Add m-esr52 at 52.6.0

1 files changed, 767 insertions, 0 deletions

diff --git a/intl/icu/source/common/utrie2.cpp b/intl/icu/source/common/utrie2.cpp
new file mode 100644
index 000000000..4bd35a924
--- /dev/null
+++ b/intl/icu/source/common/utrie2.cpp
@@ -0,0 +1,767 @@
+// Copyright (C) 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:  utrie2.cpp
+*   encoding:   US-ASCII
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 2008aug16 (starting from a copy of utrie.c)
+*   created by: Markus W. Scherer
+*
+*   This is a common implementation of a Unicode trie.
+*   It is a kind of compressed, serializable table of 16- or 32-bit values associated with
+*   Unicode code points (0..0x10ffff).
+*   This is the second common version of a Unicode trie (hence the name UTrie2).
+*   See utrie2.h for a comparison.
+*
+*   This file contains only the runtime and enumeration code, for read-only access.
+*   See utrie2_builder.c for the builder code.
+*/
+#ifdef UTRIE2_DEBUG
+#   include <stdio.h>
+#endif
+
+#include "unicode/utypes.h"
+#include "unicode/utf.h"
+#include "unicode/utf8.h"
+#include "unicode/utf16.h"
+#include "cmemory.h"
+#include "utrie2.h"
+#include "utrie2_impl.h"
+#include "uassert.h"
+
+/* Public UTrie2 API implementation ----------------------------------------- */
+
+static uint32_t
+get32(const UNewTrie2 *trie, UChar32 c, UBool fromLSCP) {
+    int32_t i2, block;
+
+    if(c>=trie->highStart && (!U_IS_LEAD(c) || fromLSCP)) {
+        return trie->data[trie->dataLength-UTRIE2_DATA_GRANULARITY];
+    }
+
+    if(U_IS_LEAD(c) && fromLSCP) {
+        i2=(UTRIE2_LSCP_INDEX_2_OFFSET-(0xd800>>UTRIE2_SHIFT_2))+
+            (c>>UTRIE2_SHIFT_2);
+    } else {
+        i2=trie->index1[c>>UTRIE2_SHIFT_1]+
+            ((c>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK);
+    }
+    block=trie->index2[i2];
+    return trie->data[block+(c&UTRIE2_DATA_MASK)];
+}
+
+U_CAPI uint32_t U_EXPORT2
+utrie2_get32(const UTrie2 *trie, UChar32 c) {
+    if(trie->data16!=NULL) {
+        return UTRIE2_GET16(trie, c);
+    } else if(trie->data32!=NULL) {
+        return UTRIE2_GET32(trie, c);
+    } else if((uint32_t)c>0x10ffff) {
+        return trie->errorValue;
+    } else {
+        return get32(trie->newTrie, c, TRUE);
+    }
+}
+
+U_CAPI uint32_t U_EXPORT2
+utrie2_get32FromLeadSurrogateCodeUnit(const UTrie2 *trie, UChar32 c) {
+    if(!U_IS_LEAD(c)) {
+        return trie->errorValue;
+    }
+    if(trie->data16!=NULL) {
+        return UTRIE2_GET16_FROM_U16_SINGLE_LEAD(trie, c);
+    } else if(trie->data32!=NULL) {
+        return UTRIE2_GET32_FROM_U16_SINGLE_LEAD(trie, c);
+    } else {
+        return get32(trie->newTrie, c, FALSE);
+    }
+}
+
+static inline int32_t
+u8Index(const UTrie2 *trie, UChar32 c, int32_t i) {
+    int32_t idx=
+        _UTRIE2_INDEX_FROM_CP(
+            trie,
+            trie->data32==NULL ? trie->indexLength : 0,
+            c);
+    return (idx<<3)|i;
+}
+
+U_CAPI int32_t U_EXPORT2
+utrie2_internalU8NextIndex(const UTrie2 *trie, UChar32 c,
+                           const uint8_t *src, const uint8_t *limit) {
+    int32_t i, length;
+    i=0;
+    /* support 64-bit pointers by avoiding cast of arbitrary difference */
+    if((limit-src)<=7) {
+        length=(int32_t)(limit-src);
+    } else {
+        length=7;
+    }
+    c=utf8_nextCharSafeBody(src, &i, length, c, -1);
+    return u8Index(trie, c, i);
+}
+
+U_CAPI int32_t U_EXPORT2
+utrie2_internalU8PrevIndex(const UTrie2 *trie, UChar32 c,
+                           const uint8_t *start, const uint8_t *src) {
+    int32_t i, length;
+    /* support 64-bit pointers by avoiding cast of arbitrary difference */
+    if((src-start)<=7) {
+        i=length=(int32_t)(src-start);
+    } else {
+        i=length=7;
+        start=src-7;
+    }
+    c=utf8_prevCharSafeBody(start, 0, &i, c, -1);
