1/*
2******************************************************************************
3*
4*   Copyright (C) 2000-2004, International Business Machines
5*   Corporation and others. All Rights Reserved.
6*   Copyright (C) 2007 Apple Inc. All rights reserved.
7*
8*   Permission is hereby granted, free of charge, to any person obtaining a copy of this
9*   software and associated documentation files (the "Software"), to deal in the Software
10*   without restriction, including without limitation the rights to use, copy, modify,
11*   merge, publish, distribute, and/or sell copies of the Software, and to permit persons
12*   to whom the Software is furnished to do so, provided that the above copyright notice(s)
13*   and this permission notice appear in all copies of the Software and that both the above
14*   copyright notice(s) and this permission notice appear in supporting documentation.
15*
16*   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
17*   INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
18*   PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER
19*   OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR
20*   CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
21*   PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
22*   OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
23*
24*   Except as contained in this notice, the name of a copyright holder shall not be used in
25*   advertising or otherwise to promote the sale, use or other dealings in this Software
26*   without prior written authorization of the copyright holder.
27*
28******************************************************************************
29*
30*   Arabic letter shaping implemented by Ayman Roshdy
31*/
32
33#include "config.h"
34
35#if USE(ATSUI)
36
37#include "ShapeArabic.h"
38
39#include <stdbool.h>
40#include <string.h>
41#include <unicode/utypes.h>
42#include <unicode/uchar.h>
43#include <unicode/ustring.h>
44#include <unicode/ushape.h>
45#include <wtf/Assertions.h>
46
47/*
48 * ### TODO in general for letter shaping:
49 * - the letter shaping code is UTF-16-unaware; needs update
50 *   + especially invertBuffer()?!
51 * - needs to handle the "Arabic Tail" that is used in some legacy codepages
52 *   as a glyph fragment of wide-glyph letters
53 *   + IBM Unicode conversion tables map it to U+200B (ZWSP)
54 *   + IBM Egypt has proposed to encode the tail in Unicode among Arabic Presentation Forms
55 */
56
57/* definitions for Arabic letter shaping ------------------------------------ */
58
59#define IRRELEVANT 4
60#define LAMTYPE    16
61#define ALEFTYPE   32
62#define LINKR      1
63#define LINKL      2
64
65static const UChar IrrelevantPos[] = {
66    0x0, 0x2, 0x4, 0x6,
67    0x8, 0xA, 0xC, 0xE,
68};
69
70static const UChar araLink[178]=
71{
72  1           + 32 + 256 * 0x11,/*0x0622*/
73  1           + 32 + 256 * 0x13,/*0x0623*/
74  1                + 256 * 0x15,/*0x0624*/
75  1           + 32 + 256 * 0x17,/*0x0625*/
76  1 + 2            + 256 * 0x19,/*0x0626*/
77  1           + 32 + 256 * 0x1D,/*0x0627*/
