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gecko-dev/layout/base/nsBidi.cpp

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/* -*- Mode: C; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "nsBidi.h"
#include "nsUnicodeProperties.h"
#include "nsCRTGlue.h"
using namespace mozilla::unicode;
// These are #defined in <sys/regset.h> under Solaris 10 x86
#undef CS
#undef ES
/* Comparing the description of the Bidi algorithm with this implementation
is easier with the same names for the Bidi types in the code as there.
*/
enum {
L = eCharType_LeftToRight,
R = eCharType_RightToLeft,
EN = eCharType_EuropeanNumber,
ES = eCharType_EuropeanNumberSeparator,
ET = eCharType_EuropeanNumberTerminator,
AN = eCharType_ArabicNumber,
CS = eCharType_CommonNumberSeparator,
B = eCharType_BlockSeparator,
S = eCharType_SegmentSeparator,
WS = eCharType_WhiteSpaceNeutral,
O_N = eCharType_OtherNeutral,
LRE = eCharType_LeftToRightEmbedding,
LRO = eCharType_LeftToRightOverride,
AL = eCharType_RightToLeftArabic,
RLE = eCharType_RightToLeftEmbedding,
RLO = eCharType_RightToLeftOverride,
PDF = eCharType_PopDirectionalFormat,
NSM = eCharType_DirNonSpacingMark,
BN = eCharType_BoundaryNeutral,
dirPropCount
};
/* to avoid some conditional statements, use tiny constant arrays */
static Flags flagLR[2]={ DIRPROP_FLAG(L), DIRPROP_FLAG(R) };
static Flags flagE[2]={ DIRPROP_FLAG(LRE), DIRPROP_FLAG(RLE) };
static Flags flagO[2]={ DIRPROP_FLAG(LRO), DIRPROP_FLAG(RLO) };
#define DIRPROP_FLAG_LR(level) flagLR[(level)&1]
#define DIRPROP_FLAG_E(level) flagE[(level)&1]
#define DIRPROP_FLAG_O(level) flagO[(level)&1]
/*
* General implementation notes:
*
* Throughout the implementation, there are comments like (W2) that refer to
* rules of the Bidi algorithm in its version 5, in this example to the second
* rule of the resolution of weak types.
*
* For handling surrogate pairs, where two UChar's form one "abstract" (or UTF-32)
* character according to UTF-16, the second UChar gets the directional property of
* the entire character assigned, while the first one gets a BN, a boundary
* neutral, type, which is ignored by most of the algorithm according to
* rule (X9) and the implementation suggestions of the Bidi algorithm.
*
* Later, AdjustWSLevels() will set the level for each BN to that of the
* following character (UChar), which results in surrogate pairs getting the
* same level on each of their surrogates.
*
* In a UTF-8 implementation, the same thing could be done: the last byte of
* a multi-byte sequence would get the "real" property, while all previous
* bytes of that sequence would get BN.
*
* It is not possible to assign all those parts of a character the same real
* property because this would fail in the resolution of weak types with rules
* that look at immediately surrounding types.
*
* As a related topic, this implementation does not remove Boundary Neutral
* types from the input, but ignores them whenever this is relevant.
* For example, the loop for the resolution of the weak types reads
* types until it finds a non-BN.
* Also, explicit embedding codes are neither changed into BN nor removed.
* They are only treated the same way real BNs are.
* As stated before, AdjustWSLevels() takes care of them at the end.
* For the purpose of conformance, the levels of all these codes
* do not matter.
*
* Note that this implementation never modifies the dirProps
* after the initial setup.
*
*
* In this implementation, the resolution of weak types (Wn),
* neutrals (Nn), and the assignment of the resolved level (In)
* are all done in one single loop, in ResolveImplicitLevels().
* Changes of dirProp values are done on the fly, without writing
* them back to the dirProps array.
*
*
* This implementation contains code that allows to bypass steps of the
* algorithm that are not needed on the specific paragraph
* in order to speed up the most common cases considerably,
* like text that is entirely LTR, or RTL text without numbers.
*
* Most of this is done by setting a bit for each directional property
* in a flags variable and later checking for whether there are
* any LTR characters or any RTL characters, or both, whether
* there are any explicit embedding codes, etc.
*
* If the (Xn) steps are performed, then the flags are re-evaluated,
* because they will then not contain the embedding codes any more
* and will be adjusted for override codes, so that subsequently
* more bypassing may be possible than what the initial flags suggested.
*
* If the text is not mixed-directional, then the
* algorithm steps for the weak type resolution are not performed,
* and all levels are set to the paragraph level.
*
* If there are no explicit embedding codes, then the (Xn) steps
* are not performed.
*
* If embedding levels are supplied as a parameter, then all
* explicit embedding codes are ignored, and the (Xn) steps
* are not performed.
*
* White Space types could get the level of the run they belong to,
* and are checked with a test of (flags&MASK_EMBEDDING) to
* consider if the paragraph direction should be considered in
* the flags variable.
*
* If there are no White Space types in the paragraph, then
* (L1) is not necessary in AdjustWSLevels().
*/
nsBidi::nsBidi()
{
Init();
mMayAllocateText=true;
mMayAllocateRuns=true;
}
nsBidi::~nsBidi()
{
Free();
}
void nsBidi::Init()
{
/* reset the object, all pointers nullptr, all flags false, all sizes 0 */
mLength = 0;
mParaLevel = 0;
mFlags = 0;
mDirection = NSBIDI_LTR;
mTrailingWSStart = 0;
mDirPropsSize = 0;
mLevelsSize = 0;
mRunsSize = 0;
mRunCount = -1;
mDirProps=nullptr;
mLevels=nullptr;
mRuns=nullptr;
mDirPropsMemory=nullptr;
mLevelsMemory=nullptr;
mRunsMemory=nullptr;
mMayAllocateText=false;
mMayAllocateRuns=false;
}
/*
* We are allowed to allocate memory if aMemory==nullptr or
* aMayAllocate==true for each array that we need.
* We also try to grow and shrink memory as needed if we
* allocate it.
*
* Assume aSizeNeeded>0.
* If *aMemory!=nullptr, then assume *aSize>0.
*
* ### this realloc() may unnecessarily copy the old data,
* which we know we don't need any more;
* is this the best way to do this??
*/
bool nsBidi::GetMemory(void **aMemory, size_t *aSize, bool aMayAllocate, size_t aSizeNeeded)
{
/* check for existing memory */
if(*aMemory==nullptr) {
/* we need to allocate memory */
if(!aMayAllocate) {
return false;
} else {
*aMemory=malloc(aSizeNeeded);
if (*aMemory!=nullptr) {
*aSize=aSizeNeeded;
return true;
} else {
*aSize=0;
return false;
}
}
} else {
/* there is some memory, is it enough or too much? */
if(aSizeNeeded>*aSize && !aMayAllocate) {
/* not enough memory, and we must not allocate */
return false;
} else if(aSizeNeeded!=*aSize && aMayAllocate) {
/* we may try to grow or shrink */
void *memory=realloc(*aMemory, aSizeNeeded);
if(memory!=nullptr) {
*aMemory=memory;
*aSize=aSizeNeeded;
return true;
} else {
/* we failed to grow */
return false;
}
} else {
/* we have at least enough memory and must not allocate */
return true;
}
}
}
void nsBidi::Free()
{
free(mDirPropsMemory);
mDirPropsMemory = nullptr;
free(mLevelsMemory);
mLevelsMemory = nullptr;
free(mRunsMemory);
mRunsMemory = nullptr;
}
/* SetPara ------------------------------------------------------------ */
nsresult nsBidi::SetPara(const char16_t *aText, int32_t aLength,
nsBidiLevel aParaLevel, nsBidiLevel *aEmbeddingLevels)
{
nsBidiDirection direction;
/* check the argument values */
if(aText==nullptr ||
((NSBIDI_MAX_EXPLICIT_LEVEL<aParaLevel) && !IS_DEFAULT_LEVEL(aParaLevel)) ||
aLength<-1
) {
return NS_ERROR_INVALID_ARG;
}
if(aLength==-1) {
aLength = NS_strlen(aText);
}
/* initialize member data */
mLength=aLength;
mParaLevel=aParaLevel;
mDirection=NSBIDI_LTR;
mTrailingWSStart=aLength; /* the levels[] will reflect the WS run */
mDirProps=nullptr;
mLevels=nullptr;
mRuns=nullptr;
if(aLength==0) {
/*
* For an empty paragraph, create an nsBidi object with the aParaLevel and
* the flags and the direction set but without allocating zero-length arrays.
* There is nothing more to do.
