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/*
******************************************************************************
*
* Copyright (C) 1999-2005, International Business Machines
* Corporation and others. All Rights Reserved.
*
******************************************************************************
* file name: ubidi.c
* encoding: US-ASCII
* tab size: 8 (not used)
* indentation:4
*
* created on: 1999jul27
* created by: Markus W. Scherer
*/
/* set import/export definitions */
#ifndef U_COMMON_IMPLEMENTATION
# define U_COMMON_IMPLEMENTATION
#endif
#include "cmemory.h"
#include "unicode/utypes.h"
#include "unicode/ustring.h"
#include "unicode/uchar.h"
#include "unicode/ubidi.h"
#include "ubidi_props.h"
#include "ubidiimp.h"
/*
* 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 wherever 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().
*/
/* to avoid some conditional statements, use tiny constant arrays */
static const Flags flagLR[2]={ DIRPROP_FLAG(L), DIRPROP_FLAG(R) };
static const Flags flagE[2]={ DIRPROP_FLAG(LRE), DIRPROP_FLAG(RLE) };
static const 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]
/* UBiDi object management -------------------------------------------------- */
U_CAPI UBiDi * U_EXPORT2
ubidi_open(void)
{
UErrorCode errorCode=U_ZERO_ERROR;
return ubidi_openSized(0, 0, &errorCode);
}
U_CAPI UBiDi * U_EXPORT2
ubidi_openSized(int32_t maxLength, int32_t maxRunCount, UErrorCode *pErrorCode) {
UBiDi *pBiDi;
/* check the argument values */
if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
return NULL;
} else if(maxLength<0 || maxRunCount<0) {
*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
return NULL; /* invalid arguments */
}
/* allocate memory for the object */
pBiDi=(UBiDi *)uprv_malloc(sizeof(UBiDi));
if(pBiDi==NULL) {
*pErrorCode=U_MEMORY_ALLOCATION_ERROR;
return NULL;
}
/* reset the object, all pointers NULL, all flags FALSE, all sizes 0 */
uprv_memset(pBiDi, 0, sizeof(UBiDi));
/* get BiDi properties */
pBiDi->bdp=ubidi_getSingleton(pErrorCode);
if(U_FAILURE(*pErrorCode)) {
uprv_free(pBiDi);
return NULL;
}
/* allocate memory for arrays as requested */
if(maxLength>0) {
if( !getInitialDirPropsMemory(pBiDi, maxLength) ||
!getInitialLevelsMemory(pBiDi, maxLength)
) {
*pErrorCode=U_MEMORY_ALLOCATION_ERROR;
}
} else {
pBiDi->mayAllocateText=TRUE;
}
if(maxRunCount>0) {
if(maxRunCount==1) {
/* use simpleRuns[] */
pBiDi->runsSize=sizeof(Run);
} else if(!getInitialRunsMemory(pBiDi, maxRunCount)) {
*pErrorCode=U_MEMORY_ALLOCATION_ERROR;
}
} else {
pBiDi->mayAllocateRuns=TRUE;
}
if(U_SUCCESS(*pErrorCode)) {
return pBiDi;
} else {
ubidi_close(pBiDi);
return NULL;
}
}
/*
* We are allowed to allocate memory if memory==NULL or
* mayAllocate==TRUE for each array that we need.
* We also try to grow and shrink memory as needed if we
* allocate it.
*
* Assume sizeNeeded>0.
* If *pMemory!=NULL, then assume *pSize>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??
*/
U_CFUNC UBool
ubidi_getMemory(void **pMemory, int32_t *pSize, UBool mayAllocate, int32_t sizeNeeded) {
/* check for existing memory */
if(*pMemory==NULL) {
/* we need to allocate memory */
if(mayAllocate && (*pMemory=uprv_malloc(sizeNeeded))!=NULL) {
*pSize=sizeNeeded;
return TRUE;
} else {
return FALSE;
}
} else {
/* there is some memory, is it enough or too much? */
if(sizeNeeded>*pSize && !mayAllocate) {
/* not enough memory, and we must not allocate */
return FALSE;
} else if(sizeNeeded!=*pSize && mayAllocate) {
/* we may try to grow or shrink */
void *memory;
if((memory=uprv_realloc(*pMemory, sizeNeeded))!=NULL) {
*pMemory=memory;
*pSize=sizeNeeded;
return TRUE;
} else {
/* we failed to grow */
return FALSE;
}
} else {
/* we have at least enough memory and must not allocate */
return TRUE;
}
}
}
U_CAPI void U_EXPORT2
ubidi_close(UBiDi *pBiDi) {
if(pBiDi!=NULL) {
pBiDi->pParaBiDi=NULL; /* in case one tries to reuse this block */
if(pBiDi->dirPropsMemory!=NULL) {
uprv_free(pBiDi->dirPropsMemory);
}
if(pBiDi->levelsMemory!=NULL) {
uprv_free(pBiDi->levelsMemory);
}
if(pBiDi->parasMemory!=NULL) {
uprv_free(pBiDi->parasMemory);
}
if(pBiDi->runsMemory!=NULL) {
uprv_free(pBiDi->runsMemory);
}
uprv_free(pBiDi);
}
}
/* set to approximate "inverse BiDi" ---------------------------------------- */
U_CAPI void U_EXPORT2
ubidi_setInverse(UBiDi *pBiDi, UBool isInverse) {
if(pBiDi!=NULL) {
pBiDi->isInverse=isInverse;
}
}
U_CAPI UBool U_EXPORT2
ubidi_isInverse(UBiDi *pBiDi) {
if(pBiDi!=NULL) {
return pBiDi->isInverse;
} else {
return FALSE;
}
}
/* perform (P2)..(P3) ------------------------------------------------------- */
/*
* Get the directional properties for the text,
* calculate the flags bit-set, and
* determine the paragraph level if necessary.
