Check in the pristine copy of ICU 4.6...

icu46/source/common/ustring.c

+/*
+******************************************************************************
+*
+*   Copyright (C) 1998-2010, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+******************************************************************************
+*
+* File ustring.h
+*
+* Modification History:
+*
+*   Date        Name        Description
+*   12/07/98    bertrand    Creation.
+******************************************************************************
+*/
+
+#include "unicode/utypes.h"
+#include "unicode/putil.h"
+#include "unicode/ustring.h"
+#include "cstring.h"
+#include "cwchar.h"
+#include "cmemory.h"
+#include "ustr_imp.h"
+
+/* ANSI string.h - style functions ------------------------------------------ */
+
+/* U+ffff is the highest BMP code point, the highest one that fits into a 16-bit UChar */
+#define U_BMP_MAX 0xffff
+
+/* Forward binary string search functions ----------------------------------- */
+
+/*
+ * Test if a substring match inside a string is at code point boundaries.
+ * All pointers refer to the same buffer.
+ * The limit pointer may be NULL, all others must be real pointers.
+ */
+static U_INLINE UBool
+isMatchAtCPBoundary(const UChar *start, const UChar *match, const UChar *matchLimit, const UChar *limit) {
+    if(U16_IS_TRAIL(*match) && start!=match && U16_IS_LEAD(*(match-1))) {
+        /* the leading edge of the match is in the middle of a surrogate pair */
+        return FALSE;
+    }
+    if(U16_IS_LEAD(*(matchLimit-1)) && match!=limit && U16_IS_TRAIL(*matchLimit)) {
+        /* the trailing edge of the match is in the middle of a surrogate pair */
+        return FALSE;
+    }
+    return TRUE;
+}
+
+U_CAPI UChar * U_EXPORT2
+u_strFindFirst(const UChar *s, int32_t length,
+               const UChar *sub, int32_t subLength) {
+    const UChar *start, *p, *q, *subLimit;
+    UChar c, cs, cq;
+
+    if(sub==NULL || subLength<-1) {
+        return (UChar *)s;
+    }
+    if(s==NULL || length<-1) {
+        return NULL;
+    }
+
+    start=s;
+
+    if(length<0 && subLength<0) {
+        /* both strings are NUL-terminated */
+        if((cs=*sub++)==0) {
+            return (UChar *)s;
+        }
+        if(*sub==0 && !U16_IS_SURROGATE(cs)) {
+            /* the substring consists of a single, non-surrogate BMP code point */
+            return u_strchr(s, cs);
+        }
+
+        while((c=*s++)!=0) {
+            if(c==cs) {
+                /* found first substring UChar, compare rest */
+                p=s;
+                q=sub;
+                for(;;) {
+                    if((cq=*q)==0) {
+                        if(isMatchAtCPBoundary(start, s-1, p, NULL)) {
+                            return (UChar *)(s-1); /* well-formed match */
+                        } else {
+                            break; /* no match because surrogate pair is split */
+                        }
+                    }
+                    if((c=*p)==0) {
+                        return NULL; /* no match, and none possible after s */
+                    }
+                    if(c!=cq) {
+                        break; /* no match */
+                    }
+                    ++p;
+                    ++q;
+                }
+            }
+        }
+
+        /* not found */
+        return NULL;
+    }
+
+    if(subLength<0) {
+        subLength=u_strlen(sub);
+    }
+    if(subLength==0) {
+        return (UChar *)s;
+    }
+
+    /* get sub[0] to search for it fast */
+    cs=*sub++;
+    --subLength;
+    subLimit=sub+subLength;
+
+    if(subLength==0 && !U16_IS_SURROGATE(cs)) {
+        /* the substring consists of a single, non-surrogate BMP code point */
+        return length<0 ? u_strchr(s, cs) : u_memchr(s, cs, length);
+    }
+
+    if(length<0) {
+        /* s is NUL-terminated */
+        while((c=*s++)!=0) {
+            if(c==cs) {
+                /* found first substring UChar, compare rest */
+                p=s;
+                q=sub;
+                for(;;) {
+                    if(q==subLimit) {
+                        if(isMatchAtCPBoundary(start, s-1, p, NULL)) {
+                            return (UChar *)(s-1); /* well-formed match */
+                        } else {
+                            break; /* no match because surrogate pair is split */
+                        }
+                    }
+                    if((c=*p)==0) {
+                        return NULL; /* no match, and none possible after s */
+                    }
+                    if(c!=*q) {
+                        break; /* no match */
+                    }
+                    ++p;
+                    ++q;
+                }
+            }
+        }
+    } else {
+        const UChar *limit, *preLimit;
+
+        /* subLength was decremented above */
+        if(length<=subLength) {
+            return NULL; /* s is shorter than sub */
+        }
+
+        limit=s+length;
+
+        /* the substring must start before preLimit */
+        preLimit=limit-subLength;
+
+        while(s!=preLimit) {
+            c=*s++;
+            if(c==cs) {
+                /* found first substring UChar, compare rest */
+                p=s;
+                q=sub;
+                for(;;) {
+                    if(q==subLimit) {
+                        if(isMatchAtCPBoundary(start, s-1, p, limit)) {
+                            return (UChar *)(s-1); /* well-formed match */
+                        } else {
+                            break; /* no match because surrogate pair is split */
+                        }
+                    }
+                    if(*p!=*q) {
+                        break; /* no match */
+                    }
+                    ++p;
+                    ++q;
+                }
+            }
+        }
+    }
+
+    /* not found */
+    return NULL;
+}
+
+U_CAPI UChar * U_EXPORT2
+u_strstr(const UChar *s, const UChar *substring) {