*/
if(IS_DEFAULT_LEVEL(aParaLevel)) {
mParaLevel&=1;
}
if(aParaLevel&1) {
mFlags=DIRPROP_FLAG(R);
mDirection=NSBIDI_RTL;
} else {
mFlags=DIRPROP_FLAG(L);
mDirection=NSBIDI_LTR;
}
mRunCount=0;
return NS_OK;
}
mRunCount=-1;
/*
* Get the directional properties,
* the flags bit-set, and
* determine the partagraph level if necessary.
*/
if(GETDIRPROPSMEMORY(aLength)) {
mDirProps=mDirPropsMemory;
GetDirProps(aText);
} else {
return NS_ERROR_OUT_OF_MEMORY;
}
/* are explicit levels specified? */
if(aEmbeddingLevels==nullptr) {
/* no: determine explicit levels according to the (Xn) rules */\
if(GETLEVELSMEMORY(aLength)) {
mLevels=mLevelsMemory;
direction=ResolveExplicitLevels();
} else {
return NS_ERROR_OUT_OF_MEMORY;
}
} else {
/* set BN for all explicit codes, check that all levels are aParaLevel..NSBIDI_MAX_EXPLICIT_LEVEL */
mLevels=aEmbeddingLevels;
nsresult rv = CheckExplicitLevels(&direction);
if(NS_FAILED(rv)) {
return rv;
}
}
/*
* The steps after (X9) in the Bidi algorithm are performed only if
* the paragraph text has mixed directionality!
*/
switch(direction) {
case NSBIDI_LTR:
/* make sure paraLevel is even */
mParaLevel=(mParaLevel+1)&~1;
/* all levels are implicitly at paraLevel (important for GetLevels()) */
mTrailingWSStart=0;
break;
case NSBIDI_RTL:
/* make sure paraLevel is odd */
mParaLevel|=1;
/* all levels are implicitly at paraLevel (important for GetLevels()) */
mTrailingWSStart=0;
break;
default:
/*
* If there are no external levels specified and there
* are no significant explicit level codes in the text,
* then we can treat the entire paragraph as one run.
* Otherwise, we need to perform the following rules on runs of
* the text with the same embedding levels. (X10)
* "Significant" explicit level codes are ones that actually
* affect non-BN characters.
* Examples for "insignificant" ones are empty embeddings
* LRE-PDF, LRE-RLE-PDF-PDF, etc.
*/
if(aEmbeddingLevels==nullptr && !(mFlags&DIRPROP_FLAG_MULTI_RUNS)) {
ResolveImplicitLevels(0, aLength,
GET_LR_FROM_LEVEL(mParaLevel),
GET_LR_FROM_LEVEL(mParaLevel));
} else {
/* sor, eor: start and end types of same-level-run */
nsBidiLevel *levels=mLevels;
int32_t start, limit=0;
nsBidiLevel level, nextLevel;
DirProp sor, eor;
/* determine the first sor and set eor to it because of the loop body (sor=eor there) */
level=mParaLevel;
nextLevel=levels[0];
if(level<nextLevel) {
eor=GET_LR_FROM_LEVEL(nextLevel);
} else {
eor=GET_LR_FROM_LEVEL(level);
}
do {
/* determine start and limit of the run (end points just behind the run) */
/* the values for this run's start are the same as for the previous run's end */
sor=eor;
start=limit;
level=nextLevel;
/* search for the limit of this run */
while(++limit<aLength && levels[limit]==level) {}
/* get the correct level of the next run */
if(limit<aLength) {
nextLevel=levels[limit];
} else {
nextLevel=mParaLevel;
}
/* determine eor from max(level, nextLevel); sor is last run's eor */
if((level&~NSBIDI_LEVEL_OVERRIDE)<(nextLevel&~NSBIDI_LEVEL_OVERRIDE)) {
eor=GET_LR_FROM_LEVEL(nextLevel);
} else {
eor=GET_LR_FROM_LEVEL(level);
}
/* if the run consists of overridden directional types, then there
are no implicit types to be resolved */
if(!(level&NSBIDI_LEVEL_OVERRIDE)) {
ResolveImplicitLevels(start, limit, sor, eor);
}
} while(limit<aLength);
}
/* reset the embedding levels for some non-graphic characters (L1), (X9) */
AdjustWSLevels();
break;
}
mDirection=direction;
return NS_OK;
}
/* perform (P2)..(P3) ------------------------------------------------------- */
/*
* Get the directional properties for the text,
* calculate the flags bit-set, and
* determine the partagraph level if necessary.
*/
void nsBidi::GetDirProps(const char16_t *aText)
{
DirProp *dirProps=mDirPropsMemory; /* mDirProps is const */
int32_t i=0, length=mLength;
Flags flags=0; /* collect all directionalities in the text */
char16_t uchar;
DirProp dirProp;
if(IS_DEFAULT_LEVEL(mParaLevel)) {
/* determine the paragraph level (P2..P3) */
for(;;) {
uchar=aText[i];
if(!IS_FIRST_SURROGATE(uchar) || i+1==length || !IS_SECOND_SURROGATE(aText[i+1])) {
/* not a surrogate pair */
flags|=DIRPROP_FLAG(dirProps[i]=dirProp=GetBidiCat((uint32_t)uchar));
} else {
/* a surrogate pair */
dirProps[i++]=BN; /* first surrogate in the pair gets the BN type */
flags|=DIRPROP_FLAG(dirProps[i]=dirProp=GetBidiCat(GET_UTF_32(uchar, aText[i])))|DIRPROP_FLAG(BN);
}
++i;
if(dirProp==L) {
mParaLevel=0;
break;
} else if(dirProp==R || dirProp==AL) {
mParaLevel=1;
break;
} else if(i==length) {
/*
* see comment in nsIBidi.h:
* the DEFAULT_XXX values are designed so that
* their bit 0 alone yields the intended default
*/
mParaLevel&=1;
break;
}
}
}
/* get the rest of the directional properties and the flags bits */
while(i<length) {
uchar=aText[i];
if(!IS_FIRST_SURROGATE(uchar) || i+1==length || !IS_SECOND_SURROGATE(aText[i+1])) {
/* not a surrogate pair */
flags|=DIRPROP_FLAG(dirProps[i]=GetBidiCat((uint32_t)uchar));
} else {
/* a surrogate pair */
dirProps[i++]=BN; /* second surrogate in the pair gets the BN type */
flags|=DIRPROP_FLAG(dirProps[i]=GetBidiCat(GET_UTF_32(uchar, aText[i])))|DIRPROP_FLAG(BN);
}
++i;
}
if(flags&MASK_EMBEDDING) {
flags|=DIRPROP_FLAG_LR(mParaLevel);
}
mFlags=flags;
}
/* perform (X1)..(X9) ------------------------------------------------------- */
/*
* Resolve the explicit levels as specified by explicit embedding codes.
* Recalculate the flags to have them reflect the real properties
* after taking the explicit embeddings into account.
*
* The Bidi algorithm is designed to result in the same behavior whether embedding
* levels are externally specified (from "styled text", supposedly the preferred
* method) or set by explicit embedding codes (LRx, RLx, PDF) in the plain text.
* That is why (X9) instructs to remove all explicit codes (and BN).
* However, in a real implementation, this removal of these codes and their index
* positions in the plain text is undesirable since it would result in
* reallocated, reindexed text.
* Instead, this implementation leaves the codes in there and just ignores them
* in the subsequent processing.
* In order to get the same reordering behavior, positions with a BN or an
* explicit embedding code just get the same level assigned as the last "real"
* character.
*
* Some implementations, not this one, then overwrite some of these
* directionality properties at "real" same-level-run boundaries by
* L or R codes so that the resolution of weak types can be performed on the
* entire paragraph at once instead of having to parse it once more and
* perform that resolution on same-level-runs.
* This limits the scope of the implicit rules in effectively
* the same way as the run limits.
*
* Instead, this implementation does not modify these codes.
* On one hand, the paragraph has to be scanned for same-level-runs, but
* on the other hand, this saves another loop to reset these codes,
* or saves making and modifying a copy of dirProps[].
*
*
* Note that (Pn) and (Xn) changed significantly from version 4 of the Bidi algorithm.
*
*
* Handling the stack of explicit levels (Xn):
*
* With the Bidi stack of explicit levels,
* as pushed with each LRE, RLE, LRO, and RLO and popped with each PDF,
* the explicit level must never exceed NSBIDI_MAX_EXPLICIT_LEVEL==61.
*
* In order to have a correct push-pop semantics even in the case of overflows,
* there are two overflow counters:
* - countOver60 is incremented with each LRx at level 60
* - from level 60, one RLx increases the level to 61
* - countOver61 is incremented with each LRx and RLx at level 61
*
* Popping levels with PDF must work in the opposite order so that level 61
* is correct at the correct point. Underflows (too many PDFs) must be checked.
