// Extracted from Bidi.cpp - version 26 // Reference implementation for Unicode Bidirectional Algorithm // Bidi include file #include "mupdf/fitz.h" #include "bidi-imp.h" #include #ifndef TRUE #define TRUE (1) #endif #ifndef FALSE #define FALSE (0) #endif /*------------------------------------------------------------------------ File: Bidi.Cpp Description ----------- Sample Implementation of the Unicode Bidirectional Algorithm as it was revised by Revision 5 of the Unicode Technical Report # 9 (1999-8-17) Verified for changes to the algorithm up through Unicode 5.2.0 (2009). This implementation is organized into several passes, each implemen- ting one or more of the rules of the Unicode Bidi Algorithm. The resolution of Weak Types and of Neutrals each use a state table approach. Both a printf based interface and a Windows DlgProc are provided for interactive testing. A stress harness comparing this implementation (v24) to a Java based implementation was used by Doug Felt to verify that the two implementations produce identical results for all strings up to six bidi classes and stochastic strings up to length 20. Version 26 was verified by the author against the Unicode 5.2.0 file BidiTest.txt, which provides an exhaustive text of strings of length 4 or less, but covers some important cases where the language in UAX#9 had been clarified. To see this code running in an actual Windows program, download the free Unibook utility from http://unicode.org/unibook The bidi demo is executed from the tools menu. It is build from this source file. Build Notes ----------- To compile the sample implementation please set the #define directives above so the correct headers get included. Not all the files are needed for all purposes. For the commandline version only bidi.h and bidi.cpp are needed. The Win32 version is provided as a dialog procedure. To use as a standalone program compile with the lbmain.cpp file. If all you need is the ability to run the code "as is", you can instead download the unibook utility from http://uincode.org/unibook/ which contains the bidi demo compiled from this source file. This code uses an extension to C++ that gives variables declared in a for() statement function the same scope as the for() statement. If your compiler does not support this extension, you may need to move the declaration, e.g. int ich = 0; in front of the for statement. Implementation Note ------------------- NOTE: The Unicode Bidirectional Algorithm removes all explicit formatting codes in rule X9, but states that this can be simulated by conformant implementations. This implementation attempts to demonstrate such a simulation To demonstrate this, the current implementation does the following: in resolveExplicit() - change LRE, LRO, RLE, RLO, PDF to BN - assign nested levels to BN in resolveWeak and resolveNeutrals - assign L and R to BN's where they exist in place of sor and eor by changing the last BN in front of a level change to a strong type - skip over BN's for the purpose of determining actions - include BN in the count of deferred runs which will resolve some of them to EN, AN and N in resolveWhiteSpace - set the level of any surviving BN to the base level, or the level of the preceding character - include LRE,LRO, RLE, RLO, PDF and BN in the count whitespace to be reset This will result in the same order for non-BN characters as if the BN characters had been removed. The clean() function can be used to remove boundary marks for verification purposes. Notation -------- Pointer variables generally start with the letter p Counter variables generally start with the letter c Index variables generally start with the letter i Boolean variables generally start with the letter f The enumerated bidirectional types have the same name as in the description for the Unicode Bidirectional Algorithm Using this code outside a demo context -------------------------------------- The way the functions are broken down in this demo code is based on the needs of the demo to show the evolution in internal state as the algorithm proceeds. This obscures how the algorithm would be used in practice. These are the steps: 1. Allocate a pair of arrays large enough to hold bidi class and calculated levels (one for each input character) 2. Provide your own function to assign directional types (bidi classes) corresponding to each character in the input, conflating ON, WS, S to N. Unlike the classify function in this demo, the input would be actual Unicode characters. 