+    return u_strFindFirst(s, -1, substring, -1);
+}
+
+U_CAPI UChar * U_EXPORT2
+u_strchr(const UChar *s, UChar c) {
+    if(U16_IS_SURROGATE(c)) {
+        /* make sure to not find half of a surrogate pair */
+        return u_strFindFirst(s, -1, &c, 1);
+    } else {
+        UChar cs;
+
+        /* trivial search for a BMP code point */
+        for(;;) {
+            if((cs=*s)==c) {
+                return (UChar *)s;
+            }
+            if(cs==0) {
+                return NULL;
+            }
+            ++s;
+        }
+    }
+}
+
+U_CAPI UChar * U_EXPORT2
+u_strchr32(const UChar *s, UChar32 c) {
+    if((uint32_t)c<=U_BMP_MAX) {
+        /* find BMP code point */
+        return u_strchr(s, (UChar)c);
+    } else if((uint32_t)c<=UCHAR_MAX_VALUE) {
+        /* find supplementary code point as surrogate pair */
+        UChar cs, lead=U16_LEAD(c), trail=U16_TRAIL(c);
+
+        while((cs=*s++)!=0) {
+            if(cs==lead && *s==trail) {
+                return (UChar *)(s-1);
+            }
+        }
+        return NULL;
+    } else {
+        /* not a Unicode code point, not findable */
+        return NULL;
+    }
+}
+
+U_CAPI UChar * U_EXPORT2
+u_memchr(const UChar *s, UChar c, int32_t count) {
+    if(count<=0) {
+        return NULL; /* no string */
+    } else if(U16_IS_SURROGATE(c)) {
+        /* make sure to not find half of a surrogate pair */
+        return u_strFindFirst(s, count, &c, 1);
+    } else {
+        /* trivial search for a BMP code point */
+        const UChar *limit=s+count;
+        do {
+            if(*s==c) {
+                return (UChar *)s;
+            }
+        } while(++s!=limit);
+        return NULL;
+    }
+}
+
+U_CAPI UChar * U_EXPORT2
+u_memchr32(const UChar *s, UChar32 c, int32_t count) {
+    if((uint32_t)c<=U_BMP_MAX) {
+        /* find BMP code point */
+        return u_memchr(s, (UChar)c, count);
+    } else if(count<2) {
+        /* too short for a surrogate pair */
+        return NULL;
+    } else if((uint32_t)c<=UCHAR_MAX_VALUE) {
+        /* find supplementary code point as surrogate pair */
+        const UChar *limit=s+count-1; /* -1 so that we do not need a separate check for the trail unit */
+        UChar lead=U16_LEAD(c), trail=U16_TRAIL(c);
+
+        do {
+            if(*s==lead && *(s+1)==trail) {
+                return (UChar *)s;
+            }
+        } while(++s!=limit);
+        return NULL;
+    } else {
+        /* not a Unicode code point, not findable */
+        return NULL;
+    }
+}
+
+/* Backward binary string search functions ---------------------------------- */
+
+U_CAPI UChar * U_EXPORT2
+u_strFindLast(const UChar *s, int32_t length,
+              const UChar *sub, int32_t subLength) {
+    const UChar *start, *limit, *p, *q, *subLimit;
+    UChar c, cs;
+
+    if(sub==NULL || subLength<-1) {
+        return (UChar *)s;
+    }
+    if(s==NULL || length<-1) {
+        return NULL;
+    }
+
+    /*
+     * This implementation is more lazy than the one for u_strFindFirst():
+     * There is no special search code for NUL-terminated strings.
+     * It does not seem to be worth it for searching substrings to
+     * search forward and find all matches like in u_strrchr() and similar.
+     * Therefore, we simply get both string lengths and search backward.
+     *
+     * markus 2002oct23
+     */
+
+    if(subLength<0) {
+        subLength=u_strlen(sub);
+    }
+    if(subLength==0) {
+        return (UChar *)s;
+    }
+
+    /* get sub[subLength-1] to search for it fast */
+    subLimit=sub+subLength;
+    cs=*(--subLimit);
+    --subLength;
+
+    if(subLength==0 && !U16_IS_SURROGATE(cs)) {
+        /* the substring consists of a single, non-surrogate BMP code point */
+        return length<0 ? u_strrchr(s, cs) : u_memrchr(s, cs, length);
+    }
+
+    if(length<0) {
+        length=u_strlen(s);
+    }
+
+    /* subLength was decremented above */
+    if(length<=subLength) {
+        return NULL; /* s is shorter than sub */
+    }
+
+    start=s;
+    limit=s+length;
+
+    /* the substring must start no later than s+subLength */
+    s+=subLength;
+
+    while(s!=limit) {
+        c=*(--limit);
+        if(c==cs) {
+            /* found last substring UChar, compare rest */
+            p=limit;
+            q=subLimit;
+            for(;;) {
+                if(q==sub) {
+                    if(isMatchAtCPBoundary(start, p, limit+1, start+length)) {
+                        return (UChar *)p; /* well-formed match */
+                    } else {
+                        break; /* no match because surrogate pair is split */
+                    }
+                }
+                if(*(--p)!=*(--q)) {
+                    break; /* no match */
+                }
+            }
+        }
+    }
+
+    /* not found */
+    return NULL;
+}
+
+U_CAPI UChar * U_EXPORT2
+u_strrstr(const UChar *s, const UChar *substring) {
+    return u_strFindLast(s, -1, substring, -1);
+}
+
+U_CAPI UChar * U_EXPORT2
+u_strrchr(const UChar *s, UChar c) {
+    if(U16_IS_SURROGATE(c)) {
+        /* make sure to not find half of a surrogate pair */
+        return u_strFindLast(s, -1, &c, 1);
+    } else {
+        const UChar *result=NULL;
+        UChar cs;
+
+        /* trivial search for a BMP code point */
+        for(;;) {
+            if((cs=*s)==c) {
+                result=s;
+            }
+            if(cs==0) {
+                return (UChar *)result;
+            }
+            ++s;
+        }
+    }
+}
+
+U_CAPI UChar * U_EXPORT2
+u_strrchr32(const UChar *s, UChar32 c) {
+    if((uint32_t)c<=U_BMP_MAX) {
+        /* find BMP code point */
+        return u_strrchr(s, (UChar)c);
+    } else if((uint32_t)c<=UCHAR_MAX_VALUE) {
+        /* find supplementary code point as surrogate pair */
+        const UChar *result=NULL;
+        UChar cs, lead=U16_LEAD(c), trail=U16_TRAIL(c);
+
+        while((cs=*s++)!=0) {
+            if(cs==lead && *s==trail) {
