Check in the pristine copy of ICU 4.6...

icu46/source/common/ustrcase.c

+/*
+*******************************************************************************
+*
+*   Copyright (C) 2001-2010, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+*******************************************************************************
+*   file name:  ustrcase.c
+*   encoding:   US-ASCII
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2002feb20
+*   created by: Markus W. Scherer
+*
+*   Implementation file for string casing C API functions.
+*   Uses functions from uchar.c for basic functionality that requires access
+*   to the Unicode Character Database (uprops.dat).
+*/
+
+#include "unicode/utypes.h"
+#include "unicode/uloc.h"
+#include "unicode/ustring.h"
+#include "unicode/ucasemap.h"
+#include "unicode/ubrk.h"
+#include "cmemory.h"
+#include "ucase.h"
+#include "ustr_imp.h"
+
+/* string casing ------------------------------------------------------------ */
+
+/* append a full case mapping result, see UCASE_MAX_STRING_LENGTH */
+static U_INLINE int32_t
+appendResult(UChar *dest, int32_t destIndex, int32_t destCapacity,
+             int32_t result, const UChar *s) {
+    UChar32 c;
+    int32_t length;
+
+    /* decode the result */
+    if(result<0) {
+        /* (not) original code point */
+        c=~result;
+        length=-1;
+    } else if(result<=UCASE_MAX_STRING_LENGTH) {
+        c=U_SENTINEL;
+        length=result;
+    } else {
+        c=result;
+        length=-1;
+    }
+
+    if(destIndex<destCapacity) {
+        /* append the result */
+        if(length<0) {
+            /* code point */
+            UBool isError=FALSE;
+            U16_APPEND(dest, destIndex, destCapacity, c, isError);
+            if(isError) {
+                /* overflow, nothing written */
+                destIndex+=U16_LENGTH(c);
+            }
+        } else {
+            /* string */
+            if((destIndex+length)<=destCapacity) {
+                while(length>0) {
+                    dest[destIndex++]=*s++;
+                    --length;
+                }
+            } else {
+                /* overflow */
+                destIndex+=length;
+            }
+        }
+    } else {
+        /* preflight */
+        if(length<0) {
+            destIndex+=U16_LENGTH(c);
+        } else {
+            destIndex+=length;
+        }
+    }
+    return destIndex;
+}
+
+static UChar32 U_CALLCONV
+utf16_caseContextIterator(void *context, int8_t dir) {
+    UCaseContext *csc=(UCaseContext *)context;
+    UChar32 c;
+
+    if(dir<0) {
+        /* reset for backward iteration */
+        csc->index=csc->cpStart;
+        csc->dir=dir;
+    } else if(dir>0) {
+        /* reset for forward iteration */
+        csc->index=csc->cpLimit;
+        csc->dir=dir;
+    } else {
+        /* continue current iteration direction */
+        dir=csc->dir;
+    }
+
+    if(dir<0) {
+        if(csc->start<csc->index) {
+            U16_PREV((const UChar *)csc->p, csc->start, csc->index, c);
+            return c;
+        }
+    } else {
+        if(csc->index<csc->limit) {
+            U16_NEXT((const UChar *)csc->p, csc->index, csc->limit, c);
+            return c;
+        }
+    }
+    return U_SENTINEL;
+}
+
+/*
+ * Case-maps [srcStart..srcLimit[ but takes
+ * context [0..srcLength[ into account.