3. Process the first paragraph by calling BidiParagraph. That function changes B into BN and returns a length including the paragraph separator. (The iteration over multiple paragraphs is left as exercise for the reader). 4. Assign directional types again, but now assign specific types to whitespace characters. 5. Instead of reordering the input in place it is often desirable to calculate an array of offsets indicating the reordering. To that end, allocate such an array here and use it instead of the input array in the next step. 6. Resolve and reorder the lines by calling BidiLines. That function 'breaks' lines on LS characters. Provide an optional array of flags indicating the location of other line breaks as needed. Update History -------------- Version 24 is the initial published and verified version of this reference implementation. Version 25 and its updates fix various minor issues with the scaffolding used for demonstrating the algorithm using pseudo-alphabets from the command line or dialog box. No changes to the implementation of the actual bidi algorithm are made in any of the minor updates to version 25. Version 26 also makes no change to the actual algorithm but was verified against the official BidiTest.txt file for Unicode 5.2.0. - updated pseudo-alphabet - Last Revised 12-10-99 (25) - enable demo mode for release builds - no other changes - Last Revised 12-10-00 (25a) - fix regression in pseudo alphabet use for Windows UI - Last Revised 02-01-01 (25b) - fixed a few comments, renamed a variable - Last Revised 03-04-01 (25c) - make base level settable, enable mirror by default, fix dialog size - Last Revised 06-02-01 (25e) - fixed some comments - Last Revised 09-29-01 (25f) - fixed classification for LS,RLM,LRM in pseudo alphabet, focus issues in UI, regression fix to commandline from 25(e) fix DEMO switch - Last Revised 11-07-01 (25g) - fixed classification for plus/minus in pseudo alphabet to track changes made in Unicode 4.0.1 - Last Revised 12-03-04 (25h) - now compiles as dialog-only program for WINDOWS_UI==1 using new bidimain.cpp - Last Revised 12-02-07 (25i) - cleaned up whitespace and indenting in the source, fixed two comments (table headers) - Last Revised 15-03-07 (25j) - named enumerations - Last Revised 30-05-07 (25k) - added usage notes, minor edits to comments, indentation, etc throughout. Added the bidiParagraph function. Checked against changes in the Unicode Bidi Algorithm for Unicode 5.2.0. No changes needed to this implementation to match the values in the BidiTest.txt file in the Unicode Character Database. Minor fixes to dialog/windows proc, updated preprocessor directives. - Last Revised 03-08-09 (26) Credits: ------- Written by: Asmus Freytag Command line interface by: Rick McGowan Verification (v24): Doug Felt Disclaimer and legal rights: --------------------------- Copyright (C) 1999-2009, ASMUS, Inc. All Rights Reserved. Distributed under the Terms of Use in http://www.unicode.org/copyright.html. THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THE SOFTWARE. The file bid.rc is included in the software covered by the above. ------------------------------------------------------------------------*/ /* === HELPER FUNCTIONS AND DECLARATIONS ================================= */ #define odd(x) ((x) & 1) /*---------------------------------------------------------------------- The following array maps character codes to types for the purpose of this sample implementation. The legend string gives a human readable explanation of the pseudo alphabet. For simplicity, characters entered