*
* This implementation assumes that NSBIDI_MAX_EXPLICIT_LEVEL is odd.
*/
nsBidiDirection nsBidi::ResolveExplicitLevels()
{
const DirProp *dirProps=mDirProps;
nsBidiLevel *levels=mLevels;
int32_t i=0, length=mLength;
Flags flags=mFlags; /* collect all directionalities in the text */
DirProp dirProp;
nsBidiLevel level=mParaLevel;
nsBidiDirection direction;
/* determine if the text is mixed-directional or single-directional */
direction=DirectionFromFlags(flags);
/* we may not need to resolve any explicit levels */
if(direction!=NSBIDI_MIXED) {
/* not mixed directionality: levels don't matter - trailingWSStart will be 0 */
} else if(!(flags&MASK_EXPLICIT)) {
/* mixed, but all characters are at the same embedding level */
/* set all levels to the paragraph level */
for(i=0; i<length; ++i) {
levels[i]=level;
}
} else {
/* continue to perform (Xn) */
/* (X1) level is set for all codes, embeddingLevel keeps track of the push/pop operations */
/* both variables may carry the NSBIDI_LEVEL_OVERRIDE flag to indicate the override status */
nsBidiLevel embeddingLevel=level, newLevel, stackTop=0;
nsBidiLevel stack[NSBIDI_MAX_EXPLICIT_LEVEL]; /* we never push anything >=NSBIDI_MAX_EXPLICIT_LEVEL */
uint32_t countOver60=0, countOver61=0; /* count overflows of explicit levels */
/* recalculate the flags */
flags=0;
/* since we assume that this is a single paragraph, we ignore (X8) */
for(i=0; i<length; ++i) {
dirProp=dirProps[i];
switch(dirProp) {
case LRE:
case LRO:
/* (X3, X5) */
newLevel=(embeddingLevel+2)&~(NSBIDI_LEVEL_OVERRIDE|1); /* least greater even level */
if(newLevel<=NSBIDI_MAX_EXPLICIT_LEVEL) {
stack[stackTop]=embeddingLevel;
++stackTop;
embeddingLevel=newLevel;
if(dirProp==LRO) {
embeddingLevel|=NSBIDI_LEVEL_OVERRIDE;
} else {
embeddingLevel&=~NSBIDI_LEVEL_OVERRIDE;
}
} else if((embeddingLevel&~NSBIDI_LEVEL_OVERRIDE)==NSBIDI_MAX_EXPLICIT_LEVEL) {
++countOver61;
} else /* (embeddingLevel&~NSBIDI_LEVEL_OVERRIDE)==NSBIDI_MAX_EXPLICIT_LEVEL-1 */ {
++countOver60;
}
flags|=DIRPROP_FLAG(BN);
break;
case RLE:
case RLO:
/* (X2, X4) */
newLevel=((embeddingLevel&~NSBIDI_LEVEL_OVERRIDE)+1)|1; /* least greater odd level */
if(newLevel<=NSBIDI_MAX_EXPLICIT_LEVEL) {
stack[stackTop]=embeddingLevel;
++stackTop;
embeddingLevel=newLevel;
if(dirProp==RLO) {
embeddingLevel|=NSBIDI_LEVEL_OVERRIDE;
} else {
embeddingLevel&=~NSBIDI_LEVEL_OVERRIDE;
}
} else {
++countOver61;
}
flags|=DIRPROP_FLAG(BN);
break;
case PDF:
/* (X7) */
/* handle all the overflow cases first */
if(countOver61>0) {
--countOver61;
} else if(countOver60>0 && (embeddingLevel&~NSBIDI_LEVEL_OVERRIDE)!=NSBIDI_MAX_EXPLICIT_LEVEL) {
/* handle LRx overflows from level 60 */
--countOver60;
} else if(stackTop>0) {
/* this is the pop operation; it also pops level 61 while countOver60>0 */
--stackTop;
embeddingLevel=stack[stackTop];
/* } else { (underflow) */
}
flags|=DIRPROP_FLAG(BN);
break;
case B:
/*
* We do not really expect to see a paragraph separator (B),
* but we should do something reasonable with it,
* especially at the end of the text.
*/
stackTop=0;
countOver60=countOver61=0;
embeddingLevel=level=mParaLevel;
flags|=DIRPROP_FLAG(B);
break;
case BN:
/* BN, LRE, RLE, and PDF are supposed to be removed (X9) */
/* they will get their levels set correctly in AdjustWSLevels() */
flags|=DIRPROP_FLAG(BN);
break;
default:
/* all other types get the "real" level */
if(level!=embeddingLevel) {
level=embeddingLevel;
if(level&NSBIDI_LEVEL_OVERRIDE) {
flags|=DIRPROP_FLAG_O(level)|DIRPROP_FLAG_MULTI_RUNS;
} else {
flags|=DIRPROP_FLAG_E(level)|DIRPROP_FLAG_MULTI_RUNS;
}
}
if(!(level&NSBIDI_LEVEL_OVERRIDE)) {
flags|=DIRPROP_FLAG(dirProp);
}
break;
}
/*
* We need to set reasonable levels even on BN codes and
* explicit codes because we will later look at same-level runs (X10).
*/
levels[i]=level;
}
if(flags&MASK_EMBEDDING) {
flags|=DIRPROP_FLAG_LR(mParaLevel);
}
/* subsequently, ignore the explicit codes and BN (X9) */
/* again, determine if the text is mixed-directional or single-directional */
mFlags=flags;
direction=DirectionFromFlags(flags);
}
return direction;
}
/*
* Use a pre-specified embedding levels array:
*
* Adjust the directional properties for overrides (->LEVEL_OVERRIDE),
* ignore all explicit codes (X9),
* and check all the preset levels.
*
* Recalculate the flags to have them reflect the real properties
* after taking the explicit embeddings into account.
*/
nsresult nsBidi::CheckExplicitLevels(nsBidiDirection *aDirection)
{
const DirProp *dirProps=mDirProps;
nsBidiLevel *levels=mLevels;
int32_t i, length=mLength;
Flags flags=0; /* collect all directionalities in the text */
nsBidiLevel level, paraLevel=mParaLevel;
for(i=0; i<length; ++i) {
level=levels[i];
if(level&NSBIDI_LEVEL_OVERRIDE) {
/* keep the override flag in levels[i] but adjust the flags */
level&=~NSBIDI_LEVEL_OVERRIDE; /* make the range check below simpler */
flags|=DIRPROP_FLAG_O(level);
} else {
/* set the flags */
flags|=DIRPROP_FLAG_E(level)|DIRPROP_FLAG(dirProps[i]);
}
if(level<paraLevel || NSBIDI_MAX_EXPLICIT_LEVEL<level) {
/* level out of bounds */
*aDirection = NSBIDI_LTR;
return NS_ERROR_INVALID_ARG;
}
}
if(flags&MASK_EMBEDDING) {
flags|=DIRPROP_FLAG_LR(mParaLevel);
}
/* determine if the text is mixed-directional or single-directional */
mFlags=flags;
*aDirection = DirectionFromFlags(flags);
return NS_OK;
}
/* determine if the text is mixed-directional or single-directional */
nsBidiDirection nsBidi::DirectionFromFlags(Flags aFlags)
{
/* if the text contains AN and neutrals, then some neutrals may become RTL */
if(!(aFlags&MASK_RTL || (aFlags&DIRPROP_FLAG(AN) && aFlags&MASK_POSSIBLE_N))) {
return NSBIDI_LTR;
} else if(!(aFlags&MASK_LTR)) {
return NSBIDI_RTL;
} else {
return NSBIDI_MIXED;
}
}
/* perform rules (Wn), (Nn), and (In) on a run of the text ------------------ */
/*
* This implementation of the (Wn) rules applies all rules in one pass.
* In order to do so, it needs a look-ahead of typically 1 character
* (except for W5: sequences of ET) and keeps track of changes
* in a rule Wp that affect a later Wq (p<q).
*
* historyOfEN is a variable-saver: it contains 4 boolean states;
* a bit in it set to 1 means:
* bit 0: the current code is an EN after W2
* bit 1: the current code is an EN after W4
* bit 2: the previous code was an EN after W2
* bit 3: the previous code was an EN after W4
* In other words, b0..1 have transitions of EN in the current iteration,
* while b2..3 have the transitions of EN in the previous iteration.
* A simple historyOfEN<<=2 suffices for the propagation.
*
* The (Nn) and (In) rules are also performed in that same single loop,
* but effectively one iteration behind for white space.