+                result=s-1;
+            }
+        }
+        return (UChar *)result;
+    } else {
+        /* not a Unicode code point, not findable */
+        return NULL;
+    }
+}
+
+U_CAPI UChar * U_EXPORT2
+u_memrchr(const UChar *s, UChar c, int32_t count) {
+    if(count<=0) {
+        return NULL; /* no string */
+    } else if(U16_IS_SURROGATE(c)) {
+        /* make sure to not find half of a surrogate pair */
+        return u_strFindLast(s, count, &c, 1);
+    } else {
+        /* trivial search for a BMP code point */
+        const UChar *limit=s+count;
+        do {
+            if(*(--limit)==c) {
+                return (UChar *)limit;
+            }
+        } while(s!=limit);
+        return NULL;
+    }
+}
+
+U_CAPI UChar * U_EXPORT2
+u_memrchr32(const UChar *s, UChar32 c, int32_t count) {
+    if((uint32_t)c<=U_BMP_MAX) {
+        /* find BMP code point */
+        return u_memrchr(s, (UChar)c, count);
+    } else if(count<2) {
+        /* too short for a surrogate pair */
+        return NULL;
+    } else if((uint32_t)c<=UCHAR_MAX_VALUE) {
+        /* find supplementary code point as surrogate pair */
+        const UChar *limit=s+count-1;
+        UChar lead=U16_LEAD(c), trail=U16_TRAIL(c);
+
+        do {
+            if(*limit==trail && *(limit-1)==lead) {
+                return (UChar *)(limit-1);
+            }
+        } while(s!=--limit);
+        return NULL;
+    } else {
+        /* not a Unicode code point, not findable */
+        return NULL;
+    }
+}
+
+/* Tokenization functions --------------------------------------------------- */
+
+/*
+ * Match each code point in a string against each code point in the matchSet.
+ * Return the index of the first string code point that
+ * is (polarity==TRUE) or is not (FALSE) contained in the matchSet.
+ * Return -(string length)-1 if there is no such code point.
+ */
+static int32_t
+_matchFromSet(const UChar *string, const UChar *matchSet, UBool polarity) {
+    int32_t matchLen, matchBMPLen, strItr, matchItr;
+    UChar32 stringCh, matchCh;
+    UChar c, c2;
+
+    /* first part of matchSet contains only BMP code points */
+    matchBMPLen = 0;
+    while((c = matchSet[matchBMPLen]) != 0 && U16_IS_SINGLE(c)) {
+        ++matchBMPLen;
+    }
+
+    /* second part of matchSet contains BMP and supplementary code points */
+    matchLen = matchBMPLen;
+    while(matchSet[matchLen] != 0) {
+        ++matchLen;
+    }
+
+    for(strItr = 0; (c = string[strItr]) != 0;) {
+        ++strItr;
+        if(U16_IS_SINGLE(c)) {
+            if(polarity) {
+                for(matchItr = 0; matchItr < matchLen; ++matchItr) {
+                    if(c == matchSet[matchItr]) {
+                        return strItr - 1; /* one matches */
+                    }
+                }
+            } else {
+                for(matchItr = 0; matchItr < matchLen; ++matchItr) {
+                    if(c == matchSet[matchItr]) {
+                        goto endloop;
+                    }
+                }
+                return strItr - 1; /* none matches */
+            }
+        } else {
+            /*
+             * No need to check for string length before U16_IS_TRAIL
+             * because c2 could at worst be the terminating NUL.
+             */
+            if(U16_IS_SURROGATE_LEAD(c) && U16_IS_TRAIL(c2 = string[strItr])) {
+                ++strItr;
+                stringCh = U16_GET_SUPPLEMENTARY(c, c2);
+            } else {
+                stringCh = c; /* unpaired trail surrogate */
+            }
+
+            if(polarity) {
+                for(matchItr = matchBMPLen; matchItr < matchLen;) {
+                    U16_NEXT(matchSet, matchItr, matchLen, matchCh);
+                    if(stringCh == matchCh) {
+                        return strItr - U16_LENGTH(stringCh); /* one matches */
+                    }
+                }
+            } else {
+                for(matchItr = matchBMPLen; matchItr < matchLen;) {
+                    U16_NEXT(matchSet, matchItr, matchLen, matchCh);
+                    if(stringCh == matchCh) {
+                        goto endloop;
+                    }
+                }
+                return strItr - U16_LENGTH(stringCh); /* none matches */
+            }
+        }
+endloop:
+        /* wish C had continue with labels like Java... */;
+    }
+
+    /* Didn't find it. */
+    return -strItr-1;
+}
+
+/* Search for a codepoint in a string that matches one of the matchSet codepoints. */
+U_CAPI UChar * U_EXPORT2
+u_strpbrk(const UChar *string, const UChar *matchSet)
+{
+    int32_t idx = _matchFromSet(string, matchSet, TRUE);
+    if(idx >= 0) {
+        return (UChar *)string + idx;
+    } else {
+        return NULL;
+    }
+}
+
+/* Search for a codepoint in a string that matches one of the matchSet codepoints. */
+U_CAPI int32_t U_EXPORT2
+u_strcspn(const UChar *string, const UChar *matchSet)
+{
+    int32_t idx = _matchFromSet(string, matchSet, TRUE);
+    if(idx >= 0) {
+        return idx;
+    } else {
+        return -idx - 1; /* == u_strlen(string) */
+    }
+}
+
+/* Search for a codepoint in a string that does not match one of the matchSet codepoints. */
+U_CAPI int32_t U_EXPORT2
+u_strspn(const UChar *string, const UChar *matchSet)
+{
+    int32_t idx = _matchFromSet(string, matchSet, FALSE);
+    if(idx >= 0) {
+        return idx;
+    } else {
+        return -idx - 1; /* == u_strlen(string) */
+    }
+}
+
+/* ----- Text manipulation functions --- */
+
+U_CAPI UChar* U_EXPORT2
+u_strtok_r(UChar    *src, 
+     const UChar    *delim,
+           UChar   **saveState)
+{
+    UChar *tokSource;
+    UChar *nextToken;
+    uint32_t nonDelimIdx;
+
+    /* If saveState is NULL, the user messed up. */
+    if (src != NULL) {
+        tokSource = src;
+        *saveState = src; /* Set to "src" in case there are no delimiters */
+    }
+    else if (*saveState) {
+        tokSource = *saveState;
+    }
+    else {