+ */
+static int32_t
+_caseMap(const UCaseMap *csm, UCaseMapFull *map,
+         UChar *dest, int32_t destCapacity,
+         const UChar *src, UCaseContext *csc,
+         int32_t srcStart, int32_t srcLimit,
+         UErrorCode *pErrorCode) {
+    const UChar *s;
+    UChar32 c, c2 = 0;
+    int32_t srcIndex, destIndex;
+    int32_t locCache;
+
+    locCache=csm->locCache;
+
+    /* case mapping loop */
+    srcIndex=srcStart;
+    destIndex=0;
+    while(srcIndex<srcLimit) {
+        csc->cpStart=srcIndex;
+        U16_NEXT(src, srcIndex, srcLimit, c);
+        csc->cpLimit=srcIndex;
+        c=map(csm->csp, c, utf16_caseContextIterator, csc, &s, csm->locale, &locCache);
+        if((destIndex<destCapacity) && (c<0 ? (c2=~c)<=0xffff : UCASE_MAX_STRING_LENGTH<c && (c2=c)<=0xffff)) {
+            /* fast path version of appendResult() for BMP results */
+            dest[destIndex++]=(UChar)c2;
+        } else {
+            destIndex=appendResult(dest, destIndex, destCapacity, c, s);
+        }
+    }
+
+    if(destIndex>destCapacity) {
+        *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+    }
+    return destIndex;
+}
+
+static void
+setTempCaseMapLocale(UCaseMap *csm, const char *locale, UErrorCode *pErrorCode) {
+    /*
+     * We could call ucasemap_setLocale(), but here we really only care about
+     * the initial language subtag, we need not return the real string via
+     * ucasemap_getLocale(), and we don't care about only getting "x" from
+     * "x-some-thing" etc.
+     *
+     * We ignore locales with a longer-than-3 initial subtag.
+     *
+     * We also do not fill in the locCache because it is rarely used,
+     * and not worth setting unless we reuse it for many case mapping operations.
+     * (That's why UCaseMap was created.)
+     */
+    int i;
+    char c;
+
+    /* the internal functions require locale!=NULL */
+    if(locale==NULL) {
+        locale=uloc_getDefault();
+    }
+    for(i=0; i<4 && (c=locale[i])!=0 && c!='-' && c!='_'; ++i) {
+        csm->locale[i]=c;
+    }
+    if(i<=3) {
+        csm->locale[i]=0;  /* Up to 3 non-separator characters. */
+    } else {
+        csm->locale[0]=0;  /* Longer-than-3 initial subtag: Ignore. */
+    }
+}
+
+/*
+ * Set parameters on an empty UCaseMap, for UCaseMap-less API functions.
+ * Do this fast because it is called with every function call.
+ */
+static U_INLINE void
+setTempCaseMap(UCaseMap *csm, const char *locale, UErrorCode *pErrorCode) {
+    if(csm->csp==NULL) {
+        csm->csp=ucase_getSingleton();
+    }
+    if(locale!=NULL && locale[0]==0) {
+        csm->locale[0]=0;
+    } else {
+        setTempCaseMapLocale(csm, locale, pErrorCode);
+    }
+}
+
+#if !UCONFIG_NO_BREAK_ITERATION
+
+/*
+ * Internal titlecasing function.
+ */
+static int32_t
+_toTitle(UCaseMap *csm,
+         UChar *dest, int32_t destCapacity,
+         const UChar *src, UCaseContext *csc,
+         int32_t srcLength,
+         UErrorCode *pErrorCode) {
+    const UChar *s;
+    UChar32 c;
+    int32_t prev, titleStart, titleLimit, idx, destIndex, length;
+    UBool isFirstIndex;
+
+    if(csm->iter!=NULL) {
+        ubrk_setText(csm->iter, src, srcLength, pErrorCode);
+    } else {
+        csm->iter=ubrk_open(UBRK_WORD, csm->locale,
+                            src, srcLength,
+                            pErrorCode);
+    }
+    if(U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    /* set up local variables */
+    destIndex=0;
+    prev=0;
+    isFirstIndex=TRUE;
+
+    /* titlecasing loop */
+    while(prev<srcLength) {
+        /* find next index where to titlecase */
+        if(isFirstIndex) {
+            isFirstIndex=FALSE;
+            idx=ubrk_first(csm->iter);
+        } else {
+            idx=ubrk_next(csm->iter);
+        }
+        if(idx==UBRK_DONE || idx>srcLength) {
+            idx=srcLength;
+        }
+
+        /*
+         * Unicode 4 & 5 section 3.13 Default Case Operations:
+         *
+         * R3  toTitlecase(X): Find the word boundaries based on Unicode Standard Annex
+         * #29, "Text Boundaries." Between each pair of word boundaries, find the first
+         * cased character F. If F exists, map F to default_title(F); then map each
+         * subsequent character C to default_lower(C).