+    i=length-i;  /* number of bytes read backward from src */
+    return u8Index(trie, c, i);
+}
+
+U_CAPI UTrie2 * U_EXPORT2
+utrie2_openFromSerialized(UTrie2ValueBits valueBits,
+                          const void *data, int32_t length, int32_t *pActualLength,
+                          UErrorCode *pErrorCode) {
+    const UTrie2Header *header;
+    const uint16_t *p16;
+    int32_t actualLength;
+
+    UTrie2 tempTrie;
+    UTrie2 *trie;
+
+    if(U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    if( length<=0 || (U_POINTER_MASK_LSB(data, 3)!=0) ||
+        valueBits<0 || UTRIE2_COUNT_VALUE_BITS<=valueBits
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* enough data for a trie header? */
+    if(length<(int32_t)sizeof(UTrie2Header)) {
+        *pErrorCode=U_INVALID_FORMAT_ERROR;
+        return 0;
+    }
+
+    /* check the signature */
+    header=(const UTrie2Header *)data;
+    if(header->signature!=UTRIE2_SIG) {
+        *pErrorCode=U_INVALID_FORMAT_ERROR;
+        return 0;
+    }
+
+    /* get the options */
+    if(valueBits!=(UTrie2ValueBits)(header->options&UTRIE2_OPTIONS_VALUE_BITS_MASK)) {
+        *pErrorCode=U_INVALID_FORMAT_ERROR;
+        return 0;
+    }
+
+    /* get the length values and offsets */
+    uprv_memset(&tempTrie, 0, sizeof(tempTrie));
+    tempTrie.indexLength=header->indexLength;
+    tempTrie.dataLength=header->shiftedDataLength<<UTRIE2_INDEX_SHIFT;
+    tempTrie.index2NullOffset=header->index2NullOffset;
+    tempTrie.dataNullOffset=header->dataNullOffset;
+
+    tempTrie.highStart=header->shiftedHighStart<<UTRIE2_SHIFT_1;
+    tempTrie.highValueIndex=tempTrie.dataLength-UTRIE2_DATA_GRANULARITY;
+    if(valueBits==UTRIE2_16_VALUE_BITS) {
+        tempTrie.highValueIndex+=tempTrie.indexLength;
+    }
+
+    /* calculate the actual length */
+    actualLength=(int32_t)sizeof(UTrie2Header)+tempTrie.indexLength*2;
+    if(valueBits==UTRIE2_16_VALUE_BITS) {
+        actualLength+=tempTrie.dataLength*2;
+    } else {
+        actualLength+=tempTrie.dataLength*4;
+    }
+    if(length<actualLength) {
+        *pErrorCode=U_INVALID_FORMAT_ERROR;  /* not enough bytes */
+        return 0;
+    }
+
+    /* allocate the trie */
+    trie=(UTrie2 *)uprv_malloc(sizeof(UTrie2));
+    if(trie==NULL) {
+        *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
+        return 0;
+    }
+    uprv_memcpy(trie, &tempTrie, sizeof(tempTrie));
+    trie->memory=(uint32_t *)data;
+    trie->length=actualLength;
+    trie->isMemoryOwned=FALSE;
+
+    /* set the pointers to its index and data arrays */
+    p16=(const uint16_t *)(header+1);
+    trie->index=p16;
+    p16+=trie->indexLength;
+
+    /* get the data */
+    switch(valueBits) {
+    case UTRIE2_16_VALUE_BITS:
+        trie->data16=p16;
+        trie->data32=NULL;
+        trie->initialValue=trie->index[trie->dataNullOffset];
+        trie->errorValue=trie->data16[UTRIE2_BAD_UTF8_DATA_OFFSET];
+        break;
+    case UTRIE2_32_VALUE_BITS:
+        trie->data16=NULL;
+        trie->data32=(const uint32_t *)p16;
+        trie->initialValue=trie->data32[trie->dataNullOffset];
+        trie->errorValue=trie->data32[UTRIE2_BAD_UTF8_DATA_OFFSET];
+        break;
+    default:
+        *pErrorCode=U_INVALID_FORMAT_ERROR;
+        return 0;
+    }
+
+    if(pActualLength!=NULL) {
+        *pActualLength=actualLength;
+    }
+    return trie;
+}
+
+U_CAPI UTrie2 * U_EXPORT2
+utrie2_openDummy(UTrie2ValueBits valueBits,
+                 uint32_t initialValue, uint32_t errorValue,
+                 UErrorCode *pErrorCode) {
+    UTrie2 *trie;
+    UTrie2Header *header;
+    uint32_t *p;
+    uint16_t *dest16;
+    int32_t indexLength, dataLength, length, i;
+    int32_t dataMove;  /* >0 if the data is moved to the end of the index array */
+