+        /* src == NULL && *saveState == NULL */
+        /* This shouldn't happen. We already finished tokenizing. */
+        return NULL;
+    }
+
+    /* Skip initial delimiters */
+    nonDelimIdx = u_strspn(tokSource, delim);
+    tokSource = &tokSource[nonDelimIdx];
+
+    if (*tokSource) {
+        nextToken = u_strpbrk(tokSource, delim);
+        if (nextToken != NULL) {
+            /* Create a token */
+            *(nextToken++) = 0;
+            *saveState = nextToken;
+            return tokSource;
+        }
+        else if (*saveState) {
+            /* Return the last token */
+            *saveState = NULL;
+            return tokSource;
+        }
+    }
+    else {
+        /* No tokens were found. Only delimiters were left. */
+        *saveState = NULL;
+    }
+    return NULL;
+}
+
+/* Miscellaneous functions -------------------------------------------------- */
+
+U_CAPI UChar* U_EXPORT2
+u_strcat(UChar     *dst, 
+    const UChar     *src)
+{
+    UChar *anchor = dst;            /* save a pointer to start of dst */
+
+    while(*dst != 0) {              /* To end of first string          */
+        ++dst;
+    }
+    while((*(dst++) = *(src++)) != 0) {     /* copy string 2 over              */
+    }
+
+    return anchor;
+}
+
+U_CAPI UChar*  U_EXPORT2
+u_strncat(UChar     *dst, 
+     const UChar     *src, 
+     int32_t     n ) 
+{
+    if(n > 0) {
+        UChar *anchor = dst;            /* save a pointer to start of dst */
+
+        while(*dst != 0) {              /* To end of first string          */
+            ++dst;
+        }
+        while((*dst = *src) != 0) {     /* copy string 2 over              */
+            ++dst;
+            if(--n == 0) {
+                *dst = 0;
+                break;
+            }
+            ++src;
+        }
+
+        return anchor;
+    } else {
+        return dst;
+    }
+}
+
+/* ----- Text property functions --- */
+
+U_CAPI int32_t   U_EXPORT2
+u_strcmp(const UChar *s1, 
+    const UChar *s2) 
+{
+    UChar  c1, c2;
+
+    for(;;) {
+        c1=*s1++;
+        c2=*s2++;
+        if (c1 != c2 || c1 == 0) {
+            break;
+        }
+    }
+    return (int32_t)c1 - (int32_t)c2;
+}
+
+U_CFUNC int32_t U_EXPORT2
+uprv_strCompare(const UChar *s1, int32_t length1,
+                const UChar *s2, int32_t length2,
+                UBool strncmpStyle, UBool codePointOrder) {
+    const UChar *start1, *start2, *limit1, *limit2;
+    UChar c1, c2;
+
+    /* setup for fix-up */
+    start1=s1;
+    start2=s2;
+
+    /* compare identical prefixes - they do not need to be fixed up */
+    if(length1<0 && length2<0) {
+        /* strcmp style, both NUL-terminated */
+        if(s1==s2) {
+            return 0;
+        }
+
+        for(;;) {
+            c1=*s1;
+            c2=*s2;
+            if(c1!=c2) {
+                break;
+            }
+            if(c1==0) {
+                return 0;
+            }
+            ++s1;
+            ++s2;
+        }
+
+        /* setup for fix-up */
+        limit1=limit2=NULL;
+    } else if(strncmpStyle) {
+        /* special handling for strncmp, assume length1==length2>=0 but also check for NUL */
+        if(s1==s2) {
+            return 0;
+        }
+
+        limit1=start1+length1;
+
+        for(;;) {
+            /* both lengths are same, check only one limit */
+            if(s1==limit1) {
+                return 0;
+            }
+
+            c1=*s1;
+            c2=*s2;
+            if(c1!=c2) {
+                break;
+            }
+            if(c1==0) {
+                return 0;
+            }
+            ++s1;
+            ++s2;
+        }
+
+        /* setup for fix-up */
+        limit2=start2+length1; /* use length1 here, too, to enforce assumption */
+    } else {
+        /* memcmp/UnicodeString style, both length-specified */
+        int32_t lengthResult;
+
+        if(length1<0) {
+            length1=u_strlen(s1);
+        }
+        if(length2<0) {
+            length2=u_strlen(s2);
+        }
+
+        /* limit1=start1+min(lenght1, length2) */
+        if(length1<length2) {
+            lengthResult=-1;
+            limit1=start1+length1;
+        } else if(length1==length2) {
+            lengthResult=0;
+            limit1=start1+length1;
+        } else /* length1>length2 */ {
+            lengthResult=1;
+            limit1=start1+length2;
+        }
+
+        if(s1==s2) {
+            return lengthResult;
+        }
+
+        for(;;) {
+            /* check pseudo-limit */
+            if(s1==limit1) {
+                return lengthResult;
+            }
+
+            c1=*s1;
+            c2=*s2;
+            if(c1!=c2) {
+                break;
+            }
+            ++s1;
+            ++s2;
+        }
+
+        /* setup for fix-up */
+        limit1=start1+length1;
+        limit2=start2+length2;
+    }
+
+    /* if both values are in or above the surrogate range, fix them up */
+    if(c1>=0xd800 && c2>=0xd800 && codePointOrder) {
+        /* subtract 0x2800 from BMP code points to make them smaller than supplementary ones */
+        if(
+            (c1<=0xdbff && (s1+1)!=limit1 && UTF_IS_TRAIL(*(s1+1))) ||
+            (UTF_IS_TRAIL(c1) && start1!=s1 && UTF_IS_LEAD(*(s1-1)))
+        ) {
+            /* part of a surrogate pair, leave >=d800 */
+        } else {
+            /* BMP code point - may be surrogate code point - make <d800 */
+            c1-=0x2800;
+        }
+
+        if(
+            (c2<=0xdbff && (s2+1)!=limit2 && UTF_IS_TRAIL(*(s2+1))) ||
+            (UTF_IS_TRAIL(c2) && start2!=s2 && UTF_IS_LEAD(*(s2-1)))
+        ) {
+            /* part of a surrogate pair, leave >=d800 */
+        } else {
+            /* BMP code point - may be surrogate code point - make <d800 */
+            c2-=0x2800;
+        }
+    }
+
+    /* now c1 and c2 are in the requested (code unit or code point) order */
+    return (int32_t)c1-(int32_t)c2;
+}
+
+/*
+ * Compare two strings as presented by UCharIterators.