by buttons are given a 1:1 mapping between their type and pseudo character value. Pseudo characters that can be typed from the keyboard are explained in the legend string. Use the Unicode Character Database for the real values in real use. ---------------------------------------------------------------------*/ enum { chLS = 0x15 }; #if 0 static const fz_bidi_chartype types_from_char[] = { // 0 1 2 3 4 5 6 7 8 9 a b c d e f BDI_BN, BDI_BN, BDI_BN, BDI_BN, BDI_L, BDI_R, BDI_BN, BDI_BN, BDI_BN, BDI_S, BDI_B, BDI_S, BDI_WS, BDI_B, BDI_BN, BDI_BN, /*00-0f*/ BDI_LRO,BDI_LRE,BDI_PDF,BDI_RLO,BDI_RLE,BDI_WS, BDI_L, BDI_R, BDI_BN, BDI_BN, BDI_BN, BDI_BN, BDI_B, BDI_B, BDI_B, BDI_S, /*10-1f*/ BDI_WS, BDI_ON, BDI_ON, BDI_ET, BDI_ET, BDI_ET, BDI_ON, BDI_ON, BDI_ON, BDI_ON, BDI_ON, BDI_ES, BDI_CS, BDI_ES, BDI_CS, BDI_ES, /*20-2f*/ BDI_EN, BDI_EN, BDI_EN, BDI_EN, BDI_EN, BDI_EN, BDI_AN, BDI_AN, BDI_AN, BDI_AN, BDI_CS, BDI_ON, BDI_ON, BDI_ON, BDI_ON, BDI_ON, /*30-3f*/ BDI_ON, BDI_AL, BDI_AL, BDI_AL, BDI_AL, BDI_AL, BDI_AL, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, /*40-4f*/ BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_R, BDI_LRE,BDI_ON, BDI_RLE,BDI_PDF,BDI_S, /*50-5f*/ BDI_NSM,BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, /*60-6f*/ BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_L, BDI_LRO,BDI_B, BDI_RLO,BDI_BN, BDI_ON, /*70-7f*/ }; #endif /*************************************** Reverse, human readable reference: LRM: 0x4 RLM: 0x5 L: 0x16,a-z LRE: 0x11,[ LRO: 0x10,{ R: 0x17,G-Z AL: A-F RLE: 0x14,] RLO: 0x13,} PDF: 0x12,^ EN: 0-5 ES: /,+,[hyphen] ET: #,$,% AN: 6-9 CS: [comma],.,: NSM: ` BN: 0x0-0x8,0xe,0xf,0x18-0x1b,~ B: 0xa,0xd,0x1c-0x1e,| S: 0x9,0xb,0x1f,_ WS: 0xc,0x15,[space] ON: !,",&,',(,),*,;,<,=,>,?,@,\,0x7f ****************************************/ // === HELPER FUNCTIONS ================================================ #ifdef BIDI_LINE_AT_A_TIME // reverse cch characters static void reverse(uint32_t *psz, int cch) { uint32_t ch_temp; int ich; for (ich = 0; ich < --cch; ich++) { ch_temp = psz[ich]; psz[ich] = psz[cch]; psz[cch] = ch_temp; } } #endif // Set a run of cval values at locations all prior to, but not including // iStart, to the new value nval. static void set_deferred_run(fz_bidi_chartype *pval, size_t cval, size_t iStart, fz_bidi_chartype nval) { size_t i; for (i = iStart; i > iStart - cval; ) { pval[--i] = nval; } } static void set_deferred_level_run(fz_bidi_level *pval, size_t cval, size_t iStart, fz_bidi_level nval) { size_t i; for (i = iStart; i > iStart - cval; ) { pval[--i] = nval; } } // === ASSIGNING BIDI CLASSES ============================================ // === THE PARAGRAPH LEVEL =============================================== /*------------------------------------------------------------------------ Function: resolve_paragraphs Resolves the input strings into blocks over which the algorithm is then applied. Implements Rule P1 of the Unicode Bidi Algorithm Input: Text string Character count Output: revised character count Note: This is a very simplistic function. In effect it restricts the action of the algorithm to the first paragraph in the input where a paragraph ends at the end of the first block separator or at the end of the input text. ------------------------------------------------------------------------*/ int fz_bidi_resolve_paragraphs(fz_bidi_chartype *types, int cch) { int ich; // skip characters not of type B for(ich = 0; ich < cch && types[ich] != BDI_B; ich++) ; // stop after first B, make it a BN for use in the next steps if (ich < cch && types[ich] == BDI_B) types[ich++] = BDI_BN; return ich; } #if 0 /*------------------------------------------------------------------------ Function: base_level Determines the base level Implements rule P2 of the Unicode Bidi Algorithm. Input: Array of directional classes Character count Note: Ignores explicit embeddings ------------------------------------------------------------------------*/ static int base_level(const fz_bidi_chartype *pcls, int cch) { int ich; for (ich = 0; ich < cch; ich++) { switch (pcls[ich]) { // strong left case BDI_L: return 0; // strong right case BDI_R: case BDI_AL: return 1; } } return 0; } #endif //====== RESOLVE EXPLICIT ================================================ static fz_bidi_level greater_even(fz_bidi_level i) { return odd(i) ? i + 1 : i + 2; } static fz_bidi_level greater_odd(fz_bidi_level i) { return odd(i) ? i + 2 : i + 1; } static fz_bidi_chartype embedding_direction(fz_bidi_chartype level) { return odd(level) ? BDI_R : BDI_L; } /*------------------------------------------------------------------------ Function: resolveExplicit Recursively resolves explicit embedding levels and overrides. Implements rules X1-X9, of the Unicode Bidirectional Algorithm. Input: Base embedding level and direction Character count Output: Array of embedding levels Caller must allocate (one level per input character) In/Out: Array of direction classes Note: The function uses two simple counters to keep track of matching explicit codes and PDF. Use the default argument for the outermost call. The nesting counter counts the recursion depth and not the embedding level. ------------------------------------------------------------------------*/ size_t fz_bidi_resolve_explicit(fz_bidi_level level, fz_bidi_chartype dir, fz_bidi_chartype *pcls, fz_bidi_level *plevel, size_t cch, fz_bidi_level n_nest) { size_t ich; // always called with a valid nesting level // nesting levels are != embedding levels int nLastValid = n_nest; // check input values assert(n_nest >= 0 && level >= 0 && level <= BIDI_LEVEL_MAX); // process the text for (ich = 0; ich < cch; ich++) { fz_bidi_chartype cls = pcls[ich]; switch (cls) { case BDI_LRO: case BDI_LRE: n_nest++; if (greater_even(level) <= BIDI_LEVEL_MAX) { plevel[ich] = greater_even(level); pcls[ich] = BDI_BN; ich += fz_bidi_resolve_explicit(plevel[ich], (cls == BDI_LRE ? BDI_N : BDI_L), &pcls[ich+1], &plevel[ich+1], cch - (ich+1), n_nest); n_nest--; continue; } cls = pcls[ich] = BDI_BN; break; case BDI_RLO: case BDI_RLE: n_nest++; if (greater_odd(level) <= BIDI_LEVEL_MAX) { plevel[ich] = greater_odd(level); pcls[ich] = BDI_BN; ich += fz_bidi_resolve_explicit(plevel[ich], (cls == BDI_RLE ? BDI_N : BDI_R), &pcls[ich+1], &plevel[ich+1], cch - (ich+1), n_nest); n_nest--; continue; } cls = pcls[ich] = BDI_BN; break; case BDI_PDF: cls = pcls[ich] = BDI_BN; if (n_nest) { if (nLastValid < n_nest) { n_nest--; } else { cch = ich; // break the loop, but complete body } } break; } // Apply the override if (dir != BDI_N) { cls = dir; } plevel[ich] = level; if (pcls[ich] != BDI_BN) pcls[ich] = cls; } return ich; } // === RESOLVE WEAK TYPES ================================================ enum bidi_state // possible states { xa, // arabic letter xr, // right letter xl, // left letter ao, // arabic lett. foll by ON ro, // right lett. foll by ON lo, // left lett. foll by ON rt, // ET following R lt, // ET following L cn, // EN, AN following AL ra, // arabic number foll R re, // european number foll R la, // arabic number foll L le, // european number foll L ac, // CS following cn rc, // CS following ra rs, // CS,ES following re lc, // CS following la ls, // CS,ES following le ret, // ET following re let // ET following le } ; const unsigned char state_weak[][10] = { // N, L, R, AN, EN, AL,NSM, CS, ES, ET, /*xa*/ { ao, xl, xr, cn, cn, xa, xa, ao, ao, ao }, /* arabic letter */ /*xr*/ { ro, xl, xr, ra, re, xa, xr, ro, ro, rt }, /* right letter */ /*xl*/ { lo, xl, xr, la, le, xa, xl, lo, lo, lt }, /* left letter */ /*ao*/ { ao, xl, xr, cn, cn, xa, ao, ao, ao, ao }, /* arabic lett. foll by ON*/ /*ro*/ { ro, xl, xr, ra, re, xa, ro, ro, ro, rt }, /* right lett. foll by ON */ /*lo*/ { lo, xl, xr, la, le, xa, lo, lo, lo, lt }, /* left lett. foll by ON */ /*rt*/ { ro, xl, xr, ra, re, xa, rt, ro, ro, rt }, /* ET following R */ /*lt*/ { lo, xl, xr, la, le, xa, lt, lo, lo, lt }, /* ET following L */ /*cn*/ { ao, xl, xr, cn, cn, xa, cn, ac, ao, ao }, /* EN, AN following AL */ /*ra*/ { ro, xl, xr, ra, re, xa, ra, rc, ro, rt }, /* arabic number foll R */ /*re*/ { ro, xl, xr, ra, re, xa, re, rs, rs,ret }, /* european number foll R */ /*la*/ { lo, xl, xr, la, le, xa, la, lc, lo, lt }, /* arabic number foll L */ /*le*/ { lo, xl, xr, la, le, xa, le, ls, ls,let }, /* european number foll L */ /*ac*/ { ao, xl, xr, cn, cn, xa, ao, ao, ao, ao }, /* CS following cn */ /*rc*/ { ro, xl, xr, ra, re, xa, ro, ro, ro, rt }, /* CS following ra */ /*rs*/ { ro, xl, xr, ra, re, xa, ro, ro, ro, rt }, /* CS,ES following re */ /*lc*/ { lo, xl, xr, la, le, xa, lo, lo, lo, lt }, /* CS following la */ /*ls*/ { lo, xl, xr, la, le, xa, lo, lo, lo, lt }, /* CS,ES following le */ /*ret*/ { ro, xl, xr, ra, re, xa,ret, ro, ro,ret }, /* ET following re */ /*let*/ { lo, xl, xr, la, le, xa,let, lo, lo,let } /* ET following le */ }; enum bidi_action // possible actions { // primitives IX = 0x100, // increment XX = 0xF, // no-op // actions xxx = (XX << 4) + XX, // no-op xIx = IX + xxx, // increment run xxN = (XX << 4) + BDI_ON, // set current to N xxE = (XX << 4) + BDI_EN, // set current to EN xxA = (XX << 4) + BDI_AN, // set current to AN xxR = (XX << 4) + BDI_R, // set current to R xxL = (XX << 4) + BDI_L, // set current to L Nxx = (BDI_ON << 4) + 0xF, // set run to neutral Axx = (BDI_AN << 4) + 0xF, // set run to AN ExE = (BDI_EN << 4) + BDI_EN, // set run to EN, set current to EN NIx = (BDI_ON << 4) + 0xF + IX, // set run to N, increment NxN = (BDI_ON << 4) + BDI_ON, // set run to N, set current to N NxR = (BDI_ON << 4) + BDI_R, // set run to N, set current to R NxE = (BDI_ON << 4) + BDI_EN, // set run to N, set current to EN AxA = (BDI_AN << 4) + BDI_AN, // set run to AN, set current to AN NxL = (BDI_ON << 4) + BDI_L, // set run to N, set current to L LxL = (BDI_L << 4) + BDI_L // set run to L, set current to L }; typedef uint16_t fz_bidi_action; const fz_bidi_action action_weak[][10] = { // N,.. L, R, AN, EN, AL, NSM, CS,..ES, ET, /*xa*/ { xxx, xxx, xxx, xxx, xxA, xxR, xxR, xxN, xxN, xxN }, /* arabic letter */ /*xr*/ { xxx, xxx, xxx, xxx, xxE, xxR, xxR, xxN, xxN, xIx }, /* right letter */ /*xl*/ { xxx, xxx, xxx, xxx, xxL, xxR, xxL, xxN, xxN, xIx }, /* left letter */ /*ao*/ { xxx, xxx, xxx, xxx, xxA, xxR, xxN, xxN, xxN, xxN }, /* arabic lett. foll by ON */ /*ro*/ { xxx, xxx, xxx, xxx, xxE, xxR, xxN, xxN, xxN, xIx }, /* right lett. foll by ON */ /*lo*/ { xxx, xxx, xxx, xxx, xxL, xxR, xxN, xxN, xxN, xIx }, /* left lett. foll by ON */ /*rt*/ { Nxx, Nxx, Nxx, Nxx, ExE, NxR, xIx, NxN, NxN, xIx }, /* ET following R */ /*lt*/ { Nxx, Nxx, Nxx, Nxx, LxL, NxR, xIx, NxN, NxN, xIx }, /* ET following L */ /*cn*/ { xxx, xxx, xxx, xxx, xxA, xxR, xxA, xIx, xxN, xxN }, /* EN, AN following AL */ /*ra*/ { xxx, xxx, xxx, xxx, xxE, xxR, xxA, xIx, xxN, xIx }, /* arabic number foll R */ /*re*/ { xxx, xxx, xxx, xxx, xxE, xxR, xxE, xIx, xIx, xxE }, /* european number foll R */ /*la*/ { xxx, xxx, xxx, xxx, xxL, xxR, xxA, xIx, xxN, xIx }, /* arabic number foll L */ /*le*/ { xxx, xxx, xxx, xxx, xxL, xxR, xxL, xIx, xIx, xxL }, /* european number foll L */ /*ac*/ { Nxx, Nxx, Nxx, Axx, AxA, NxR, NxN, NxN, NxN, NxN }, /* CS following cn */ /*rc*/ { Nxx, Nxx, Nxx, Axx, NxE, NxR, NxN, NxN, NxN, NIx }, /* CS following ra */ /*rs*/ { Nxx, Nxx, Nxx, Nxx, ExE, NxR, NxN, NxN, NxN, NIx }, /* CS,ES following re */ /*lc*/ { Nxx, Nxx, Nxx, Axx, NxL, NxR, NxN, NxN, NxN, NIx }, /* CS following la */ /*ls*/ { Nxx, Nxx, Nxx, Nxx, LxL, NxR, NxN, NxN, NxN, NIx }, /* CS,ES following le */ /*ret*/{ xxx, xxx, xxx, xxx, xxE, xxR, xxE, xxN, xxN, xxE }, /* ET following re */ /*let*/{ xxx, xxx, xxx, xxx, xxL, xxR, xxL, xxN, xxN, xxL } /* ET following le */ }; static fz_bidi_chartype get_deferred_type(fz_bidi_action action) { return (action >> 4) & 0xF; } static fz_bidi_chartype get_resolved_type(fz_bidi_action action) { return action & 0xF; } /* Note on action table: States can be of two kinds: - Immediate Resolution State, where each input token is resolved as soon as it is seen. These states have only single action codes (xxN) or the no-op (xxx) for static input