical LTR, Visual RTL>,</li>
160 * <li><Visual RTL, Logical RTL>.</li>
161 * </ul>
162 * <p>Example of usage of the transformation engine:<br>
163 * <pre>
164 * \code
165 * UChar text1[] = {'a', 'b', 'c', 0x0625, '1', 0};
166 * UChar text2[] = {'a', 'b', 'c', 0x0625, '1', 0};
167 * UErrorCode errorCode = U_ZERO_ERROR;
168 * // Run a transformation.
169 * ubiditransform_transform(pBidiTransform,
170 * text1, -1, text2, -1,
171 * UBIDI_LTR, UBIDI_VISUAL,
172 * UBIDI_RTL, UBIDI_LOGICAL,
173 * UBIDI_MIRRORING_OFF,
174 * U_SHAPE_DIGITS_AN2EN | U_SHAPE_DIGIT_TYPE_AN_EXTENDED,
175 * &errorCode);
176 * // Do something with text2.
177 * text2[4] = '2';
178 * // Run a reverse transformation.
179 * ubiditransform_transform(pBidiTransform,
180 * text2, -1, text1, -1,
181 * UBIDI_RTL, UBIDI_LOGICAL,
182 * UBIDI_LTR, UBIDI_VISUAL,
183 * UBIDI_MIRRORING_OFF,
184 * U_SHAPE_DIGITS_EN2AN | U_SHAPE_DIGIT_TYPE_AN_EXTENDED,
185 * &errorCode);
186 *\endcode
187 * </pre>
188 * </p>
189 *
190 * @param pBiDiTransform A pointer to a <code>UBiDiTransform</code> object
191 * allocated with <code>ubiditransform_open()</code> or
192 * <code>NULL</code>.<p>
193 * This object serves for one-time setup to amortize initialization
194 * overheads. Use of this object is not thread-safe. All other threads
195 * should allocate a new <code>UBiDiTransform</code> object by calling
196 * <code>ubiditransform_open()</code> before using it. Alternatively,
197 * a caller can set this parameter to <code>NULL</code>, in which case
198 * the object will be allocated by the engine on the fly.</p>
199 * @param src A pointer to the text that the Bidi layout transformations will
200 * be performed on.
201 * <p><strong>Note:</strong> the text must be (at least)
202 * <code>srcLength</code> long.</p>
203 * @param srcLength The length of the text, in number of UChars. If
204 * <code>length == -1</code> then the text must be zero-terminated.
205 * @param dest A pointer to where the processed text is to be copied.
206 * @param destSize The size of the <code>dest</code> buffer, in number of
207 * UChars. If the <code>U_SHAPE_LETTERS_UNSHAPE</code> option is set,
208 * then the destination length could be as large as
209 * <code>srcLength * 2</code>. Otherwise, the destination length will
210 * not exceed <code>srcLength</code>. If the caller reserves the last
211 * position for zero-termination, it should be excluded from
212 * <code>destSize</code>.
213 * <p><code>destSize == -1</code> is allowed and makes sense when
214 * <code>dest</code> was holds some meaningful value, e.g. that of
215 * <code>src</code>. In this case <code>dest</code> must be
216 * zero-terminated.</p>
217 * @param inParaLevel A base embedding level of the input as defined in
218 * <code>ubidi_setPara</code> documentation for the
219 * <code>paraLevel</code> parameter.
220 * @param inOrder An order of the input, which can be one of the
221 * <code>UBiDiOrder</code> values.
222 * @param outParaLevel A base embedding level of the output as defined in
223 * <code>ubidi_setPara</code> documentation for the
224 * <code>paraLevel</code> parameter.
225 * @param outOrder An order of the output, which can be one of the
226 * <code>UBiDiOrder</code> values.
227 * @param doMirroring Indicates whether or not to perform character mirroring,
228 * and can accept one of the <code>UBiDiMirroring</code> values.