*
* Since all implicit rules are performed in one step, it is not necessary
* to actually store the intermediate directional properties in dirProps[].
*/
#define EN_SHIFT 2
#define EN_AFTER_W2 1
#define EN_AFTER_W4 2
#define EN_ALL 3
#define PREV_EN_AFTER_W2 4
#define PREV_EN_AFTER_W4 8
void nsBidi::ResolveImplicitLevels(int32_t aStart, int32_t aLimit,
DirProp aSOR, DirProp aEOR)
{
const DirProp *dirProps=mDirProps;
nsBidiLevel *levels=mLevels;
int32_t i, next, neutralStart=-1;
DirProp prevDirProp, dirProp, nextDirProp, lastStrong, beforeNeutral;
uint8_t historyOfEN;
/* initialize: current at aSOR, next at aStart (it is aStart<aLimit) */
next=aStart;
beforeNeutral=dirProp=lastStrong=aSOR;
nextDirProp=dirProps[next];
historyOfEN=0;
/*
* In all steps of this implementation, BN and explicit embedding codes
* must be treated as if they didn't exist (X9).
* They will get levels set before a non-neutral character, and remain
* undefined before a neutral one, but AdjustWSLevels() will take care
* of all of them.
*/
while(DIRPROP_FLAG(nextDirProp)&MASK_BN_EXPLICIT) {
if(++next<aLimit) {
nextDirProp=dirProps[next];
} else {
nextDirProp=aEOR;
break;
}
}
/* loop for entire run */
while(next<aLimit) {
/* advance */
prevDirProp=dirProp;
dirProp=nextDirProp;
i=next;
do {
if(++next<aLimit) {
nextDirProp=dirProps[next];
} else {
nextDirProp=aEOR;
break;
}
} while(DIRPROP_FLAG(nextDirProp)&MASK_BN_EXPLICIT);
historyOfEN<<=EN_SHIFT;
/* (W1..W7) */
switch(dirProp) {
case L:
lastStrong=L;
break;
case R:
lastStrong=R;
break;
case AL:
/* (W3) */
lastStrong=AL;
dirProp=R;
break;
case EN:
/* we have to set historyOfEN correctly */
if(lastStrong==AL) {
/* (W2) */
dirProp=AN;
} else {
if(lastStrong==L) {
/* (W7) */
dirProp=L;
}
/* this EN stays after (W2) and (W4) - at least before (W7) */
historyOfEN|=EN_ALL;
}
break;
case ES:
if( historyOfEN&PREV_EN_AFTER_W2 && /* previous was EN before (W4) */
nextDirProp==EN && lastStrong!=AL /* next is EN and (W2) won't make it AN */
) {
/* (W4) */
if(lastStrong!=L) {
dirProp=EN;
} else {
/* (W7) */
dirProp=L;
}
historyOfEN|=EN_AFTER_W4;
} else {
/* (W6) */
dirProp=O_N;
}
break;
case CS:
if( historyOfEN&PREV_EN_AFTER_W2 && /* previous was EN before (W4) */
nextDirProp==EN && lastStrong!=AL /* next is EN and (W2) won't make it AN */
) {
/* (W4) */
if(lastStrong!=L) {
dirProp=EN;
} else {
/* (W7) */
dirProp=L;
}
historyOfEN|=EN_AFTER_W4;
} else if(prevDirProp==AN && /* previous was AN */
(nextDirProp==AN || /* next is AN */
(nextDirProp==EN && lastStrong==AL)) /* or (W2) will make it one */
) {
/* (W4) */
dirProp=AN;
} else {
/* (W6) */
dirProp=O_N;
}
break;
case ET:
/* get sequence of ET; advance only next, not current, previous or historyOfEN */
while(next<aLimit && DIRPROP_FLAG(nextDirProp)&MASK_ET_NSM_BN /* (W1), (X9) */) {
if(++next<aLimit) {
nextDirProp=dirProps[next];
} else {
nextDirProp=aEOR;
break;
}
}
if( historyOfEN&PREV_EN_AFTER_W4 || /* previous was EN before (W5) */
(nextDirProp==EN && lastStrong!=AL) /* next is EN and (W2) won't make it AN */
) {
/* (W5) */
if(lastStrong!=L) {
dirProp=EN;
} else {
/* (W7) */
dirProp=L;
}
} else {
/* (W6) */
dirProp=O_N;
}
/* apply the result of (W1), (W5)..(W7) to the entire sequence of ET */
break;
case NSM:
/* (W1) */
dirProp=prevDirProp;
/* set historyOfEN back to prevDirProp's historyOfEN */
historyOfEN>>=EN_SHIFT;
/*
* Technically, this should be done before the switch() in the form
* if(nextDirProp==NSM) {
* dirProps[next]=nextDirProp=dirProp;
* }
*
* - effectively one iteration ahead.
* However, whether the next dirProp is NSM or is equal to the current dirProp
* does not change the outcome of any condition in (W2)..(W7).
*/
break;
default:
break;
}
/* here, it is always [prev,this,next]dirProp!=BN; it may be next>i+1 */
/* perform (Nn) - here, only L, R, EN, AN, and neutrals are left */
/* this is one iteration late for the neutrals */
if(DIRPROP_FLAG(dirProp)&MASK_N) {
if(neutralStart<0) {
/* start of a sequence of neutrals */
neutralStart=i;
beforeNeutral=prevDirProp;
}
} else /* not a neutral, can be only one of { L, R, EN, AN } */ {
/*
* Note that all levels[] values are still the same at this
* point because this function is called for an entire
* same-level run.
* Therefore, we need to read only one actual level.
*/
nsBidiLevel level=levels[i];
if(neutralStart>=0) {
nsBidiLevel final;
/* end of a sequence of neutrals (dirProp is "afterNeutral") */
if(beforeNeutral==L) {
if(dirProp==L) {
final=0; /* make all neutrals L (N1) */
} else {
final=level; /* make all neutrals "e" (N2) */
}
} else /* beforeNeutral is one of { R, EN, AN } */ {
if(dirProp==L) {
final=level; /* make all neutrals "e" (N2) */
} else {
final=1; /* make all neutrals R (N1) */
}
}
/* perform (In) on the sequence of neutrals */
if((level^final)&1) {
/* do something only if we need to _change_ the level */
do {
++levels[neutralStart];
} while(++neutralStart<i);
}
neutralStart=-1;
}
/* perform (In) on the non-neutral character */
/*
* in the cases of (W5), processing a sequence of ET,
* and of (X9), skipping BN,
* there may be multiple characters from i to <next
* that all get (virtually) the same dirProp and (really) the same level
*/
if(dirProp==L) {
if(level&1) {
++level;
} else {
i=next; /* we keep the levels */
}
} else if(dirProp==R) {
if(!(level&1)) {
++level;
} else {
i=next; /* we keep the levels */
}
} else /* EN or AN */ {
level=(level+2)&~1; /* least greater even level */
}
/* apply the new level to the sequence, if necessary */
while(i<next) {
levels[i++]=level;
}
}
}
/* perform (Nn) - here,
the character after the neutrals is aEOR, which is either L or R */
/* this is one iteration late for the neutrals */
if(neutralStart>=0) {
/*
* Note that all levels[] values are still the same at this
* point because this function is called for an entire
* same-level run.
* Therefore, we need to read only one actual level.
*/
nsBidiLevel level=levels[neutralStart], final;
/* end of a sequence of neutrals (aEOR is "afterNeutral") */
if(beforeNeutral==L) {
if(aEOR==L) {
final=0; /* make all neutrals L (N1) */
} else {
final=level; /* make all neutrals "e" (N2) */
}
} else /* beforeNeutral is one of { R, EN, AN } */ {
if(aEOR==L) {
final=level; /* make all neutrals "e" (N2) */
} else {
final=1; /* make all neutrals R (N1) */
}
}
/* perform (In) on the sequence of neutrals */
if((level^final)&1) {
/* do something only if we need to _change_ the level */
do {
++levels[neutralStart];
} while(++neutralStart<aLimit);
}
}
}
/* perform (L1) and (X9) ---------------------------------------------------- */
/*
* Reset the embedding levels for some non-graphic characters (L1).
* This function also sets appropriate levels for BN, and
* explicit embedding types that are supposed to have been removed
* from the paragraph in (X9).