*/
static void
getDirProps(UBiDi *pBiDi) {
const UChar *text=pBiDi->text;
DirProp *dirProps=pBiDi->dirPropsMemory; /* pBiDi->dirProps is const */
int32_t i=0, i0, i1, length=pBiDi->length;
Flags flags=0; /* collect all directionalities in the text */
UChar32 uchar;
DirProp dirProp = 0, paraDirDefault = 0; /* initialize to avoid compiler warnings */
UBool isDefaultLevel=IS_DEFAULT_LEVEL(pBiDi->paraLevel);
UBool paraLevelStillDefault=FALSE; /* flag for real value not set */
typedef enum {
NOT_CONTEXTUAL, /* 0: not contextual paraLevel */
LOOKING_FOR_STRONG, /* 1: looking for first strong char */
FOUND_STRONG_CHAR /* 2: found first strong char */
} State;
State state;
int32_t paraStart=0; /* index of first char in paragraph */
DirProp paraDir; /* == CONTEXT_RTL within paragraphs
starting with strong R char */
if(isDefaultLevel) {
paraDirDefault=pBiDi->paraLevel&1 ? CONTEXT_RTL : 0;
state=LOOKING_FOR_STRONG;
paraStart=0;
paraDir=paraDirDefault;
pBiDi->paraLevel&=1; /* set to default */
paraLevelStillDefault=TRUE;
} else {
state=NOT_CONTEXTUAL;
paraDir=0;
}
/* count paragraphs and determine the paragraph level (P2..P3) */
/*
* see comment in ubidi.h:
* the DEFAULT_XXX values are designed so that
* their bit 0 alone yields the intended default
*/
for( /* i=0 above */ ; i<length; /* i is incremented by UTF_NEXT_CHAR */) {
i0=i; /* index of first code unit */
UTF_NEXT_CHAR(text, i, length, uchar);
i1=i-1; /* index of last code unit, gets the directional property */
flags|=DIRPROP_FLAG(dirProp=ubidi_getClass(pBiDi->bdp, uchar));
dirProps[i1]=dirProp|paraDir;
if(i1>i0) { /* set previous code units' properties to BN */
flags|=DIRPROP_FLAG(BN);
do {
dirProps[--i1]=BN|paraDir;
} while(i1>i0);
}
if(state==LOOKING_FOR_STRONG) {
if(dirProp==L) {
state=FOUND_STRONG_CHAR;
if(paraLevelStillDefault) {
paraLevelStillDefault=FALSE;
pBiDi->paraLevel=0;
}
if(paraDir) {
paraDir=0;
for(i1=paraStart; i1<=i; i1++) {
dirProps[i1]&=~CONTEXT_RTL;
}
}
continue;
}
if(dirProp==R || dirProp==AL) {
state=FOUND_STRONG_CHAR;
if(paraLevelStillDefault) {
paraLevelStillDefault=FALSE;
pBiDi->paraLevel=1;
}
if(paraDir==0) {
paraDir=CONTEXT_RTL;
for(i1=paraStart; i1<=i; i1++) {
dirProps[i1]|=CONTEXT_RTL;
}
}
continue;
}
}
if((dirProp==B)&&(i<length)) { /* B not last char in text */
if(!((uchar==CR) && (text[i]==LF))) {
pBiDi->paraCount++;
if(isDefaultLevel) {
state=LOOKING_FOR_STRONG;
paraStart=i; /* i is index to next character */
paraDir=paraDirDefault;
/* keep the paraLevel of the first paragraph even if it
defaulted (no strong char was found) */
paraLevelStillDefault=FALSE;
}
}
}
}
/* The following line does nothing new for contextual paraLevel, but is
needed for absolute paraLevel. */
flags|=DIRPROP_FLAG_LR(pBiDi->paraLevel);
if(pBiDi->orderParagraphsLTR && (flags&DIRPROP_FLAG(B))) {
flags|=DIRPROP_FLAG(L);
}
pBiDi->flags=flags;
}
/* perform (X1)..(X9) ------------------------------------------------------- */
/* determine if the text is mixed-directional or single-directional */
static UBiDiDirection
directionFromFlags(Flags flags) {
/* if the text contains AN and neutrals, then some neutrals may become RTL */
if(!(flags&MASK_RTL || ((flags&DIRPROP_FLAG(AN)) && (flags&MASK_POSSIBLE_N)))) {
return UBIDI_LTR;
} else if(!(flags&MASK_LTR)) {
return UBIDI_RTL;
} else {
return UBIDI_MIXED;
}
}
/*
* 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 UBIDI_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 UBIDI_MAX_EXPLICIT_LEVEL is odd.
