• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 // Copyright (C) 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 ******************************************************************************
5 *
6 *   Copyright (C) 1999-2013, International Business Machines
7 *   Corporation and others.  All Rights Reserved.
8 *
9 ******************************************************************************
10 *   file name:  ubidi.h
11 *   encoding:   US-ASCII
12 *   tab size:   8 (not used)
13 *   indentation:4
14 *
15 *   created on: 1999jul27
16 *   created by: Markus W. Scherer, updated by Matitiahu Allouche
17 */
18 
19 #ifndef UBIDI_H
20 #define UBIDI_H
21 
22 #include "unicode/utypes.h"
23 #include "unicode/uchar.h"
24 #include "unicode/localpointer.h"
25 
26 /**
27  *\file
28  * \brief C API: Bidi algorithm
29  *
30  * <h2>Bidi algorithm for ICU</h2>
31  *
32  * This is an implementation of the Unicode Bidirectional Algorithm.
33  * The algorithm is defined in the
34  * <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Standard Annex #9</a>.<p>
35  *
36  * Note: Libraries that perform a bidirectional algorithm and
37  * reorder strings accordingly are sometimes called "Storage Layout Engines".
38  * ICU's Bidi and shaping (u_shapeArabic()) APIs can be used at the core of such
39  * "Storage Layout Engines".
40  *
41  * <h3>General remarks about the API:</h3>
42  *
43  * In functions with an error code parameter,
44  * the <code>pErrorCode</code> pointer must be valid
45  * and the value that it points to must not indicate a failure before
46  * the function call. Otherwise, the function returns immediately.
47  * After the function call, the value indicates success or failure.<p>
48  *
49  * The &quot;limit&quot; of a sequence of characters is the position just after their
50  * last character, i.e., one more than that position.<p>
51  *
52  * Some of the API functions provide access to &quot;runs&quot;.
53  * Such a &quot;run&quot; is defined as a sequence of characters
54  * that are at the same embedding level
55  * after performing the Bidi algorithm.<p>
56  *
57  * @author Markus W. Scherer
58  * @version 1.0
59  *
60  *
61  * <h4> Sample code for the ICU Bidi API </h4>
62  *
63  * <h5>Rendering a paragraph with the ICU Bidi API</h5>
64  *
65  * This is (hypothetical) sample code that illustrates
66  * how the ICU Bidi API could be used to render a paragraph of text.
67  * Rendering code depends highly on the graphics system,
68  * therefore this sample code must make a lot of assumptions,
69  * which may or may not match any existing graphics system's properties.
70  *
71  * <p>The basic assumptions are:</p>
72  * <ul>
73  * <li>Rendering is done from left to right on a horizontal line.</li>
74  * <li>A run of single-style, unidirectional text can be rendered at once.</li>
75  * <li>Such a run of text is passed to the graphics system with
76  *     characters (code units) in logical order.</li>
77  * <li>The line-breaking algorithm is very complicated
78  *     and Locale-dependent -
79  *     and therefore its implementation omitted from this sample code.</li>
80  * </ul>
81  *
82  * <pre>
83  * \code
84  *#include "unicode/ubidi.h"
85  *
86  *typedef enum {
87  *     styleNormal=0, styleSelected=1,
88  *     styleBold=2, styleItalics=4,
89  *     styleSuper=8, styleSub=16
90  *} Style;
91  *
92  *typedef struct { int32_t limit; Style style; } StyleRun;
93  *
94  *int getTextWidth(const UChar *text, int32_t start, int32_t limit,
95  *                  const StyleRun *styleRuns, int styleRunCount);
96  *
97  * // set *pLimit and *pStyleRunLimit for a line
98  * // from text[start] and from styleRuns[styleRunStart]
99  * // using ubidi_getLogicalRun(para, ...)
100  *void getLineBreak(const UChar *text, int32_t start, int32_t *pLimit,
101  *                  UBiDi *para,
102  *                  const StyleRun *styleRuns, int styleRunStart, int *pStyleRunLimit,
103  *                  int *pLineWidth);
104  *
105  * // render runs on a line sequentially, always from left to right
106  *
107  * // prepare rendering a new line
108  * void startLine(UBiDiDirection textDirection, int lineWidth);
109  *
110  * // render a run of text and advance to the right by the run width
111  * // the text[start..limit-1] is always in logical order
112  * void renderRun(const UChar *text, int32_t start, int32_t limit,
113  *               UBiDiDirection textDirection, Style style);
114  *
115  * // We could compute a cross-product
116  * // from the style runs with the directional runs
117  * // and then reorder it.
118  * // Instead, here we iterate over each run type
119  * // and render the intersections -
120  * // with shortcuts in simple (and common) cases.
121  * // renderParagraph() is the main function.
122  *
123  * // render a directional run with
124  * // (possibly) multiple style runs intersecting with it
125  * void renderDirectionalRun(const UChar *text,
126  *                           int32_t start, int32_t limit,
127  *                           UBiDiDirection direction,
128  *                           const StyleRun *styleRuns, int styleRunCount) {
129  *     int i;
130  *
131  *     // iterate over style runs
132  *     if(direction==UBIDI_LTR) {
133  *         int styleLimit;
134  *
135  *         for(i=0; i<styleRunCount; ++i) {
136  *             styleLimit=styleRun[i].limit;
137  *             if(start<styleLimit) {
138  *                 if(styleLimit>limit) { styleLimit=limit; }
139  *                 renderRun(text, start, styleLimit,
140  *                           direction, styleRun[i].style);
141  *                 if(styleLimit==limit) { break; }
142  *                 start=styleLimit;
143  *             }
144  *         }
145  *     } else {
146  *         int styleStart;
147  *
148  *         for(i=styleRunCount-1; i>=0; --i) {
149  *             if(i>0) {
150  *                 styleStart=styleRun[i-1].limit;
151  *             } else {
152  *                 styleStart=0;
153  *             }
154  *             if(limit>=styleStart) {
155  *                 if(styleStart<start) { styleStart=start; }
156  *                 renderRun(text, styleStart, limit,
157  *                           direction, styleRun[i].style);
158  *                 if(styleStart==start) { break; }
159  *                 limit=styleStart;
160  *             }
161  *         }
162  *     }
163  * }
164  *
165  * // the line object represents text[start..limit-1]
166  * void renderLine(UBiDi *line, const UChar *text,
167  *                 int32_t start, int32_t limit,
168  *                 const StyleRun *styleRuns, int styleRunCount) {
169  *     UBiDiDirection direction=ubidi_getDirection(line);
170  *     if(direction!=UBIDI_MIXED) {
171  *         // unidirectional
172  *         if(styleRunCount<=1) {
173  *             renderRun(text, start, limit, direction, styleRuns[0].style);
174  *         } else {
175  *             renderDirectionalRun(text, start, limit,
176  *                                  direction, styleRuns, styleRunCount);
177  *         }
178  *     } else {
179  *         // mixed-directional
180  *         int32_t count, i, length;
181  *         UBiDiLevel level;
182  *
183  *         count=ubidi_countRuns(para, pErrorCode);
184  *         if(U_SUCCESS(*pErrorCode)) {
185  *             if(styleRunCount<=1) {
186  *                 Style style=styleRuns[0].style;
187  *
188  *                 // iterate over directional runs
189  *                for(i=0; i<count; ++i) {
190  *                    direction=ubidi_getVisualRun(para, i, &start, &length);
191  *                     renderRun(text, start, start+length, direction, style);
192  *                }
193  *             } else {
194  *                 int32_t j;
195  *
196  *                 // iterate over both directional and style runs
197  *                 for(i=0; i<count; ++i) {
198  *                     direction=ubidi_getVisualRun(line, i, &start, &length);
199  *                     renderDirectionalRun(text, start, start+length,
200  *                                          direction, styleRuns, styleRunCount);
201  *                 }
202  *             }
203  *         }
204  *     }
205  * }
206  *
207  *void renderParagraph(const UChar *text, int32_t length,
208  *                     UBiDiDirection textDirection,
209  *                      const StyleRun *styleRuns, int styleRunCount,
210  *                      int lineWidth,
211  *                      UErrorCode *pErrorCode) {
212  *     UBiDi *para;
213  *
214  *     if(pErrorCode==NULL || U_FAILURE(*pErrorCode) || length<=0) {
215  *         return;
216  *     }
217  *
218  *     para=ubidi_openSized(length, 0, pErrorCode);
219  *     if(para==NULL) { return; }
220  *
221  *     ubidi_setPara(para, text, length,
222  *                   textDirection ? UBIDI_DEFAULT_RTL : UBIDI_DEFAULT_LTR,
223  *                   NULL, pErrorCode);
224  *     if(U_SUCCESS(*pErrorCode)) {
225  *         UBiDiLevel paraLevel=1&ubidi_getParaLevel(para);
226  *         StyleRun styleRun={ length, styleNormal };
227  *         int width;
228  *
229  *         if(styleRuns==NULL || styleRunCount<=0) {
230  *            styleRunCount=1;
231  *             styleRuns=&styleRun;
232  *         }
233  *
234  *        // assume styleRuns[styleRunCount-1].limit>=length
235  *
236  *         width=getTextWidth(text, 0, length, styleRuns, styleRunCount);
237  *         if(width<=lineWidth) {
238  *             // everything fits onto one line
239  *
240  *            // prepare rendering a new line from either left or right
241  *             startLine(paraLevel, width);
242  *
243  *             renderLine(para, text, 0, length,
244  *                        styleRuns, styleRunCount);
245  *         } else {
246  *             UBiDi *line;
247  *
248  *             // we need to render several lines
249  *             line=ubidi_openSized(length, 0, pErrorCode);
250  *             if(line!=NULL) {
251  *                 int32_t start=0, limit;
252  *                 int styleRunStart=0, styleRunLimit;
253  *
254  *                 for(;;) {
255  *                     limit=length;
256  *                     styleRunLimit=styleRunCount;
257  *                     getLineBreak(text, start, &limit, para,
258  *                                  styleRuns, styleRunStart, &styleRunLimit,
259  *                                 &width);
260  *                     ubidi_setLine(para, start, limit, line, pErrorCode);
261  *                     if(U_SUCCESS(*pErrorCode)) {
262  *                         // prepare rendering a new line
263  *                         // from either left or right
264  *                         startLine(paraLevel, width);
265  *
266  *                         renderLine(line, text, start, limit,
267  *                                    styleRuns+styleRunStart,
268  *                                    styleRunLimit-styleRunStart);
269  *                     }
270  *                     if(limit==length) { break; }
271  *                     start=limit;
272  *                     styleRunStart=styleRunLimit-1;
273  *                     if(start>=styleRuns[styleRunStart].limit) {
274  *                         ++styleRunStart;
275  *                     }
276  *                 }
277  *
278  *                 ubidi_close(line);
279  *             }
280  *        }
281  *    }
282  *
283  *     ubidi_close(para);
284  *}
285  *\endcode
286  * </pre>
287  */
288 
289 /*DOCXX_TAG*/
290 /*@{*/
291 
292 /**
293  * UBiDiLevel is the type of the level values in this
294  * Bidi implementation.
295  * It holds an embedding level and indicates the visual direction
296  * by its bit&nbsp;0 (even/odd value).<p>
297  *
298  * It can also hold non-level values for the
299  * <code>paraLevel</code> and <code>embeddingLevels</code>
300  * arguments of <code>ubidi_setPara()</code>; there:
301  * <ul>
302  * <li>bit&nbsp;7 of an <code>embeddingLevels[]</code>
303  * value indicates whether the using application is
304  * specifying the level of a character to <i>override</i> whatever the
305  * Bidi implementation would resolve it to.</li>
306  * <li><code>paraLevel</code> can be set to the
307  * pseudo-level values <code>UBIDI_DEFAULT_LTR</code>
308  * and <code>UBIDI_DEFAULT_RTL</code>.</li>
309  * </ul>
310  *
311  * @see ubidi_setPara
312  *
313  * <p>The related constants are not real, valid level values.
