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+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+*******************************************************************************
+*
+* Copyright (C) 2001-2014, International Business Machines
+* Corporation and others. All Rights Reserved.
+*
+*******************************************************************************
+* file name: unormcmp.cpp
+* encoding: UTF-8
+* 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
+
+/* 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 char16_t *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 char16_t *s1, int32_t length1,
+ const char16_t *s2, int32_t length2,
+ uint32_t options,
+ UErrorCode *pErrorCode) {
+ const Normalizer2Impl *nfcImpl;
+
+ /* current-level start/limit - s1/s2 as current */
+ const char16_t *start1, *start2, *limit1, *limit2;
+
+ /* decomposition and case folding variables */
+ const char16_t *p;
+ int32_t length;
+
+ /* stacks of previous-level start/current/limit */
+ CmpEquivLevel stack1[2], stack2[2];
+
+ /* buffers for algorithmic decompositions */
+ char16_t decomp1[4], decomp2[4];
+
+ /* case folding buffers, only use current-level start/limit */
+ char16_t 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=nullptr;
+ }
+ if(U_FAILURE(*pErrorCode)) {
+ return 0;
+ }
+
+ /* initialize */
+ start1=s1;
+ if(length1==-1) {
+ limit1=nullptr;
+ } else {
+ limit1=s1+length1;
+ }
+
+ start2=s2;
+ if(length2==-1) {
+ limit2=nullptr;
+ } 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==nullptr || (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; /*Not uninitialized*/
+ } while(start1==nullptr);
+ s1=stack1[level1].s; /*Not uninitialized*/
+ limit1=stack1[level1].limit; /*Not uninitialized*/
+ }
+ }
+
+ if(c2<0) {
+ /* get next code unit from string 2, post-increment */
+ for(;;) {
+ if(s2==limit2 || ((c2=*s2)==0 && (limit2==nullptr || (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; /*Not uninitialized*/
+ } while(start2==nullptr);
+ s2=stack2[level2].s; /*Not uninitialized*/
+ limit2=stack2[level2].limit; /*Not uninitialized*/
+ }
+ }
+
+ /*
+ * 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)) {
+ char16_t 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)) {
+ char16_t 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((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((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=nullptr;
+ }
+
+ /* 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=nullptr;
+ }
+
+ /* 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;
+ }
+}
+
+static
+UBool _normalize(const Normalizer2 *n2, const char16_t *s, int32_t length,
+ UnicodeString &normalized, UErrorCode *pErrorCode) {
+ UnicodeString str(length<0, s, length);
+
+ // check if s fulfill the conditions
+ int32_t spanQCYes=n2->spanQuickCheckYes(str, *pErrorCode);
+ if (U_FAILURE(*pErrorCode)) {
+ return false;
+ }
+ /*
+ * 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(spanQCYes<str.length()) {
+ UnicodeString unnormalized=str.tempSubString(spanQCYes);
+ normalized.setTo(false, str.getBuffer(), spanQCYes);
+ n2->normalizeSecondAndAppend(normalized, unnormalized, *pErrorCode);
+ if (U_SUCCESS(*pErrorCode)) {
+ return true;
+ }
+ }
+ return false;
+}
+
+U_CAPI int32_t U_EXPORT2
+unorm_compare(const char16_t *s1, int32_t length1,
+ const char16_t *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=Normalizer2::getNFDInstance(*pErrorCode);
+ } else {
+ n2=Normalizer2Factory::getFCDInstance(*pErrorCode);
+ }
+ if (U_FAILURE(*pErrorCode)) {
+ return 0;
+ }
+
+ if(normOptions&UNORM_UNICODE_3_2) {
+ const UnicodeSet *uni32=uniset_getUnicode32Instance(*pErrorCode);
+ FilteredNormalizer2 fn2(*n2, *uni32);
+ if(_normalize(&fn2, s1, length1, fcd1, pErrorCode)) {
+ s1=fcd1.getBuffer();
+ length1=fcd1.length();
+ }
+ if(_normalize(&fn2, s2, length2, fcd2, pErrorCode)) {
+ s2=fcd2.getBuffer();
+ length2=fcd2.length();
+ }
+ } else {
+ if(_normalize(n2, s1, length1, fcd1, pErrorCode)) {
+ s1=fcd1.getBuffer();
+ length1=fcd1.length();
+ }
+ if(_normalize(n2, s2, length2, fcd2, 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 */
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