/*
*******************************************************************************
*
* Copyright (C) 2001-2010, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
* file name: unormcmp.cpp
* encoding: US-ASCII
* tab size: 8 (not used)
* indentation:4
*
* created on: 2004sep13
* created by: Markus W. Scherer
*
* unorm_compare() function moved here from unorm.cpp for better modularization.
* Depends on both normalization and case folding.
* Allows unorm.cpp to not depend on any character properties code.
*/
#include "unicode/utypes.h"
#if !UCONFIG_NO_NORMALIZATION
#include "unicode/unorm.h"
#include "unicode/ustring.h"
#include "cmemory.h"
#include "normalizer2impl.h"
#include "ucase.h"
#include "uprops.h"
#include "ustr_imp.h"
U_NAMESPACE_USE
#define LENGTHOF(array) (int32_t)(sizeof(array)/sizeof((array)[0]))
/* compare canonically equivalent ------------------------------------------- */
/*
* Compare two strings for canonical equivalence.
* Further options include case-insensitive comparison and
* code point order (as opposed to code unit order).
*
* In this function, canonical equivalence is optional as well.
* If canonical equivalence is tested, then both strings must fulfill
* the FCD check.
*
* Semantically, this is equivalent to
* strcmp[CodePointOrder](NFD(foldCase(s1)), NFD(foldCase(s2)))
* where code point order, NFD and foldCase are all optional.
*
* String comparisons almost always yield results before processing both strings
* completely.
* They are generally more efficient working incrementally instead of
* performing the sub-processing (strlen, normalization, case-folding)
* on the entire strings first.
*
* It is also unnecessary to not normalize identical characters.
*
* This function works in principle as follows:
*
* loop {
* get one code unit c1 from s1 (-1 if end of source)
* get one code unit c2 from s2 (-1 if end of source)
*
* if(either string finished) {
* return result;
* }
* if(c1==c2) {
* continue;
* }
*
* // c1!=c2
* try to decompose/case-fold c1/c2, and continue if one does;
*
* // still c1!=c2 and neither decomposes/case-folds, return result
* return c1-c2;
* }
*
* When a character decomposes, then the pointer for that source changes to
* the decomposition, pushing the previous pointer onto a stack.
* When the end of the decomposition is reached, then the code unit reader
* pops the previous source from the stack.
* (Same for case-folding.)
*
* This is complicated further by operating on variable-width UTF-16.
* The top part of the loop works on code units, while lookups for decomposition
* and case-folding need code points.
* Code points are assembled after the equality/end-of-source part.
* The source pointer is only advanced beyond all code units when the code point
* actually decomposes/case-folds.
*
* If we were on a trail surrogate unit when assembling a code point,
* and the code point decomposes/case-folds, then the decomposition/folding
* result must be compared with the part of the other string that corresponds to
* this string's lead surrogate.
* Since we only assemble a code point when hitting a trail unit when the
* preceding lead units were identical, we back up the other string by one unit
* in such a case.
*
* The optional code point order comparison at the end works with
* the same fix-up as the other code point order comparison functions.
* See ustring.c and the comment near the end of this function.
*
* Assumption: A decomposition or case-folding result string never contains
* a single surrogate. This is a safe assumption in the Unicode Standard.
* Therefore, we do not need to check for surrogate pairs across
* decomposition/case-folding boundaries.
*
* Further assumptions (see verifications tstnorm.cpp):
* The API function checks for FCD first, while the core function
* first case-folds and then decomposes. This requires that case-folding does not
* un-FCD any strings.
*
* The API function may also NFD the input and turn off decomposition.
* This requires that case-folding does not un-NFD strings either.
*
* TODO If any of the above two assumptions is violated,
* then this entire code must be re-thought.
* If this happens, then a simple solution is to case-fold both strings up front
* and to turn off UNORM_INPUT_IS_FCD.
* We already do this when not both strings are in FCD because makeFCD
* would be a partial NFD before the case folding, which does not work.
* Note that all of this is only a problem when case-folding _and_
* canonical equivalence come together.