+         *
+         * In this implementation, segment [prev..index[ into 3 parts:
+         * a) uncased characters (copy as-is) [prev..titleStart[
+         * b) first case letter (titlecase)         [titleStart..titleLimit[
+         * c) subsequent characters (lowercase)                 [titleLimit..index[
+         */
+        if(prev<idx) {
+            /* find and copy uncased characters [prev..titleStart[ */
+            titleStart=titleLimit=prev;
+            U16_NEXT(src, titleLimit, idx, c);
+            if((csm->options&U_TITLECASE_NO_BREAK_ADJUSTMENT)==0 && UCASE_NONE==ucase_getType(csm->csp, c)) {
+                /* Adjust the titlecasing index (titleStart) to the next cased character. */
+                for(;;) {
+                    titleStart=titleLimit;
+                    if(titleLimit==idx) {
+                        /*
+                         * only uncased characters in [prev..index[
+                         * stop with titleStart==titleLimit==index
+                         */
+                        break;
+                    }
+                    U16_NEXT(src, titleLimit, idx, c);
+                    if(UCASE_NONE!=ucase_getType(csm->csp, c)) {
+                        break; /* cased letter at [titleStart..titleLimit[ */
+                    }
+                }
+                length=titleStart-prev;
+                if(length>0) {
+                    if((destIndex+length)<=destCapacity) {
+                        uprv_memcpy(dest+destIndex, src+prev, length*U_SIZEOF_UCHAR);
+                    }
+                    destIndex+=length;
+                }
+            }
+
+            if(titleStart<titleLimit) {
+                /* titlecase c which is from [titleStart..titleLimit[ */
+                csc->cpStart=titleStart;
+                csc->cpLimit=titleLimit;
+                c=ucase_toFullTitle(csm->csp, c, utf16_caseContextIterator, csc, &s, csm->locale, &csm->locCache);
+                destIndex=appendResult(dest, destIndex, destCapacity, c, s); 
+
+                /* Special case Dutch IJ titlecasing */
+                if ( titleStart+1 < idx && 
+                     ucase_getCaseLocale(csm->locale,&csm->locCache) == UCASE_LOC_DUTCH &&
+                     ( src[titleStart] == (UChar32) 0x0049 || src[titleStart] == (UChar32) 0x0069 ) &&
+                     ( src[titleStart+1] == (UChar32) 0x004A || src[titleStart+1] == (UChar32) 0x006A )) { 
+                            c=(UChar32) 0x004A;
+                            destIndex=appendResult(dest, destIndex, destCapacity, c, s);
+                            titleLimit++;
+                }
+
+                /* lowercase [titleLimit..index[ */
+                if(titleLimit<idx) {
+                    if((csm->options&U_TITLECASE_NO_LOWERCASE)==0) {
+                        /* Normal operation: Lowercase the rest of the word. */
+                        destIndex+=
+                            _caseMap(
+                                csm, ucase_toFullLower,
+                                dest+destIndex, destCapacity-destIndex,
+                                src, csc,
+                                titleLimit, idx,
+                                pErrorCode);
+                    } else {
+                        /* Optionally just copy the rest of the word unchanged. */
+                        length=idx-titleLimit;
+                        if((destIndex+length)<=destCapacity) {