*/
void nsBidi::AdjustWSLevels()
{
const DirProp *dirProps=mDirProps;
nsBidiLevel *levels=mLevels;
int32_t i;
if(mFlags&MASK_WS) {
nsBidiLevel paraLevel=mParaLevel;
Flags flag;
i=mTrailingWSStart;
while(i>0) {
/* reset a sequence of WS/BN before eop and B/S to the paragraph paraLevel */
while(i>0 && DIRPROP_FLAG(dirProps[--i])&MASK_WS) {
levels[i]=paraLevel;
}
/* reset BN to the next character's paraLevel until B/S, which restarts above loop */
/* here, i+1 is guaranteed to be <length */
while(i>0) {
flag=DIRPROP_FLAG(dirProps[--i]);
if(flag&MASK_BN_EXPLICIT) {
levels[i]=levels[i+1];
} else if(flag&MASK_B_S) {
levels[i]=paraLevel;
break;
}
}
}
}
/* now remove the NSBIDI_LEVEL_OVERRIDE flags, if any */
/* (a separate loop can be optimized more easily by a compiler) */
if(mFlags&MASK_OVERRIDE) {
for(i=mTrailingWSStart; i>0;) {
levels[--i]&=~NSBIDI_LEVEL_OVERRIDE;
}
}
}
nsresult nsBidi::GetDirection(nsBidiDirection* aDirection)
{
*aDirection = mDirection;
return NS_OK;
}
nsresult nsBidi::GetParaLevel(nsBidiLevel* aParaLevel)
{
*aParaLevel = mParaLevel;
return NS_OK;
}
#ifdef FULL_BIDI_ENGINE
/* -------------------------------------------------------------------------- */
nsresult nsBidi::GetLength(int32_t* aLength)
{
*aLength = mLength;
return NS_OK;
}
/*
* General remarks about the functions in this section:
*
* These functions deal with the aspects of potentially mixed-directional
* text in a single paragraph or in a line of a single paragraph
* which has already been processed according to
* the Unicode 3.0 Bidi algorithm as defined in
* http://www.unicode.org/unicode/reports/tr9/ , version 5,
* also described in The Unicode Standard, Version 3.0 .
*
* This means that there is a nsBidi object with a levels
* and a dirProps array.
* paraLevel and direction are also set.
* Only if the length of the text is zero, then levels==dirProps==nullptr.
*
* The overall directionality of the paragraph
* or line is used to bypass the reordering steps if possible.
* Even purely RTL text does not need reordering there because
* the getLogical/VisualIndex() functions can compute the
* index on the fly in such a case.
*
* The implementation of the access to same-level-runs and of the reordering
* do attempt to provide better performance and less memory usage compared to
* a direct implementation of especially rule (L2) with an array of
* one (32-bit) integer per text character.
*
* Here, the levels array is scanned as soon as necessary, and a vector of
* same-level-runs is created. Reordering then is done on this vector.
* For each run of text positions that were resolved to the same level,
* only 8 bytes are stored: the first text position of the run and the visual
* position behind the run after reordering.
* One sign bit is used to hold the directionality of the run.
* This is inefficient if there are many very short runs. If the average run
* length is <2, then this uses more memory.
*
* In a further attempt to save memory, the levels array is never changed
* after all the resolution rules (Xn, Wn, Nn, In).
* Many functions have to consider the field trailingWSStart:
* if it is less than length, then there is an implicit trailing run
* at the paraLevel,
* which is not reflected in the levels array.
* This allows a line nsBidi object to use the same levels array as
* its paragraph parent object.
*
* When a nsBidi object is created for a line of a paragraph, then the
* paragraph's levels and dirProps arrays are reused by way of setting
* a pointer into them, not by copying. This again saves memory and forbids to
* change the now shared levels for (L1).
*/
nsresult nsBidi::SetLine(nsIBidi* aParaBidi, int32_t aStart, int32_t aLimit)
{
nsBidi* pParent = (nsBidi*)aParaBidi;
int32_t length;
/* check the argument values */
if(pParent==nullptr) {
return NS_ERROR_INVALID_POINTER;
} else if(aStart<0 || aStart>aLimit || aLimit>pParent->mLength) {
return NS_ERROR_INVALID_ARG;
}
/* set members from our aParaBidi parent */
length=mLength=aLimit-aStart;
mParaLevel=pParent->mParaLevel;
mRuns=nullptr;
mFlags=0;
if(length>0) {
mDirProps=pParent->mDirProps+aStart;
mLevels=pParent->mLevels+aStart;
mRunCount=-1;
if(pParent->mDirection!=NSBIDI_MIXED) {
/* the parent is already trivial */
mDirection=pParent->mDirection;
/*
* The parent's levels are all either
* implicitly or explicitly ==paraLevel;
* do the same here.
*/
if(pParent->mTrailingWSStart<=aStart) {
mTrailingWSStart=0;
} else if(pParent->mTrailingWSStart<aLimit) {
mTrailingWSStart=pParent->mTrailingWSStart-aStart;
} else {
mTrailingWSStart=length;
}
} else {
const nsBidiLevel *levels=mLevels;
int32_t i, trailingWSStart;
nsBidiLevel level;
Flags flags=0;
SetTrailingWSStart();
trailingWSStart=mTrailingWSStart;
/* recalculate pLineBidi->direction */
if(trailingWSStart==0) {
/* all levels are at paraLevel */
mDirection=(nsBidiDirection)(mParaLevel&1);
} else {
/* get the level of the first character */
level=levels[0]&1;
/* if there is anything of a different level, then the line is mixed */
if(trailingWSStart<length && (mParaLevel&1)!=level) {
/* the trailing WS is at paraLevel, which differs from levels[0] */
mDirection=NSBIDI_MIXED;
} else {
/* see if levels[1..trailingWSStart-1] have the same direction as levels[0] and paraLevel */
i=1;
for(;;) {
if(i==trailingWSStart) {
/* the direction values match those in level */
mDirection=(nsBidiDirection)level;
break;
} else if((levels[i]&1)!=level) {
mDirection=NSBIDI_MIXED;
break;
}
++i;
}
}
}
switch(mDirection) {
case NSBIDI_LTR:
/* make sure paraLevel is even */
mParaLevel=(mParaLevel+1)&~1;
/* all levels are implicitly at paraLevel (important for GetLevels()) */
mTrailingWSStart=0;
break;
case NSBIDI_RTL:
/* make sure paraLevel is odd */
mParaLevel|=1;
/* all levels are implicitly at paraLevel (important for GetLevels()) */
mTrailingWSStart=0;
break;
default:
break;
}
}
} else {
/* create an object for a zero-length line */
mDirection=mParaLevel&1 ? NSBIDI_RTL : NSBIDI_LTR;
mTrailingWSStart=mRunCount=0;
mDirProps=nullptr;
mLevels=nullptr;
}
return NS_OK;
}
/* handle trailing WS (L1) -------------------------------------------------- */
/*
* SetTrailingWSStart() sets the start index for a trailing
* run of WS in the line. This is necessary because we do not modify
* the paragraph's levels array that we just point into.
* Using trailingWSStart is another form of performing (L1).
*
* To make subsequent operations easier, we also include the run
* before the WS if it is at the paraLevel - we merge the two here.
*/
void nsBidi::SetTrailingWSStart() {
/* mDirection!=NSBIDI_MIXED */
const DirProp *dirProps=mDirProps;
nsBidiLevel *levels=mLevels;
int32_t start=mLength;
nsBidiLevel paraLevel=mParaLevel;
/* go backwards across all WS, BN, explicit codes */
while(start>0 && DIRPROP_FLAG(dirProps[start-1])&MASK_WS) {
--start;
}
/* if the WS run can be merged with the previous run then do so here */
while(start>0 && levels[start-1]==paraLevel) {
--start;
}
mTrailingWSStart=start;
}
nsresult nsBidi::GetLevelAt(int32_t aCharIndex, nsBidiLevel* aLevel)
{
/* return paraLevel if in the trailing WS run, otherwise the real level */
if(aCharIndex<0 || mLength<=aCharIndex) {
*aLevel = 0;
} else if(mDirection!=NSBIDI_MIXED || aCharIndex>=mTrailingWSStart) {
*aLevel = mParaLevel;
} else {
*aLevel = mLevels[aCharIndex];
}
return NS_OK;
}
nsresult nsBidi::GetLevels(nsBidiLevel** aLevels)
{
int32_t start, length;
length = mLength;
if(length<=0) {
*aLevels = nullptr;
return NS_ERROR_INVALID_ARG;
}
start = mTrailingWSStart;
if(start==length) {
/* the current levels array reflects the WS run */
*aLevels = mLevels;
return NS_OK;
}
/*
* After the previous if(), we know that the levels array
* has an implicit trailing WS run and therefore does not fully
* reflect itself all the levels.
* This must be a nsBidi object for a line, and
* we need to create a new levels array.