* (Comments in unorm_compare() are more up to date than this TODO.)
*/
/* stack element for previous-level source/decomposition pointers */
struct CmpEquivLevel {
const UChar *start, *s, *limit;
};
typedef struct CmpEquivLevel CmpEquivLevel;
/**
* Internal option for unorm_cmpEquivFold() for decomposing.
* If not set, just do strcasecmp().
*/
#define _COMPARE_EQUIV 0x80000
/* internal function */
static int32_t
unorm_cmpEquivFold(const UChar *s1, int32_t length1,
const UChar *s2, int32_t length2,
uint32_t options,
UErrorCode *pErrorCode) {
const Normalizer2Impl *nfcImpl;
const UCaseProps *csp;
/* current-level start/limit - s1/s2 as current */
const UChar *start1, *start2, *limit1, *limit2;
/* decomposition and case folding variables */
const UChar *p;
int32_t length;
/* stacks of previous-level start/current/limit */
CmpEquivLevel stack1[2], stack2[2];
/* buffers for algorithmic decompositions */
UChar decomp1[4], decomp2[4];
/* case folding buffers, only use current-level start/limit */
UChar fold1[UCASE_MAX_STRING_LENGTH+1], fold2[UCASE_MAX_STRING_LENGTH+1];
/* track which is the current level per string */
int32_t level1, level2;
/* current code units, and code points for lookups */
UChar32 c1, c2, cp1, cp2;
/* no argument error checking because this itself is not an API */
/*
* assume that at least one of the options _COMPARE_EQUIV and U_COMPARE_IGNORE_CASE is set
* otherwise this function must behave exactly as uprv_strCompare()
* not checking for that here makes testing this function easier
*/
/* normalization/properties data loaded? */
if((options&_COMPARE_EQUIV)!=0) {
nfcImpl=Normalizer2Factory::getNFCImpl(*pErrorCode);
} else {
nfcImpl=NULL;
}
if((options&U_COMPARE_IGNORE_CASE)!=0) {
csp=ucase_getSingleton(pErrorCode);
} else {
csp=NULL;
}
if(U_FAILURE(*pErrorCode)) {
return 0;
}
/* initialize */
start1=s1;
if(length1==-1) {
limit1=NULL;
} else {
limit1=s1+length1;
}
start2=s2;
if(length2==-1) {
limit2=NULL;
} else {
limit2=s2+length2;
}
level1=level2=0;
c1=c2=-1;
/* comparison loop */
for(;;) {
/*
* here a code unit value of -1 means "get another code unit"
* below it will mean "this source is finished"
*/
if(c1<0) {
/* get next code unit from string 1, post-increment */
for(;;) {
if(s1==limit1 || ((c1=*s1)==0 && (limit1==NULL || (options&_STRNCMP_STYLE)))) {
if(level1==0) {
c1=-1;
break;
}
} else {
++s1;
break;
}
/* reached end of level buffer, pop one level */
do {
--level1;
start1=stack1[level1].start;
} while(start1==NULL);
s1=stack1[level1].s;
limit1=stack1[level1].limit;
}
}
if(c2<0) {
/* get next code unit from string 2, post-increment */
for(;;) {
if(s2==limit2 || ((c2=*s2)==0 && (limit2==NULL || (options&_STRNCMP_STYLE)))) {
if(level2==0) {
c2=-1;
break;
}
} else {
++s2;
break;
}
/* reached end of level buffer, pop one level */
do {
--level2;
start2=stack2[level2].start;
} while(start2==NULL);
s2=stack2[level2].s;
limit2=stack2[level2].limit;
}
}
/*
* compare c1 and c2
* either variable c1, c2 is -1 only if the corresponding string is finished
*/
if(c1==c2) {
if(c1<0) {
return 0; /* c1==c2==-1 indicating end of strings */
}
c1=c2=-1; /* make us fetch new code units */
continue;
} else if(c1<0) {
return -1; /* string 1 ends before string 2 */
} else if(c2<0) {
return 1; /* string 2 ends before string 1 */
}
/* c1!=c2 && c1>=0 && c2>=0 */
/* get complete code points for c1, c2 for lookups if either is a surrogate */
cp1=c1;
if(U_IS_SURROGATE(c1)) {
UChar c;
if(U_IS_SURROGATE_LEAD(c1)) {
if(s1!=limit1 && U16_IS_TRAIL(c=*s1)) {
/* advance ++s1; only below if cp1 decomposes/case-folds */