+                            uprv_memcpy(dest+destIndex, src+titleLimit, length*U_SIZEOF_UCHAR);
+                        }
+                        destIndex+=length;
+                    }
+                }
+            }
+        }
+
+        prev=idx;
+    }
+
+    if(destIndex>destCapacity) {
+        *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+    }
+    return destIndex;
+}
+
+#endif
+
+/* functions available in the common library (for unistr_case.cpp) */
+
+U_CFUNC int32_t
+ustr_toLower(const UCaseProps *csp,
+             UChar *dest, int32_t destCapacity,
+             const UChar *src, int32_t srcLength,
+             const char *locale,
+             UErrorCode *pErrorCode) {
+    UCaseMap csm={ NULL };
+    UCaseContext csc={ NULL };
+
+    csm.csp=csp;
+    setTempCaseMap(&csm, locale, pErrorCode);
+    csc.p=(void *)src;
+    csc.limit=srcLength;
+
+    return _caseMap(&csm, ucase_toFullLower,
+                    dest, destCapacity,
+                    src, &csc, 0, srcLength,
+                    pErrorCode);
+}
+
+U_CFUNC int32_t
+ustr_toUpper(const UCaseProps *csp,
+             UChar *dest, int32_t destCapacity,
+             const UChar *src, int32_t srcLength,
+             const char *locale,
+             UErrorCode *pErrorCode) {
+    UCaseMap csm={ NULL };
+    UCaseContext csc={ NULL };
+
+    csm.csp=csp;
+    setTempCaseMap(&csm, locale, pErrorCode);
+    csc.p=(void *)src;
+    csc.limit=srcLength;
+
+    return _caseMap(&csm, ucase_toFullUpper,
+                    dest, destCapacity,
+                    src, &csc, 0, srcLength,
+                    pErrorCode);
+}
+
+#if !UCONFIG_NO_BREAK_ITERATION
+
+U_CFUNC int32_t
+ustr_toTitle(const UCaseProps *csp,
+             UChar *dest, int32_t destCapacity,
+             const UChar *src, int32_t srcLength,
+             UBreakIterator *titleIter,
+             const char *locale, uint32_t options,
+             UErrorCode *pErrorCode) {
+    UCaseMap csm={ NULL };
+    UCaseContext csc={ NULL };
+    int32_t length;
+
+    csm.csp=csp;
+    csm.iter=titleIter;
+    csm.options=options;
+    setTempCaseMap(&csm, locale, pErrorCode);
+    csc.p=(void *)src;
+    csc.limit=srcLength;
+
+    length=_toTitle(&csm,
+                    dest, destCapacity,
+                    src, &csc, srcLength,
+                    pErrorCode);
+    if(titleIter==NULL && csm.iter!=NULL) {
+        ubrk_close(csm.iter);
+    }
+    return length;
+}
+
+#endif
+
+U_CFUNC int32_t
+ustr_foldCase(const UCaseProps *csp,
+              UChar *dest, int32_t destCapacity,
+              const UChar *src, int32_t srcLength,
+              uint32_t options,
+              UErrorCode *pErrorCode) {
+    int32_t srcIndex, destIndex;
+
+    const UChar *s;
+    UChar32 c, c2 = 0;
+
+    /* case mapping loop */
+    srcIndex=destIndex=0;
+    while(srcIndex<srcLength) {
+        U16_NEXT(src, srcIndex, srcLength, c);
+        c=ucase_toFullFolding(csp, c, &s, options);
+        if((destIndex<destCapacity) && (c<0 ? (c2=~c)<=0xffff : UCASE_MAX_STRING_LENGTH<c && (c2=c)<=0xffff)) {
+            /* fast path version of appendResult() for BMP results */
+            dest[destIndex++]=(UChar)c2;
+        } else {
+            destIndex=appendResult(dest, destIndex, destCapacity, c, s);
+        }
+    }
+
+    if(destIndex>destCapacity) {
+        *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+    }
+    return destIndex;
+}
+
+/*
+ * Implement argument checking and buffer handling
+ * for string case mapping as a common function.