314  * <code>UBIDI_DEFAULT_XXX</code> can be used to specify
315  * a default for the paragraph level for
316  * when the <code>ubidi_setPara()</code> function
317  * shall determine it but there is no
318  * strongly typed character in the input.<p>
319  *
320  * Note that the value for <code>UBIDI_DEFAULT_LTR</code> is even
321  * and the one for <code>UBIDI_DEFAULT_RTL</code> is odd,
322  * just like with normal LTR and RTL level values -
323  * these special values are designed that way. Also, the implementation
324  * assumes that UBIDI_MAX_EXPLICIT_LEVEL is odd.
325  *
326  * @see UBIDI_DEFAULT_LTR
327  * @see UBIDI_DEFAULT_RTL
328  * @see UBIDI_LEVEL_OVERRIDE
329  * @see UBIDI_MAX_EXPLICIT_LEVEL
330  * @stable ICU 2.0
331  */
332 typedef uint8_t UBiDiLevel;
333 
334 /** Paragraph level setting.<p>
335  *
336  * Constant indicating that the base direction depends on the first strong
337  * directional character in the text according to the Unicode Bidirectional
338  * Algorithm. If no strong directional character is present,
339  * then set the paragraph level to 0 (left-to-right).<p>
340  *
341  * If this value is used in conjunction with reordering modes
342  * <code>UBIDI_REORDER_INVERSE_LIKE_DIRECT</code> or
343  * <code>UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code>, the text to reorder
344  * is assumed to be visual LTR, and the text after reordering is required
345  * to be the corresponding logical string with appropriate contextual
346  * direction. The direction of the result string will be RTL if either
347  * the righmost or leftmost strong character of the source text is RTL
348  * or Arabic Letter, the direction will be LTR otherwise.<p>
349  *
350  * If reordering option <code>UBIDI_OPTION_INSERT_MARKS</code> is set, an RLM may
351  * be added at the beginning of the result string to ensure round trip
352  * (that the result string, when reordered back to visual, will produce
353  * the original source text).
354  * @see UBIDI_REORDER_INVERSE_LIKE_DIRECT
355  * @see UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL
356  * @stable ICU 2.0
357  */
358 #define UBIDI_DEFAULT_LTR 0xfe
359 
360 /** Paragraph level setting.<p>
361  *
362  * Constant indicating that the base direction depends on the first strong
363  * directional character in the text according to the Unicode Bidirectional
364  * Algorithm. If no strong directional character is present,
365  * then set the paragraph level to 1 (right-to-left).<p>
366  *
367  * If this value is used in conjunction with reordering modes
368  * <code>UBIDI_REORDER_INVERSE_LIKE_DIRECT</code> or
369  * <code>UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code>, the text to reorder
370  * is assumed to be visual LTR, and the text after reordering is required
371  * to be the corresponding logical string with appropriate contextual
372  * direction. The direction of the result string will be RTL if either
373  * the righmost or leftmost strong character of the source text is RTL
374  * or Arabic Letter, or if the text contains no strong character;
375  * the direction will be LTR otherwise.<p>
376  *
377  * If reordering option <code>UBIDI_OPTION_INSERT_MARKS</code> is set, an RLM may
378  * be added at the beginning of the result string to ensure round trip
379  * (that the result string, when reordered back to visual, will produce
380  * the original source text).
381  * @see UBIDI_REORDER_INVERSE_LIKE_DIRECT
382  * @see UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL
383  * @stable ICU 2.0
384  */
385 #define UBIDI_DEFAULT_RTL 0xff
386 
387 /**
388  * Maximum explicit embedding level.
389  * (The maximum resolved level can be up to <code>UBIDI_MAX_EXPLICIT_LEVEL+1</code>).
390  * @stable ICU 2.0
391  */
392 #define UBIDI_MAX_EXPLICIT_LEVEL 125
393 
394 /** Bit flag for level input.
395  *  Overrides directional properties.
396  * @stable ICU 2.0
397  */
398 #define UBIDI_LEVEL_OVERRIDE 0x80
399 
400 /**
401  * Special value which can be returned by the mapping functions when a logical
402  * index has no corresponding visual index or vice-versa. This may happen
403  * for the logical-to-visual mapping of a Bidi control when option
404  * <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> is specified. This can also happen
405  * for the visual-to-logical mapping of a Bidi mark (LRM or RLM) inserted
406  * by option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
407  * @see ubidi_getVisualIndex
408  * @see ubidi_getVisualMap
409  * @see ubidi_getLogicalIndex
410  * @see ubidi_getLogicalMap
411  * @stable ICU 3.6
412  */
413 #define UBIDI_MAP_NOWHERE   (-1)
414 
415 /**
416  * <code>UBiDiDirection</code> values indicate the text direction.
417  * @stable ICU 2.0
418  */
419 enum UBiDiDirection {
420   /** Left-to-right text. This is a 0 value.
421    * <ul>
422    * <li>As return value for <code>ubidi_getDirection()</code>, it means
423    *     that the source string contains no right-to-left characters, or
424    *     that the source string is empty and the paragraph level is even.
425    * <li> As return value for <code>ubidi_getBaseDirection()</code>, it
426    *      means that the first strong character of the source string has
427    *      a left-to-right direction.
428    * </ul>
429    * @stable ICU 2.0
430    */
431   UBIDI_LTR,
432   /** Right-to-left text. This is a 1 value.
433    * <ul>
434    * <li>As return value for <code>ubidi_getDirection()</code>, it means
435    *     that the source string contains no left-to-right characters, or
436    *     that the source string is empty and the paragraph level is odd.
437    * <li> As return value for <code>ubidi_getBaseDirection()</code>, it
438    *      means that the first strong character of the source string has
439    *      a right-to-left direction.
440    * </ul>
441    * @stable ICU 2.0
442    */
443   UBIDI_RTL,
444   /** Mixed-directional text.
445    * <p>As return value for <code>ubidi_getDirection()</code>, it means
446    *    that the source string contains both left-to-right and
447    *    right-to-left characters.
448    * @stable ICU 2.0
449    */
450   UBIDI_MIXED,
451   /** No strongly directional text.
452    * <p>As return value for <code>ubidi_getBaseDirection()</code>, it means
453    *    that the source string is missing or empty, or contains neither left-to-right
454    *    nor right-to-left characters.
455    * @stable ICU 4.6
456    */
457   UBIDI_NEUTRAL
458 };
459 
460 /** @stable ICU 2.0 */
461 typedef enum UBiDiDirection UBiDiDirection;
462 
463 /**
464  * Forward declaration of the <code>UBiDi</code> structure for the declaration of
465  * the API functions. Its fields are implementation-specific.<p>
466  * This structure holds information about a paragraph (or multiple paragraphs)
467  * of text with Bidi-algorithm-related details, or about one line of
468  * such a paragraph.<p>
469  * Reordering can be done on a line, or on one or more paragraphs which are
470  * then interpreted each as one single line.
471  * @stable ICU 2.0
472  */
473 struct UBiDi;
474 
475 /** @stable ICU 2.0 */
476 typedef struct UBiDi UBiDi;
477 
478 /**
479  * Allocate a <code>UBiDi</code> structure.
480  * Such an object is initially empty. It is assigned
481  * the Bidi properties of a piece of text containing one or more paragraphs
482  * by <code>ubidi_setPara()</code>
483  * or the Bidi properties of a line within a paragraph by
484  * <code>ubidi_setLine()</code>.<p>
485  * This object can be reused for as long as it is not deallocated
486  * by calling <code>ubidi_close()</code>.<p>
487  * <code>ubidi_setPara()</code> and <code>ubidi_setLine()</code> will allocate
488  * additional memory for internal structures as necessary.
489  *
490  * @return An empty <code>UBiDi</code> object.
491  * @stable ICU 2.0
492  */
493 U_STABLE UBiDi * U_EXPORT2
494 ubidi_open(void);
495 
496 /**
497  * Allocate a <code>UBiDi</code> structure with preallocated memory
498  * for internal structures.
499  * This function provides a <code>UBiDi</code> object like <code>ubidi_open()</code>
500  * with no arguments, but it also preallocates memory for internal structures
501  * according to the sizings supplied by the caller.<p>
502  * Subsequent functions will not allocate any more memory, and are thus
503  * guaranteed not to fail because of lack of memory.<p>
504  * The preallocation can be limited to some of the internal memory
505  * by setting some values to 0 here. That means that if, e.g.,
506  * <code>maxRunCount</code> cannot be reasonably predetermined and should not
507  * be set to <code>maxLength</code> (the only failproof value) to avoid
508  * wasting memory, then <code>maxRunCount</code> could be set to 0 here
509  * and the internal structures that are associated with it will be allocated
510  * on demand, just like with <code>ubidi_open()</code>.
511  *
512  * @param maxLength is the maximum text or line length that internal memory
513  *        will be preallocated for. An attempt to associate this object with a
514  *        longer text will fail, unless this value is 0, which leaves the allocation
515  *        up to the implementation.
516  *
517  * @param maxRunCount is the maximum anticipated number of same-level runs
518  *        that internal memory will be preallocated for. An attempt to access
519  *        visual runs on an object that was not preallocated for as many runs
520  *        as the text was actually resolved to will fail,
521  *        unless this value is 0, which leaves the allocation up to the implementation.<br><br>
522  *        The number of runs depends on the actual text and maybe anywhere between
523  *        1 and <code>maxLength</code>. It is typically small.
524  *
525  * @param pErrorCode must be a valid pointer to an error code value.
526  *
527  * @return An empty <code>UBiDi</code> object with preallocated memory.
528  * @stable ICU 2.0
529  */
530 U_STABLE UBiDi * U_EXPORT2
531 ubidi_openSized(int32_t maxLength, int32_t maxRunCount, UErrorCode *pErrorCode);
532 
533 /**
534  * <code>ubidi_close()</code> must be called to free the memory
535  * associated with a UBiDi object.<p>
536  *
537  * <strong>Important: </strong>
538  * A parent <code>UBiDi</code> object must not be destroyed or reused if
539  * it still has children.
540  * If a <code>UBiDi</code> object has become the <i>child</i>
541  * of another one (its <i>parent</i>) by calling
542  * <code>ubidi_setLine()</code>, then the child object must
543  * be destroyed (closed) or reused (by calling
544  * <code>ubidi_setPara()</code> or <code>ubidi_setLine()</code>)
545  * before the parent object.
546  *
547  * @param pBiDi is a <code>UBiDi</code> object.
548  *
549  * @see ubidi_setPara
550  * @see ubidi_setLine
551  * @stable ICU 2.0
552  */
553 U_STABLE void U_EXPORT2
554 ubidi_close(UBiDi *pBiDi);
555 
556 #if U_SHOW_CPLUSPLUS_API
557 
558 U_NAMESPACE_BEGIN
559 
560 /**
561  * \class LocalUBiDiPointer
562  * "Smart pointer" class, closes a UBiDi via ubidi_close().
563  * For most methods see the LocalPointerBase base class.
564  *
565  * @see LocalPointerBase
566  * @see LocalPointer
567  * @stable ICU 4.4
568  */
569 U_DEFINE_LOCAL_OPEN_POINTER(LocalUBiDiPointer, UBiDi, ubidi_close);
570 
571 U_NAMESPACE_END
572 
573 #endif
574 
575 /**
576  * Modify the operation of the Bidi algorithm such that it
577  * approximates an "inverse Bidi" algorithm. This function
578  * must be called before <code>ubidi_setPara()</code>.
579  *
580  * <p>The normal operation of the Bidi algorithm as described
581  * in the Unicode Technical Report is to take text stored in logical
582  * (keyboard, typing) order and to determine the reordering of it for visual
583  * rendering.
584  * Some legacy systems store text in visual order, and for operations
585  * with standard, Unicode-based algorithms, the text needs to be transformed
586  * to logical order. This is effectively the inverse algorithm of the
587  * described Bidi algorithm. Note that there is no standard algorithm for
588  * this "inverse Bidi" and that the current implementation provides only an
589  * approximation of "inverse Bidi".</p>
590  *
591  * <p>With <code>isInverse</code> set to <code>TRUE</code>,
592  * this function changes the behavior of some of the subsequent functions
593  * in a way that they can be used for the inverse Bidi algorithm.
594  * Specifically, runs of text with numeric characters will be treated in a
595  * special way and may need to be surrounded with LRM characters when they are
596  * written in reordered sequence.</p>
597  *
598  * <p>Output runs should be retrieved using <code>ubidi_getVisualRun()</code>.