cp1=U16_GET_SUPPLEMENTARY(c1, c);
}
} else /* isTrail(c1) */ {
if(start1<=(s1-2) && U16_IS_LEAD(c=*(s1-2))) {
cp1=U16_GET_SUPPLEMENTARY(c, c1);
}
}
}
cp2=c2;
if(U_IS_SURROGATE(c2)) {
UChar c;
if(U_IS_SURROGATE_LEAD(c2)) {
if(s2!=limit2 && U16_IS_TRAIL(c=*s2)) {
/* advance ++s2; only below if cp2 decomposes/case-folds */
cp2=U16_GET_SUPPLEMENTARY(c2, c);
}
} else /* isTrail(c2) */ {
if(start2<=(s2-2) && U16_IS_LEAD(c=*(s2-2))) {
cp2=U16_GET_SUPPLEMENTARY(c, c2);
}
}
}
/*
* go down one level for each string
* continue with the main loop as soon as there is a real change
*/
if( level1==0 && (options&U_COMPARE_IGNORE_CASE) &&
(length=ucase_toFullFolding(csp, (UChar32)cp1, &p, options))>=0
) {
/* cp1 case-folds to the code point "length" or to p[length] */
if(U_IS_SURROGATE(c1)) {
if(U_IS_SURROGATE_LEAD(c1)) {
/* advance beyond source surrogate pair if it case-folds */
++s1;
} else /* isTrail(c1) */ {
/*
* we got a supplementary code point when hitting its trail surrogate,
* therefore the lead surrogate must have been the same as in the other string;
* compare this decomposition with the lead surrogate in the other string
* remember that this simulates bulk text replacement:
* the decomposition would replace the entire code point
*/
--s2;
c2=*(s2-1);
}
}
/* push current level pointers */
stack1[0].start=start1;
stack1[0].s=s1;
stack1[0].limit=limit1;
++level1;
/* copy the folding result to fold1[] */
if(length<=UCASE_MAX_STRING_LENGTH) {
u_memcpy(fold1, p, length);
} else {
int32_t i=0;
U16_APPEND_UNSAFE(fold1, i, length);
length=i;
}
/* set next level pointers to case folding */
start1=s1=fold1;
limit1=fold1+length;
/* get ready to read from decomposition, continue with loop */
c1=-1;
continue;
}
if( level2==0 && (options&U_COMPARE_IGNORE_CASE) &&
(length=ucase_toFullFolding(csp, (UChar32)cp2, &p, options))>=0
) {
/* cp2 case-folds to the code point "length" or to p[length] */
if(U_IS_SURROGATE(c2)) {
if(U_IS_SURROGATE_LEAD(c2)) {
/* advance beyond source surrogate pair if it case-folds */
++s2;
} else /* isTrail(c2) */ {
/*
* we got a supplementary code point when hitting its trail surrogate,
* therefore the lead surrogate must have been the same as in the other string;
* compare this decomposition with the lead surrogate in the other string
* remember that this simulates bulk text replacement:
* the decomposition would replace the entire code point
*/
--s1;
c1=*(s1-1);
}
}
/* push current level pointers */
stack2[0].start=start2;
stack2[0].s=s2;
stack2[0].limit=limit2;
++level2;
/* copy the folding result to fold2[] */
if(length<=UCASE_MAX_STRING_LENGTH) {
u_memcpy(fold2, p, length);
} else {
int32_t i=0;
U16_APPEND_UNSAFE(fold2, i, length);
length=i;
}
/* set next level pointers to case folding */
start2=s2=fold2;
limit2=fold2+length;
/* get ready to read from decomposition, continue with loop */
c2=-1;
continue;
}
if( level1<2 && (options&_COMPARE_EQUIV) &&
0!=(p=nfcImpl->getDecomposition((UChar32)cp1, decomp1, length))
) {
/* cp1 decomposes into p[length] */
if(U_IS_SURROGATE(c1)) {
if(U_IS_SURROGATE_LEAD(c1)) {
/* advance beyond source surrogate pair if it decomposes */
++s1;
} else /* isTrail(c1) */ {
/*
* we got a supplementary code point when hitting its trail surrogate,
* therefore the lead surrogate must have been the same as in the other string;
* compare this decomposition with the lead surrogate in the other string
* remember that this simulates bulk text replacement:
* the decomposition would replace the entire code point
*/
--s2;
c2=*(s2-1);
}
}
/* push current level pointers */
stack1[level1].start=start1;