*/
static UBiDiDirection
resolveExplicitLevels(UBiDi *pBiDi) {
const DirProp *dirProps=pBiDi->dirProps;
UBiDiLevel *levels=pBiDi->levels;
const UChar *text=pBiDi->text;
int32_t i=0, length=pBiDi->length;
Flags flags=pBiDi->flags; /* collect all directionalities in the text */
DirProp dirProp;
UBiDiLevel level=GET_PARALEVEL(pBiDi, 0);
UBiDiDirection direction;
int32_t paraIndex=0;
/* determine if the text is mixed-directional or single-directional */
direction=directionFromFlags(flags);
/* we may not need to resolve any explicit levels */
if(direction!=UBIDI_MIXED) {
/* not mixed directionality: levels don't matter - trailingWSStart will be 0 */
} else if((pBiDi->paraCount==1) &&
(!(flags&MASK_EXPLICIT) || pBiDi->isInverse)) {
/* mixed, but all characters are at the same embedding level */
/* or we are in "inverse BiDi" */
/* and we don't have contextual multiple paragraphs with some B char */
/* 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 UBIDI_LEVEL_OVERRIDE flag to indicate the override status */
UBiDiLevel embeddingLevel=level, newLevel, stackTop=0;
UBiDiLevel stack[UBIDI_MAX_EXPLICIT_LEVEL]; /* we never push anything >=UBIDI_MAX_EXPLICIT_LEVEL */
uint32_t countOver60=0, countOver61=0; /* count overflows of explicit levels */
/* recalculate the flags */
flags=0;
for(i=0; i<length; ++i) {
dirProp=NO_CONTEXT_RTL(dirProps[i]);
switch(dirProp) {
case LRE:
case LRO:
/* (X3, X5) */
newLevel=(UBiDiLevel)((embeddingLevel+2)&~(UBIDI_LEVEL_OVERRIDE|1)); /* least greater even level */
if(newLevel<=UBIDI_MAX_EXPLICIT_LEVEL) {
stack[stackTop]=embeddingLevel;
++stackTop;
embeddingLevel=newLevel;
if(dirProp==LRO) {
embeddingLevel|=UBIDI_LEVEL_OVERRIDE;
}
/* we don't need to set UBIDI_LEVEL_OVERRIDE off for LRE
since this has already been done for newLevel which is
the source for embeddingLevel.
*/
} else if((embeddingLevel&~UBIDI_LEVEL_OVERRIDE)==UBIDI_MAX_EXPLICIT_LEVEL) {
++countOver61;
} else /* (embeddingLevel&~UBIDI_LEVEL_OVERRIDE)==UBIDI_MAX_EXPLICIT_LEVEL-1 */ {
++countOver60;
}
flags|=DIRPROP_FLAG(BN);
break;
case RLE:
case RLO:
/* (X2, X4) */
newLevel=(UBiDiLevel)(((embeddingLevel&~UBIDI_LEVEL_OVERRIDE)+1)|1); /* least greater odd level */
if(newLevel<=UBIDI_MAX_EXPLICIT_LEVEL) {
stack[stackTop]=embeddingLevel;
++stackTop;
embeddingLevel=newLevel;
if(dirProp==RLO) {
embeddingLevel|=UBIDI_LEVEL_OVERRIDE;
}
/* we don't need to set UBIDI_LEVEL_OVERRIDE off for RLE
since this has already been done for newLevel which is
the source for embeddingLevel.