599  * Since the actual input for "inverse Bidi" is visually ordered text and
600  * <code>ubidi_getVisualRun()</code> gets the reordered runs, these are actually
601  * the runs of the logically ordered output.</p>
602  *
603  * <p>Calling this function with argument <code>isInverse</code> set to
604  * <code>TRUE</code> is equivalent to calling
605  * <code>ubidi_setReorderingMode</code> with argument
606  * <code>reorderingMode</code>
607  * set to <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>.<br>
608  * Calling this function with argument <code>isInverse</code> set to
609  * <code>FALSE</code> is equivalent to calling
610  * <code>ubidi_setReorderingMode</code> with argument
611  * <code>reorderingMode</code>
612  * set to <code>#UBIDI_REORDER_DEFAULT</code>.
613  *
614  * @param pBiDi is a <code>UBiDi</code> object.
615  *
616  * @param isInverse specifies "forward" or "inverse" Bidi operation.
617  *
618  * @see ubidi_setPara
619  * @see ubidi_writeReordered
620  * @see ubidi_setReorderingMode
621  * @stable ICU 2.0
622  */
623 U_STABLE void U_EXPORT2
624 ubidi_setInverse(UBiDi *pBiDi, UBool isInverse);
625 
626 /**
627  * Is this Bidi object set to perform the inverse Bidi algorithm?
628  * <p>Note: calling this function after setting the reordering mode with
629  * <code>ubidi_setReorderingMode</code> will return <code>TRUE</code> if the
630  * reordering mode was set to <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>,
631  * <code>FALSE</code> for all other values.</p>
632  *
633  * @param pBiDi is a <code>UBiDi</code> object.
634  * @return TRUE if the Bidi object is set to perform the inverse Bidi algorithm
635  * by handling numbers as L.
636  *
637  * @see ubidi_setInverse
638  * @see ubidi_setReorderingMode
639  * @stable ICU 2.0
640  */
641 
642 U_STABLE UBool U_EXPORT2
643 ubidi_isInverse(UBiDi *pBiDi);
644 
645 /**
646  * Specify whether block separators must be allocated level zero,
647  * so that successive paragraphs will progress from left to right.
648  * This function must be called before <code>ubidi_setPara()</code>.
649  * Paragraph separators (B) may appear in the text.  Setting them to level zero
650  * means that all paragraph separators (including one possibly appearing
651  * in the last text position) are kept in the reordered text after the text
652  * that they follow in the source text.
653  * When this feature is not enabled, a paragraph separator at the last
654  * position of the text before reordering will go to the first position
655  * of the reordered text when the paragraph level is odd.
656  *
657  * @param pBiDi is a <code>UBiDi</code> object.
658  *
659  * @param orderParagraphsLTR specifies whether paragraph separators (B) must
660  * receive level 0, so that successive paragraphs progress from left to right.
661  *
662  * @see ubidi_setPara
663  * @stable ICU 3.4
664  */
665 U_STABLE void U_EXPORT2
666 ubidi_orderParagraphsLTR(UBiDi *pBiDi, UBool orderParagraphsLTR);
667 
668 /**
669  * Is this Bidi object set to allocate level 0 to block separators so that
670  * successive paragraphs progress from left to right?
671  *
672  * @param pBiDi is a <code>UBiDi</code> object.
673  * @return TRUE if the Bidi object is set to allocate level 0 to block
674  *         separators.
675  *
676  * @see ubidi_orderParagraphsLTR
677  * @stable ICU 3.4
678  */
679 U_STABLE UBool U_EXPORT2
680 ubidi_isOrderParagraphsLTR(UBiDi *pBiDi);
681 
682 /**
683  * <code>UBiDiReorderingMode</code> values indicate which variant of the Bidi
684  * algorithm to use.
685  *
686  * @see ubidi_setReorderingMode
687  * @stable ICU 3.6
688  */
689 typedef enum UBiDiReorderingMode {
690     /** Regular Logical to Visual Bidi algorithm according to Unicode.
691       * This is a 0 value.
692       * @stable ICU 3.6 */
693     UBIDI_REORDER_DEFAULT = 0,
694     /** Logical to Visual algorithm which handles numbers in a way which
695       * mimicks the behavior of Windows XP.
696       * @stable ICU 3.6 */
697     UBIDI_REORDER_NUMBERS_SPECIAL,
698     /** Logical to Visual algorithm grouping numbers with adjacent R characters
699       * (reversible algorithm).
700       * @stable ICU 3.6 */
701     UBIDI_REORDER_GROUP_NUMBERS_WITH_R,
702     /** Reorder runs only to transform a Logical LTR string to the Logical RTL
703       * string with the same display, or vice-versa.<br>
704       * If this mode is set together with option
705       * <code>#UBIDI_OPTION_INSERT_MARKS</code>, some Bidi controls in the source
706       * text may be removed and other controls may be added to produce the
707       * minimum combination which has the required display.
708       * @stable ICU 3.6 */
709     UBIDI_REORDER_RUNS_ONLY,
710     /** Visual to Logical algorithm which handles numbers like L
711       * (same algorithm as selected by <code>ubidi_setInverse(TRUE)</code>.
712       * @see ubidi_setInverse
713       * @stable ICU 3.6 */
714     UBIDI_REORDER_INVERSE_NUMBERS_AS_L,
715     /** Visual to Logical algorithm equivalent to the regular Logical to Visual
716       * algorithm.
717       * @stable ICU 3.6 */
718     UBIDI_REORDER_INVERSE_LIKE_DIRECT,
719     /** Inverse Bidi (Visual to Logical) algorithm for the
720       * <code>UBIDI_REORDER_NUMBERS_SPECIAL</code> Bidi algorithm.
721       * @stable ICU 3.6 */
722     UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL,
723 #ifndef U_HIDE_DEPRECATED_API
724     /**
725      * Number of values for reordering mode.
726      * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
727      */
728     UBIDI_REORDER_COUNT
729 #endif  // U_HIDE_DEPRECATED_API
730 } UBiDiReorderingMode;
731 
732 /**
733  * Modify the operation of the Bidi algorithm such that it implements some
734  * variant to the basic Bidi algorithm or approximates an "inverse Bidi"
735  * algorithm, depending on different values of the "reordering mode".
736  * This function must be called before <code>ubidi_setPara()</code>, and stays
737  * in effect until called again with a different argument.
738  *
739  * <p>The normal operation of the Bidi algorithm as described
740  * in the Unicode Standard Annex #9 is to take text stored in logical
741  * (keyboard, typing) order and to determine how to reorder it for visual
742  * rendering.</p>
743  *
744  * <p>With the reordering mode set to a value other than
745  * <code>#UBIDI_REORDER_DEFAULT</code>, this function changes the behavior of
746  * some of the subsequent functions in a way such that they implement an
747  * inverse Bidi algorithm or some other algorithm variants.</p>
748  *
749  * <p>Some legacy systems store text in visual order, and for operations
750  * with standard, Unicode-based algorithms, the text needs to be transformed
751  * into logical order. This is effectively the inverse algorithm of the
752  * described Bidi algorithm. Note that there is no standard algorithm for
753  * this "inverse Bidi", so a number of variants are implemented here.</p>
754  *
755  * <p>In other cases, it may be desirable to emulate some variant of the
756  * Logical to Visual algorithm (e.g. one used in MS Windows), or perform a
757  * Logical to Logical transformation.</p>
758  *
759  * <ul>
760  * <li>When the reordering mode is set to <code>#UBIDI_REORDER_DEFAULT</code>,
761  * the standard Bidi Logical to Visual algorithm is applied.</li>
762  *
763  * <li>When the reordering mode is set to
764  * <code>#UBIDI_REORDER_NUMBERS_SPECIAL</code>,
765  * the algorithm used to perform Bidi transformations when calling
766  * <code>ubidi_setPara</code> should approximate the algorithm used in
767  * Microsoft Windows XP rather than strictly conform to the Unicode Bidi
768  * algorithm.
769  * <br>
770  * The differences between the basic algorithm and the algorithm addressed
771  * by this option are as follows:
772  * <ul>
773  *   <li>Within text at an even embedding level, the sequence "123AB"
774  *   (where AB represent R or AL letters) is transformed to "123BA" by the
775  *   Unicode algorithm and to "BA123" by the Windows algorithm.</li>
776  *   <li>Arabic-Indic numbers (AN) are handled by the Windows algorithm just
777  *   like regular numbers (EN).</li>
778  * </ul></li>
779  *
780  * <li>When the reordering mode is set to
781  * <code>#UBIDI_REORDER_GROUP_NUMBERS_WITH_R</code>,
782  * numbers located between LTR text and RTL text are associated with the RTL
783  * text. For instance, an LTR paragraph with content "abc 123 DEF" (where
784  * upper case letters represent RTL characters) will be transformed to
785  * "abc FED 123" (and not "abc 123 FED"), "DEF 123 abc" will be transformed
786  * to "123 FED abc" and "123 FED abc" will be transformed to "DEF 123 abc".
787  * This makes the algorithm reversible and makes it useful when round trip
788  * (from visual to logical and back to visual) must be achieved without
789  * adding LRM characters. However, this is a variation from the standard
790  * Unicode Bidi algorithm.<br>
791  * The source text should not contain Bidi control characters other than LRM
792  * or RLM.</li>
793  *
794  * <li>When the reordering mode is set to
795  * <code>#UBIDI_REORDER_RUNS_ONLY</code>,
796  * a "Logical to Logical" transformation must be performed:
797  * <ul>
798  * <li>If the default text level of the source text (argument <code>paraLevel</code>
799  * in <code>ubidi_setPara</code>) is even, the source text will be handled as
800  * LTR logical text and will be transformed to the RTL logical text which has
801  * the same LTR visual display.</li>
802  * <li>If the default level of the source text is odd, the source text
803  * will be handled as RTL logical text and will be transformed to the
804  * LTR logical text which has the same LTR visual display.</li>
805  * </ul>
806  * This mode may be needed when logical text which is basically Arabic or
807  * Hebrew, with possible included numbers or phrases in English, has to be
808  * displayed as if it had an even embedding level (this can happen if the
809  * displaying application treats all text as if it was basically LTR).
810  * <br>
811  * This mode may also be needed in the reverse case, when logical text which is
812  * basically English, with possible included phrases in Arabic or Hebrew, has to
813  * be displayed as if it had an odd embedding level.
814  * <br>
815  * Both cases could be handled by adding LRE or RLE at the head of the text,
816  * if the display subsystem supports these formatting controls. If it does not,
817  * the problem may be handled by transforming the source text in this mode
818  * before displaying it, so that it will be displayed properly.<br>
819  * The source text should not contain Bidi control characters other than LRM
820  * or RLM.</li>
821  *
822  * <li>When the reordering mode is set to
823  * <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>, an "inverse Bidi" algorithm
824  * is applied.
825  * Runs of text with numeric characters will be treated like LTR letters and
826  * may need to be surrounded with LRM characters when they are written in
827  * reordered sequence (the option <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> can
828  * be used with function <code>ubidi_writeReordered</code> to this end. This
829  * mode is equivalent to calling <code>ubidi_setInverse()</code> with
830  * argument <code>isInverse</code> set to <code>TRUE</code>.</li>
831  *
832  * <li>When the reordering mode is set to
833  * <code>#UBIDI_REORDER_INVERSE_LIKE_DIRECT</code>, the "direct" Logical to Visual
834  * Bidi algorithm is used as an approximation of an "inverse Bidi" algorithm.
835  * This mode is similar to mode <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>
836  * but is closer to the regular Bidi algorithm.
837  * <br>
838  * For example, an LTR paragraph with the content "FED 123 456 CBA" (where
839  * upper case represents RTL characters) will be transformed to
840  * "ABC 456 123 DEF", as opposed to "DEF 123 456 ABC"
841  * with mode <code>UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>.<br>
842  * When used in conjunction with option
843  * <code>#UBIDI_OPTION_INSERT_MARKS</code>, this mode generally
844  * adds Bidi marks to the output significantly more sparingly than mode
845  * <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code> with option
846  * <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> in calls to
847  * <code>ubidi_writeReordered</code>.</li>
848  *
849  * <li>When the reordering mode is set to
850  * <code>#UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code>, the Logical to Visual
851  * Bidi algorithm used in Windows XP is used as an approximation of an "inverse Bidi" algorithm.