78  1 + 2            + 256 * 0x1F,/*0x0628*/
79  1                + 256 * 0x23,/*0x0629*/
80  1 + 2            + 256 * 0x25,/*0x062A*/
81  1 + 2            + 256 * 0x29,/*0x062B*/
82  1 + 2            + 256 * 0x2D,/*0x062C*/
83  1 + 2            + 256 * 0x31,/*0x062D*/
84  1 + 2            + 256 * 0x35,/*0x062E*/
85  1                + 256 * 0x39,/*0x062F*/
86  1                + 256 * 0x3B,/*0x0630*/
87  1                + 256 * 0x3D,/*0x0631*/
88  1                + 256 * 0x3F,/*0x0632*/
89  1 + 2            + 256 * 0x41,/*0x0633*/
90  1 + 2            + 256 * 0x45,/*0x0634*/
91  1 + 2            + 256 * 0x49,/*0x0635*/
92  1 + 2            + 256 * 0x4D,/*0x0636*/
93  1 + 2            + 256 * 0x51,/*0x0637*/
94  1 + 2            + 256 * 0x55,/*0x0638*/
95  1 + 2            + 256 * 0x59,/*0x0639*/
96  1 + 2            + 256 * 0x5D,/*0x063A*/
97  0, 0, 0, 0, 0,                /*0x063B-0x063F*/
98  1 + 2,                        /*0x0640*/
99  1 + 2            + 256 * 0x61,/*0x0641*/
100  1 + 2            + 256 * 0x65,/*0x0642*/
101  1 + 2            + 256 * 0x69,/*0x0643*/
102  1 + 2       + 16 + 256 * 0x6D,/*0x0644*/
103  1 + 2            + 256 * 0x71,/*0x0645*/
104  1 + 2            + 256 * 0x75,/*0x0646*/
105  1 + 2            + 256 * 0x79,/*0x0647*/
106  1                + 256 * 0x7D,/*0x0648*/
107  1                + 256 * 0x7F,/*0x0649*/
108  1 + 2            + 256 * 0x81,/*0x064A*/
109  4, 4, 4, 4,                   /*0x064B-0x064E*/
110  4, 4, 4, 4,                   /*0x064F-0x0652*/
111  4, 4, 4, 0, 0,                /*0x0653-0x0657*/
112  0, 0, 0, 0,                   /*0x0658-0x065B*/
113  1                + 256 * 0x85,/*0x065C*/
114  1                + 256 * 0x87,/*0x065D*/
115  1                + 256 * 0x89,/*0x065E*/
116  1                + 256 * 0x8B,/*0x065F*/
117  0, 0, 0, 0, 0,                /*0x0660-0x0664*/
118  0, 0, 0, 0, 0,                /*0x0665-0x0669*/
119  0, 0, 0, 0, 0, 0,             /*0x066A-0x066F*/
120  4,                            /*0x0670*/
121  0,                            /*0x0671*/
122  1           + 32,             /*0x0672*/
123  1           + 32,             /*0x0673*/
124  0,                            /*0x0674*/
125  1           + 32,             /*0x0675*/
126  1, 1,                         /*0x0676-0x0677*/
127  1+2,                          /*0x0678*/
128  1+2              + 256 * 0x16,/*0x0679*/
129  1+2              + 256 * 0x0E,/*0x067A*/
130  1+2              + 256 * 0x02,/*0x067B*/
131  1+2, 1+2,                     /*0x067C-0x067D*/
132  1+2              + 256 * 0x06,/*0x067E*/
133  1+2              + 256 * 0x12,/*0x067F*/
134  1+2              + 256 * 0x0A,/*0x0680*/
135  1+2, 1+2,                     /*0x0681-0x0682*/
136  1+2              + 256 * 0x26,/*0x0683*/
137  1+2              + 256 * 0x22,/*0x0684*/
138  1+2,                          /*0x0685*/
139  1+2              + 256 * 0x2A,/*0x0686*/
140  1+2              + 256 * 0x2E,/*0x0687*/
141  1                + 256 * 0x38,/*0x0688*/
142  1, 1, 1,                      /*0x0689-0x068B*/
143  1                + 256 * 0x34,/*0x068C*/