stack1[level1].s=s1;
stack1[level1].limit=limit1;
++level1;
/* set empty intermediate level if skipped */
if(level1<2) {
stack1[level1++].start=NULL;
}
/* set next level pointers to decomposition */
start1=s1=p;
limit1=p+length;
/* get ready to read from decomposition, continue with loop */
c1=-1;
continue;
}
if( level2<2 && (options&_COMPARE_EQUIV) &&
0!=(p=nfcImpl->getDecomposition((UChar32)cp2, decomp2, length))
) {
/* cp2 decomposes into p[length] */
if(U_IS_SURROGATE(c2)) {
if(U_IS_SURROGATE_LEAD(c2)) {
/* advance beyond source surrogate pair if it decomposes */
++s2;
} else /* isTrail(c2) */ {
/*
* we got a supplementary code point when hitting its trail surrogate,
* therefore the lead surrogate must have been the same as in the other string;
* compare this decomposition with the lead surrogate in the other string
* remember that this simulates bulk text replacement:
* the decomposition would replace the entire code point
*/
--s1;
c1=*(s1-1);
}
}
/* push current level pointers */
stack2[level2].start=start2;
stack2[level2].s=s2;
stack2[level2].limit=limit2;
++level2;
/* set empty intermediate level if skipped */
if(level2<2) {
stack2[level2++].start=NULL;
}
/* set next level pointers to decomposition */
start2=s2=p;
limit2=p+length;
/* get ready to read from decomposition, continue with loop */
c2=-1;
continue;
}
/*
* no decomposition/case folding, max level for both sides:
* return difference result
*
* code point order comparison must not just return cp1-cp2
* because when single surrogates are present then the surrogate pairs
* that formed cp1 and cp2 may be from different string indexes
*
* example: { d800 d800 dc01 } vs. { d800 dc00 }, compare at second code units
* c1=d800 cp1=10001 c2=dc00 cp2=10000
* cp1-cp2>0 but c1-c2<0 and in fact in UTF-32 it is { d800 10001 } < { 10000 }
*
* therefore, use same fix-up as in ustring.c/uprv_strCompare()
* except: uprv_strCompare() fetches c=*s while this functions fetches c=*s++
* so we have slightly different pointer/start/limit comparisons here
*/
if(c1>=0xd800 && c2>=0xd800 && (options&U_COMPARE_CODE_POINT_ORDER)) {
/* subtract 0x2800 from BMP code points to make them smaller than supplementary ones */
if(
(c1<=0xdbff && s1!=limit1 && U16_IS_TRAIL(*s1)) ||
(U16_IS_TRAIL(c1) && start1!=(s1-1) && U16_IS_LEAD(*(s1-2)))
) {
/* part of a surrogate pair, leave >=d800 */
} else {
/* BMP code point - may be surrogate code point - make <d800 */
c1-=0x2800;
}
if(
(c2<=0xdbff && s2!=limit2 && U16_IS_TRAIL(*s2)) ||
(U16_IS_TRAIL(c2) && start2!=(s2-1) && U16_IS_LEAD(*(s2-2)))
) {
/* part of a surrogate pair, leave >=d800 */
} else {
/* BMP code point - may be surrogate code point - make <d800 */
c2-=0x2800;
}
}
return c1-c2;
}
}
U_CAPI int32_t U_EXPORT2
unorm_compare(const UChar *s1, int32_t length1,
const UChar *s2, int32_t length2,
uint32_t options,
UErrorCode *pErrorCode) {
/* argument checking */
if(U_FAILURE(*pErrorCode)) {
return 0;
}
if(s1==0 || length1<-1 || s2==0 || length2<-1) {
*pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
return 0;
}
UnicodeString fcd1, fcd2;
int32_t normOptions=(int32_t)(options>>UNORM_COMPARE_NORM_OPTIONS_SHIFT);
options|=_COMPARE_EQUIV;
/*
* UAX #21 Case Mappings, as fixed for Unicode version 4
* (see Jitterbug 2021), defines a canonical caseless match as
*
* A string X is a canonical caseless match
* for a string Y if and only if
* NFD(toCasefold(NFD(X))) = NFD(toCasefold(NFD(Y)))
*
* For better performance, we check for FCD (or let the caller tell us that
* both strings are in FCD) for the inner normalization.