852  * <br>
853  * For example, an LTR paragraph with the content "abc FED123" (where
854  * upper case represents RTL characters) will be transformed to "abc 123DEF."</li>
855  * </ul>
856  *
857  * <p>In all the reordering modes specifying an "inverse Bidi" algorithm
858  * (i.e. those with a name starting with <code>UBIDI_REORDER_INVERSE</code>),
859  * output runs should be retrieved using
860  * <code>ubidi_getVisualRun()</code>, and the output text with
861  * <code>ubidi_writeReordered()</code>. The caller should keep in mind that in
862  * "inverse Bidi" modes the input is actually visually ordered text and
863  * reordered output returned by <code>ubidi_getVisualRun()</code> or
864  * <code>ubidi_writeReordered()</code> are actually runs or character string
865  * of logically ordered output.<br>
866  * For all the "inverse Bidi" modes, the source text should not contain
867  * Bidi control characters other than LRM or RLM.</p>
868  *
869  * <p>Note that option <code>#UBIDI_OUTPUT_REVERSE</code> of
870  * <code>ubidi_writeReordered</code> has no useful meaning and should not be
871  * used in conjunction with any value of the reordering mode specifying
872  * "inverse Bidi" or with value <code>UBIDI_REORDER_RUNS_ONLY</code>.
873  *
874  * @param pBiDi is a <code>UBiDi</code> object.
875  * @param reorderingMode specifies the required variant of the Bidi algorithm.
876  *
877  * @see UBiDiReorderingMode
878  * @see ubidi_setInverse
879  * @see ubidi_setPara
880  * @see ubidi_writeReordered
881  * @stable ICU 3.6
882  */
883 U_STABLE void U_EXPORT2
884 ubidi_setReorderingMode(UBiDi *pBiDi, UBiDiReorderingMode reorderingMode);
885 
886 /**
887  * What is the requested reordering mode for a given Bidi object?
888  *
889  * @param pBiDi is a <code>UBiDi</code> object.
890  * @return the current reordering mode of the Bidi object
891  * @see ubidi_setReorderingMode
892  * @stable ICU 3.6
893  */
894 U_STABLE UBiDiReorderingMode U_EXPORT2
895 ubidi_getReorderingMode(UBiDi *pBiDi);
896 
897 /**
898  * <code>UBiDiReorderingOption</code> values indicate which options are
899  * specified to affect the Bidi algorithm.
900  *
901  * @see ubidi_setReorderingOptions
902  * @stable ICU 3.6
903  */
904 typedef enum UBiDiReorderingOption {
905     /**
906      * option value for <code>ubidi_setReorderingOptions</code>:
907      * disable all the options which can be set with this function
908      * @see ubidi_setReorderingOptions
909      * @stable ICU 3.6
910      */
911     UBIDI_OPTION_DEFAULT = 0,
912 
913     /**
914      * option bit for <code>ubidi_setReorderingOptions</code>:
915      * insert Bidi marks (LRM or RLM) when needed to ensure correct result of
916      * a reordering to a Logical order
917      *
918      * <p>This option must be set or reset before calling
919      * <code>ubidi_setPara</code>.</p>
920      *
921      * <p>This option is significant only with reordering modes which generate
922      * a result with Logical order, specifically:</p>
923      * <ul>
924      *   <li><code>#UBIDI_REORDER_RUNS_ONLY</code></li>
925      *   <li><code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code></li>
926      *   <li><code>#UBIDI_REORDER_INVERSE_LIKE_DIRECT</code></li>
927      *   <li><code>#UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code></li>
928      * </ul>
929      *
930      * <p>If this option is set in conjunction with reordering mode
931      * <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code> or with calling
932      * <code>ubidi_setInverse(TRUE)</code>, it implies
933      * option <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code>
934      * in calls to function <code>ubidi_writeReordered()</code>.</p>
935      *
936      * <p>For other reordering modes, a minimum number of LRM or RLM characters
937      * will be added to the source text after reordering it so as to ensure
938      * round trip, i.e. when applying the inverse reordering mode on the
939      * resulting logical text with removal of Bidi marks
940      * (option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> set before calling
941      * <code>ubidi_setPara()</code> or option <code>#UBIDI_REMOVE_BIDI_CONTROLS</code>
942      * in <code>ubidi_writeReordered</code>), the result will be identical to the
943      * source text in the first transformation.
944      *
945      * <p>This option will be ignored if specified together with option
946      * <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>. It inhibits option
947      * <code>UBIDI_REMOVE_BIDI_CONTROLS</code> in calls to function
948      * <code>ubidi_writeReordered()</code> and it implies option
949      * <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> in calls to function
950      * <code>ubidi_writeReordered()</code> if the reordering mode is
951      * <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>.</p>
952      *
953      * @see ubidi_setReorderingMode
954      * @see ubidi_setReorderingOptions
955      * @stable ICU 3.6
956      */
957     UBIDI_OPTION_INSERT_MARKS = 1,
958 
959     /**
960      * option bit for <code>ubidi_setReorderingOptions</code>:
961      * remove Bidi control characters
962      *
963      * <p>This option must be set or reset before calling
964      * <code>ubidi_setPara</code>.</p>
965      *
966      * <p>This option nullifies option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
967      * It inhibits option <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> in calls
968      * to function <code>ubidi_writeReordered()</code> and it implies option
969      * <code>#UBIDI_REMOVE_BIDI_CONTROLS</code> in calls to that function.</p>
970      *
971      * @see ubidi_setReorderingMode
972      * @see ubidi_setReorderingOptions
973      * @stable ICU 3.6
974      */
975     UBIDI_OPTION_REMOVE_CONTROLS = 2,
976 
977     /**
978      * option bit for <code>ubidi_setReorderingOptions</code>:
979      * process the output as part of a stream to be continued
980      *
981      * <p>This option must be set or reset before calling
982      * <code>ubidi_setPara</code>.</p>
983      *
984      * <p>This option specifies that the caller is interested in processing large
985      * text object in parts.
986      * The results of the successive calls are expected to be concatenated by the
987      * caller. Only the call for the last part will have this option bit off.</p>
988      *
989      * <p>When this option bit is on, <code>ubidi_setPara()</code> may process
990      * less than the full source text in order to truncate the text at a meaningful
991      * boundary. The caller should call <code>ubidi_getProcessedLength()</code>
992      * immediately after calling <code>ubidi_setPara()</code> in order to
993      * determine how much of the source text has been processed.
994      * Source text beyond that length should be resubmitted in following calls to
995      * <code>ubidi_setPara</code>. The processed length may be less than
996      * the length of the source text if a character preceding the last character of
997      * the source text constitutes a reasonable boundary (like a block separator)
998      * for text to be continued.<br>
999      * If the last character of the source text constitutes a reasonable
1000      * boundary, the whole text will be processed at once.<br>
1001      * If nowhere in the source text there exists
1002      * such a reasonable boundary, the processed length will be zero.<br>
1003      * The caller should check for such an occurrence and do one of the following:
1004      * <ul><li>submit a larger amount of text with a better chance to include
1005      *         a reasonable boundary.</li>
1006      *     <li>resubmit the same text after turning off option
1007      *         <code>UBIDI_OPTION_STREAMING</code>.</li></ul>
1008      * In all cases, this option should be turned off before processing the last
1009      * part of the text.</p>
1010      *
1011      * <p>When the <code>UBIDI_OPTION_STREAMING</code> option is used,
1012      * it is recommended to call <code>ubidi_orderParagraphsLTR()</code> with
1013      * argument <code>orderParagraphsLTR</code> set to <code>TRUE</code> before
1014      * calling <code>ubidi_setPara</code> so that later paragraphs may be
1015      * concatenated to previous paragraphs on the right.</p>
1016      *
1017      * @see ubidi_setReorderingMode
1018      * @see ubidi_setReorderingOptions
1019      * @see ubidi_getProcessedLength
1020      * @see ubidi_orderParagraphsLTR
1021      * @stable ICU 3.6
1022      */
1023     UBIDI_OPTION_STREAMING = 4
1024 } UBiDiReorderingOption;
1025 
1026 /**
1027  * Specify which of the reordering options
1028  * should be applied during Bidi transformations.
1029  *
1030  * @param pBiDi is a <code>UBiDi</code> object.
1031  * @param reorderingOptions is a combination of zero or more of the following
1032  * options:
1033  * <code>#UBIDI_OPTION_DEFAULT</code>, <code>#UBIDI_OPTION_INSERT_MARKS</code>,
1034  * <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>, <code>#UBIDI_OPTION_STREAMING</code>.
1035  *
1036  * @see ubidi_getReorderingOptions
1037  * @stable ICU 3.6
1038  */
1039 U_STABLE void U_EXPORT2
1040 ubidi_setReorderingOptions(UBiDi *pBiDi, uint32_t reorderingOptions);
1041 
1042 /**
1043  * What are the reordering options applied to a given Bidi object?
1044  *
1045  * @param pBiDi is a <code>UBiDi</code> object.
1046  * @return the current reordering options of the Bidi object
1047  * @see ubidi_setReorderingOptions
1048  * @stable ICU 3.6
1049  */
1050 U_STABLE uint32_t U_EXPORT2
1051 ubidi_getReorderingOptions(UBiDi *pBiDi);
1052 
1053 /**
1054  * Set the context before a call to ubidi_setPara().<p>
1055  *
1056  * ubidi_setPara() computes the left-right directionality for a given piece
1057  * of text which is supplied as one of its arguments. Sometimes this piece
1058  * of text (the "main text") should be considered in context, because text
1059  * appearing before ("prologue") and/or after ("epilogue") the main text
1060  * may affect the result of this computation.<p>
1061  *
1062  * This function specifies the prologue and/or the epilogue for the next
1063  * call to ubidi_setPara(). The characters specified as prologue and
1064  * epilogue should not be modified by the calling program until the call
1065  * to ubidi_setPara() has returned. If successive calls to ubidi_setPara()
1066  * all need specification of a context, ubidi_setContext() must be called
1067  * before each call to ubidi_setPara(). In other words, a context is not
1068  * "remembered" after the following successful call to ubidi_setPara().<p>
1069  *
1070  * If a call to ubidi_setPara() specifies UBIDI_DEFAULT_LTR or
1071  * UBIDI_DEFAULT_RTL as paraLevel and is preceded by a call to
1072  * ubidi_setContext() which specifies a prologue, the paragraph level will
1073  * be computed taking in consideration the text in the prologue.<p>
1074  *
1075  * When ubidi_setPara() is called without a previous call to
1076  * ubidi_setContext, the main text is handled as if preceded and followed
1077  * by strong directional characters at the current paragraph level.
1078  * Calling ubidi_setContext() with specification of a prologue will change
1079  * this behavior by handling the main text as if preceded by the last
1080  * strong character appearing in the prologue, if any.
1081  * Calling ubidi_setContext() with specification of an epilogue will change
1082  * the behavior of ubidi_setPara() by handling the main text as if followed
1083  * by the first strong character or digit appearing in the epilogue, if any.<p>
1084  *
1085  * Note 1: if <code>ubidi_setContext</code> is called repeatedly without
1086  *         calling <code>ubidi_setPara</code>, the earlier calls have no effect,
1087  *         only the last call will be remembered for the next call to
1088  *         <code>ubidi_setPara</code>.<p>
1089  *
1090  * Note 2: calling <code>ubidi_setContext(pBiDi, NULL, 0, NULL, 0, &errorCode)</code>
1091  *         cancels any previous setting of non-empty prologue or epilogue.
1092  *         The next call to <code>ubidi_setPara()</code> will process no
1093  *         prologue or epilogue.<p>
1094  *
1095  * Note 3: users must be aware that even after setting the context
1096  *         before a call to ubidi_setPara() to perform e.g. a logical to visual
1097  *         transformation, the resulting string may not be identical to what it
1098  *         would have been if all the text, including prologue and epilogue, had
1099  *         been processed together.<br>
1100  * Example (upper case letters represent RTL characters):<br>
1101  * &nbsp;&nbsp;prologue = "<code>abc DE</code>"<br>
1102  * &nbsp;&nbsp;epilogue = none<br>
1103  * &nbsp;&nbsp;main text = "<code>FGH xyz</code>"<br>
1104  * &nbsp;&nbsp;paraLevel = UBIDI_LTR<br>
1105  * &nbsp;&nbsp;display without prologue = "<code>HGF xyz</code>"
1106  *             ("HGF" is adjacent to "xyz")<br>
1107  * &nbsp;&nbsp;display with prologue = "<code>abc HGFED xyz</code>"
1108  *             ("HGF" is not adjacent to "xyz")<br>
1109  *
1110  * @param pBiDi is a paragraph <code>UBiDi</code> object.