144  1                + 256 * 0x32,/*0x068D*/
145  1                + 256 * 0x36,/*0x068E*/
146  1, 1,                         /*0x068F-0x0690*/
147  1                + 256 * 0x3C,/*0x0691*/
148  1, 1, 1, 1, 1, 1,             /*0x0692-0x0697*/
149  1                + 256 * 0x3A,/*0x0698*/
150  1,                            /*0x0699*/
151  1+2, 1+2, 1+2, 1+2, 1+2, 1+2, /*0x069A-0x069F*/
152  1+2, 1+2, 1+2, 1+2,           /*0x06A0-0x06A3*/
153  1+2              + 256 * 0x2E,/*0x06A4*/
154  1+2,                          /*0x06A5*/
155  1+2              + 256 * 0x1E,/*0x06A6*/
156  1+2, 1+2,                     /*0x06A7-0x06A8*/
157  1+2              + 256 * 0x3E,/*0x06A9*/
158  1+2, 1+2, 1+2,                /*0x06AA-0x06AC*/
159  1+2              + 256 * 0x83,/*0x06AD*/
160  1+2,                          /*0x06AE*/
161  1+2              + 256 * 0x42,/*0x06AF*/
162  1+2,                          /*0x06B0*/
163  1+2              + 256 * 0x4A,/*0x06B1*/
164  1+2,                          /*0x06B2*/
165  1+2              + 256 * 0x46,/*0x06B3*/
166  1+2, 1+2, 1+2, 1+2, 1+2, 1+2, /*0x06B4-0x06B9*/
167  1+2,                          /*0x06BA*/          // FIXME: Seems to have a final form
168  1+2              + 256 * 0x50,/*0x06BB*/
169  1+2, 1+2,                     /*0x06BC-0x06BD*/
170  1+2              + 256 * 0x5A,/*0x06BE*/
171  1+2,                          /*0x06BF*/
172  1,                            /*0x06C0*/
173  1+2              + 256 * 0x56,/*0x06C1*/
174  1+2,                          /*0x06C2*/
175  1, 1,                         /*0x06C3-0x06C4*/
176  1                + 256 * 0x90,/*0x06C5*/
177  1                + 256 * 0x89,/*0x06C6*/
178  1                + 256 * 0x87,/*0x06C7*/
179  1                + 256 * 0x8B,/*0x06C8*/
180  1                + 256 * 0x92,/*0x06C9*/
181  1,                            /*0x06CA*/
182  1                + 256 * 0x8E,/*0x06CB*/
183  1+2              + 256 * 0xAC,/*0x06CC*/
184  1,                            /*0x06CD*/
185  1+2,                          /*0x06CE*/
186  1,                            /*0x06CF*/
187  1+2              + 256 * 0x94,/*0x06D0*/
188  1+2,                          /*0x06D1*/
189  1                + 256 * 0x5E,/*0x06D2*/
190  1                + 256 * 0x60 /*0x06D3*/
191};
192
193static const UChar presLink[141]=
194{
195  1 + 2,                        /*0xFE70*/
196  1 + 2,                        /*0xFE71*/
197  1 + 2, 0, 1+ 2, 0, 1+ 2,      /*0xFE72-0xFE76*/
198  1 + 2,                        /*0xFE77*/
199  1+ 2, 1 + 2, 1+2, 1 + 2,      /*0xFE78-0xFE81*/
200  1+ 2, 1 + 2, 1+2, 1 + 2,      /*0xFE82-0xFE85*/
201  0, 0 + 32, 1 + 32, 0 + 32,    /*0xFE86-0xFE89*/
202  1 + 32, 0, 1,  0 + 32,        /*0xFE8A-0xFE8D*/
203  1 + 32, 0, 2,  1 + 2,         /*0xFE8E-0xFE91*/
204  1, 0 + 32, 1 + 32, 0,         /*0xFE92-0xFE95*/
205  2, 1 + 2, 1, 0,               /*0xFE96-0xFE99*/
206  1, 0, 2, 1 + 2,               /*0xFE9A-0xFE9D*/
207  1, 0, 2, 1 + 2,               /*0xFE9E-0xFEA1*/
208  1, 0, 2, 1 + 2,               /*0xFEA2-0xFEA5*/