*/
} 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&~UBIDI_LEVEL_OVERRIDE)!=UBIDI_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:
stackTop=0;
countOver60=countOver61=0;
level=GET_PARALEVEL(pBiDi, i);
if((i+1)<length) {
embeddingLevel=GET_PARALEVEL(pBiDi, i+1);
if(!((text[i]==CR) && (text[i+1]==LF))) {
pBiDi->paras[paraIndex++]=i+1;
}
}
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&UBIDI_LEVEL_OVERRIDE) {
flags|=DIRPROP_FLAG_O(level)|DIRPROP_FLAG_MULTI_RUNS;
} else {
flags|=DIRPROP_FLAG_E(level)|DIRPROP_FLAG_MULTI_RUNS;
}
}
if(!(level&UBIDI_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(pBiDi->paraLevel);
}
if(pBiDi->orderParagraphsLTR && (flags&DIRPROP_FLAG(B))) {
flags|=DIRPROP_FLAG(L);
}
/* subsequently, ignore the explicit codes and BN (X9) */
/* again, determine if the text is mixed-directional or single-directional */
pBiDi->flags=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.
*/
static UBiDiDirection
checkExplicitLevels(UBiDi *pBiDi, UErrorCode *pErrorCode) {
const DirProp *dirProps=pBiDi->dirProps;
DirProp dirProp;
UBiDiLevel *levels=pBiDi->levels;
const UChar *text=pBiDi->text;
int32_t i, length=pBiDi->length;
Flags flags=0; /* collect all directionalities in the text */
UBiDiLevel level;
uint32_t paraIndex=0;
for(i=0; i<length; ++i) {
level=levels[i];
dirProp=NO_CONTEXT_RTL(dirProps[i]);
if(level&UBIDI_LEVEL_OVERRIDE) {
/* keep the override flag in levels[i] but adjust the flags */
level&=~UBIDI_LEVEL_OVERRIDE; /* make the range check below simpler */
flags|=DIRPROP_FLAG_O(level);
} else {
/* set the flags */
flags|=DIRPROP_FLAG_E(level)|DIRPROP_FLAG(dirProp);
}
if((level<GET_PARALEVEL(pBiDi, i) &&
!((0==level)&&(dirProp==B))) ||
(UBIDI_MAX_EXPLICIT_LEVEL<level)) {
/* level out of bounds */
*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
return UBIDI_LTR;
}
if((dirProp==B) && ((i+1)<length)) {
if(!((text[i]==CR) && (text[i+1]==LF))) {
pBiDi->paras[paraIndex++]=i+1;
}
}
}
if(flags&MASK_EMBEDDING) {
flags|=DIRPROP_FLAG_LR(pBiDi->paraLevel);
}
/* determine if the text is mixed-directional or single-directional */
pBiDi->flags=flags;
return directionFromFlags(flags);
}
/* 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
static void
resolveImplicitLevels(UBiDi *pBiDi,
int32_t start, int32_t limit,
DirProp sor, DirProp eor) {
const DirProp *dirProps=pBiDi->dirProps;
UBiDiLevel *levels=pBiDi->levels;
int32_t i, next, neutralStart=-1;
DirProp prevDirProp, dirProp, nextDirProp, lastStrong, beforeNeutral=L;
UBiDiLevel numberLevel;
uint8_t historyOfEN;
/* initialize: current at sor, next at start (it is start<limit) */
next=start;
dirProp=lastStrong=sor;
nextDirProp=NO_CONTEXT_RTL(dirProps[next]);
historyOfEN=0;
if(pBiDi->isInverse) {
/*
* For "inverse BiDi", we set the levels of numbers just like for
* regular L characters, plus a flag that ubidi_getRuns() will use
* to set a similar flag on the corresponding output run.
*/
numberLevel=levels[start];
if(numberLevel&1) {
++numberLevel;
}
} else {
/* normal BiDi: least greater even level */
numberLevel=(UBiDiLevel)((levels[start]+2)&~1);
}
/*
* 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<limit) {
nextDirProp=NO_CONTEXT_RTL(dirProps[next]);
} else {
nextDirProp=eor;
break;
}
}
/*
* Note: at the end of this file, there is a prototype
* of a version of this function that uses a statetable
* at the core of this state machine.
* If you make changes to this state machine,
* please update that prototype as well.
*/
/* loop for entire run */
while(next<limit) {
/* advance */
prevDirProp=dirProp;
dirProp=nextDirProp;
i=next;
do {
if(++next<limit) {
nextDirProp=NO_CONTEXT_RTL(dirProps[next]);
} else {
nextDirProp=eor;
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=ON;
}
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=ON;
}
break;
case ET:
/* get sequence of ET; advance only next, not current, previous or historyOfEN */
if(next<limit) {
while(DIRPROP_FLAG(nextDirProp)&MASK_ET_NSM_BN /* (W1), (X9) */) {
if(++next<limit) {
nextDirProp=NO_CONTEXT_RTL(dirProps[next]);
} else {
nextDirProp=eor;
break;
}
}
}
/* now process the sequence of ET like a single ET */
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=ON;
}
/* 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;
case B:
lastStrong=sor;
dirProp=GET_LR_FROM_LEVEL(levels[i]);
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 */
/* for "inverse BiDi", treat neutrals like L */
/* 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.
