Bidi.cpp
/* GRAPHITE2 LICENSING
Copyright 2010, SIL International
All rights reserved.
This library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2.1 of License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should also have received a copy of the GNU Lesser General Public
License along with this library in the file named "LICENSE".
If not, write to the Free Software Foundation, 51 Franklin Street,
suite 500, Boston, MA 02110-1335, USA or visit their web page on the
internet at http://www.fsf.org/licenses/lgpl.html.
Alternatively, the contents of this file may be used under the terms of the
Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
License, as published by the Free Software Foundation, either version 2
of the License or (at your option) any later version.
*/
#include "inc/Main.h"
#include "inc/Slot.h"
#include "inc/Segment.h"
using namespace graphite2;
enum DirCode { // Hungarian: dirc
Unk = -1,
N = 0, // other neutrals (default) - ON
L = 1, // left-to-right, strong - L
R = 2, // right-to-left, strong - R
AL = 3, // Arabic letter, right-to-left, strong, AR
EN = 4, // European number, left-to-right, weak - EN
ES = 5, // European separator, left-to-right, weak - ES
ET = 6, // European number terminator, left-to-right, weak - ET
AN = 7, // Arabic number, left-to-right, weak - AN
CS = 8, // Common number separator, left-to-right, weak - CS
WS = 9, // white space, neutral - WS
BN = 10, // boundary neutral - BN
LRO = 11, // LTR override
RLO = 12, // RTL override
LRE = 13, // LTR embedding
RLE = 14, // RTL embedding
PDF = 15, // pop directional format
NSM = 16, // non-space mark
ON = N
};
enum DirMask {
Nmask = 1,
Lmask = 2,
Rmask = 4,
ALmask = 8,
ENmask = 0x10,
ESmask = 0x20,
ETmask = 0x40,
ANmask = 0x80,
CSmask = 0x100,
WSmask = 0x200,
BNmask = 0x400,
LROmask = 0x800,
RLOmask = 0x1000,
LREmask = 0x2000,
RLEmask = 0x4000,
PDFmask = 0x8000,
NSMmask = 0x10000
};
unsigned int bidi_class_map[] = { 0, 1, 2, 5, 4, 8, 9, 3, 7, 0, 0, 0, 0, 0, 0, 0, 6 };
// Algorithms based on Unicode reference standard code. Thanks Asmus Freitag.
#define MAX_LEVEL 61
Slot *resolveExplicit(int level, int dir, Slot *s, int nNest = 0)
{
int nLastValid = nNest;
Slot *res = NULL;
for ( ; s && !res; s = s->next())
{
int cls = s->getBidiClass();
switch(cls)
{
case LRO:
case LRE:
nNest++;
if (level & 1)
s->setBidiLevel(level + 1);
else
s->setBidiLevel(level + 2);
if (s->getBidiLevel() > MAX_LEVEL)
s->setBidiLevel(level);
else
{
s = resolveExplicit(s->getBidiLevel(), (cls == LRE ? N : L), s->next(), nNest);
nNest--;
if (s) continue; else break;
}
cls = BN;
s->setBidiClass(cls);
break;
case RLO:
case RLE:
nNest++;
if (level & 1)
s->setBidiLevel(level + 2);
else
s->setBidiLevel(level + 1);
if (s->getBidiLevel() > MAX_LEVEL)
s->setBidiLevel(level);
else
{
s = resolveExplicit(s->getBidiLevel(), (cls == RLE ? N : R), s->next(), nNest);
nNest--;
if (s) continue; else break;
}
cls = BN;
s->setBidiClass(cls);
break;
case PDF:
cls = BN;
s->setBidiClass(cls);
if (nNest)
{
if (nLastValid < nNest)
--nNest;
else
res = s;
}
break;
}
if (dir != N)
cls = dir;
if (s)
{
s->setBidiLevel(level);
if (s->getBidiClass() != BN)
s->setBidiClass(cls);
}
else
break;
}
return res;
}
// === 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
} ;
enum bidi_state_mask
{
xamask = 1,
xrmask = 2,
xlmask = 4,
aomask = 8,
romask = 0x10,
lomask = 0x20,
rtmask = 0x40,