1111  *
1112  * @param prologue is a pointer to the text which precedes the text that
1113  *        will be specified in a coming call to ubidi_setPara().
1114  *        If there is no prologue to consider, then <code>proLength</code>
1115  *        must be zero and this pointer can be NULL.
1116  *
1117  * @param proLength is the length of the prologue; if <code>proLength==-1</code>
1118  *        then the prologue must be zero-terminated.
1119  *        Otherwise proLength must be >= 0. If <code>proLength==0</code>, it means
1120  *        that there is no prologue to consider.
1121  *
1122  * @param epilogue is a pointer to the text which follows the text that
1123  *        will be specified in a coming call to ubidi_setPara().
1124  *        If there is no epilogue to consider, then <code>epiLength</code>
1125  *        must be zero and this pointer can be NULL.
1126  *
1127  * @param epiLength is the length of the epilogue; if <code>epiLength==-1</code>
1128  *        then the epilogue must be zero-terminated.
1129  *        Otherwise epiLength must be >= 0. If <code>epiLength==0</code>, it means
1130  *        that there is no epilogue to consider.
1131  *
1132  * @param pErrorCode must be a valid pointer to an error code value.
1133  *
1134  * @see ubidi_setPara
1135  * @stable ICU 4.8
1136  */
1137 U_STABLE void U_EXPORT2
1138 ubidi_setContext(UBiDi *pBiDi,
1139                  const UChar *prologue, int32_t proLength,
1140                  const UChar *epilogue, int32_t epiLength,
1141                  UErrorCode *pErrorCode);
1142 
1143 /**
1144  * Perform the Unicode Bidi algorithm. It is defined in the
1145  * <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Standard Anned #9</a>,
1146  * version 13,
1147  * also described in The Unicode Standard, Version 4.0 .<p>
1148  *
1149  * This function takes a piece of plain text containing one or more paragraphs,
1150  * with or without externally specified embedding levels from <i>styled</i>
1151  * text and computes the left-right-directionality of each character.<p>
1152  *
1153  * If the entire text is all of the same directionality, then
1154  * the function may not perform all the steps described by the algorithm,
1155  * i.e., some levels may not be the same as if all steps were performed.
1156  * This is not relevant for unidirectional text.<br>
1157  * For example, in pure LTR text with numbers the numbers would get
1158  * a resolved level of 2 higher than the surrounding text according to
1159  * the algorithm. This implementation may set all resolved levels to
1160  * the same value in such a case.<p>
1161  *
1162  * The text can be composed of multiple paragraphs. Occurrence of a block
1163  * separator in the text terminates a paragraph, and whatever comes next starts
1164  * a new paragraph. The exception to this rule is when a Carriage Return (CR)
1165  * is followed by a Line Feed (LF). Both CR and LF are block separators, but
1166  * in that case, the pair of characters is considered as terminating the
1167  * preceding paragraph, and a new paragraph will be started by a character
1168  * coming after the LF.
1169  *
1170  * @param pBiDi A <code>UBiDi</code> object allocated with <code>ubidi_open()</code>
1171  *        which will be set to contain the reordering information,
1172  *        especially the resolved levels for all the characters in <code>text</code>.
1173  *
1174  * @param text is a pointer to the text that the Bidi algorithm will be performed on.
1175  *        This pointer is stored in the UBiDi object and can be retrieved
1176  *        with <code>ubidi_getText()</code>.<br>
1177  *        <strong>Note:</strong> the text must be (at least) <code>length</code> long.
1178  *
1179  * @param length is the length of the text; if <code>length==-1</code> then
1180  *        the text must be zero-terminated.
1181  *
1182  * @param paraLevel specifies the default level for the text;
1183  *        it is typically 0 (LTR) or 1 (RTL).
1184  *        If the function shall determine the paragraph level from the text,
1185  *        then <code>paraLevel</code> can be set to
1186  *        either <code>#UBIDI_DEFAULT_LTR</code>
1187  *        or <code>#UBIDI_DEFAULT_RTL</code>; if the text contains multiple
1188  *        paragraphs, the paragraph level shall be determined separately for
1189  *        each paragraph; if a paragraph does not include any strongly typed
1190  *        character, then the desired default is used (0 for LTR or 1 for RTL).
1191  *        Any other value between 0 and <code>#UBIDI_MAX_EXPLICIT_LEVEL</code>
1192  *        is also valid, with odd levels indicating RTL.
1193  *
1194  * @param embeddingLevels (in) may be used to preset the embedding and override levels,
1195  *        ignoring characters like LRE and PDF in the text.
1196  *        A level overrides the directional property of its corresponding
1197  *        (same index) character if the level has the
1198  *        <code>#UBIDI_LEVEL_OVERRIDE</code> bit set.<br><br>
1199  *        Except for that bit, it must be
1200  *        <code>paraLevel<=embeddingLevels[]<=UBIDI_MAX_EXPLICIT_LEVEL</code>,
1201  *        with one exception: a level of zero may be specified for a paragraph
1202  *        separator even if <code>paraLevel>0</code> when multiple paragraphs
1203  *        are submitted in the same call to <code>ubidi_setPara()</code>.<br><br>
1204  *        <strong>Caution: </strong>A copy of this pointer, not of the levels,
1205  *        will be stored in the <code>UBiDi</code> object;
1206  *        the <code>embeddingLevels</code> array must not be
1207  *        deallocated before the <code>UBiDi</code> structure is destroyed or reused,
1208  *        and the <code>embeddingLevels</code>
1209  *        should not be modified to avoid unexpected results on subsequent Bidi operations.
1210  *        However, the <code>ubidi_setPara()</code> and
1211  *        <code>ubidi_setLine()</code> functions may modify some or all of the levels.<br><br>
1212  *        After the <code>UBiDi</code> object is reused or destroyed, the caller
1213  *        must take care of the deallocation of the <code>embeddingLevels</code> array.<br><br>
1214  *        <strong>Note:</strong> the <code>embeddingLevels</code> array must be
1215  *        at least <code>length</code> long.
1216  *        This pointer can be <code>NULL</code> if this
1217  *        value is not necessary.
1218  *
1219  * @param pErrorCode must be a valid pointer to an error code value.
1220  * @stable ICU 2.0
1221  */
1222 U_STABLE void U_EXPORT2
1223 ubidi_setPara(UBiDi *pBiDi, const UChar *text, int32_t length,
1224               UBiDiLevel paraLevel, UBiDiLevel *embeddingLevels,
1225               UErrorCode *pErrorCode);
1226 
1227 /**
1228  * <code>ubidi_setLine()</code> sets a <code>UBiDi</code> to
1229  * contain the reordering information, especially the resolved levels,
1230  * for all the characters in a line of text. This line of text is
1231  * specified by referring to a <code>UBiDi</code> object representing
1232  * this information for a piece of text containing one or more paragraphs,
1233  * and by specifying a range of indexes in this text.<p>
1234  * In the new line object, the indexes will range from 0 to <code>limit-start-1</code>.<p>
1235  *
1236  * This is used after calling <code>ubidi_setPara()</code>
1237  * for a piece of text, and after line-breaking on that text.
1238  * It is not necessary if each paragraph is treated as a single line.<p>
1239  *
1240  * After line-breaking, rules (L1) and (L2) for the treatment of
1241  * trailing WS and for reordering are performed on
1242  * a <code>UBiDi</code> object that represents a line.<p>
1243  *
1244  * <strong>Important: </strong><code>pLineBiDi</code> shares data with
1245  * <code>pParaBiDi</code>.
1246  * You must destroy or reuse <code>pLineBiDi</code> before <code>pParaBiDi</code>.
1247  * In other words, you must destroy or reuse the <code>UBiDi</code> object for a line
1248  * before the object for its parent paragraph.<p>
1249  *
1250  * The text pointer that was stored in <code>pParaBiDi</code> is also copied,
1251  * and <code>start</code> is added to it so that it points to the beginning of the
1252  * line for this object.
1253  *
1254  * @param pParaBiDi is the parent paragraph object. It must have been set
1255  * by a successful call to ubidi_setPara.
1256  *
1257  * @param start is the line's first index into the text.
1258  *
1259  * @param limit is just behind the line's last index into the text
1260  *        (its last index +1).<br>
1261  *        It must be <code>0<=start<limit<=</code>containing paragraph limit.
1262  *        If the specified line crosses a paragraph boundary, the function
1263  *        will terminate with error code U_ILLEGAL_ARGUMENT_ERROR.
1264  *
1265  * @param pLineBiDi is the object that will now represent a line of the text.
1266  *
1267  * @param pErrorCode must be a valid pointer to an error code value.
1268  *
1269  * @see ubidi_setPara
1270  * @see ubidi_getProcessedLength
1271  * @stable ICU 2.0
1272  */
1273 U_STABLE void U_EXPORT2
1274 ubidi_setLine(const UBiDi *pParaBiDi,
1275               int32_t start, int32_t limit,
1276               UBiDi *pLineBiDi,
1277               UErrorCode *pErrorCode);
1278 
1279 /**
1280  * Get the directionality of the text.
1281  *
1282  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1283  *
1284  * @return a value of <code>UBIDI_LTR</code>, <code>UBIDI_RTL</code>
1285  *         or <code>UBIDI_MIXED</code>
1286  *         that indicates if the entire text
1287  *         represented by this object is unidirectional,
1288  *         and which direction, or if it is mixed-directional.
1289  * Note -  The value <code>UBIDI_NEUTRAL</code> is never returned from this method.
1290  *
1291  * @see UBiDiDirection
1292  * @stable ICU 2.0
1293  */
1294 U_STABLE UBiDiDirection U_EXPORT2
1295 ubidi_getDirection(const UBiDi *pBiDi);
1296 
1297 /**
1298  * Gets the base direction of the text provided according
1299  * to the Unicode Bidirectional Algorithm. The base direction
1300  * is derived from the first character in the string with bidirectional
1301  * character type L, R, or AL. If the first such character has type L,
1302  * <code>UBIDI_LTR</code> is returned. If the first such character has
1303  * type R or AL, <code>UBIDI_RTL</code> is returned. If the string does
1304  * not contain any character of these types, then
1305  * <code>UBIDI_NEUTRAL</code> is returned.
1306  *
1307  * This is a lightweight function for use when only the base direction
1308  * is needed and no further bidi processing of the text is needed.
1309  *
1310  * @param text is a pointer to the text whose base
1311  *             direction is needed.
1312  * Note: the text must be (at least) @c length long.
1313  *
1314  * @param length is the length of the text;
1315  *               if <code>length==-1</code> then the text
1316  *               must be zero-terminated.
1317  *
1318  * @return  <code>UBIDI_LTR</code>, <code>UBIDI_RTL</code>,
1319  *          <code>UBIDI_NEUTRAL</code>
1320  *
1321  * @see UBiDiDirection
1322  * @stable ICU 4.6
1323  */
1324 U_STABLE UBiDiDirection U_EXPORT2
1325 ubidi_getBaseDirection(const UChar *text,  int32_t length );
1326 
1327 /**
1328  * Get the pointer to the text.
1329  *
1330  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1331  *
1332  * @return The pointer to the text that the UBiDi object was created for.
1333  *
1334  * @see ubidi_setPara
1335  * @see ubidi_setLine
1336  * @stable ICU 2.0
1337  */
1338 U_STABLE const UChar * U_EXPORT2
1339 ubidi_getText(const UBiDi *pBiDi);
1340 
1341 /**
1342  * Get the length of the text.
1343  *
1344  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1345  *
1346  * @return The length of the text that the UBiDi object was created for.
1347  * @stable ICU 2.0
1348  */
1349 U_STABLE int32_t U_EXPORT2
1350 ubidi_getLength(const UBiDi *pBiDi);
1351 
1352 /**
1353  * Get the paragraph level of the text.