* BasicNormalizerTest::FindFoldFCDExceptions() makes sure that
* case-folding preserves the FCD-ness of a string.
* The outer normalization is then only performed by unorm_cmpEquivFold()
* when there is a difference.
*
* Exception: When using the Turkic case-folding option, we do perform
* full NFD first. This is because in the Turkic case precomposed characters
* with 0049 capital I or 0069 small i fold differently whether they
* are first decomposed or not, so an FCD check - a check only for
* canonical order - is not sufficient.
*/
if(!(options&UNORM_INPUT_IS_FCD) || (options&U_FOLD_CASE_EXCLUDE_SPECIAL_I)) {
const Normalizer2 *n2;
if(options&U_FOLD_CASE_EXCLUDE_SPECIAL_I) {
n2=Normalizer2Factory::getNFDInstance(*pErrorCode);
} else {
n2=Normalizer2Factory::getFCDInstance(*pErrorCode);
}
if (U_FAILURE(*pErrorCode)) {
return 0;
}
// check if s1 and/or s2 fulfill the FCD conditions
const UnicodeSet *uni32;
if(normOptions&UNORM_UNICODE_3_2) {
uni32=uniset_getUnicode32Instance(*pErrorCode);
} else {
uni32=NULL; // unused
}
FilteredNormalizer2 fn2(*n2, *uni32);
if(normOptions&UNORM_UNICODE_3_2) {
n2=&fn2;
}
UnicodeString str1(length1<0, s1, length1);
UnicodeString str2(length2<0, s2, length2);
int32_t spanQCYes1=n2->spanQuickCheckYes(str1, *pErrorCode);
int32_t spanQCYes2=n2->spanQuickCheckYes(str2, *pErrorCode);
if(U_FAILURE(*pErrorCode)) {
return 0;
}
/*
* ICU 2.4 had a further optimization:
* If both strings were not in FCD, then they were both NFD'ed,
* and the _COMPARE_EQUIV option was turned off.
* It is not entirely clear that this is valid with the current
* definition of the canonical caseless match.
* Therefore, ICU 2.6 removes that optimization.
*/
if(spanQCYes1<str1.length()) {
UnicodeString unnormalized=str1.tempSubString(spanQCYes1);
fcd1.setTo(FALSE, str1.getBuffer(), spanQCYes1);
n2->normalizeSecondAndAppend(fcd1, unnormalized, *pErrorCode);
s1=fcd1.getBuffer();
length1=fcd1.length();
}
if(spanQCYes2<str2.length()) {
UnicodeString unnormalized=str2.tempSubString(spanQCYes2);
fcd2.setTo(FALSE, str2.getBuffer(), spanQCYes2);
n2->normalizeSecondAndAppend(fcd2, unnormalized, *pErrorCode);
s2=fcd2.getBuffer();
length2=fcd2.length();
}
}
if(U_SUCCESS(*pErrorCode)) {
return unorm_cmpEquivFold(s1, length1, s2, length2, options, pErrorCode);
} else {
return 0;
}
}
#endif /* #if !UCONFIG_NO_NORMALIZATION */