*/
UBiDiLevel level=levels[i];
if(neutralStart>=0) {
UBiDiLevel final;
/* end of a sequence of neutrals (dirProp is "afterNeutral") */
if(!(pBiDi->isInverse)) {
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) */
}
}
} else {
/* "inverse BiDi": collapse [before]dirProps L, EN, AN into L */
if(beforeNeutral!=R) {
if(dirProp!=R) {
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!=R) {
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 */ {
/* this level depends on whether we do "inverse BiDi" */
level=numberLevel;
}
/* apply the new level to the sequence, if necessary */
while(i<next) {
levels[i++]=level;
}
}
if(pBiDi->defaultParaLevel&&((i+1)<limit)&&(dirProps[i]==B)) {
dirProp=GET_LR_FROM_LEVEL(levels[i+1]);
}
}
/* perform (Nn) - here,
the character after the neutrals is eor, 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.
*/
UBiDiLevel level=levels[neutralStart], final;
/* end of a sequence of neutrals (eor is "afterNeutral") */
if(!(pBiDi->isInverse)) {
if(beforeNeutral==L) {
if(eor==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(eor==L) {
final=level; /* make all neutrals "e" (N2) */
} else {
final=1; /* make all neutrals R (N1) */
}
}
} else {
/* "inverse BiDi": collapse [before]dirProps L, EN, AN into L */
if(beforeNeutral!=R) {
if(eor!=R) {
final=0; /* make all neutrals L (N1) */
} else {
final=level; /* make all neutrals "e" (N2) */
}
} else /* beforeNeutral is one of { R, EN, AN } */ {
if(eor!=R) {
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<limit);
}
}
}
/* 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).
*/
static void
adjustWSLevels(UBiDi *pBiDi) {
const DirProp *dirProps=pBiDi->dirProps;
UBiDiLevel *levels=pBiDi->levels;
int32_t i;
if(pBiDi->flags&MASK_WS) {
UBool orderParagraphsLTR=pBiDi->orderParagraphsLTR;
Flags flag;
i=pBiDi->trailingWSStart;
while(i>0) {
/* reset a sequence of WS/BN before eop and B/S to the paragraph paraLevel */
while(i>0 && (flag=DIRPROP_FLAG_NC(dirProps[--i]))&MASK_WS) {
if(orderParagraphsLTR&&(flag&DIRPROP_FLAG(B))) {
levels[i]=0;
} else {
levels[i]=GET_PARALEVEL(pBiDi, i);
}
}
/* 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_NC(dirProps[--i]);
if(flag&MASK_BN_EXPLICIT) {
levels[i]=levels[i+1];
} else if(orderParagraphsLTR&&(flag&DIRPROP_FLAG(B))) {
levels[i]=0;
break;
} else if(flag&MASK_B_S) {
levels[i]=GET_PARALEVEL(pBiDi, i);
break;
}
}
}
}
}
/* ubidi_setPara ------------------------------------------------------------ */
U_CAPI void U_EXPORT2
ubidi_setPara(UBiDi *pBiDi, const UChar *text, int32_t length,
UBiDiLevel paraLevel, UBiDiLevel *embeddingLevels,
UErrorCode *pErrorCode) {
UBiDiDirection direction;
/* check the argument values */
if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
return;
} else if(pBiDi==NULL || text==NULL ||
((UBIDI_MAX_EXPLICIT_LEVEL<paraLevel) && !IS_DEFAULT_LEVEL(paraLevel)) ||
length<-1
) {
*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
return;
}
if(length==-1) {
length=u_strlen(text);
}
/* initialize the UBiDi structure */
pBiDi->pParaBiDi=NULL; /* mark unfinished setPara */
pBiDi->text=text;
pBiDi->length=length;
pBiDi->paraLevel=paraLevel;
pBiDi->direction=UBIDI_LTR;
pBiDi->trailingWSStart=length; /* the levels[] will reflect the WS run */
pBiDi->dirProps=NULL;
pBiDi->levels=NULL;
pBiDi->runs=NULL;
/* initialize paras for single paragraph */
pBiDi->paraCount=1;
pBiDi->paras=pBiDi->simpleParas;
pBiDi->simpleParas[0]=length;
/*
* Save the original paraLevel if contextual; otherwise, set to 0.