1354  *
1355  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1356  *
1357  * @return The paragraph level. If there are multiple paragraphs, their
1358  *         level may vary if the required paraLevel is UBIDI_DEFAULT_LTR or
1359  *         UBIDI_DEFAULT_RTL.  In that case, the level of the first paragraph
1360  *         is returned.
1361  *
1362  * @see UBiDiLevel
1363  * @see ubidi_getParagraph
1364  * @see ubidi_getParagraphByIndex
1365  * @stable ICU 2.0
1366  */
1367 U_STABLE UBiDiLevel U_EXPORT2
1368 ubidi_getParaLevel(const UBiDi *pBiDi);
1369 
1370 /**
1371  * Get the number of paragraphs.
1372  *
1373  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1374  *
1375  * @return The number of paragraphs.
1376  * @stable ICU 3.4
1377  */
1378 U_STABLE int32_t U_EXPORT2
1379 ubidi_countParagraphs(UBiDi *pBiDi);
1380 
1381 /**
1382  * Get a paragraph, given a position within the text.
1383  * This function returns information about a paragraph.<br>
1384  * Note: if the paragraph index is known, it is more efficient to
1385  * retrieve the paragraph information using ubidi_getParagraphByIndex().<p>
1386  *
1387  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1388  *
1389  * @param charIndex is the index of a character within the text, in the
1390  *        range <code>[0..ubidi_getProcessedLength(pBiDi)-1]</code>.
1391  *
1392  * @param pParaStart will receive the index of the first character of the
1393  *        paragraph in the text.
1394  *        This pointer can be <code>NULL</code> if this
1395  *        value is not necessary.
1396  *
1397  * @param pParaLimit will receive the limit of the paragraph.
1398  *        The l-value that you point to here may be the
1399  *        same expression (variable) as the one for
1400  *        <code>charIndex</code>.
1401  *        This pointer can be <code>NULL</code> if this
1402  *        value is not necessary.
1403  *
1404  * @param pParaLevel will receive the level of the paragraph.
1405  *        This pointer can be <code>NULL</code> if this
1406  *        value is not necessary.
1407  *
1408  * @param pErrorCode must be a valid pointer to an error code value.
1409  *
1410  * @return The index of the paragraph containing the specified position.
1411  *
1412  * @see ubidi_getProcessedLength
1413  * @stable ICU 3.4
1414  */
1415 U_STABLE int32_t U_EXPORT2
1416 ubidi_getParagraph(const UBiDi *pBiDi, int32_t charIndex, int32_t *pParaStart,
1417                    int32_t *pParaLimit, UBiDiLevel *pParaLevel,
1418                    UErrorCode *pErrorCode);
1419 
1420 /**
1421  * Get a paragraph, given the index of this paragraph.
1422  *
1423  * This function returns information about a paragraph.<p>
1424  *
1425  * @param pBiDi is the paragraph <code>UBiDi</code> object.
1426  *
1427  * @param paraIndex is the number of the paragraph, in the
1428  *        range <code>[0..ubidi_countParagraphs(pBiDi)-1]</code>.
1429  *
1430  * @param pParaStart will receive the index of the first character of the
1431  *        paragraph in the text.
1432  *        This pointer can be <code>NULL</code> if this
1433  *        value is not necessary.
1434  *
1435  * @param pParaLimit will receive the limit of the paragraph.
1436  *        This pointer can be <code>NULL</code> if this
1437  *        value is not necessary.
1438  *
1439  * @param pParaLevel will receive the level of the paragraph.
1440  *        This pointer can be <code>NULL</code> if this
1441  *        value is not necessary.
1442  *
1443  * @param pErrorCode must be a valid pointer to an error code value.
1444  *
1445  * @stable ICU 3.4
1446  */
1447 U_STABLE void U_EXPORT2
1448 ubidi_getParagraphByIndex(const UBiDi *pBiDi, int32_t paraIndex,
1449                           int32_t *pParaStart, int32_t *pParaLimit,
1450                           UBiDiLevel *pParaLevel, UErrorCode *pErrorCode);
1451 
1452 /**
1453  * Get the level for one character.
1454  *
1455  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1456  *
1457  * @param charIndex the index of a character. It must be in the range
1458  *         [0..ubidi_getProcessedLength(pBiDi)].
1459  *
1460  * @return The level for the character at charIndex (0 if charIndex is not
1461  *         in the valid range).
1462  *
1463  * @see UBiDiLevel
1464  * @see ubidi_getProcessedLength
1465  * @stable ICU 2.0
1466  */
1467 U_STABLE UBiDiLevel U_EXPORT2
1468 ubidi_getLevelAt(const UBiDi *pBiDi, int32_t charIndex);
1469 
1470 /**
1471  * Get an array of levels for each character.<p>
1472  *
1473  * Note that this function may allocate memory under some
1474  * circumstances, unlike <code>ubidi_getLevelAt()</code>.
1475  *
1476  * @param pBiDi is the paragraph or line <code>UBiDi</code> object, whose
1477  *        text length must be strictly positive.
1478  *
1479  * @param pErrorCode must be a valid pointer to an error code value.
1480  *
1481  * @return The levels array for the text,
1482  *         or <code>NULL</code> if an error occurs.
1483  *
1484  * @see UBiDiLevel
1485  * @see ubidi_getProcessedLength
1486  * @stable ICU 2.0
1487  */
1488 U_STABLE const UBiDiLevel * U_EXPORT2
1489 ubidi_getLevels(UBiDi *pBiDi, UErrorCode *pErrorCode);
1490 
1491 /**
1492  * Get a logical run.
1493  * This function returns information about a run and is used
1494  * to retrieve runs in logical order.<p>
1495  * This is especially useful for line-breaking on a paragraph.
1496  *
1497  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1498  *
1499  * @param logicalPosition is a logical position within the source text.
1500  *
1501  * @param pLogicalLimit will receive the limit of the corresponding run.
1502  *        The l-value that you point to here may be the
1503  *        same expression (variable) as the one for
1504  *        <code>logicalPosition</code>.
1505  *        This pointer can be <code>NULL</code> if this
1506  *        value is not necessary.
1507  *
1508  * @param pLevel will receive the level of the corresponding run.
1509  *        This pointer can be <code>NULL</code> if this
1510  *        value is not necessary.
1511  *
1512  * @see ubidi_getProcessedLength
1513  * @stable ICU 2.0
1514  */
1515 U_STABLE void U_EXPORT2
1516 ubidi_getLogicalRun(const UBiDi *pBiDi, int32_t logicalPosition,
1517                     int32_t *pLogicalLimit, UBiDiLevel *pLevel);
1518 
1519 /**
1520  * Get the number of runs.
1521  * This function may invoke the actual reordering on the
1522  * <code>UBiDi</code> object, after <code>ubidi_setPara()</code>
1523  * may have resolved only the levels of the text. Therefore,
1524  * <code>ubidi_countRuns()</code> may have to allocate memory,
1525  * and may fail doing so.
1526  *
1527  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1528  *
1529  * @param pErrorCode must be a valid pointer to an error code value.
1530  *
1531  * @return The number of runs.
1532  * @stable ICU 2.0
1533  */
1534 U_STABLE int32_t U_EXPORT2
1535 ubidi_countRuns(UBiDi *pBiDi, UErrorCode *pErrorCode);
1536 
1537 /**
1538  * Get one run's logical start, length, and directionality,
1539  * which can be 0 for LTR or 1 for RTL.
1540  * In an RTL run, the character at the logical start is
1541  * visually on the right of the displayed run.
1542  * The length is the number of characters in the run.<p>
1543  * <code>ubidi_countRuns()</code> should be called
1544  * before the runs are retrieved.
1545  *
1546  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1547  *
1548  * @param runIndex is the number of the run in visual order, in the
1549  *        range <code>[0..ubidi_countRuns(pBiDi)-1]</code>.
1550  *
1551  * @param pLogicalStart is the first logical character index in the text.
1552  *        The pointer may be <code>NULL</code> if this index is not needed.
1553  *
1554  * @param pLength is the number of characters (at least one) in the run.
1555  *        The pointer may be <code>NULL</code> if this is not needed.
1556  *
1557  * @return the directionality of the run,
1558  *         <code>UBIDI_LTR==0</code> or <code>UBIDI_RTL==1</code>,
1559  *         never <code>UBIDI_MIXED</code>,
1560  *         never <code>UBIDI_NEUTRAL</code>.
1561  *
1562  * @see ubidi_countRuns
1563  *
1564  * Example:
1565  * <pre>
1566  * \code
1567  * int32_t i, count=ubidi_countRuns(pBiDi),
1568  *         logicalStart, visualIndex=0, length;
1569  * for(i=0; i<count; ++i) {
1570  *    if(UBIDI_LTR==ubidi_getVisualRun(pBiDi, i, &logicalStart, &length)) {
1571  *         do { // LTR
1572  *             show_char(text[logicalStart++], visualIndex++);
1573  *         } while(--length>0);
1574  *     } else {
1575  *         logicalStart+=length;  // logicalLimit
1576  *         do { // RTL
1577  *             show_char(text[--logicalStart], visualIndex++);
1578  *         } while(--length>0);
1579  *     }
1580  * }
1581  *\endcode
1582  * </pre>
1583  *
1584  * Note that in right-to-left runs, code like this places
1585  * second surrogates before first ones (which is generally a bad idea)
1586  * and combining characters before base characters.
1587  * <p>
1588  * Use of <code>ubidi_writeReordered()</code>, optionally with the
1589  * <code>#UBIDI_KEEP_BASE_COMBINING</code> option, can be considered in order
1590  * to avoid these issues.
1591  * @stable ICU 2.0
1592  */
1593 U_STABLE UBiDiDirection U_EXPORT2
1594 ubidi_getVisualRun(UBiDi *pBiDi, int32_t runIndex,
1595                    int32_t *pLogicalStart, int32_t *pLength);
1596 
1597 /**
1598  * Get the visual position from a logical text position.
1599  * If such a mapping is used many times on the same
1600  * <code>UBiDi</code> object, then calling
1601  * <code>ubidi_getLogicalMap()</code> is more efficient.<p>
1602  *
1603  * The value returned may be <code>#UBIDI_MAP_NOWHERE</code> if there is no
1604  * visual position because the corresponding text character is a Bidi control
1605  * removed from output by the option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>.
1606  * <p>
1607  * When the visual output is altered by using options of
1608  * <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
1609  * <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
1610  * <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the visual position returned may not
1611  * be correct. It is advised to use, when possible, reordering options
1612  * such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
1613  * <p>
1614  * Note that in right-to-left runs, this mapping places
1615  * second surrogates before first ones (which is generally a bad idea)
1616  * and combining characters before base characters.
1617  * Use of <code>ubidi_writeReordered()</code>, optionally with the
1618  * <code>#UBIDI_KEEP_BASE_COMBINING</code> option can be considered instead
1619  * of using the mapping, in order to avoid these issues.
1620  *
1621  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1622  *
1623  * @param logicalIndex is the index of a character in the text.
1624  *
1625  * @param pErrorCode must be a valid pointer to an error code value.
1626  *
1627  * @return The visual position of this character.
1628  *
1629  * @see ubidi_getLogicalMap
1630  * @see ubidi_getLogicalIndex
1631  * @see ubidi_getProcessedLength
1632  * @stable ICU 2.0
1633  */
1634 U_STABLE int32_t U_EXPORT2
1635 ubidi_getVisualIndex(UBiDi *pBiDi, int32_t logicalIndex, UErrorCode *pErrorCode);
1636 
1637 /**
1638  * Get the logical text position from a visual position.
1639  * If such a mapping is used many times on the same
1640  * <code>UBiDi</code> object, then calling
1641  * <code>ubidi_getVisualMap()</code> is more efficient.<p>
1642  *
1643  * The value returned may be <code>#UBIDI_MAP_NOWHERE</code> if there is no
1644  * logical position because the corresponding text character is a Bidi mark
1645  * inserted in the output by option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
1646  * <p>
1647  * This is the inverse function to <code>ubidi_getVisualIndex()</code>.