*/
if(GETLEVELSMEMORY(length)) {
nsBidiLevel *levels=mLevelsMemory;
if(start>0 && levels!=mLevels) {
memcpy(levels, mLevels, start);
}
memset(levels+start, mParaLevel, length-start);
/* this new levels array is set for the line and reflects the WS run */
mTrailingWSStart=length;
*aLevels=mLevels=levels;
return NS_OK;
} else {
/* out of memory */
*aLevels = nullptr;
return NS_ERROR_OUT_OF_MEMORY;
}
}
#endif // FULL_BIDI_ENGINE
nsresult nsBidi::GetCharTypeAt(int32_t aCharIndex, nsCharType* pType)
{
if(aCharIndex<0 || mLength<=aCharIndex) {
return NS_ERROR_INVALID_ARG;
}
*pType = (nsCharType)mDirProps[aCharIndex];
return NS_OK;
}
nsresult nsBidi::GetLogicalRun(int32_t aLogicalStart, int32_t *aLogicalLimit, nsBidiLevel *aLevel)
{
int32_t length = mLength;
if(aLogicalStart<0 || length<=aLogicalStart) {
return NS_ERROR_INVALID_ARG;
}
if(mDirection!=NSBIDI_MIXED || aLogicalStart>=mTrailingWSStart) {
if(aLogicalLimit!=nullptr) {
*aLogicalLimit=length;
}
if(aLevel!=nullptr) {
*aLevel=mParaLevel;
}
} else {
nsBidiLevel *levels=mLevels;
nsBidiLevel level=levels[aLogicalStart];
/* search for the end of the run */
length=mTrailingWSStart;
while(++aLogicalStart<length && level==levels[aLogicalStart]) {}
if(aLogicalLimit!=nullptr) {
*aLogicalLimit=aLogicalStart;
}
if(aLevel!=nullptr) {
*aLevel=level;
}
}
return NS_OK;
}
/* runs API functions ------------------------------------------------------- */
nsresult nsBidi::CountRuns(int32_t* aRunCount)
{
if(mRunCount<0 && !GetRuns()) {
return NS_ERROR_OUT_OF_MEMORY;
} else {
if (aRunCount)
*aRunCount = mRunCount;
return NS_OK;
}
}
nsresult nsBidi::GetVisualRun(int32_t aRunIndex, int32_t *aLogicalStart, int32_t *aLength, nsBidiDirection *aDirection)
{
if( aRunIndex<0 ||
(mRunCount==-1 && !GetRuns()) ||
aRunIndex>=mRunCount
) {
*aDirection = NSBIDI_LTR;
return NS_OK;
} else {
int32_t start=mRuns[aRunIndex].logicalStart;
if(aLogicalStart!=nullptr) {
*aLogicalStart=GET_INDEX(start);
}
if(aLength!=nullptr) {
if(aRunIndex>0) {
*aLength=mRuns[aRunIndex].visualLimit-
mRuns[aRunIndex-1].visualLimit;
} else {
*aLength=mRuns[0].visualLimit;
}
}
*aDirection = (nsBidiDirection)GET_ODD_BIT(start);
return NS_OK;
}
}
/* compute the runs array --------------------------------------------------- */
/*
* Compute the runs array from the levels array.
* After GetRuns() returns true, runCount is guaranteed to be >0
* and the runs are reordered.
* Odd-level runs have visualStart on their visual right edge and
* they progress visually to the left.
*/
bool nsBidi::GetRuns()
{
if(mDirection!=NSBIDI_MIXED) {
/* simple, single-run case - this covers length==0 */
GetSingleRun(mParaLevel);
} else /* NSBIDI_MIXED, length>0 */ {
/* mixed directionality */
int32_t length=mLength, limit=mTrailingWSStart;
/*
* If there are WS characters at the end of the line
* and the run preceding them has a level different from
* paraLevel, then they will form their own run at paraLevel (L1).
* Count them separately.
* We need some special treatment for this in order to not
* modify the levels array which a line nsBidi object shares
* with its paragraph parent and its other line siblings.
* In other words, for the trailing WS, it may be
* levels[]!=paraLevel but we have to treat it like it were so.
*/
if(limit==0) {
/* there is only WS on this line */
GetSingleRun(mParaLevel);
} else {
nsBidiLevel *levels=mLevels;
int32_t i, runCount;
nsBidiLevel level=NSBIDI_DEFAULT_LTR; /* initialize with no valid level */
/* count the runs, there is at least one non-WS run, and limit>0 */
runCount=0;
for(i=0; i<limit; ++i) {
/* increment runCount at the start of each run */
if(levels[i]!=level) {
++runCount;
level=levels[i];
}
}
/*
* We don't need to see if the last run can be merged with a trailing
* WS run because SetTrailingWSStart() would have done that.
*/
if(runCount==1 && limit==length) {
/* There is only one non-WS run and no trailing WS-run. */
GetSingleRun(levels[0]);
} else /* runCount>1 || limit<length */ {
/* allocate and set the runs */
Run *runs;
int32_t runIndex, start;
nsBidiLevel minLevel=NSBIDI_MAX_EXPLICIT_LEVEL+1, maxLevel=0;
/* now, count a (non-mergable) WS run */
if(limit<length) {
++runCount;
}
/* runCount>1 */
if(GETRUNSMEMORY(runCount)) {
runs=mRunsMemory;
} else {
return false;
}
/* set the runs */
/* this could be optimized, e.g.: 464->444, 484->444, 575->555, 595->555 */
/* however, that would take longer and make other functions more complicated */
runIndex=0;
/* search for the run ends */
start=0;
level=levels[0];
if(level<minLevel) {
minLevel=level;
}
if(level>maxLevel) {
maxLevel=level;
}
/* initialize visualLimit values with the run lengths */
for(i=1; i<limit; ++i) {
if(levels[i]!=level) {
/* i is another run limit */
runs[runIndex].logicalStart=start;
runs[runIndex].visualLimit=i-start;
start=i;
level=levels[i];
if(level<minLevel) {
minLevel=level;
}
if(level>maxLevel) {
maxLevel=level;
}
++runIndex;
}
}
/* finish the last run at i==limit */
runs[runIndex].logicalStart=start;
runs[runIndex].visualLimit=limit-start;
++runIndex;
if(limit<length) {
/* there is a separate WS run */
runs[runIndex].logicalStart=limit;
runs[runIndex].visualLimit=length-limit;
if(mParaLevel<minLevel) {
minLevel=mParaLevel;
}
}
/* set the object fields */
mRuns=runs;
mRunCount=runCount;
ReorderLine(minLevel, maxLevel);
/* now add the direction flags and adjust the visualLimit's to be just that */
ADD_ODD_BIT_FROM_LEVEL(runs[0].logicalStart, levels[runs[0].logicalStart]);
limit=runs[0].visualLimit;
for(i=1; i<runIndex; ++i) {
ADD_ODD_BIT_FROM_LEVEL(runs[i].logicalStart, levels[runs[i].logicalStart]);
limit=runs[i].visualLimit+=limit;
}
/* same for the trailing WS run */
if(runIndex<runCount) {
ADD_ODD_BIT_FROM_LEVEL(runs[i].logicalStart, mParaLevel);
runs[runIndex].visualLimit+=limit;
}
}
}
}
return true;
}
/* in trivial cases there is only one trivial run; called by GetRuns() */
void nsBidi::GetSingleRun(nsBidiLevel aLevel)
{
/* simple, single-run case */
mRuns=mSimpleRuns;
mRunCount=1;
/* fill and reorder the single run */
mRuns[0].logicalStart=MAKE_INDEX_ODD_PAIR(0, aLevel);
mRuns[0].visualLimit=mLength;
}
/* reorder the runs array (L2) ---------------------------------------------- */
/*
* Reorder the same-level runs in the runs array.
* Here, runCount>1 and maxLevel>=minLevel>=paraLevel.
* All the visualStart fields=logical start before reordering.
* The "odd" bits are not set yet.
*
* Reordering with this data structure lends itself to some handy shortcuts:
*
* Since each run is moved but not modified, and since at the initial maxLevel
* each sequence of same-level runs consists of only one run each, we
* don't need to do anything there and can predecrement maxLevel.
* In many simple cases, the reordering is thus done entirely in the
* index mapping.
* Also, reordering occurs only down to the lowest odd level that occurs,
* which is minLevel|1. However, if the lowest level itself is odd, then
* in the last reordering the sequence of the runs at this level or higher
* will be all runs, and we don't need the elaborate loop to search for them.
* This is covered by ++minLevel instead of minLevel|=1 followed
* by an extra reorder-all after the reorder-some loop.
* About a trailing WS run:
* Such a run would need special treatment because its level is not
* reflected in levels[] if this is not a paragraph object.