209  1, 0, 2, 1 + 2,               /*0xFEA6-0xFEA9*/
210  1, 0, 2, 1 + 2,               /*0xFEAA-0xFEAD*/
211  1, 0, 1, 0,                   /*0xFEAE-0xFEB1*/
212  1, 0, 1, 0,                   /*0xFEB2-0xFEB5*/
213  1, 0, 2, 1+2,                 /*0xFEB6-0xFEB9*/
214  1, 0, 2, 1+2,                 /*0xFEBA-0xFEBD*/
215  1, 0, 2, 1+2,                 /*0xFEBE-0xFEC1*/
216  1, 0, 2, 1+2,                 /*0xFEC2-0xFEC5*/
217  1, 0, 2, 1+2,                 /*0xFEC6-0xFEC9*/
218  1, 0, 2, 1+2,                 /*0xFECA-0xFECD*/
219  1, 0, 2, 1+2,                 /*0xFECE-0xFED1*/
220  1, 0, 2, 1+2,                 /*0xFED2-0xFED5*/
221  1, 0, 2, 1+2,                 /*0xFED6-0xFED9*/
222  1, 0, 2, 1+2,                 /*0xFEDA-0xFEDD*/
223  1, 0, 2, 1+2,                 /*0xFEDE-0xFEE1*/
224  1, 0 + 16, 2 + 16, 1 + 2 +16, /*0xFEE2-0xFEE5*/
225  1 + 16, 0, 2, 1+2,            /*0xFEE6-0xFEE9*/
226  1, 0, 2, 1+2,                 /*0xFEEA-0xFEED*/
227  1, 0, 2, 1+2,                 /*0xFEEE-0xFEF1*/
228  1, 0, 1, 0,                   /*0xFEF2-0xFEF5*/
229  1, 0, 2, 1+2,                 /*0xFEF6-0xFEF9*/
230  1, 0, 1, 0,                   /*0xFEFA-0xFEFD*/
231  1, 0, 1, 0,
232  1
233};
234
235static const UChar convertFEto06[] =
236{
237/***********0******1******2******3******4******5******6******7******8******9******A******B******C******D******E******F***/
238/*FE7*/   0x64B, 0x64B, 0x64C, 0x64C, 0x64D, 0x64D, 0x64E, 0x64E, 0x64F, 0x64F, 0x650, 0x650, 0x651, 0x651, 0x652, 0x652,
239/*FE8*/   0x621, 0x622, 0x622, 0x623, 0x623, 0x624, 0x624, 0x625, 0x625, 0x626, 0x626, 0x626, 0x626, 0x627, 0x627, 0x628,
240/*FE9*/   0x628, 0x628, 0x628, 0x629, 0x629, 0x62A, 0x62A, 0x62A, 0x62A, 0x62B, 0x62B, 0x62B, 0x62B, 0x62C, 0x62C, 0x62C,
241/*FEA*/   0x62C, 0x62D, 0x62D, 0x62D, 0x62D, 0x62E, 0x62E, 0x62E, 0x62E, 0x62F, 0x62F, 0x630, 0x630, 0x631, 0x631, 0x632,
242/*FEB*/   0x632, 0x633, 0x633, 0x633, 0x633, 0x634, 0x634, 0x634, 0x634, 0x635, 0x635, 0x635, 0x635, 0x636, 0x636, 0x636,
243/*FEC*/   0x636, 0x637, 0x637, 0x637, 0x637, 0x638, 0x638, 0x638, 0x638, 0x639, 0x639, 0x639, 0x639, 0x63A, 0x63A, 0x63A,
244/*FED*/   0x63A, 0x641, 0x641, 0x641, 0x641, 0x642, 0x642, 0x642, 0x642, 0x643, 0x643, 0x643, 0x643, 0x644, 0x644, 0x644,
245/*FEE*/   0x644, 0x645, 0x645, 0x645, 0x645, 0x646, 0x646, 0x646, 0x646, 0x647, 0x647, 0x647, 0x647, 0x648, 0x648, 0x649,
246/*FEF*/   0x649, 0x64A, 0x64A, 0x64A, 0x64A, 0x65C, 0x65C, 0x65D, 0x65D, 0x65E, 0x65E, 0x65F, 0x65F
247};
248
249static const UChar shapeTable[4][4][4]=
250{
251  { {0,0,0,0}, {0,0,0,0}, {0,1,0,3}, {0,1,0,1} },
252  { {0,0,2,2}, {0,0,1,2}, {0,1,1,2}, {0,1,1,3} },
253  { {0,0,0,0}, {0,0,0,0}, {0,1,0,3}, {0,1,0,3} },
254  { {0,0,1,2}, {0,0,1,2}, {0,1,1,2}, {0,1,1,3} }
255};
256
257/*
258 *Name     : changeLamAlef
259 *Function : Converts the Alef characters into an equivalent
260 *           LamAlef location in the 0x06xx Range, this is an
261 *           intermediate stage in the operation of the program
262 *           later it'll be converted into the 0xFExx LamAlefs
263 *           in the shaping function.