ltmask = 0x80,
cnmask = 0x100,
ramask = 0x200,
remask = 0x400,
lamask = 0x800,
lemask = 0x1000,
acmask = 0x2000,
rcmask = 0x4000,
rsmask = 0x8000,
lcmask = 0x10000,
lsmask = 0x20000,
retmask = 0x40000,
letmask = 0x80000
};
const bidi_state stateWeak[][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) + ON, // set current to N
xxE = (XX << 4) + EN, // set current to EN
xxA = (XX << 4) + AN, // set current to AN
xxR = (XX << 4) + R, // set current to R
xxL = (XX << 4) + L, // set current to L
Nxx = (ON << 4) + 0xF, // set run to neutral
Axx = (AN << 4) + 0xF, // set run to AN
ExE = (EN << 4) + EN, // set run to EN, set current to EN
NIx = (ON << 4) + 0xF + IX, // set run to N, increment
NxN = (ON << 4) + ON, // set run to N, set current to N
NxR = (ON << 4) + R, // set run to N, set current to R
NxE = (ON << 4) + EN, // set run to N, set current to EN
AxA = (AN << 4) + AN, // set run to AN, set current to AN
NxL = (ON << 4) + L, // set run to N, set current to L
LxL = (L << 4) + L, // set run to L, set current to L
};
const bidi_action actionWeak[][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 */ },
};
inline uint8 GetDeferredType(bidi_action a) { return (a >> 4) & 0xF; }
inline uint8 GetResolvedType(bidi_action a) { return a & 0xF; }
inline DirCode EmbeddingDirection(int l) { return l & 1 ? R : L; }
inline bool IsDeferredState(bidi_state a) { return 0 != ((1 << a) & (rtmask | ltmask | acmask | rcmask | rsmask | lcmask | lsmask)); }
inline bool IsModifiedClass(DirCode a) { return 0 != ((1 << a) & (ALmask | NSMmask | ESmask | CSmask | ETmask | ENmask)); }
void SetDeferredRunClass(Slot *s, Slot *sRun, int nval)
{
if (!sRun || s == sRun) return;
for (Slot *p = s->prev(); p != sRun; p = p->prev())
p->setBidiClass(nval);
}
void resolveWeak(int baseLevel, Slot *s)
{
int state = (baseLevel & 1) ? xr : xl;
int cls;
int level = baseLevel;
Slot *sRun = NULL;
Slot *sLast = s;
for ( ; s; s = s->next())
{
sLast = s;
cls = s->getBidiClass();
if (cls == BN)
{
s->setBidiLevel(level);
if (!s->next() && level != baseLevel)
s->setBidiClass(EmbeddingDirection(level));
else if (s->next() && level != s->next()->getBidiLevel() && s->next()->getBidiClass() != BN)
{
int newLevel = s->next()->getBidiLevel();
if (level > newLevel)
newLevel = level;
s->setBidiLevel(newLevel);
s->setBidiClass(EmbeddingDirection(newLevel));
level = s->next()->getBidiLevel();
}
else
continue;
}
bidi_action action = actionWeak[state][bidi_class_map[cls]];
int clsRun = GetDeferredType(action);
if (clsRun != XX)
{
SetDeferredRunClass(s, sRun, clsRun);
sRun = NULL;
}
int clsNew = GetResolvedType(action);
if (clsNew != XX)
s->setBidiClass(clsNew);
if (!sRun && (IX & action))
sRun = s->prev();
state = stateWeak[state][bidi_class_map[cls]];
}
cls = EmbeddingDirection(level);
int clsRun = GetDeferredType(actionWeak[state][bidi_class_map[cls]]);
if (clsRun != XX)
SetDeferredRunClass(sLast, sRun, clsRun);
}
// Neutrals
enum neutral_action
{
// action to resolve previous input
nL = L, // resolve EN to L
En = 3 << 4, // resolve neutrals run to embedding level direction
Rn = R << 4, // resolve neutrals run to strong right
Ln = L << 4, // resolved neutrals run to strong left
In = (1<<8), // increment count of deferred neutrals
LnL = (1<<4)+L, // set run and EN to L
};
int GetDeferredNeutrals(int action, int level)
{
action = (action >> 4) & 0xF;
if (action == (En >> 4))