*/
if(IS_DEFAULT_LEVEL(paraLevel)) {
pBiDi->defaultParaLevel=paraLevel;
} else {
pBiDi->defaultParaLevel=0;
}
if(length==0) {
/*
* For an empty paragraph, create a UBiDi object with the paraLevel and
* the flags and the direction set but without allocating zero-length arrays.
* There is nothing more to do.
*/
if(IS_DEFAULT_LEVEL(paraLevel)) {
pBiDi->paraLevel&=1;
pBiDi->defaultParaLevel=0;
}
if(paraLevel&1) {
pBiDi->flags=DIRPROP_FLAG(R);
pBiDi->direction=UBIDI_RTL;
} else {
pBiDi->flags=DIRPROP_FLAG(L);
pBiDi->direction=UBIDI_LTR;
}
pBiDi->runCount=0;
pBiDi->pParaBiDi=pBiDi; /* mark successful setPara */
return;
}
pBiDi->runCount=-1;
/*
* Get the directional properties,
* the flags bit-set, and
* determine the paragraph level if necessary.
*/
if(getDirPropsMemory(pBiDi, length)) {
pBiDi->dirProps=pBiDi->dirPropsMemory;
getDirProps(pBiDi);
} else {
*pErrorCode=U_MEMORY_ALLOCATION_ERROR;
return;
}
/* allocate paras memory */
if(pBiDi->paraCount>1) {
if(getInitialParasMemory(pBiDi, pBiDi->paraCount)) {
pBiDi->paras=pBiDi->parasMemory;
pBiDi->paras[pBiDi->paraCount-1]=length;
} else {
*pErrorCode=U_MEMORY_ALLOCATION_ERROR;
return;
}
}
/* are explicit levels specified? */
if(embeddingLevels==NULL) {
/* no: determine explicit levels according to the (Xn) rules */\
if(getLevelsMemory(pBiDi, length)) {
pBiDi->levels=pBiDi->levelsMemory;
direction=resolveExplicitLevels(pBiDi);
} else {
*pErrorCode=U_MEMORY_ALLOCATION_ERROR;
return;
}
} else {
/* set BN for all explicit codes, check that all levels are 0 or paraLevel..UBIDI_MAX_EXPLICIT_LEVEL */
pBiDi->levels=embeddingLevels;
direction=checkExplicitLevels(pBiDi, pErrorCode);
if(U_FAILURE(*pErrorCode)) {
return;
}
}
/*
* The steps after (X9) in the UBiDi algorithm are performed only if
* the paragraph text has mixed directionality!
*/
pBiDi->direction=direction;
switch(direction) {
case UBIDI_LTR:
/* make sure paraLevel is even */
pBiDi->paraLevel=(UBiDiLevel)((pBiDi->paraLevel+1)&~1);
/* all levels are implicitly at paraLevel (important for ubidi_getLevels()) */
pBiDi->trailingWSStart=0;
break;
case UBIDI_RTL:
/* make sure paraLevel is odd */
pBiDi->paraLevel|=1;
/* all levels are implicitly at paraLevel (important for ubidi_getLevels()) */
pBiDi->trailingWSStart=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(embeddingLevels==NULL && !(pBiDi->flags&DIRPROP_FLAG_MULTI_RUNS)) {
resolveImplicitLevels(pBiDi, 0, length,
GET_LR_FROM_LEVEL(GET_PARALEVEL(pBiDi, 0)),
GET_LR_FROM_LEVEL(GET_PARALEVEL(pBiDi, length-1)));
} else {
/* sor, eor: start and end types of same-level-run */
UBiDiLevel *levels=pBiDi->levels;
int32_t start, limit=0;
UBiDiLevel level, nextLevel;
DirProp sor, eor;
/* determine the first sor and set eor to it because of the loop body (sor=eor there) */
level=GET_PARALEVEL(pBiDi, 0);
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 */
start=limit;
level=nextLevel;
if((start>0) && (NO_CONTEXT_RTL(pBiDi->dirProps[start-1])==B)) {
/* except if this is a new paragraph, then set sor = para level */
sor=GET_LR_FROM_LEVEL(GET_PARALEVEL(pBiDi, start));
} else {
sor=eor;
}
/* search for the limit of this run */
while(++limit<length && levels[limit]==level) {}
/* get the correct level of the next run */
if(limit<length) {
nextLevel=levels[limit];
} else {
nextLevel=GET_PARALEVEL(pBiDi, length-1);
}
/* determine eor from max(level, nextLevel); sor is last run's eor */
if((level&~UBIDI_LEVEL_OVERRIDE)<(nextLevel&~UBIDI_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&UBIDI_LEVEL_OVERRIDE)) {
