// Extracted from Bidi.cpp - version 26
// Reference implementation for Unicode Bidirectional Algorithm
// Bidi include file
#include "mupdf/fitz.h"
#include "bidi-impl.h"
#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 Uniode 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 uitlity 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 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 excercise 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 algrithm
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, int cval, int iStart, fz_bidi_chartype nval)
{
int i;
for (i = iStart - 1; i >= iStart - cval; i--)
{
pval[i] = nval;
}
}
static
void set_deferred_level_run(fz_bidi_level *pval, int cval, int iStart, fz_bidi_level nval)
{
int i;
for (i = iStart - 1; i >= iStart - cval; i--)
{
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.
------------------------------------------------------------------------*/
#if 0
static int 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;
}
/*------------------------------------------------------------------------
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.
------------------------------------------------------------------------*/
int fz_bidi_resolve_explicit(fz_bidi_level level, fz_bidi_chartype dir, fz_bidi_chartype *pcls, fz_bidi_level *plevel, int cch,
fz_bidi_level n_nest)
{
int 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 leter
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 leter */
/*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 havve
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, int cch)
{
int state = odd(baselevel) ? xr : xl;
fz_bidi_chartype cls;
int ich;
fz_bidi_action action;
fz_bidi_chartype cls_run;
fz_bidi_chartype cls_new;
fz_bidi_level level = baselevel;
int cch_run = 0;
for (ich = 0; ich < cch; ich++)
{
if (pcls[ich] > BDI_BN) {
fz_warn(ctx, "error: pcls[%d] > 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 NEUTAL 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 preceeded 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, int cch)
{
// the state at the start of text depends on the base level
int state = odd(baselevel) ? r : l;
fz_bidi_chartype cls;
int ich;
fz_bidi_chartype cls_run;
int 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 IMPLLICIT =================================================
/*------------------------------------------------------------------------
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, int cch)
{
int 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,
int cch)
{
int cchrun = 0;
fz_bidi_level oldlevel = baselevel;
int 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