229 * @param shapingOptions Arabic digit and letter shaping options defined in the
230 * ushape.h documentation.
231 * <p><strong>Note:</strong> Direction indicator options are computed by
232 * the transformation engine based on the effective ordering schemes, so
233 * user-defined direction indicators will be ignored.</p>
234 * @param pErrorCode A pointer to an error code value.
235 *
236 * @return The destination length, i.e. the number of UChars written to
237 * <code>dest</code>. If the transformation fails, the return value
238 * will be 0 (and the error code will be written to
239 * <code>pErrorCode</code>).
240 *
241 * @see UBiDiLevel
242 * @see UBiDiOrder
243 * @see UBiDiMirroring
244 * @see ubidi_setPara
245 * @see u_shapeArabic
246 * @stable ICU 58
247 */
248U_STABLE uint32_t U_EXPORT2
249ubiditransform_transform(UBiDiTransform *pBiDiTransform,
250 const UChar *src, int32_t srcLength,
251 UChar *dest, int32_t destSize,
252 UBiDiLevel inParaLevel, UBiDiOrder inOrder,
253 UBiDiLevel outParaLevel, UBiDiOrder outOrder,
254 UBiDiMirroring doMirroring, uint32_t shapingOptions,
255 UErrorCode *pErrorCode);
256
257/**
258 * Allocates a <code>UBiDiTransform</code> object. This object can be reused,
259 * e.g. with different ordering schemes, mirroring or shaping options.<p>
260 * <strong>Note:</strong>The object can only be reused in the same thread.
261 * All other threads should allocate a new <code>UBiDiTransform</code> object
262 * before using it.<p>
263 * Example of usage:<p>
264 * <pre>
265 * \code
266 * UErrorCode errorCode = U_ZERO_ERROR;
267 * // Open a new UBiDiTransform.
268 * UBiDiTransform* transform = ubiditransform_open(&errorCode);
269 * // Run a transformation.
270 * ubiditransform_transform(transform,
271 * text1, -1, text2, -1,
272 * UBIDI_RTL, UBIDI_LOGICAL,
273 * UBIDI_LTR, UBIDI_VISUAL,
274 * UBIDI_MIRRORING_ON,
275 * U_SHAPE_DIGITS_EN2AN,
276 * &errorCode);
277 * // Do something with the output text and invoke another transformation using
278 * // that text as input.
279 * ubiditransform_transform(transform,
280 * text2, -1, text3, -1,
281 * UBIDI_LTR, UBIDI_VISUAL,
282 * UBIDI_RTL, UBIDI_VISUAL,
283 * UBIDI_MIRRORING_ON,
284 * 0, &errorCode);
285 *\endcode
286 * </pre>
287 * <p>
288 * The <code>UBiDiTransform</code> object must be deallocated by calling
289 * <code>ubiditransform_close()</code>.
290 *
291 * @return An empty <code>UBiDiTransform</code> object.
292 * @stable ICU 58
293 */
294U_STABLE UBiDiTransform* U_EXPORT2
295ubiditransform_open(UErrorCode *pErrorCode);
296
297/**
298 * Deallocates the given <code>UBiDiTransform</code> object.
299 * @stable ICU 58
300 */
301U_STABLE void U_EXPORT2
302ubiditransform_close(UBiDiTransform *pBidiTransform);
303
304#if U_SHOW_CPLUSPLUS_API
305
306U_NAMESPACE_BEGIN
307
308/**
309 * \class LocalUBiDiTransformPointer
310 * "Smart pointer" class, closes a UBiDiTransform via ubiditransform_close().
311 * For most methods see the LocalPointerBase base class.
312 *
313 * @see LocalPointerBase
314 * @see LocalPointer
315 * @stable ICU 58
316 */
317U_DEFINE_LOCAL_OPEN_POINTER(LocalUBiDiTransformPointer, UBiDiTransform, ubiditransform_close);
318
319U_NAMESPACE_END
320
321#endif
322
323#endif
324