tokens. - Deferred Resolution State, where input tokens either either extend the run (xIx) or resolve its Type (e.g. Nxx). Input classes are of three kinds - Static Input Token, where the class of the token remains unchanged on output (AN, L, N, R) - Replaced Input Token, where the class of the token is always replaced on output (AL, BDI_BN, NSM, CS, ES, ET) - Conditional Input Token, where the class of the token is changed on output in some but not all cases (EN) Where tokens are subject to change, a double action (e.g. NxA, or NxN) is _required_ after deferred states, resolving both the deferred state and changing the current token. These properties of the table are verified by assertions below. This code is needed only during debugging and maintenance */ /*------------------------------------------------------------------------ Function: resolveWeak Resolves the directionality of numeric and other weak character types Implements rules X10 and W1-W6 of the Unicode Bidirectional Algorithm. Input: Array of embedding levels Character count In/Out: Array of directional classes Note: On input only these directional classes are expected AL, HL, R, L, ON, BDI_BN, NSM, AN, EN, ES, ET, CS, ------------------------------------------------------------------------*/ void fz_bidi_resolve_weak(fz_context *ctx, fz_bidi_level baselevel, fz_bidi_chartype *pcls, fz_bidi_level *plevel, size_t cch) { int state = odd(baselevel) ? xr : xl; fz_bidi_chartype cls; size_t ich; fz_bidi_action action; fz_bidi_chartype cls_run; fz_bidi_chartype cls_new; fz_bidi_level level = baselevel; size_t cch_run = 0; for (ich = 0; ich < cch; ich++) { if (pcls[ich] > BDI_BN) { fz_warn(ctx, "error: pcls[%zu] > BN (%d)\n", ich, pcls[ich]); } // ignore boundary neutrals if (pcls[ich] == BDI_BN) { // must flatten levels unless at a level change; plevel[ich] = level; // lookahead for level changes if (ich + 1 == cch && level != baselevel) { // have to fixup last BN before end of the loop, since // its fix-upped value will be needed below the assert pcls[ich] = embedding_direction(level); } else if (ich + 1 < cch && level != plevel[ich+1] && pcls[ich+1] != BDI_BN) { // fixup LAST BN in front / after a level run to make // it act like the SOR/EOR in rule X10 int newlevel = plevel[ich+1]; if (level > newlevel) { newlevel = level; } plevel[ich] = newlevel; // must match assigned level pcls[ich] = embedding_direction(newlevel); level = plevel[ich+1]; } else { // don't interrupt runs if (cch_run) { cch_run++; } continue; } } assert(pcls[ich] <= BDI_BN); cls = pcls[ich]; action = action_weak[state][cls]; // resolve the directionality for deferred runs cls_run = get_deferred_type(action); if (cls_run != XX) { set_deferred_run(pcls, cch_run, ich, cls_run); cch_run = 0; } // resolve the directionality class at the current location cls_new = get_resolved_type(action); if (cls_new != XX) pcls[ich] = cls_new; // increment a deferred run if (IX & action) cch_run++; state = state_weak[state][cls]; } // resolve any deferred runs // use the direction of the current level to emulate PDF cls = embedding_direction(level); // resolve the directionality for deferred runs cls_run = get_deferred_type(action_weak[state][cls]); if (cls_run != XX) set_deferred_run(pcls, cch_run, ich, cls_run); } // === RESOLVE NEUTRAL TYPES ============================================== // action values enum neutral_action { // action to resolve previous input nL = BDI_L, // resolve EN to L En = 3 << 4, // resolve neutrals run to embedding level direction Rn = BDI_R << 4, // resolve neutrals run to strong right Ln = BDI_L << 4, // resolved neutrals run to strong left In = (1<<8), // increment count of deferred neutrals LnL = (1<<4)+BDI_L // set run and EN to L }; static fz_bidi_chartype get_deferred_neutrals(fz_bidi_action action, fz_bidi_level level) { action = (action >> 4) & 0xF; if (action == (En >> 4)) return embedding_direction(level); else return action; } static fz_bidi_chartype get_resolved_neutrals(fz_bidi_action action) { action = action & 0xF; if (action == In) return 0; else return action; } // state values enum neutral_state { // new temporary class r, // R and characters resolved to R l, // L and characters resolved to L rn, // N preceded by right ln, // N preceded by left a, // AN preceded by left (the abbrev 'la' is used up above) na // N preceded by a } ; /*------------------------------------------------------------------------ Notes: By rule W7, whenever a EN is 'dominated' by an L (including start of run with embedding direction = L) it is resolved to, and further treated as L. This leads to the need for 'a' and 'na' states. ------------------------------------------------------------------------*/ const int action_neutrals[][5] = { // N, L, R, AN, EN, = cls // state = {In, 0, 0, 0, 0}, // r right {In, 0, 0, 0, BDI_L}, // l left {In, En, Rn, Rn, Rn}, // rn N preceded by right {In, Ln, En, En, LnL}, // ln N preceded by left {In, 0, 0, 0, BDI_L}, // a AN preceded by left {In, En, Rn, Rn, En} // na N preceded by a } ; const int state_neutrals[][5] = { // N, L, R, AN, EN = cls // state = {rn, l, r, r, r}, // r right {ln, l, r, a, l}, // l left {rn, l, r, r, r}, // rn N preceded by right {ln, l, r, a, l}, // ln N preceded by left {na, l, r, a, l}, // a AN preceded by left {na, l, r, a, l} // na N preceded by la } ; /*------------------------------------------------------------------------ Function: resolveNeutrals Resolves the directionality of neutral character types. Implements rules W7, N1 and N2 of the Unicode Bidi Algorithm. Input: Array of embedding levels Character count Baselevel In/Out: Array of directional classes Note: On input only these directional classes are expected R, L, N, AN, EN and BN W8 resolves a number of ENs to L ------------------------------------------------------------------------*/ void fz_bidi_resolve_neutrals(fz_bidi_level baselevel, fz_bidi_chartype *pcls, const fz_bidi_level *plevel, size_t cch) { // the state at the start of text depends on the base level int state = odd(baselevel) ? r : l; fz_bidi_chartype cls; size_t ich; fz_bidi_chartype cls_run; size_t cch_run = 0; fz_bidi_level level = baselevel; for (ich = 0; ich < cch; ich++) { int action; fz_bidi_chartype cls_new; // ignore boundary neutrals if (pcls[ich] == BDI_BN) { // include in the count for a deferred run if (cch_run) cch_run++; // skip any further processing continue; } assert(pcls[ich] < 5); // "Only N, L, R, AN, EN are allowed" cls = pcls[ich]; action = action_neutrals[state][cls]; // resolve the directionality for deferred runs cls_run = get_deferred_neutrals(action, level); if (cls_run != BDI_N) { set_deferred_run(pcls, cch_run, ich, cls_run); cch_run = 0; } // resolve the directionality class at the current location cls_new = get_resolved_neutrals(action); if (cls_new != BDI_N) pcls[ich] = cls_new; if (In & action) cch_run++; state = state_neutrals[state][cls]; level = plevel[ich]; } // resolve any deferred runs cls = embedding_direction(level); // eor has type of current level // resolve the directionality for deferred runs cls_run = get_deferred_neutrals(action_neutrals[state][cls], level); if (cls_run != BDI_N) set_deferred_run(pcls, cch_run, ich, cls_run); } // === RESOLVE IMPLICITLY ================================================= /*------------------------------------------------------------------------ Function: resolveImplicit Recursively resolves implicit embedding levels. Implements rules I1 and I2 of the Unicode Bidirectional Algorithm. Input: Array of direction classes Character count Base level In/Out: Array of embedding levels Note: levels may exceed 15 on output. Accepted subset of direction classes R, L, AN, EN ------------------------------------------------------------------------*/ const fz_bidi_level add_level[][4] = { // L, R, AN, EN = cls // level = /* even */ { 0, 1, 2, 2 }, // EVEN /* odd */ { 1, 0, 1, 1 } // ODD }; void fz_bidi_resolve_implicit(const fz_bidi_chartype *pcls, fz_bidi_level *plevel, size_t cch) { size_t ich; for (ich = 0; ich < cch; ich++) { // cannot resolve bn here, since some