return EmbeddingDirection(level);
else
return action;
}
int GetResolvedNeutrals(int 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
} ;
const uint8 neutral_class_map[] = { 0, 1, 2, 0, 4, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0 };
const int actionNeutrals[][5] =
{
// N, L, R, AN, EN, = cls
// state =
{ In, 0, 0, 0, 0, }, // r right
{ In, 0, 0, 0, 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, L, }, // a AN preceded by left
{ In, En, Rn, Rn, En, }, // na N preceded by a
} ;
const int stateNeutrals[][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
} ;
void resolveNeutrals(int baseLevel, Slot *s)
{
int state = baseLevel ? r : l;
int cls;
Slot *sRun = NULL;
Slot *sLast = s;
int level = baseLevel;
for ( ; s; s = s->next())
{
sLast = s;
cls = s->getBidiClass();
if (cls == BN)
{
if (sRun)
sRun = sRun->prev();
continue;
}
int action = actionNeutrals[state][neutral_class_map[cls]];
int clsRun = GetDeferredNeutrals(action, level);
if (clsRun != N)
{
SetDeferredRunClass(s, sRun, clsRun);
sRun = NULL;
}
int clsNew = GetResolvedNeutrals(action);
if (clsNew != N)
s->setBidiClass(clsNew);
if (!sRun && (action & In))
sRun = s->prev();
state = stateNeutrals[state][neutral_class_map[cls]];
level = s->getBidiLevel();
}
cls = EmbeddingDirection(level);
int clsRun = GetDeferredNeutrals(actionNeutrals[state][neutral_class_map[cls]], level);
if (clsRun != N)
SetDeferredRunClass(sLast, sRun, clsRun);
}
const int addLevel[][4] =
{
// L, R, AN, EN = cls
// level =
/* even */ { 0, 1, 2, 2, }, // EVEN
/* odd */ { 1, 0, 1, 1, }, // ODD
};
void resolveImplicit(Slot *s, Segment *seg, uint8 aMirror)
{
bool rtl = seg->dir() & 1;
for ( ; s; s = s->next())
{
int cls = s->getBidiClass();
if (cls == BN)
continue;
else if (cls == AN)
cls = AL;
if (cls < 5 && cls > 0)
{
int level = s->getBidiLevel();
level += addLevel[level & 1][cls - 1];
s->setBidiLevel(level);
if (aMirror)
{
int hasChar = seg->glyphAttr(s->gid(), aMirror + 1);
if ( ((level & 1) && (!(seg->dir() & 4) || !hasChar))
|| ((rtl ^ (level & 1)) && (seg->dir() & 4) && hasChar) )
{
unsigned short g = seg->glyphAttr(s->gid(), aMirror);
if (g) s->setGlyph(seg, g);
}
}
}
}
}
void resolveWhitespace(int baseLevel, Segment *seg, uint8 aBidi, Slot *s)
{
for ( ; s; s = s->prev())
{
int cls = seg->glyphAttr(s->gid(), aBidi);
if (cls == WS)
s->setBidiLevel(baseLevel);
else
break;
}
}
inline
Slot * join(int level, Slot * a, Slot * b)
{
if (!a) return b;
if (level & 1) { Slot * const t = a; a = b; b = t; }
Slot * const t = b->prev();
a->prev()->next(b); b->prev(a->prev()); // splice middle
t->next(a); a->prev(t); // splice ends
return a;
}
Slot * span(Slot * & cs, const bool rtl)
{
Slot * r = cs, * re = cs; cs = cs->next();
if (rtl)
{
Slot * t = r->next(); r->next(r->prev()); r->prev(t);
for (int l = r->getBidiLevel(); cs && l == cs->getBidiLevel(); cs = cs->prev())
{
re = cs;
t = cs->next(); cs->next(cs->prev()); cs->prev(t);
}
r->next(re);
re->prev(r);
r = re;
}
else
{
for (int l = r->getBidiLevel(); cs && l == cs->getBidiLevel(); cs = cs->next())
re = cs;
r->prev(re);
re->next(r);
}
if (cs) cs->prev(0);
return r;
}
Slot *resolveOrder(Slot * & cs, const bool reordered, const int level)
{
Slot * r = 0;
int ls;
while (cs && level <= (ls = cs->getBidiLevel() - reordered))
{
r = join(level, r, level >= ls
? span(cs, level & 1)
: resolveOrder(cs, reordered, level+1));
}
return r;
}