+ * Use code unit or code point order.
+ * When the function returns, it is undefined where the iterators
+ * have stopped.
+ */
+U_CAPI int32_t U_EXPORT2
+u_strCompareIter(UCharIterator *iter1, UCharIterator *iter2, UBool codePointOrder) {
+    UChar32 c1, c2;
+
+    /* argument checking */
+    if(iter1==NULL || iter2==NULL) {
+        return 0; /* bad arguments */
+    }
+    if(iter1==iter2) {
+        return 0; /* identical iterators */
+    }
+
+    /* reset iterators to start? */
+    iter1->move(iter1, 0, UITER_START);
+    iter2->move(iter2, 0, UITER_START);
+
+    /* compare identical prefixes - they do not need to be fixed up */
+    for(;;) {
+        c1=iter1->next(iter1);
+        c2=iter2->next(iter2);
+        if(c1!=c2) {
+            break;
+        }
+        if(c1==-1) {
+            return 0;
+        }
+    }
+
+    /* if both values are in or above the surrogate range, fix them up */
+    if(c1>=0xd800 && c2>=0xd800 && codePointOrder) {
+        /* subtract 0x2800 from BMP code points to make them smaller than supplementary ones */
+        if(
+            (c1<=0xdbff && UTF_IS_TRAIL(iter1->current(iter1))) ||
+            (UTF_IS_TRAIL(c1) && (iter1->previous(iter1), UTF_IS_LEAD(iter1->previous(iter1))))
+        ) {
+            /* part of a surrogate pair, leave >=d800 */
+        } else {
+            /* BMP code point - may be surrogate code point - make <d800 */
+            c1-=0x2800;
+        }
+
+        if(
+            (c2<=0xdbff && UTF_IS_TRAIL(iter2->current(iter2))) ||
+            (UTF_IS_TRAIL(c2) && (iter2->previous(iter2), UTF_IS_LEAD(iter2->previous(iter2))))
+        ) {
+            /* part of a surrogate pair, leave >=d800 */
+        } else {
+            /* BMP code point - may be surrogate code point - make <d800 */
+            c2-=0x2800;
+        }
+    }
+
+    /* now c1 and c2 are in the requested (code unit or code point) order */
+    return (int32_t)c1-(int32_t)c2;
+}
+
+#if 0
+/*
+ * u_strCompareIter() does not leave the iterators _on_ the different units.
+ * This is possible but would cost a few extra indirect function calls to back
+ * up if the last unit (c1 or c2 respectively) was >=0.
+ *
+ * Consistently leaving them _behind_ the different units is not an option
+ * because the current "unit" is the end of the string if that is reached,
+ * and in such a case the iterator does not move.
+ * For example, when comparing "ab" with "abc", both iterators rest _on_ the end
+ * of their strings. Calling previous() on each does not move them to where
+ * the comparison fails.
+ *
+ * So the simplest semantics is to not define where the iterators end up.
+ *
+ * The following fragment is part of what would need to be done for backing up.