264 */
265static UChar
266changeLamAlef(UChar ch) {
267
268    switch(ch) {
269    case 0x0622 :
270        return(0x065C);
271        break;
272    case 0x0623 :
273        return(0x065D);
274        break;
275    case 0x0625 :
276        return(0x065E);
277        break;
278    case 0x0627 :
279        return(0x065F);
280        break;
281    default :
282        return(0);
283        break;
284    }
285}
286
287/*
288 *Name     : specialChar
289 *Function : Special Arabic characters need special handling in the shapeUnicode
290 *           function, this function returns 1 or 2 for these special characters
291 */
292static int32_t
293specialChar(UChar ch) {
294
295    if( (ch>0x0621 && ch<0x0626)||(ch==0x0627)||(ch>0x062e && ch<0x0633)||
296        (ch>0x0647 && ch<0x064a)||(ch==0x0629) ) {
297        return (1);
298    }
299    else
300    if( ch>=0x064B && ch<= 0x0652 )
301        return (2);
302    else
303    if( (ch>=0x0653 && ch<= 0x0655) || ch == 0x0670 ||
304        (ch>=0xFE70 && ch<= 0xFE7F) )
305        return (3);
306    else
307        return (0);
308}
309
310/*
311 *Name     : getLink
312 *Function : Resolves the link between the characters as
313 *           Arabic characters have four forms :
314 *           Isolated, Initial, Middle and Final Form
315 */
316static UChar
317getLink(UChar ch) {
318
319    if(ch >= 0x0622 && ch <= 0x06D3) {
320        return(araLink[ch-0x0622]);
321    } else if(ch == 0x200D) {
322        return(3);
323    } else if(ch >= 0x206D && ch <= 0x206F) {
324        return(4);
325    } else if(ch >= 0xFE70 && ch <= 0xFEFC) {
326        return(presLink[ch-0xFE70]);
327    } else {
328        return(0);
329    }
330}
331
332/*
333 *Name     : isTashkeelChar
334 *Function : Returns 1 for Tashkeel characters else return 0
335 */
336static int32_t
337isTashkeelChar(UChar ch) {
338
339    if( ch>=0x064B && ch<= 0x0652 )
340        return (1);
341    else
342        return (0);
343}
344
345/*
346 *Name     : shapeUnicode
347 *Function : Converts an Arabic Unicode buffer in 06xx Range into a shaped
348 *           arabic Unicode buffer in FExx Range
349 */
350static int32_t
351shapeUnicode(UChar *dest, int32_t sourceLength,
352             int32_t destSize,
353             int tashkeelFlag) {
354
355    int32_t          i, iend;
356    int32_t          prevPos, lastPos,Nx, Nw;
357    unsigned int     Shape;
358    int32_t          flag;
359    int32_t          lamalef_found = 0;
360    UChar            prevLink = 0, lastLink = 0, currLink, nextLink = 0;
361    UChar            wLamalef;
362
363    /*
364     * Converts the input buffer from FExx Range into 06xx Range
365     * to make sure that all characters are in the 06xx range
366     * even the lamalef is converted to the special region in
367     * the 06xx range
368     */
369    for (i = 0; i < sourceLength; i++) {
370        UChar inputChar = dest[i];
371        if ( (inputChar >= 0xFE70) && (inputChar <= 0xFEFC)) {
372            dest[i] = convertFEto06 [ (inputChar - 0xFE70) ] ;
373        }
374    }
375
376    /* sets the index to the end of the buffer, together with the step point to -1 */
377    i = 0;
378    iend = sourceLength;
379
380    /*
381     * This function resolves the link between the characters .
382     * Arabic characters have four forms :
383     * Isolated Form, Initial Form, Middle Form and Final Form
384     */
385    currLink = getLink(dest[i]);
386
387    prevPos = i;
388    lastPos = i;
389    Nx = sourceLength + 2, Nw = 0;
390
391    while (i != iend) {
392        /* If high byte of currLink > 0 then more than one shape */
393        if ((currLink & 0xFF00) > 0 || isTashkeelChar(dest[i])) {
394            Nw = i + 1;
395            while (Nx >= sourceLength) {         /* we need to know about next char */
396                if(Nw == iend) {
397                    nextLink = 0;
398                    Nx = -1;
399                } else {
400                    nextLink = getLink(dest[Nw]);
401                    if((nextLink & IRRELEVANT) == 0) {
402                        Nx = Nw;
403                    } else {
404                        Nw = Nw + 1;
405                    }
406                }
407            }
408
409            if ( ((currLink & ALEFTYPE) > 0)  &&  ((lastLink & LAMTYPE) > 0) ) {
410                lamalef_found = 1;
411                wLamalef = changeLamAlef(dest[i]); /*get from 0x065C-0x065f */
412                if ( wLamalef != 0) {
413                    dest[i] = ' ';               /* The default case is to drop the Alef and replace */
414                    dest[lastPos] =wLamalef;     /* it by a space.                                   */
415                    i=lastPos;
416                }
417                lastLink = prevLink;
418                currLink = getLink(wLamalef);
419            }
420            /*