+ */
+
+/* common internal function for public API functions */
+
+static int32_t
+caseMap(const UCaseMap *csm,
+        UChar *dest, int32_t destCapacity,
+        const UChar *src, int32_t srcLength,
+        int32_t toWhichCase,
+        UErrorCode *pErrorCode) {
+    UChar buffer[300];
+    UChar *temp;
+
+    int32_t destLength;
+
+    /* check argument values */
+    if(pErrorCode==NULL || U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+    if( destCapacity<0 ||
+        (dest==NULL && destCapacity>0) ||
+        src==NULL ||
+        srcLength<-1
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* get the string length */
+    if(srcLength==-1) {
+        srcLength=u_strlen(src);
+    }
+
+    /* check for overlapping source and destination */
+    if( dest!=NULL &&
+        ((src>=dest && src<(dest+destCapacity)) ||
+         (dest>=src && dest<(src+srcLength)))
+    ) {
+        /* overlap: provide a temporary destination buffer and later copy the result */
+        if(destCapacity<=(sizeof(buffer)/U_SIZEOF_UCHAR)) {
+            /* the stack buffer is large enough */
+            temp=buffer;
+        } else {
+            /* allocate a buffer */
+            temp=(UChar *)uprv_malloc(destCapacity*U_SIZEOF_UCHAR);
+            if(temp==NULL) {
+                *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
+                return 0;
+            }
+        }
+    } else {
+        temp=dest;
+    }
+
+    destLength=0;
+
+    if(toWhichCase==FOLD_CASE) {
+        destLength=ustr_foldCase(csm->csp, temp, destCapacity, src, srcLength,
+                                 csm->options, pErrorCode);
+    } else {
+        UCaseContext csc={ NULL };
+
+        csc.p=(void *)src;
+        csc.limit=srcLength;
+
+        if(toWhichCase==TO_LOWER) {
+            destLength=_caseMap(csm, ucase_toFullLower,
+                                temp, destCapacity,
+                                src, &csc,
+                                0, srcLength,
+                                pErrorCode);
+        } else if(toWhichCase==TO_UPPER) {
+            destLength=_caseMap(csm, ucase_toFullUpper,
+                                temp, destCapacity,
+                                src, &csc,
+                                0, srcLength,
+                                pErrorCode);
+        } else /* if(toWhichCase==TO_TITLE) */ {
+#if UCONFIG_NO_BREAK_ITERATION
+            *pErrorCode=U_UNSUPPORTED_ERROR;
+#else
+            /* UCaseMap is actually non-const in toTitle() APIs. */
+            destLength=_toTitle((UCaseMap *)csm, temp, destCapacity,
+                                src, &csc, srcLength,
+                                pErrorCode);
+#endif
+        }
+    }
+    if(temp!=dest) {
+        /* copy the result string to the destination buffer */
+        if(destLength>0) {
+            int32_t copyLength= destLength<=destCapacity ? destLength : destCapacity;
+            if(copyLength>0) {
+                uprv_memmove(dest, temp, copyLength*U_SIZEOF_UCHAR);
+            }
+        }
+        if(temp!=buffer) {
+            uprv_free(temp);
+        }
+    }
+
+    return u_terminateUChars(dest, destCapacity, destLength, pErrorCode);
+}
+
+/* public API functions */
+
+U_CAPI int32_t U_EXPORT2
+u_strToLower(UChar *dest, int32_t destCapacity,
+             const UChar *src, int32_t srcLength,
+             const char *locale,
+             UErrorCode *pErrorCode) {
+    UCaseMap csm={ NULL };
+    setTempCaseMap(&csm, locale, pErrorCode);
+    return caseMap(&csm,
+                   dest, destCapacity,
+                   src, srcLength,
+                   TO_LOWER, pErrorCode);
+}
+
+U_CAPI int32_t U_EXPORT2
+u_strToUpper(UChar *dest, int32_t destCapacity,
+             const UChar *src, int32_t srcLength,
+             const char *locale,
+             UErrorCode *pErrorCode) {
+    UCaseMap csm={ NULL };
+    setTempCaseMap(&csm, locale, pErrorCode);
+    return caseMap(&csm,
+                   dest, destCapacity,
+                   src, srcLength,
+                   TO_UPPER, pErrorCode);
+}
+
+#if !UCONFIG_NO_BREAK_ITERATION
+
+U_CAPI int32_t U_EXPORT2
+u_strToTitle(UChar *dest, int32_t destCapacity,
+             const UChar *src, int32_t srcLength,
+             UBreakIterator *titleIter,
+             const char *locale,
+             UErrorCode *pErrorCode) {
+    UCaseMap csm={ NULL };
+    int32_t length;
+
+    csm.iter=titleIter;
+    setTempCaseMap(&csm, locale, pErrorCode);
+    length=caseMap(&csm,
+                   dest, destCapacity,
+                   src, srcLength,
+                   TO_TITLE, pErrorCode);
+    if(titleIter==NULL && csm.iter!=NULL) {
+        ubrk_close(csm.iter);
+    }
+    return length;
+}
+
+U_CAPI int32_t U_EXPORT2
+ucasemap_toTitle(UCaseMap *csm,
+                 UChar *dest, int32_t destCapacity,
+                 const UChar *src, int32_t srcLength,
+                 UErrorCode *pErrorCode) {
+    return caseMap(csm,
+                   dest, destCapacity,
+                   src, srcLength,
+                   TO_TITLE, pErrorCode);
+}
+
+#endif
+
+U_CAPI int32_t U_EXPORT2
+u_strFoldCase(UChar *dest, int32_t destCapacity,
+              const UChar *src, int32_t srcLength,
+              uint32_t options,
+              UErrorCode *pErrorCode) {
+    UCaseMap csm={ NULL };
+    csm.csp=ucase_getSingleton();
+    csm.options=options;
+    return caseMap(&csm,
+                   dest, destCapacity,
+                   src, srcLength,
+                   FOLD_CASE, pErrorCode);
+}
+
+/* case-insensitive string comparisons -------------------------------------- */
+
+/*
+ * This function is a copy of unorm_cmpEquivFold() minus the parts for
+ * canonical equivalence.