bn were resolved to strong // types in resolveWeak. To remove these we need the original // types, which are available again in resolveWhiteSpace if (pcls[ich] == BDI_BN) { continue; } assert(pcls[ich] > 0); // "No Neutrals allowed to survive here." assert(pcls[ich] < 5); // "Out of range." plevel[ich] += add_level[odd(plevel[ich])][pcls[ich] - 1]; } } #if 0 // === REORDER =========================================================== /*------------------------------------------------------------------------ Function: resolve_lines Breaks a paragraph into lines Input: Character count Array of line break flags In/Out: Array of characters Returns the count of characters on the first line Note: This function only breaks lines at hard line breaks. Other line breaks can be passed in. If pbrk[n] is true, then a break occurs after the character in psz_input[n]. Breaks before the first character are not allowed. ------------------------------------------------------------------------*/ static int resolve_lines(uint32_t *psz_input, int *pbrk, int cch) { int ich; // skip characters not of type LS for(ich = 0; ich < cch; ich++) { if (psz_input[ich] == chLS || (pbrk && pbrk[ich])) { ich++; break; } } return ich; } #endif /*------------------------------------------------------------------------ Function: fz_bidi_resolve_whitespace Resolves levels for WS and S Implements rule L1 of the Unicode bidi Algorithm. Input: Base embedding level Character count Array of direction classes (for one line of text) In/Out: Array of embedding levels (for one line of text) Note: this should be applied a line at a time. The default driver code supplied in this file assumes a single line of text; for a real implementation, cch and the initial pointer values would have to be adjusted. ------------------------------------------------------------------------*/ void fz_bidi_resolve_whitespace(fz_bidi_level baselevel, const fz_bidi_chartype *pcls, fz_bidi_level *plevel, size_t cch) { size_t cchrun = 0; fz_bidi_level oldlevel = baselevel; size_t ich; for (ich = 0; ich < cch; ich++) { switch(pcls[ich]) { default: cchrun = 0; // any other character breaks the run break; case BDI_WS: cchrun++; break; case BDI_RLE: case BDI_LRE: case BDI_LRO: case BDI_RLO: case BDI_PDF: case BDI_BN: plevel[ich] = oldlevel; cchrun++; break; case BDI_S: case BDI_B: // reset levels for WS before eot set_deferred_level_run(plevel, cchrun, ich, baselevel); cchrun = 0; plevel[ich] = baselevel; break; } oldlevel = plevel[ich]; } // reset level before eot set_deferred_level_run(plevel, cchrun, ich, baselevel); } #ifdef BIDI_LINE_AT_A_TIME /*------------------------------------------------------------------------ Functions: reorder/reorderLevel Recursively reorders the display string "From the highest level down, reverse all characters at that level and higher, down to the lowest odd level" Implements rule L2 of the Unicode bidi Algorithm. Input: Array of embedding levels Character count Flag enabling reversal (set to false by initial caller) In/Out: Text to reorder Note: levels may exceed 15 resp. 61 on input. Rule L3 - reorder combining marks is not implemented here Rule L4 - glyph mirroring is implemented as a display option below Note: this should be applied a line at a time -------------------------------------------------------------------------*/ static int reorderLevel(fz_bidi_level level, uint32_t *psz_text, const fz_bidi_level *plevel, int cch, int f_reverse) { int ich; // true as soon as first odd level encountered f_reverse = f_reverse || odd(level); for (ich = 0; ich < cch; ich++) { if (plevel[ich] < level) { break; } else if (plevel[ich] > level) { ich += reorderLevel(level + 1, psz_text + ich, plevel + ich, cch - ich, f_reverse) - 1; } } if (f_reverse) { reverse(psz_text, ich); } return ich; } int Bidi_reorder(fz_bidi_level baselevel, uint32_t *psz_text, const fz_bidi_level *plevel, int cch) { int ich = 0; while (ich < cch) { ich += reorderLevel(baselevel, psz_text + ich, plevel + ich, cch - ich, FALSE); } return ich; } #endif