resolveImplicitLevels(pBiDi, start, limit, sor, eor);
} else {
/* remove the UBIDI_LEVEL_OVERRIDE flags */
do {
levels[start++]&=~UBIDI_LEVEL_OVERRIDE;
} while(start<limit);
}
} while(limit<length);
}
/* reset the embedding levels for some non-graphic characters (L1), (X9) */
adjustWSLevels(pBiDi);
/* for "inverse BiDi", ubidi_getRuns() modifies the levels of numeric runs following RTL runs */
if(pBiDi->isInverse) {
if(!ubidi_getRuns(pBiDi)) {
*pErrorCode=U_MEMORY_ALLOCATION_ERROR;
return;
}
}
break;
}
pBiDi->pParaBiDi=pBiDi; /* mark successful setPara */
}
U_CAPI void U_EXPORT2
ubidi_orderParagraphsLTR(UBiDi *pBiDi, UBool orderParagraphsLTR) {
if(pBiDi!=NULL) {
pBiDi->orderParagraphsLTR=orderParagraphsLTR;
}
}
U_CAPI UBool U_EXPORT2
ubidi_isOrderParagraphsLTR(UBiDi *pBiDi) {
if(pBiDi!=NULL) {
return pBiDi->orderParagraphsLTR;
} else {
return FALSE;
}
}
U_CAPI UBiDiDirection U_EXPORT2
ubidi_getDirection(const UBiDi *pBiDi) {
if(IS_VALID_PARA_OR_LINE(pBiDi)) {
return pBiDi->direction;
} else {
return UBIDI_LTR;
}
}
U_CAPI const UChar * U_EXPORT2
ubidi_getText(const UBiDi *pBiDi) {
if(IS_VALID_PARA_OR_LINE(pBiDi)) {
return pBiDi->text;
} else {
return NULL;
}
}
U_CAPI int32_t U_EXPORT2
ubidi_getLength(const UBiDi *pBiDi) {
if(IS_VALID_PARA_OR_LINE(pBiDi)) {
return pBiDi->length;
} else {
return 0;
}
}
/* paragraphs API functions ------------------------------------------------- */
U_CAPI UBiDiLevel U_EXPORT2
ubidi_getParaLevel(const UBiDi *pBiDi) {
if(IS_VALID_PARA_OR_LINE(pBiDi)) {
return pBiDi->paraLevel;
} else {
return 0;
}
}
U_CAPI int32_t U_EXPORT2
ubidi_countParagraphs(UBiDi *pBiDi) {
if(!IS_VALID_PARA_OR_LINE(pBiDi)) {
return 0;
} else {
return pBiDi->paraCount;
}
}
U_STABLE void U_EXPORT2
ubidi_getParagraphByIndex(const UBiDi *pBiDi, int32_t paraIndex,
int32_t *pParaStart, int32_t *pParaLimit,
UBiDiLevel *pParaLevel, UErrorCode *pErrorCode) {
int32_t paraStart;
/* check the argument values */
if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
return;
} else if( !IS_VALID_PARA_OR_LINE(pBiDi) || /* no valid setPara/setLine */
paraIndex<0 || paraIndex>=pBiDi->paraCount ) {
*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
return;
}
pBiDi=pBiDi->pParaBiDi; /* get Para object if Line object */
if(paraIndex) {
paraStart=pBiDi->paras[paraIndex-1];
} else {
paraStart=0;
}
if(pParaStart!=NULL) {
*pParaStart=paraStart;
}
if(pParaLimit!=NULL) {
*pParaLimit=pBiDi->paras[paraIndex];
}
if(pParaLevel!=NULL) {
*pParaLevel=GET_PARALEVEL(pBiDi, paraStart);
}
return;
}
U_STABLE int32_t U_EXPORT2
ubidi_getParagraph(const UBiDi *pBiDi, int32_t charIndex,
int32_t *pParaStart, int32_t *pParaLimit,
UBiDiLevel *pParaLevel, UErrorCode *pErrorCode) {
uint32_t paraIndex;
/* check the argument values */
/* pErrorCode will be checked by the call to ubidi_getParagraphByIndex */
if( !IS_VALID_PARA_OR_LINE(pBiDi)) {/* no valid setPara/setLine */
*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
return -1;
}
pBiDi=pBiDi->pParaBiDi; /* get Para object if Line object */
if( charIndex<0 || charIndex>=pBiDi->length ) {
*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
return -1;
}
for(paraIndex=0; charIndex>=pBiDi->paras[paraIndex]; paraIndex++);
ubidi_getParagraphByIndex(pBiDi, paraIndex, pParaStart, pParaLimit, pParaLevel, pErrorCode);
return paraIndex;
}
/* statetable prototype ----------------------------------------------------- */
/*
* This is here for possible future
* performance work and is not compiled right now.