* Instead, all characters from trailingWSStart on are implicitly at
* paraLevel.
* However, for all maxLevel>paraLevel, this run will never be reordered
* and does not need to be taken into account. maxLevel==paraLevel is only reordered
* if minLevel==paraLevel is odd, which is done in the extra segment.
* This means that for the main reordering loop we don't need to consider
* this run and can --runCount. If it is later part of the all-runs
* reordering, then runCount is adjusted accordingly.
*/
void nsBidi::ReorderLine(nsBidiLevel aMinLevel, nsBidiLevel aMaxLevel)
{
Run *runs;
nsBidiLevel *levels;
int32_t firstRun, endRun, limitRun, runCount, temp;
/* nothing to do? */
if(aMaxLevel<=(aMinLevel|1)) {
return;
}
/*
* Reorder only down to the lowest odd level
* and reorder at an odd aMinLevel in a separate, simpler loop.
* See comments above for why aMinLevel is always incremented.
*/
++aMinLevel;
runs=mRuns;
levels=mLevels;
runCount=mRunCount;
/* do not include the WS run at paraLevel<=old aMinLevel except in the simple loop */
if(mTrailingWSStart<mLength) {
--runCount;
}
while(--aMaxLevel>=aMinLevel) {
firstRun=0;
/* loop for all sequences of runs */
for(;;) {
/* look for a sequence of runs that are all at >=aMaxLevel */
/* look for the first run of such a sequence */
while(firstRun<runCount && levels[runs[firstRun].logicalStart]<aMaxLevel) {
++firstRun;
}
if(firstRun>=runCount) {
break; /* no more such runs */
}
/* look for the limit run of such a sequence (the run behind it) */
for(limitRun=firstRun; ++limitRun<runCount && levels[runs[limitRun].logicalStart]>=aMaxLevel;) {}
/* Swap the entire sequence of runs from firstRun to limitRun-1. */
endRun=limitRun-1;
while(firstRun<endRun) {
temp=runs[firstRun].logicalStart;
runs[firstRun].logicalStart=runs[endRun].logicalStart;
runs[endRun].logicalStart=temp;
temp=runs[firstRun].visualLimit;
runs[firstRun].visualLimit=runs[endRun].visualLimit;
runs[endRun].visualLimit=temp;
++firstRun;
--endRun;
}
if(limitRun==runCount) {
break; /* no more such runs */
} else {
firstRun=limitRun+1;
}
}
}
/* now do aMaxLevel==old aMinLevel (==odd!), see above */
if(!(aMinLevel&1)) {
firstRun=0;
/* include the trailing WS run in this complete reordering */
if(mTrailingWSStart==mLength) {
--runCount;
}
/* Swap the entire sequence of all runs. (endRun==runCount) */
while(firstRun<runCount) {
temp=runs[firstRun].logicalStart;
runs[firstRun].logicalStart=runs[runCount].logicalStart;
runs[runCount].logicalStart=temp;
temp=runs[firstRun].visualLimit;
runs[firstRun].visualLimit=runs[runCount].visualLimit;
runs[runCount].visualLimit=temp;
++firstRun;
--runCount;
}
}
}
nsresult nsBidi::ReorderVisual(const nsBidiLevel *aLevels, int32_t aLength, int32_t *aIndexMap)
{
int32_t start, end, limit, temp;
nsBidiLevel minLevel, maxLevel;
if(aIndexMap==nullptr ||
!PrepareReorder(aLevels, aLength, aIndexMap, &minLevel, &maxLevel)) {
return NS_OK;
}
/* nothing to do? */
if(minLevel==maxLevel && (minLevel&1)==0) {
return NS_OK;
}
/* reorder only down to the lowest odd level */
minLevel|=1;
/* loop maxLevel..minLevel */
do {
start=0;
/* loop for all sequences of levels to reorder at the current maxLevel */
for(;;) {
/* look for a sequence of levels that are all at >=maxLevel */
/* look for the first index of such a sequence */
while(start<aLength && aLevels[start]<maxLevel) {
++start;
}
if(start>=aLength) {
break; /* no more such runs */
}
/* look for the limit of such a sequence (the index behind it) */
for(limit=start; ++limit<aLength && aLevels[limit]>=maxLevel;) {}
/*
* Swap the entire interval of indexes from start to limit-1.
* We don't need to swap the levels for the purpose of this
* algorithm: the sequence of levels that we look at does not
* move anyway.
*/
end=limit-1;
while(start<end) {
temp=aIndexMap[start];
aIndexMap[start]=aIndexMap[end];
aIndexMap[end]=temp;
++start;
--end;
}
if(limit==aLength) {
break; /* no more such sequences */
} else {
start=limit+1;
}
}
} while(--maxLevel>=minLevel);
return NS_OK;
}
bool nsBidi::PrepareReorder(const nsBidiLevel *aLevels, int32_t aLength,
int32_t *aIndexMap,
nsBidiLevel *aMinLevel, nsBidiLevel *aMaxLevel)
{
int32_t start;
nsBidiLevel level, minLevel, maxLevel;
if(aLevels==nullptr || aLength<=0) {
return false;
}
/* determine minLevel and maxLevel */
minLevel=NSBIDI_MAX_EXPLICIT_LEVEL+1;
maxLevel=0;
for(start=aLength; start>0;) {
level=aLevels[--start];
if(level>NSBIDI_MAX_EXPLICIT_LEVEL+1) {
return false;
}
if(level<minLevel) {
minLevel=level;
}
if(level>maxLevel) {
maxLevel=level;
}
}
*aMinLevel=minLevel;
*aMaxLevel=maxLevel;
/* initialize the index map */
for(start=aLength; start>0;) {
--start;
aIndexMap[start]=start;
}
return true;
}
#ifdef FULL_BIDI_ENGINE
/* API functions for logical<->visual mapping ------------------------------- */
nsresult nsBidi::GetVisualIndex(int32_t aLogicalIndex, int32_t* aVisualIndex) {
if(aLogicalIndex<0 || mLength<=aLogicalIndex) {
return NS_ERROR_INVALID_ARG;
} else {
/* we can do the trivial cases without the runs array */
switch(mDirection) {
case NSBIDI_LTR:
*aVisualIndex = aLogicalIndex;
return NS_OK;
case NSBIDI_RTL:
*aVisualIndex = mLength-aLogicalIndex-1;
return NS_OK;
default:
if(mRunCount<0 && !GetRuns()) {
return NS_ERROR_OUT_OF_MEMORY;
} else {
Run *runs=mRuns;
int32_t i, visualStart=0, offset, length;
/* linear search for the run, search on the visual runs */
for(i=0;; ++i) {
length=runs[i].visualLimit-visualStart;
offset=aLogicalIndex-GET_INDEX(runs[i].logicalStart);
if(offset>=0 && offset<length) {
if(IS_EVEN_RUN(runs[i].logicalStart)) {
/* LTR */
*aVisualIndex = visualStart+offset;
return NS_OK;
} else {
/* RTL */
*aVisualIndex = visualStart+length-offset-1;
return NS_OK;
}
}
visualStart+=length;
}
}
}
}
}
nsresult nsBidi::GetLogicalIndex(int32_t aVisualIndex, int32_t *aLogicalIndex)
{
if(aVisualIndex<0 || mLength<=aVisualIndex) {
return NS_ERROR_INVALID_ARG;
} else {
/* we can do the trivial cases without the runs array */
switch(mDirection) {
case NSBIDI_LTR:
*aLogicalIndex = aVisualIndex;
return NS_OK;
case NSBIDI_RTL:
*aLogicalIndex = mLength-aVisualIndex-1;
return NS_OK;
default:
if(mRunCount<0 && !GetRuns()) {
return NS_ERROR_OUT_OF_MEMORY;
} else {
Run *runs=mRuns;
int32_t i, runCount=mRunCount, start;
if(runCount<=10) {
/* linear search for the run */
for(i=0; aVisualIndex>=runs[i].visualLimit; ++i) {}
} else {
/* binary search for the run */
int32_t start=0, limit=runCount;
/* the middle if() will guaranteed find the run, we don't need a loop limit */
for(;;) {
i=(start+limit)/2;
if(aVisualIndex>=runs[i].visualLimit) {
start=i+1;
} else if(i==0 || aVisualIndex>=runs[i-1].visualLimit) {
break;
} else {
limit=i;
}
}
}
start=runs[i].logicalStart;
if(IS_EVEN_RUN(start)) {
/* LTR */
/* the offset in runs[i] is aVisualIndex-runs[i-1].visualLimit */
if(i>0) {
aVisualIndex-=runs[i-1].visualLimit;
}
*aLogicalIndex = GET_INDEX(start)+aVisualIndex;
return NS_OK;
} else {
/* RTL */
*aLogicalIndex = GET_INDEX(start)+runs[i].visualLimit-aVisualIndex-1;
return NS_OK;
}
}
}
}
}
nsresult nsBidi::GetLogicalMap(int32_t *aIndexMap)
{
nsBidiLevel *levels;
nsresult rv;
/* GetLevels() checks all of its and our arguments */