+ */
+void fragment {
+        /* iff a surrogate is part of a surrogate pair, leave >=d800 */
+        if(c1<=0xdbff) {
+            if(!UTF_IS_TRAIL(iter1->current(iter1))) {
+                /* lead surrogate code point - make <d800 */
+                c1-=0x2800;
+            }
+        } else if(c1<=0xdfff) {
+            int32_t idx=iter1->getIndex(iter1, UITER_CURRENT);
+            iter1->previous(iter1); /* ==c1 */
+            if(!UTF_IS_LEAD(iter1->previous(iter1))) {
+                /* trail surrogate code point - make <d800 */
+                c1-=0x2800;
+            }
+            /* go back to behind where the difference is */
+            iter1->move(iter1, idx, UITER_ZERO);
+        } else /* 0xe000<=c1<=0xffff */ {
+            /* BMP code point - make <d800 */
+            c1-=0x2800;
+        }
+}
+#endif
+
+U_CAPI int32_t U_EXPORT2
+u_strCompare(const UChar *s1, int32_t length1,
+             const UChar *s2, int32_t length2,
+             UBool codePointOrder) {
+    /* argument checking */
+    if(s1==NULL || length1<-1 || s2==NULL || length2<-1) {
+        return 0;
+    }
+    return uprv_strCompare(s1, length1, s2, length2, FALSE, codePointOrder);
+}
+
+/* String compare in code point order - u_strcmp() compares in code unit order. */
+U_CAPI int32_t U_EXPORT2
+u_strcmpCodePointOrder(const UChar *s1, const UChar *s2) {
+    return uprv_strCompare(s1, -1, s2, -1, FALSE, TRUE);
+}
+
+U_CAPI int32_t   U_EXPORT2
+u_strncmp(const UChar     *s1, 
+     const UChar     *s2, 
+     int32_t     n) 
+{
+    if(n > 0) {
+        int32_t rc;
+        for(;;) {
+            rc = (int32_t)*s1 - (int32_t)*s2;
+            if(rc != 0 || *s1 == 0 || --n == 0) {
+                return rc;
+            }
+            ++s1;
+            ++s2;
+        }
+    } else {
+        return 0;
+    }
+}
+
+U_CAPI int32_t U_EXPORT2
+u_strncmpCodePointOrder(const UChar *s1, const UChar *s2, int32_t n) {
+    return uprv_strCompare(s1, n, s2, n, TRUE, TRUE);
+}
+
+U_CAPI UChar* U_EXPORT2
+u_strcpy(UChar     *dst, 
+    const UChar     *src) 
+{
+    UChar *anchor = dst;            /* save a pointer to start of dst */
+
+    while((*(dst++) = *(src++)) != 0) {     /* copy string 2 over              */
+    }
+
+    return anchor;
+}
+
+U_CAPI UChar*  U_EXPORT2
+u_strncpy(UChar     *dst, 
+     const UChar     *src, 
+     int32_t     n) 
+{
+    UChar *anchor = dst;            /* save a pointer to start of dst */
+
+    /* copy string 2 over */
+    while(n > 0 && (*(dst++) = *(src++)) != 0) {
+        --n;
+    }
+
+    return anchor;
+}
+
+U_CAPI int32_t   U_EXPORT2
+u_strlen(const UChar *s) 
+{
+#if U_SIZEOF_WCHAR_T == U_SIZEOF_UCHAR
+    return (int32_t)uprv_wcslen(s);
+#else
+    const UChar *t = s;
+    while(*t != 0) {
+      ++t;
+    }
+    return t - s;
+#endif
+}
+
+U_CAPI int32_t U_EXPORT2
+u_countChar32(const UChar *s, int32_t length) {
+    int32_t count;
+
+    if(s==NULL || length<-1) {
+        return 0;
+    }
+
+    count=0;
+    if(length>=0) {
+        while(length>0) {
+            ++count;
+            if(UTF_IS_LEAD(*s) && length>=2 && UTF_IS_TRAIL(*(s+1))) {
+                s+=2;
+                length-=2;
+            } else {
+                ++s;
+                --length;
+            }
+        }
+    } else /* length==-1 */ {
+        UChar c;
+
+        for(;;) {
+            if((c=*s++)==0) {
+                break;
+            }
+            ++count;
+
+            /*
+             * sufficient to look ahead one because of UTF-16;
+             * safe to look ahead one because at worst that would be the terminating NUL
+             */
+            if(UTF_IS_LEAD(c) && UTF_IS_TRAIL(*s)) {
+                ++s;
+            }
+        }
+    }
+    return count;
+}
+
+U_CAPI UBool U_EXPORT2
+u_strHasMoreChar32Than(const UChar *s, int32_t length, int32_t number) {
+
+    if(number<0) {
+        return TRUE;
+    }
+    if(s==NULL || length<-1) {
+        return FALSE;
+    }
+
+    if(length==-1) {
+        /* s is NUL-terminated */
+        UChar c;
+
+        /* count code points until they exceed */
+        for(;;) {
+            if((c=*s++)==0) {
+                return FALSE;
+            }
+            if(number==0) {
+                return TRUE;
+            }
+            if(U16_IS_LEAD(c) && U16_IS_TRAIL(*s)) {
+                ++s;
+            }
+            --number;
+        }
+    } else {
+        /* length>=0 known */
+        const UChar *limit;
+        int32_t maxSupplementary;
+
+        /* s contains at least (length+1)/2 code points: <=2 UChars per cp */
+        if(((length+1)/2)>number) {
+            return TRUE;
+        }
+
+        /* check if s does not even contain enough UChars */
+        maxSupplementary=length-number;
+        if(maxSupplementary<=0) {
+            return FALSE;
+        }
+        /* there are maxSupplementary=length-number more UChars than asked-for code points */
+
+        /*
+         * count code points until they exceed and also check that there are
+         * no more than maxSupplementary supplementary code points (UChar pairs)
+         */
+        limit=s+length;
+        for(;;) {
+            if(s==limit) {
+                return FALSE;
+            }
+            if(number==0) {
+                return TRUE;
+            }
+            if(U16_IS_LEAD(*s++) && s!=limit && U16_IS_TRAIL(*s)) {
+                ++s;
+                if(--maxSupplementary<=0) {
+                    /* too many pairs - too few code points */
+                    return FALSE;
+                }
+            }
+            --number;
+        }
+    }
+}
+
+U_CAPI UChar * U_EXPORT2
+u_memcpy(UChar *dest, const UChar *src, int32_t count) {
+    return (UChar *)uprv_memcpy(dest, src, count*U_SIZEOF_UCHAR);
+}
+
+U_CAPI UChar * U_EXPORT2