+ * Keep the functions in sync, and see there for how this works.
+ * The duplication is for modularization:
+ * It makes caseless (but not canonical caseless) matches independent of
+ * the normalization code.
+ */
+
+/* stack element for previous-level source/decomposition pointers */
+struct CmpEquivLevel {
+    const UChar *start, *s, *limit;
+};
+typedef struct CmpEquivLevel CmpEquivLevel;
+
+/* internal function */
+U_CFUNC int32_t
+u_strcmpFold(const UChar *s1, int32_t length1,
+             const UChar *s2, int32_t length2,
+             uint32_t options,
+             UErrorCode *pErrorCode) {
+    const UCaseProps *csp;
+
+    /* current-level start/limit - s1/s2 as current */
+    const UChar *start1, *start2, *limit1, *limit2;
+
+    /* case folding variables */
+    const UChar *p;
+    int32_t length;
+
+    /* stacks of previous-level start/current/limit */
+    CmpEquivLevel stack1[2], stack2[2];
+
+    /* 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 the option U_COMPARE_IGNORE_CASE is set
+     * otherwise this function would have to behave exactly as uprv_strCompare()
+     */
+    csp=ucase_getSingleton();
+    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 &&
+            (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 &&
+            (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;
+        }
+
+        /*
+         * 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;
+    }
+}
+
+/* public API functions */
+
+U_CAPI int32_t U_EXPORT2
+u_strCaseCompare(const UChar *s1, int32_t length1,
+                 const UChar *s2, int32_t length2,
+                 uint32_t options,
+                 UErrorCode *pErrorCode) {
+    /* argument checking */
+    if(pErrorCode==0 || U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+    if(s1==NULL || length1<-1 || s2==NULL || length2<-1) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+    return u_strcmpFold(s1, length1, s2, length2,
+                        options|U_COMPARE_IGNORE_CASE,
+                        pErrorCode);
+}
+
+U_CAPI int32_t U_EXPORT2
+u_strcasecmp(const UChar *s1, const UChar *s2, uint32_t options) {
+    UErrorCode errorCode=U_ZERO_ERROR;
+    return u_strcmpFold(s1, -1, s2, -1,
+                        options|U_COMPARE_IGNORE_CASE,
+                        &errorCode);
+}
+
+U_CAPI int32_t U_EXPORT2
+u_memcasecmp(const UChar *s1, const UChar *s2, int32_t length, uint32_t options) {
+    UErrorCode errorCode=U_ZERO_ERROR;
+    return u_strcmpFold(s1, length, s2, length,
+                        options|U_COMPARE_IGNORE_CASE,
+                        &errorCode);
+}
+
+U_CAPI int32_t U_EXPORT2
+u_strncasecmp(const UChar *s1, const UChar *s2, int32_t n, uint32_t options) {
+    UErrorCode errorCode=U_ZERO_ERROR;
+    return u_strcmpFold(s1, n, s2, n,
+                        options|(U_COMPARE_IGNORE_CASE|_STRNCMP_STYLE),
+                        &errorCode);
+}