1648  * <p>
1649  * When the visual output is altered by using options of
1650  * <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
1651  * <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
1652  * <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the logical position returned may not
1653  * be correct. It is advised to use, when possible, reordering options
1654  * such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
1655  *
1656  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1657  *
1658  * @param visualIndex is the visual position of a character.
1659  *
1660  * @param pErrorCode must be a valid pointer to an error code value.
1661  *
1662  * @return The index of this character in the text.
1663  *
1664  * @see ubidi_getVisualMap
1665  * @see ubidi_getVisualIndex
1666  * @see ubidi_getResultLength
1667  * @stable ICU 2.0
1668  */
1669 U_STABLE int32_t U_EXPORT2
1670 ubidi_getLogicalIndex(UBiDi *pBiDi, int32_t visualIndex, UErrorCode *pErrorCode);
1671 
1672 /**
1673  * Get a logical-to-visual index map (array) for the characters in the UBiDi
1674  * (paragraph or line) object.
1675  * <p>
1676  * Some values in the map may be <code>#UBIDI_MAP_NOWHERE</code> if the
1677  * corresponding text characters are Bidi controls removed from the visual
1678  * output by the option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>.
1679  * <p>
1680  * When the visual output is altered by using options of
1681  * <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
1682  * <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
1683  * <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the visual positions returned may not
1684  * be correct. It is advised to use, when possible, reordering options
1685  * such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
1686  * <p>
1687  * Note that in right-to-left runs, this mapping places
1688  * second surrogates before first ones (which is generally a bad idea)
1689  * and combining characters before base characters.
1690  * Use of <code>ubidi_writeReordered()</code>, optionally with the
1691  * <code>#UBIDI_KEEP_BASE_COMBINING</code> option can be considered instead
1692  * of using the mapping, in order to avoid these issues.
1693  *
1694  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1695  *
1696  * @param indexMap is a pointer to an array of <code>ubidi_getProcessedLength()</code>
1697  *        indexes which will reflect the reordering of the characters.
1698  *        If option <code>#UBIDI_OPTION_INSERT_MARKS</code> is set, the number
1699  *        of elements allocated in <code>indexMap</code> must be no less than
1700  *        <code>ubidi_getResultLength()</code>.
1701  *        The array does not need to be initialized.<br><br>
1702  *        The index map will result in <code>indexMap[logicalIndex]==visualIndex</code>.
1703  *
1704  * @param pErrorCode must be a valid pointer to an error code value.
1705  *
1706  * @see ubidi_getVisualMap
1707  * @see ubidi_getVisualIndex
1708  * @see ubidi_getProcessedLength
1709  * @see ubidi_getResultLength
1710  * @stable ICU 2.0
1711  */
1712 U_STABLE void U_EXPORT2
1713 ubidi_getLogicalMap(UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode);
1714 
1715 /**
1716  * Get a visual-to-logical index map (array) for the characters in the UBiDi
1717  * (paragraph or line) object.
1718  * <p>
1719  * Some values in the map may be <code>#UBIDI_MAP_NOWHERE</code> if the
1720  * corresponding text characters are Bidi marks inserted in the visual output
1721  * by the option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
1722  * <p>
1723  * When the visual output is altered by using options of
1724  * <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
1725  * <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
1726  * <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the logical positions returned may not
1727  * be correct. It is advised to use, when possible, reordering options
1728  * such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
1729  *
1730  * @param pBiDi is the paragraph or line <code>UBiDi</code> object.
1731  *
1732  * @param indexMap is a pointer to an array of <code>ubidi_getResultLength()</code>
1733  *        indexes which will reflect the reordering of the characters.
1734  *        If option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> is set, the number
1735  *        of elements allocated in <code>indexMap</code> must be no less than
1736  *        <code>ubidi_getProcessedLength()</code>.
1737  *        The array does not need to be initialized.<br><br>
1738  *        The index map will result in <code>indexMap[visualIndex]==logicalIndex</code>.
1739  *
1740  * @param pErrorCode must be a valid pointer to an error code value.
1741  *
1742  * @see ubidi_getLogicalMap
1743  * @see ubidi_getLogicalIndex
1744  * @see ubidi_getProcessedLength
1745  * @see ubidi_getResultLength
1746  * @stable ICU 2.0
1747  */
1748 U_STABLE void U_EXPORT2
1749 ubidi_getVisualMap(UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode);
1750 
1751 /**
1752  * This is a convenience function that does not use a UBiDi object.
1753  * It is intended to be used for when an application has determined the levels
1754  * of objects (character sequences) and just needs to have them reordered (L2).
1755  * This is equivalent to using <code>ubidi_getLogicalMap()</code> on a
1756  * <code>UBiDi</code> object.
1757  *
1758  * @param levels is an array with <code>length</code> levels that have been determined by
1759  *        the application.
1760  *
1761  * @param length is the number of levels in the array, or, semantically,
1762  *        the number of objects to be reordered.
1763  *        It must be <code>length>0</code>.
1764  *
1765  * @param indexMap is a pointer to an array of <code>length</code>
1766  *        indexes which will reflect the reordering of the characters.
1767  *        The array does not need to be initialized.<p>
1768  *        The index map will result in <code>indexMap[logicalIndex]==visualIndex</code>.
1769  * @stable ICU 2.0
1770  */
1771 U_STABLE void U_EXPORT2
1772 ubidi_reorderLogical(const UBiDiLevel *levels, int32_t length, int32_t *indexMap);
1773 
1774 /**
1775  * This is a convenience function that does not use a UBiDi object.
1776  * It is intended to be used for when an application has determined the levels
1777  * of objects (character sequences) and just needs to have them reordered (L2).
1778  * This is equivalent to using <code>ubidi_getVisualMap()</code> on a
1779  * <code>UBiDi</code> object.
1780  *
1781  * @param levels is an array with <code>length</code> levels that have been determined by
1782  *        the application.
1783  *
1784  * @param length is the number of levels in the array, or, semantically,
1785  *        the number of objects to be reordered.
1786  *        It must be <code>length>0</code>.
1787  *
1788  * @param indexMap is a pointer to an array of <code>length</code>
1789  *        indexes which will reflect the reordering of the characters.
1790  *        The array does not need to be initialized.<p>
1791  *        The index map will result in <code>indexMap[visualIndex]==logicalIndex</code>.
1792  * @stable ICU 2.0
1793  */
1794 U_STABLE void U_EXPORT2
1795 ubidi_reorderVisual(const UBiDiLevel *levels, int32_t length, int32_t *indexMap);
1796 
1797 /**
1798  * Invert an index map.
1799  * The index mapping of the first map is inverted and written to
1800  * the second one.
1801  *
1802  * @param srcMap is an array with <code>length</code> elements
1803  *        which defines the original mapping from a source array containing
1804  *        <code>length</code> elements to a destination array.
1805  *        Some elements of the source array may have no mapping in the
1806  *        destination array. In that case, their value will be
1807  *        the special value <code>UBIDI_MAP_NOWHERE</code>.
1808  *        All elements must be >=0 or equal to <code>UBIDI_MAP_NOWHERE</code>.
1809  *        Some elements may have a value >= <code>length</code>, if the
1810  *        destination array has more elements than the source array.
1811  *        There must be no duplicate indexes (two or more elements with the
1812  *        same value except <code>UBIDI_MAP_NOWHERE</code>).
1813  *
1814  * @param destMap is an array with a number of elements equal to 1 + the highest
1815  *        value in <code>srcMap</code>.
1816  *        <code>destMap</code> will be filled with the inverse mapping.
1817  *        If element with index i in <code>srcMap</code> has a value k different
1818  *        from <code>UBIDI_MAP_NOWHERE</code>, this means that element i of
1819  *        the source array maps to element k in the destination array.
1820  *        The inverse map will have value i in its k-th element.
1821  *        For all elements of the destination array which do not map to
1822  *        an element in the source array, the corresponding element in the
1823  *        inverse map will have a value equal to <code>UBIDI_MAP_NOWHERE</code>.
1824  *
1825  * @param length is the length of each array.
1826  * @see UBIDI_MAP_NOWHERE
1827  * @stable ICU 2.0
1828  */
1829 U_STABLE void U_EXPORT2
1830 ubidi_invertMap(const int32_t *srcMap, int32_t *destMap, int32_t length);
1831 
1832 /** option flags for ubidi_writeReordered() */
1833 
1834 /**
1835  * option bit for ubidi_writeReordered():
1836  * keep combining characters after their base characters in RTL runs
1837  *
1838  * @see ubidi_writeReordered
1839  * @stable ICU 2.0
1840  */
1841 #define UBIDI_KEEP_BASE_COMBINING       1
1842 
1843 /**
1844  * option bit for ubidi_writeReordered():
1845  * replace characters with the "mirrored" property in RTL runs
1846  * by their mirror-image mappings
1847  *
1848  * @see ubidi_writeReordered
1849  * @stable ICU 2.0
1850  */
1851 #define UBIDI_DO_MIRRORING              2
1852 
1853 /**
1854  * option bit for ubidi_writeReordered():
1855  * surround the run with LRMs if necessary;
1856  * this is part of the approximate "inverse Bidi" algorithm
1857  *
1858  * <p>This option does not imply corresponding adjustment of the index
1859  * mappings.</p>
1860  *
1861  * @see ubidi_setInverse
1862  * @see ubidi_writeReordered
1863  * @stable ICU 2.0
1864  */
1865 #define UBIDI_INSERT_LRM_FOR_NUMERIC    4
1866 
1867 /**
1868  * option bit for ubidi_writeReordered():
1869  * remove Bidi control characters
1870  * (this does not affect #UBIDI_INSERT_LRM_FOR_NUMERIC)
1871  *
1872  * <p>This option does not imply corresponding adjustment of the index
1873  * mappings.</p>
1874  *
1875  * @see ubidi_writeReordered
1876  * @stable ICU 2.0
1877  */
1878 #define UBIDI_REMOVE_BIDI_CONTROLS      8
1879 
1880 /**
1881  * option bit for ubidi_writeReordered():
1882  * write the output in reverse order
1883  *
1884  * <p>This has the same effect as calling <code>ubidi_writeReordered()</code>
1885  * first without this option, and then calling
1886  * <code>ubidi_writeReverse()</code> without mirroring.
1887  * Doing this in the same step is faster and avoids a temporary buffer.
1888  * An example for using this option is output to a character terminal that
1889  * is designed for RTL scripts and stores text in reverse order.</p>
1890  *
1891  * @see ubidi_writeReordered
1892  * @stable ICU 2.0
1893  */
1894 #define UBIDI_OUTPUT_REVERSE            16
1895 
1896 /**
1897  * Get the length of the source text processed by the last call to
1898  * <code>ubidi_setPara()</code>. This length may be different from the length
1899  * of the source text if option <code>#UBIDI_OPTION_STREAMING</code>
1900  * has been set.
1901  * <br>
1902  * Note that whenever the length of the text affects the execution or the
1903  * result of a function, it is the processed length which must be considered,
1904  * except for <code>ubidi_setPara</code> (which receives unprocessed source
1905  * text) and <code>ubidi_getLength</code> (which returns the original length
1906  * of the source text).<br>
1907  * In particular, the processed length is the one to consider in the following
1908  * cases:
1909  * <ul>
1910  * <li>maximum value of the <code>limit</code> argument of
1911  * <code>ubidi_setLine</code></li>
1912  * <li>maximum value of the <code>charIndex</code> argument of
1913  * <code>ubidi_getParagraph</code></li>
1914  * <li>maximum value of the <code>charIndex</code> argument of
1915  * <code>ubidi_getLevelAt</code></li>
1916  * <li>number of elements in the array returned by <code>ubidi_getLevels</code></li>
1917  * <li>maximum value of the <code>logicalStart</code> argument of
1918  * <code>ubidi_getLogicalRun</code></li>
1919  * <li>maximum value of the <code>logicalIndex</code> argument of
1920  * <code>ubidi_getVisualIndex</code></li>
1921  * <li>number of elements filled in the <code>*indexMap</code> argument of
1922  * <code>ubidi_getLogicalMap</code></li>
1923  * <li>length of text processed by <code>ubidi_writeReordered</code></li>
1924  * </ul>
1925  *
1926  * @param pBiDi is the paragraph <code>UBiDi</code> object.
1927  *
1928  * @return The length of the part of the source text processed by
1929  *         the last call to <code>ubidi_setPara</code>.