*/
#if 0
/*
* This is a piece of code that could be part of ubidi.c/resolveImplicitLevels().
* It replaces in the (Wn) state machine the switch()-if()-cascade with
* just a few if()s and a state table.
*/
/* use the state table only for the following dirProp's */
#define MASK_W_TABLE (FLAG(L)|FLAG(R)|FLAG(AL)|FLAG(EN)|FLAG(ES)|FLAG(CS)|FLAG(ET)|FLAG(AN))
/*
* inputs:
*
* 0..1 historyOfEN - 2b
* 2 prevDirProp==AN - 1b
* 3..4 lastStrong, one of { L, R, AL, none } - 2b
* 5..7 dirProp, one of { L, R, AL, EN, ES, CS, ET, AN } - 3b
* 8..9 nextDirProp, one of { EN, AN, other }
*
* total: 10b=1024 states
*/
enum { _L, _R, _AL, _EN, _ES, _CS, _ET, _AN, _OTHER }; /* lastStrong, dirProp */
enum { __EN, __AN, __OTHER }; /* nextDirProp */
#define LAST_STRONG_SHIFT 3
#define DIR_PROP_SHIFT 5
#define NEXT_DIR_PROP_SHIFT 8
/* masks after shifting */
#define LAST_STRONG_MASK 3
#define DIR_PROP_MASK 7
#define STATE_MASK 0x1f
/* convert dirProp into _dirProp (above enum) */
static DirProp inputDirProp[dirPropCount]={ _X<<DIR_PROP_SHIFT, ... };
/* convert dirProp into __dirProp (above enum) */
static DirProp inputNextDirProp[dirPropCount]={ __X<<NEXT_DIR_PROP_SHIFT, ... };
/*
* outputs:
*
* dirProp, one of { L, R, EN, AN, ON } - 3b
*
* 0..1 historyOfEN - 2b
* 2 prevDirProp==AN - 1b
* 3..4 lastStrong, one of { L, R, AL, none } - 2b
* 5..7 new dirProp, one of { L, R, EN, AN, ON }
*
* total: 8 bits=1 byte per state
*/
enum { ___L, ___R, ___EN, ___AN, ___ON, ___count };
/* convert ___dirProp into dirProp (above enum) */
static DirProp outputDirProp[___count]={ X, ... };
/* state table */
static uint8_t wnTable[1024]={ /* calculate with switch()-if()-cascade */ };
static void
resolveImplicitLevels(BiDi *pBiDi,
Index start, Index end,
DirProp sor, DirProp eor) {
/* new variable */
uint8_t state;
/* remove variable lastStrong */
/* set initial state (set lastStrong, the rest is 0) */
state= sor==L ? 0 : _R<<LAST_STRONG_SHIFT;
while(next<limit) {
/* advance */
prevDirProp=dirProp;
dirProp=nextDirProp;
i=next;
do {
if(++next<limit) {
nextDirProp=NO_CONTEXT_RTL(dirProps[next]);
} else {
nextDirProp=eor;
break;
}
} while(FLAG(nextDirProp)&MASK_BN_EXPLICIT);
/* (W1..W7) */
/* ### This may be more efficient with a switch(dirProp). */
if(FLAG(dirProp)&MASK_W_TABLE) {
state=wnTable[
((int)state)|
inputDirProp[dirProp]|
inputNextDirProp[nextDirProp]
];
dirProp=outputDirProp[state>>DIR_PROP_SHIFT];
state&=STATE_MASK;
} else if(dirProp==ET) {
/* get sequence of ET; advance only next, not current, previous or historyOfEN */
while(next<limit && FLAG(nextDirProp)&MASK_ET_NSM_BN /* (W1), (X9) */) {
if(++next<limit) {
nextDirProp=NO_CONTEXT_RTL(dirProps[next]);
} else {
nextDirProp=eor;
break;
}
}
state=wnTable[
((int)state)|
_ET<<DIR_PROP_SHIFT|
inputNextDirProp[nextDirProp]
];
dirProp=outputDirProp[state>>DIR_PROP_SHIFT];
state&=STATE_MASK;
/* apply the result of (W1), (W5)..(W7) to the entire sequence of ET */
} else if(dirProp==NSM) {
/* (W1) */
dirProp=prevDirProp;
/* keep prevDirProp's EN and AN states! */
} else /* other */ {
/* set EN and AN states to 0 */
state&=LAST_STRONG_MASK<<LAST_STRONG_SHIFT;
}
/* perform (Nn) and (In) as usual */
}
/* perform (Nn) and (In) as usual */
}
#endif