rv = GetLevels(&levels);
if(NS_FAILED(rv)) {
return rv;
} else if(aIndexMap==nullptr) {
return NS_ERROR_INVALID_ARG;
} else {
return ReorderLogical(levels, mLength, aIndexMap);
}
}
nsresult nsBidi::GetVisualMap(int32_t *aIndexMap)
{
int32_t* runCount=nullptr;
nsresult rv;
/* CountRuns() checks all of its and our arguments */
rv = CountRuns(runCount);
if(NS_FAILED(rv)) {
return rv;
} else if(aIndexMap==nullptr) {
return NS_ERROR_INVALID_ARG;
} else {
/* fill a visual-to-logical index map using the runs[] */
Run *runs=mRuns, *runsLimit=runs+mRunCount;
int32_t logicalStart, visualStart, visualLimit;
visualStart=0;
for(; runs<runsLimit; ++runs) {
logicalStart=runs->logicalStart;
visualLimit=runs->visualLimit;
if(IS_EVEN_RUN(logicalStart)) {
do { /* LTR */
*aIndexMap++ = logicalStart++;
} while(++visualStart<visualLimit);
} else {
REMOVE_ODD_BIT(logicalStart);
logicalStart+=visualLimit-visualStart; /* logicalLimit */
do { /* RTL */
*aIndexMap++ = --logicalStart;
} while(++visualStart<visualLimit);
}
/* visualStart==visualLimit; */
}
return NS_OK;
}
}
/* reorder a line based on a levels array (L2) ------------------------------ */
nsresult nsBidi::ReorderLogical(const nsBidiLevel *aLevels, int32_t aLength, int32_t *aIndexMap)
{
int32_t start, limit, sumOfSosEos;
nsBidiLevel minLevel, maxLevel;
if(aIndexMap==nullptr ||
!PrepareReorder(aLevels, aLength, aIndexMap, &minLevel, &maxLevel)) {
return NS_OK;
}
/* nothing to do? */
if(minLevel==maxLevel && (minLevel&1)==0) {
return NS_OK;
}
/* reorder only down to the lowest odd level */
minLevel|=1;
/* loop maxLevel..minLevel */
do {
start=0;
/* loop for all sequences of levels to reorder at the current maxLevel */
for(;;) {
/* look for a sequence of levels that are all at >=maxLevel */
/* look for the first index of such a sequence */
while(start<aLength && aLevels[start]<maxLevel) {
++start;
}
if(start>=aLength) {
break; /* no more such sequences */
}
/* look for the limit of such a sequence (the index behind it) */
for(limit=start; ++limit<aLength && aLevels[limit]>=maxLevel;) {}
/*
* sos=start of sequence, eos=end of sequence
*
* The closed (inclusive) interval from sos to eos includes all the logical
* and visual indexes within this sequence. They are logically and
* visually contiguous and in the same range.
*
* For each run, the new visual index=sos+eos-old visual index;
* we pre-add sos+eos into sumOfSosEos ->
* new visual index=sumOfSosEos-old visual index;
*/
sumOfSosEos=start+limit-1;
/* reorder each index in the sequence */
do {
aIndexMap[start]=sumOfSosEos-aIndexMap[start];
} while(++start<limit);
/* start==limit */
if(limit==aLength) {
break; /* no more such sequences */
} else {
start=limit+1;
}
}
} while(--maxLevel>=minLevel);
return NS_OK;
}
nsresult nsBidi::InvertMap(const int32_t *aSrcMap, int32_t *aDestMap, int32_t aLength)
{
if(aSrcMap!=nullptr && aDestMap!=nullptr) {
aSrcMap+=aLength;
while(aLength>0) {
aDestMap[*--aSrcMap]=--aLength;
}
}
return NS_OK;
}
int32_t nsBidi::doWriteReverse(const char16_t *src, int32_t srcLength,
char16_t *dest, uint16_t options) {
/*
* RTL run -
*
* RTL runs need to be copied to the destination in reverse order
* of code points, not code units, to keep Unicode characters intact.
*
* The general strategy for this is to read the source text
* in backward order, collect all code units for a code point
* (and optionally following combining characters, see below),
* and copy all these code units in ascending order
* to the destination for this run.
*
* Several options request whether combining characters
* should be kept after their base characters,
* whether Bidi control characters should be removed, and
* whether characters should be replaced by their mirror-image
* equivalent Unicode characters.
*/
int32_t i, j, destSize;
uint32_t c;
/* optimize for several combinations of options */
switch(options&(NSBIDI_REMOVE_BIDI_CONTROLS|NSBIDI_DO_MIRRORING|NSBIDI_KEEP_BASE_COMBINING)) {
case 0:
/*
* With none of the "complicated" options set, the destination
* run will have the same length as the source run,
* and there is no mirroring and no keeping combining characters
* with their base characters.
*/
destSize=srcLength;
/* preserve character integrity */
do {
/* i is always after the last code unit known to need to be kept in this segment */
i=srcLength;
/* collect code units for one base character */
UTF_BACK_1(src, 0, srcLength);
/* copy this base character */
j=srcLength;
do {
*dest++=src[j++];
} while(j<i);
} while(srcLength>0);
break;
case NSBIDI_KEEP_BASE_COMBINING:
/*
* Here, too, the destination
* run will have the same length as the source run,
* and there is no mirroring.
* We do need to keep combining characters with their base characters.
*/
destSize=srcLength;
/* preserve character integrity */
do {
/* i is always after the last code unit known to need to be kept in this segment */
i=srcLength;
/* collect code units and modifier letters for one base character */
do {
UTF_PREV_CHAR(src, 0, srcLength, c);
} while(srcLength>0 && IsBidiCategory(c, eBidiCat_NSM));
/* copy this "user character" */
j=srcLength;
do {
*dest++=src[j++];
} while(j<i);
} while(srcLength>0);
break;
default:
/*
* With several "complicated" options set, this is the most
* general and the slowest copying of an RTL run.
* We will do mirroring, remove Bidi controls, and
* keep combining characters with their base characters
* as requested.
*/
if(!(options&NSBIDI_REMOVE_BIDI_CONTROLS)) {
i=srcLength;
} else {
/* we need to find out the destination length of the run,
which will not include the Bidi control characters */
int32_t length=srcLength;
char16_t ch;
i=0;
do {
ch=*src++;
if (!IsBidiControl((uint32_t)ch)) {
++i;
}
} while(--length>0);
src-=srcLength;
}
destSize=i;
/* preserve character integrity */
do {
/* i is always after the last code unit known to need to be kept in this segment */
i=srcLength;
/* collect code units for one base character */
UTF_PREV_CHAR(src, 0, srcLength, c);
if(options&NSBIDI_KEEP_BASE_COMBINING) {
/* collect modifier letters for this base character */
while(srcLength>0 && IsBidiCategory(c, eBidiCat_NSM)) {
UTF_PREV_CHAR(src, 0, srcLength, c);
}
}
if(options&NSBIDI_REMOVE_BIDI_CONTROLS && IsBidiControl(c)) {
/* do not copy this Bidi control character */
continue;
}
/* copy this "user character" */
j=srcLength;
if(options&NSBIDI_DO_MIRRORING) {
/* mirror only the base character */
c = SymmSwap(c);
int32_t k=0;
UTF_APPEND_CHAR_UNSAFE(dest, k, c);
dest+=k;
j+=k;
}
while(j<i) {
*dest++=src[j++];
}
} while(srcLength>0);
break;
} /* end of switch */
return destSize;
}
nsresult nsBidi::WriteReverse(const char16_t *aSrc, int32_t aSrcLength, char16_t *aDest, uint16_t aOptions, int32_t *aDestSize)
{
if( aSrc==nullptr || aSrcLength<0 ||
aDest==nullptr
) {
return NS_ERROR_INVALID_ARG;
}
/* do input and output overlap? */
if( aSrc>=aDest && aSrc<aDest+aSrcLength ||
aDest>=aSrc && aDest<aSrc+aSrcLength
) {
return NS_ERROR_INVALID_ARG;
}
if(aSrcLength>0) {
*aDestSize = doWriteReverse(aSrc, aSrcLength, aDest, aOptions);
}
return NS_OK;
}
#endif // FULL_BIDI_ENGINE
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