+u_memmove(UChar *dest, const UChar *src, int32_t count) {
+    return (UChar *)uprv_memmove(dest, src, count*U_SIZEOF_UCHAR);
+}
+
+U_CAPI UChar * U_EXPORT2
+u_memset(UChar *dest, UChar c, int32_t count) {
+    if(count > 0) {
+        UChar *ptr = dest;
+        UChar *limit = dest + count;
+
+        while (ptr < limit) {
+            *(ptr++) = c;
+        }
+    }
+    return dest;
+}
+
+U_CAPI int32_t U_EXPORT2
+u_memcmp(const UChar *buf1, const UChar *buf2, int32_t count) {
+    if(count > 0) {
+        const UChar *limit = buf1 + count;
+        int32_t result;
+
+        while (buf1 < limit) {
+            result = (int32_t)(uint16_t)*buf1 - (int32_t)(uint16_t)*buf2;
+            if (result != 0) {
+                return result;
+            }
+            buf1++;
+            buf2++;
+        }
+    }
+    return 0;
+}
+
+U_CAPI int32_t U_EXPORT2
+u_memcmpCodePointOrder(const UChar *s1, const UChar *s2, int32_t count) {
+    return uprv_strCompare(s1, count, s2, count, FALSE, TRUE);
+}
+
+/* u_unescape & support fns ------------------------------------------------- */
+
+/* This map must be in ASCENDING ORDER OF THE ESCAPE CODE */
+static const UChar UNESCAPE_MAP[] = {
+    /*"   0x22, 0x22 */
+    /*'   0x27, 0x27 */
+    /*?   0x3F, 0x3F */
+    /*\   0x5C, 0x5C */
+    /*a*/ 0x61, 0x07,
+    /*b*/ 0x62, 0x08,
+    /*e*/ 0x65, 0x1b,
+    /*f*/ 0x66, 0x0c,
+    /*n*/ 0x6E, 0x0a,
+    /*r*/ 0x72, 0x0d,
+    /*t*/ 0x74, 0x09,
+    /*v*/ 0x76, 0x0b
+};
+enum { UNESCAPE_MAP_LENGTH = sizeof(UNESCAPE_MAP) / sizeof(UNESCAPE_MAP[0]) };
+
+/* Convert one octal digit to a numeric value 0..7, or -1 on failure */
+static int8_t _digit8(UChar c) {
+    if (c >= 0x0030 && c <= 0x0037) {
+        return (int8_t)(c - 0x0030);
+    }
+    return -1;
+}
+
+/* Convert one hex digit to a numeric value 0..F, or -1 on failure */
+static int8_t _digit16(UChar c) {
+    if (c >= 0x0030 && c <= 0x0039) {
+        return (int8_t)(c - 0x0030);
+    }
+    if (c >= 0x0041 && c <= 0x0046) {
+        return (int8_t)(c - (0x0041 - 10));
+    }
+    if (c >= 0x0061 && c <= 0x0066) {
+        return (int8_t)(c - (0x0061 - 10));
+    }
+    return -1;
+}
+
+/* Parse a single escape sequence.  Although this method deals in
+ * UChars, it does not use C++ or UnicodeString.  This allows it to
+ * be used from C contexts. */
+U_CAPI UChar32 U_EXPORT2
+u_unescapeAt(UNESCAPE_CHAR_AT charAt,
+             int32_t *offset,
+             int32_t length,
+             void *context) {
+
+    int32_t start = *offset;
+    UChar c;
+    UChar32 result = 0;
+    int8_t n = 0;
+    int8_t minDig = 0;
+    int8_t maxDig = 0;
+    int8_t bitsPerDigit = 4; 
+    int8_t dig;
+    int32_t i;
+    UBool braces = FALSE;
+
+    /* Check that offset is in range */
+    if (*offset < 0 || *offset >= length) {
+        goto err;
+    }
+
+    /* Fetch first UChar after '\\' */
+    c = charAt((*offset)++, context);
+
+    /* Convert hexadecimal and octal escapes */
+    switch (c) {
+    case 0x0075 /*'u'*/:
+        minDig = maxDig = 4;
+        break;
+    case 0x0055 /*'U'*/:
+        minDig = maxDig = 8;
+        break;
+    case 0x0078 /*'x'*/:
+        minDig = 1;
+        if (*offset < length && charAt(*offset, context) == 0x7B /*{*/) {
+            ++(*offset);
+            braces = TRUE;
+            maxDig = 8;
+        } else {
+            maxDig = 2;
+        }
+        break;
+    default:
+        dig = _digit8(c);
+        if (dig >= 0) {
+            minDig = 1;
+            maxDig = 3;
+            n = 1; /* Already have first octal digit */
+            bitsPerDigit = 3;
+            result = dig;
+        }
+        break;
+    }
+    if (minDig != 0) {
+        while (*offset < length && n < maxDig) {
+            c = charAt(*offset, context);
+            dig = (int8_t)((bitsPerDigit == 3) ? _digit8(c) : _digit16(c));
+            if (dig < 0) {
+                break;
+            }
+            result = (result << bitsPerDigit) | dig;
+            ++(*offset);
+            ++n;
+        }
+        if (n < minDig) {
+            goto err;
+        }
+        if (braces) {
+            if (c != 0x7D /*}*/) {
+                goto err;
+            }
+            ++(*offset);
+        }
+        if (result < 0 || result >= 0x110000) {
+            goto err;
+        }
+        /* If an escape sequence specifies a lead surrogate, see if
+         * there is a trail surrogate after it, either as an escape or
+         * as a literal.  If so, join them up into a supplementary.
+         */
+        if (*offset < length && U16_IS_LEAD(result)) {
+            int32_t ahead = *offset + 1;
+            c = charAt(*offset, context);
+            if (c == 0x5C /*'\\'*/ && ahead < length) {
+                c = (UChar) u_unescapeAt(charAt, &ahead, length, context);
+            }
+            if (U16_IS_TRAIL(c)) {
+                *offset = ahead;
+                result = U16_GET_SUPPLEMENTARY(result, c);
+            }
+        }
+        return result;
+    }
+
+    /* Convert C-style escapes in table */
+    for (i=0; i<UNESCAPE_MAP_LENGTH; i+=2) {
+        if (c == UNESCAPE_MAP[i]) {
+            return UNESCAPE_MAP[i+1];
+        } else if (c < UNESCAPE_MAP[i]) {
+            break;
+        }
+    }
+
+    /* Map \cX to control-X: X & 0x1F */
+    if (c == 0x0063 /*'c'*/ && *offset < length) {
+        c = charAt((*offset)++, context);
+        if (UTF_IS_FIRST_SURROGATE(c) && *offset < length) {
+            UChar c2 = charAt(*offset, context);
+            if (UTF_IS_SECOND_SURROGATE(c2)) {
+                ++(*offset);
+                c = (UChar) UTF16_GET_PAIR_VALUE(c, c2); /* [sic] */
+            }
+        }
+        return 0x1F & c;
+    }
+
+    /* If no special forms are recognized, then consider
+     * the backslash to generically escape the next character.