1930  * @see ubidi_setPara
1931  * @see UBIDI_OPTION_STREAMING
1932  * @stable ICU 3.6
1933  */
1934 U_STABLE int32_t U_EXPORT2
1935 ubidi_getProcessedLength(const UBiDi *pBiDi);
1936 
1937 /**
1938  * Get the length of the reordered text resulting from the last call to
1939  * <code>ubidi_setPara()</code>. This length may be different from the length
1940  * of the source text if option <code>#UBIDI_OPTION_INSERT_MARKS</code>
1941  * or option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> has been set.
1942  * <br>
1943  * This resulting length is the one to consider in the following cases:
1944  * <ul>
1945  * <li>maximum value of the <code>visualIndex</code> argument of
1946  * <code>ubidi_getLogicalIndex</code></li>
1947  * <li>number of elements of the <code>*indexMap</code> argument of
1948  * <code>ubidi_getVisualMap</code></li>
1949  * </ul>
1950  * Note that this length stays identical to the source text length if
1951  * Bidi marks are inserted or removed using option bits of
1952  * <code>ubidi_writeReordered</code>, or if option
1953  * <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code> has been set.
1954  *
1955  * @param pBiDi is the paragraph <code>UBiDi</code> object.
1956  *
1957  * @return The length of the reordered text resulting from
1958  *         the last call to <code>ubidi_setPara</code>.
1959  * @see ubidi_setPara
1960  * @see UBIDI_OPTION_INSERT_MARKS
1961  * @see UBIDI_OPTION_REMOVE_CONTROLS
1962  * @stable ICU 3.6
1963  */
1964 U_STABLE int32_t U_EXPORT2
1965 ubidi_getResultLength(const UBiDi *pBiDi);
1966 
1967 U_CDECL_BEGIN
1968 
1969 #ifndef U_HIDE_DEPRECATED_API
1970 /**
1971  * Value returned by <code>UBiDiClassCallback</code> callbacks when
1972  * there is no need to override the standard Bidi class for a given code point.
1973  *
1974  * This constant is deprecated; use u_getIntPropertyMaxValue(UCHAR_BIDI_CLASS)+1 instead.
1975  *
1976  * @see UBiDiClassCallback
1977  * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
1978  */
1979 #define U_BIDI_CLASS_DEFAULT  U_CHAR_DIRECTION_COUNT
1980 #endif  // U_HIDE_DEPRECATED_API
1981 
1982 /**
1983  * Callback type declaration for overriding default Bidi class values with
1984  * custom ones.
1985  * <p>Usually, the function pointer will be propagated to a <code>UBiDi</code>
1986  * object by calling the <code>ubidi_setClassCallback()</code> function;
1987  * then the callback will be invoked by the UBA implementation any time the
1988  * class of a character is to be determined.</p>
1989  *
1990  * @param context is a pointer to the callback private data.
1991  *
1992  * @param c       is the code point to get a Bidi class for.
1993  *
1994  * @return The directional property / Bidi class for the given code point
1995  *         <code>c</code> if the default class has been overridden, or
1996  *         <code>#U_BIDI_CLASS_DEFAULT=u_getIntPropertyMaxValue(UCHAR_BIDI_CLASS)+1</code>
1997  *         if the standard Bidi class value for <code>c</code> is to be used.
1998  * @see ubidi_setClassCallback
1999  * @see ubidi_getClassCallback
2000  * @stable ICU 3.6
2001  */
2002 typedef UCharDirection U_CALLCONV
2003 UBiDiClassCallback(const void *context, UChar32 c);
2004 
2005 U_CDECL_END
2006 
2007 /**
2008  * Retrieve the Bidi class for a given code point.
2009  * <p>If a <code>#UBiDiClassCallback</code> callback is defined and returns a
2010  * value other than <code>#U_BIDI_CLASS_DEFAULT=u_getIntPropertyMaxValue(UCHAR_BIDI_CLASS)+1</code>,
2011  * that value is used; otherwise the default class determination mechanism is invoked.</p>
2012  *
2013  * @param pBiDi is the paragraph <code>UBiDi</code> object.
2014  *
2015  * @param c     is the code point whose Bidi class must be retrieved.
2016  *
2017  * @return The Bidi class for character <code>c</code> based
2018  *         on the given <code>pBiDi</code> instance.
2019  * @see UBiDiClassCallback
2020  * @stable ICU 3.6
2021  */
2022 U_STABLE UCharDirection U_EXPORT2
2023 ubidi_getCustomizedClass(UBiDi *pBiDi, UChar32 c);
2024 
2025 /**
2026  * Set the callback function and callback data used by the UBA
2027  * implementation for Bidi class determination.
2028  * <p>This may be useful for assigning Bidi classes to PUA characters, or
2029  * for special application needs. For instance, an application may want to
2030  * handle all spaces like L or R characters (according to the base direction)
2031  * when creating the visual ordering of logical lines which are part of a report
2032  * organized in columns: there should not be interaction between adjacent
2033  * cells.<p>
2034  *
2035  * @param pBiDi is the paragraph <code>UBiDi</code> object.
2036  *
2037  * @param newFn is the new callback function pointer.
2038  *
2039  * @param newContext is the new callback context pointer. This can be NULL.
2040  *
2041  * @param oldFn fillin: Returns the old callback function pointer. This can be
2042  *                      NULL.
2043  *
2044  * @param oldContext fillin: Returns the old callback's context. This can be
2045  *                           NULL.
2046  *
2047  * @param pErrorCode must be a valid pointer to an error code value.
2048  *
2049  * @see ubidi_getClassCallback
2050  * @stable ICU 3.6
2051  */
2052 U_STABLE void U_EXPORT2
2053 ubidi_setClassCallback(UBiDi *pBiDi, UBiDiClassCallback *newFn,
2054                        const void *newContext, UBiDiClassCallback **oldFn,
2055                        const void **oldContext, UErrorCode *pErrorCode);
2056 
2057 /**
2058  * Get the current callback function used for Bidi class determination.
2059  *
2060  * @param pBiDi is the paragraph <code>UBiDi</code> object.
2061  *
2062  * @param fn fillin: Returns the callback function pointer.
2063  *
2064  * @param context fillin: Returns the callback's private context.
2065  *
2066  * @see ubidi_setClassCallback
2067  * @stable ICU 3.6
2068  */
2069 U_STABLE void U_EXPORT2
2070 ubidi_getClassCallback(UBiDi *pBiDi, UBiDiClassCallback **fn, const void **context);
2071 
2072 /**
2073  * Take a <code>UBiDi</code> object containing the reordering
2074  * information for a piece of text (one or more paragraphs) set by
2075  * <code>ubidi_setPara()</code> or for a line of text set by
2076  * <code>ubidi_setLine()</code> and write a reordered string to the
2077  * destination buffer.
2078  *
2079  * This function preserves the integrity of characters with multiple
2080  * code units and (optionally) combining characters.
2081  * Characters in RTL runs can be replaced by mirror-image characters
2082  * in the destination buffer. Note that "real" mirroring has
2083  * to be done in a rendering engine by glyph selection
2084  * and that for many "mirrored" characters there are no
2085  * Unicode characters as mirror-image equivalents.
2086  * There are also options to insert or remove Bidi control
2087  * characters; see the description of the <code>destSize</code>
2088  * and <code>options</code> parameters and of the option bit flags.
2089  *
2090  * @param pBiDi A pointer to a <code>UBiDi</code> object that
2091  *              is set by <code>ubidi_setPara()</code> or
2092  *              <code>ubidi_setLine()</code> and contains the reordering
2093  *              information for the text that it was defined for,
2094  *              as well as a pointer to that text.<br><br>
2095  *              The text was aliased (only the pointer was stored
2096  *              without copying the contents) and must not have been modified
2097  *              since the <code>ubidi_setPara()</code> call.
2098  *
2099  * @param dest A pointer to where the reordered text is to be copied.
2100  *             The source text and <code>dest[destSize]</code>
2101  *             must not overlap.
2102  *
2103  * @param destSize The size of the <code>dest</code> buffer,
2104  *                 in number of UChars.
2105  *                 If the <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>
2106  *                 option is set, then the destination length could be
2107  *                 as large as
2108  *                 <code>ubidi_getLength(pBiDi)+2*ubidi_countRuns(pBiDi)</code>.
2109  *                 If the <code>UBIDI_REMOVE_BIDI_CONTROLS</code> option
2110  *                 is set, then the destination length may be less than
2111  *                 <code>ubidi_getLength(pBiDi)</code>.
2112  *                 If none of these options is set, then the destination length
2113  *                 will be exactly <code>ubidi_getProcessedLength(pBiDi)</code>.
2114  *
2115  * @param options A bit set of options for the reordering that control
2116  *                how the reordered text is written.
2117  *                The options include mirroring the characters on a code
2118  *                point basis and inserting LRM characters, which is used
2119  *                especially for transforming visually stored text
2120  *                to logically stored text (although this is still an
2121  *                imperfect implementation of an "inverse Bidi" algorithm
2122  *                because it uses the "forward Bidi" algorithm at its core).
2123  *                The available options are:
2124  *                <code>#UBIDI_DO_MIRRORING</code>,
2125  *                <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
2126  *                <code>#UBIDI_KEEP_BASE_COMBINING</code>,
2127  *                <code>#UBIDI_OUTPUT_REVERSE</code>,
2128  *                <code>#UBIDI_REMOVE_BIDI_CONTROLS</code>
2129  *
2130  * @param pErrorCode must be a valid pointer to an error code value.
2131  *
2132  * @return The length of the output string.
2133  *
2134  * @see ubidi_getProcessedLength
2135  * @stable ICU 2.0
2136  */
2137 U_STABLE int32_t U_EXPORT2
2138 ubidi_writeReordered(UBiDi *pBiDi,
2139                      UChar *dest, int32_t destSize,
2140                      uint16_t options,
2141                      UErrorCode *pErrorCode);
2142 
2143 /**
2144  * Reverse a Right-To-Left run of Unicode text.
2145  *
2146  * This function preserves the integrity of characters with multiple
2147  * code units and (optionally) combining characters.
2148  * Characters can be replaced by mirror-image characters
2149  * in the destination buffer. Note that "real" mirroring has
2150  * to be done in a rendering engine by glyph selection
2151  * and that for many "mirrored" characters there are no
2152  * Unicode characters as mirror-image equivalents.
2153  * There are also options to insert or remove Bidi control
2154  * characters.
2155  *
2156  * This function is the implementation for reversing RTL runs as part
2157  * of <code>ubidi_writeReordered()</code>. For detailed descriptions
2158  * of the parameters, see there.
2159  * Since no Bidi controls are inserted here, the output string length
2160  * will never exceed <code>srcLength</code>.
2161  *
2162  * @see ubidi_writeReordered
2163  *
2164  * @param src A pointer to the RTL run text.
2165  *
2166  * @param srcLength The length of the RTL run.
2167  *
2168  * @param dest A pointer to where the reordered text is to be copied.
2169  *             <code>src[srcLength]</code> and <code>dest[destSize]</code>
2170  *             must not overlap.
2171  *
2172  * @param destSize The size of the <code>dest</code> buffer,
2173  *                 in number of UChars.
2174  *                 If the <code>UBIDI_REMOVE_BIDI_CONTROLS</code> option
2175  *                 is set, then the destination length may be less than
2176  *                 <code>srcLength</code>.
2177  *                 If this option is not set, then the destination length
2178  *                 will be exactly <code>srcLength</code>.
2179  *
2180  * @param options A bit set of options for the reordering that control
2181  *                how the reordered text is written.
2182  *                See the <code>options</code> parameter in <code>ubidi_writeReordered()</code>.
2183  *
2184  * @param pErrorCode must be a valid pointer to an error code value.
2185  *
2186  * @return The length of the output string.
2187  * @stable ICU 2.0
2188  */
2189 U_STABLE int32_t U_EXPORT2
2190 ubidi_writeReverse(const UChar *src, int32_t srcLength,
2191                    UChar *dest, int32_t destSize,
2192                    uint16_t options,
2193                    UErrorCode *pErrorCode);
2194 
2195 /*#define BIDI_SAMPLE_CODE*/
2196 /*@}*/
2197 
2198 #endif
2199