421             * get the proper shape according to link ability of neighbors
422             * and of character; depends on the order of the shapes
423             * (isolated, initial, middle, final) in the compatibility area
424             */
425             flag  = specialChar(dest[i]);
426
427             Shape = shapeTable[nextLink & (LINKR + LINKL)]
428                               [lastLink & (LINKR + LINKL)]
429                               [currLink & (LINKR + LINKL)];
430
431             if (flag == 1) {
432                 Shape = (Shape == 1 || Shape == 3) ? 1 : 0;
433             }
434             else
435             if(flag == 2) {
436                 if( (lastLink & LINKL) && (nextLink & LINKR) && (tashkeelFlag == 1) &&
437                      dest[i] != 0x064C && dest[i] != 0x064D ) {
438                     Shape = 1;
439                     if( (nextLink&ALEFTYPE) == ALEFTYPE && (lastLink&LAMTYPE) == LAMTYPE )
440                         Shape = 0;
441                 }
442                 else {
443                     Shape = 0;
444                 }
445             }
446
447             if(flag == 2) {
448                 dest[i] =  0xFE70 + IrrelevantPos[(dest[i] - 0x064B)] + Shape;
449             }
450             else
451                 dest[i] = (UChar)((dest[i] < 0x0670 ? 0xFE70 : 0xFB50) + (currLink >> 8) + Shape);
452        }
453
454        /* move one notch forward */
455        if ((currLink & IRRELEVANT) == 0) {
456              prevLink = lastLink;
457              lastLink = currLink;
458              prevPos = lastPos;
459              lastPos = i;
460        }
461
462        i++;
463        if (i == Nx) {
464            currLink = nextLink;
465            Nx = sourceLength + 2;
466        }
467        else if(i != iend) {
468            currLink = getLink(dest[i]);
469        }
470    }
471
472    destSize = sourceLength;
473
474    return destSize;
475}
476
477int32_t shapeArabic(const UChar *source, int32_t sourceLength, UChar *dest, int32_t destCapacity, uint32_t options, UErrorCode *pErrorCode) {
478    int32_t destLength;
479
480    /* usual error checking */
481    if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
482        return 0;
483    }
484
485    /* make sure that no reserved options values are used; allow dest==NULL only for preflighting */
486    if( source==NULL || sourceLength<-1 ||
487        (dest==NULL && destCapacity!=0) || destCapacity<0 ||
488        options>=U_SHAPE_DIGIT_TYPE_RESERVED ||
489        (options&U_SHAPE_DIGITS_MASK)>=U_SHAPE_DIGITS_RESERVED
490    ) {
491        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
492        return 0;
493    }
494
495    /* determine the source length */
496    if(sourceLength==-1) {
497        sourceLength=u_strlen(source);
498    }
499    if(sourceLength==0) {
500        return 0;
501    }
502
503    /* check that source and destination do not overlap */
504    if( dest!=NULL &&
505        ((source<=dest && dest<source+sourceLength) ||
506         (dest<=source && source<dest+destCapacity))
507    ) {
508        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
509        return 0;
510    }
511
512    if((options&U_SHAPE_LETTERS_MASK)!=U_SHAPE_LETTERS_NOOP) {
513        int32_t outputSize = sourceLength;
514
515        /* calculate destination size */
516        /* TODO: do we ever need to do this pure preflighting? */
517        ASSERT((options&U_SHAPE_LENGTH_MASK) != U_SHAPE_LENGTH_GROW_SHRINK);
518
519        if(outputSize>destCapacity) {
520            *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
521            return outputSize;
522        }
523
524        /* Start of Arabic letter shaping part */
525        memcpy(dest, source, sourceLength*U_SIZEOF_UCHAR);
526
527        ASSERT((options&U_SHAPE_TEXT_DIRECTION_MASK) == U_SHAPE_TEXT_DIRECTION_LOGICAL);
528
529        switch(options&U_SHAPE_LETTERS_MASK) {
530        case U_SHAPE_LETTERS_SHAPE :
531            /* Call the shaping function with tashkeel flag == 1 */
532            destLength = shapeUnicode(dest,sourceLength,destCapacity,1);
533            break;
534        case U_SHAPE_LETTERS_SHAPE_TASHKEEL_ISOLATED :
535            /* Call the shaping function with tashkeel flag == 0 */
536            destLength = shapeUnicode(dest,sourceLength,destCapacity,0);
537            break;
538        case U_SHAPE_LETTERS_UNSHAPE :
539            ASSERT_NOT_REACHED();
540            break;
541        default :
542            /* will never occur because of validity checks above */
543            destLength = 0;
544            break;
545        }
546
547        /* End of Arabic letter shaping part */
548    } else
549        ASSERT_NOT_REACHED();
550
551    ASSERT((options & U_SHAPE_DIGITS_MASK) == U_SHAPE_DIGITS_NOOP);
552
553    return sourceLength;
554}
555
556#endif // USE(ATSUI)
557