+     * Deal with surrogate pairs. */
+    if (UTF_IS_FIRST_SURROGATE(c) && *offset < length) {
+        UChar c2 = charAt(*offset, context);
+        if (UTF_IS_SECOND_SURROGATE(c2)) {
+            ++(*offset);
+            return UTF16_GET_PAIR_VALUE(c, c2);
+        }
+    }
+    return c;
+
+ err:
+    /* Invalid escape sequence */
+    *offset = start; /* Reset to initial value */
+    return (UChar32)0xFFFFFFFF;
+}
+
+/* u_unescapeAt() callback to return a UChar from a char* */
+static UChar U_CALLCONV
+_charPtr_charAt(int32_t offset, void *context) {
+    UChar c16;
+    /* It would be more efficient to access the invariant tables
+     * directly but there is no API for that. */
+    u_charsToUChars(((char*) context) + offset, &c16, 1);
+    return c16;
+}
+
+/* Append an escape-free segment of the text; used by u_unescape() */
+static void _appendUChars(UChar *dest, int32_t destCapacity,
+                          const char *src, int32_t srcLen) {
+    if (destCapacity < 0) {
+        destCapacity = 0;
+    }
+    if (srcLen > destCapacity) {
+        srcLen = destCapacity;
+    }
+    u_charsToUChars(src, dest, srcLen);
+}
+
+/* Do an invariant conversion of char* -> UChar*, with escape parsing */
+U_CAPI int32_t U_EXPORT2
+u_unescape(const char *src, UChar *dest, int32_t destCapacity) {
+    const char *segment = src;
+    int32_t i = 0;
+    char c;
+
+    while ((c=*src) != 0) {
+        /* '\\' intentionally written as compiler-specific
+         * character constant to correspond to compiler-specific
+         * char* constants. */
+        if (c == '\\') {
+            int32_t lenParsed = 0;
+            UChar32 c32;
+            if (src != segment) {
+                if (dest != NULL) {
+                    _appendUChars(dest + i, destCapacity - i,
+                                  segment, (int32_t)(src - segment));
+                }
+                i += (int32_t)(src - segment);
+            }
+            ++src; /* advance past '\\' */
+            c32 = (UChar32)u_unescapeAt(_charPtr_charAt, &lenParsed, (int32_t)uprv_strlen(src), (void*)src);
+            if (lenParsed == 0) {
+                goto err;
+            }
+            src += lenParsed; /* advance past escape seq. */
+            if (dest != NULL && UTF_CHAR_LENGTH(c32) <= (destCapacity - i)) {
+                UTF_APPEND_CHAR_UNSAFE(dest, i, c32);
+            } else {
+                i += UTF_CHAR_LENGTH(c32);
+            }
+            segment = src;
+        } else {
+            ++src;
+        }
+    }
+    if (src != segment) {
+        if (dest != NULL) {
+            _appendUChars(dest + i, destCapacity - i,
+                          segment, (int32_t)(src - segment));
+        }
+        i += (int32_t)(src - segment);
+    }
+    if (dest != NULL && i < destCapacity) {
+        dest[i] = 0;
+    }
+    return i;
+
+ err:
+    if (dest != NULL && destCapacity > 0) {
+        *dest = 0;
+    }
+    return 0;
+}
+
+/* NUL-termination of strings ----------------------------------------------- */
+
+/**
+ * NUL-terminate a string no matter what its type.
+ * Set warning and error codes accordingly.
+ */
+#define __TERMINATE_STRING(dest, destCapacity, length, pErrorCode)      \
+    if(pErrorCode!=NULL && U_SUCCESS(*pErrorCode)) {                    \
+        /* not a public function, so no complete argument checking */   \
+                                                                        \
+        if(length<0) {                                                  \
+            /* assume that the caller handles this */                   \
+        } else if(length<destCapacity) {                                \
+            /* NUL-terminate the string, the NUL fits */                \
+            dest[length]=0;                                             \
+            /* unset the not-terminated warning but leave all others */ \
+            if(*pErrorCode==U_STRING_NOT_TERMINATED_WARNING) {          \
+                *pErrorCode=U_ZERO_ERROR;                               \
+            }                                                           \
+        } else if(length==destCapacity) {                               \
+            /* unable to NUL-terminate, but the string itself fit - set a warning code */ \
+            *pErrorCode=U_STRING_NOT_TERMINATED_WARNING;                \
+        } else /* length>destCapacity */ {                              \
+            /* even the string itself did not fit - set an error code */ \
+            *pErrorCode=U_BUFFER_OVERFLOW_ERROR;                        \
+        }                                                               \
+    }
+
+U_CAPI int32_t U_EXPORT2
+u_terminateUChars(UChar *dest, int32_t destCapacity, int32_t length, UErrorCode *pErrorCode) {
+    __TERMINATE_STRING(dest, destCapacity, length, pErrorCode);
+    return length;
+}
+
+U_CAPI int32_t U_EXPORT2
+u_terminateChars(char *dest, int32_t destCapacity, int32_t length, UErrorCode *pErrorCode) {
+    __TERMINATE_STRING(dest, destCapacity, length, pErrorCode);
+    return length;
+}
+
+U_CAPI int32_t U_EXPORT2
+u_terminateUChar32s(UChar32 *dest, int32_t destCapacity, int32_t length, UErrorCode *pErrorCode) {
+    __TERMINATE_STRING(dest, destCapacity, length, pErrorCode);
+    return length;
+}
+
+U_CAPI int32_t U_EXPORT2
+u_terminateWChars(wchar_t *dest, int32_t destCapacity, int32_t length, UErrorCode *pErrorCode) {
+    __TERMINATE_STRING(dest, destCapacity, length, pErrorCode);
+    return length;
+}