+    if(U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    if(valueBits<0 || UTRIE2_COUNT_VALUE_BITS<=valueBits) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* calculate the total length of the dummy trie data */
+    indexLength=UTRIE2_INDEX_1_OFFSET;
+    dataLength=UTRIE2_DATA_START_OFFSET+UTRIE2_DATA_GRANULARITY;
+    length=(int32_t)sizeof(UTrie2Header)+indexLength*2;
+    if(valueBits==UTRIE2_16_VALUE_BITS) {
+        length+=dataLength*2;
+    } else {
+        length+=dataLength*4;
+    }
+
+    /* allocate the trie */
+    trie=(UTrie2 *)uprv_malloc(sizeof(UTrie2));
+    if(trie==NULL) {
+        *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
+        return 0;
+    }
+    uprv_memset(trie, 0, sizeof(UTrie2));
+    trie->memory=uprv_malloc(length);
+    if(trie->memory==NULL) {
+        uprv_free(trie);
+        *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
+        return 0;
+    }
+    trie->length=length;
+    trie->isMemoryOwned=TRUE;
+
+    /* set the UTrie2 fields */
+    if(valueBits==UTRIE2_16_VALUE_BITS) {
+        dataMove=indexLength;
+    } else {
+        dataMove=0;
+    }
+
+    trie->indexLength=indexLength;
+    trie->dataLength=dataLength;
+    trie->index2NullOffset=UTRIE2_INDEX_2_OFFSET;
+    trie->dataNullOffset=(uint16_t)dataMove;
+    trie->initialValue=initialValue;
+    trie->errorValue=errorValue;
+    trie->highStart=0;
+    trie->highValueIndex=dataMove+UTRIE2_DATA_START_OFFSET;
+
+    /* set the header fields */
+    header=(UTrie2Header *)trie->memory;
+
+    header->signature=UTRIE2_SIG; /* "Tri2" */
+    header->options=(uint16_t)valueBits;
+
+    header->indexLength=(uint16_t)indexLength;
+    header->shiftedDataLength=(uint16_t)(dataLength>>UTRIE2_INDEX_SHIFT);
+    header->index2NullOffset=(uint16_t)UTRIE2_INDEX_2_OFFSET;
+    header->dataNullOffset=(uint16_t)dataMove;
+    header->shiftedHighStart=0;
+
+    /* fill the index and data arrays */
+    dest16=(uint16_t *)(header+1);
+    trie->index=dest16;
+
+    /* write the index-2 array values shifted right by UTRIE2_INDEX_SHIFT */
+    for(i=0; i<UTRIE2_INDEX_2_BMP_LENGTH; ++i) {
+        *dest16++=(uint16_t)(dataMove>>UTRIE2_INDEX_SHIFT);  /* null data block */
+    }
+
+    /* write UTF-8 2-byte index-2 values, not right-shifted */
+    for(i=0; i<(0xc2-0xc0); ++i) {                                  /* C0..C1 */
+        *dest16++=(uint16_t)(dataMove+UTRIE2_BAD_UTF8_DATA_OFFSET);
+    }
+    for(; i<(0xe0-0xc0); ++i) {                                     /* C2..DF */
+        *dest16++=(uint16_t)dataMove;
+    }
+
+    /* write the 16/32-bit data array */
+    switch(valueBits) {
+    case UTRIE2_16_VALUE_BITS:
+        /* write 16-bit data values */
+        trie->data16=dest16;
+        trie->data32=NULL;
+        for(i=0; i<0x80; ++i) {
+            *dest16++=(uint16_t)initialValue;
+        }
+        for(; i<0xc0; ++i) {
+            *dest16++=(uint16_t)errorValue;
+        }
+        /* highValue and reserved values */
+        for(i=0; i<UTRIE2_DATA_GRANULARITY; ++i) {
+            *dest16++=(uint16_t)initialValue;
+        }
+        break;
+    case UTRIE2_32_VALUE_BITS:
+        /* write 32-bit data values */
+        p=(uint32_t *)dest16;
+        trie->data16=NULL;
+        trie->data32=p;
+        for(i=0; i<0x80; ++i) {
+            *p++=initialValue;
+        }
+        for(; i<0xc0; ++i) {
+            *p++=errorValue;
+        }
+        /* highValue and reserved values */
+        for(i=0; i<UTRIE2_DATA_GRANULARITY; ++i) {
+            *p++=initialValue;
+        }
+        break;
+    default:
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    return trie;
+}
+
+U_CAPI void U_EXPORT2
+utrie2_close(UTrie2 *trie) {
+    if(trie!=NULL) {
+        if(trie->isMemoryOwned) {
+            uprv_free(trie->memory);
+        }
+        if(trie->newTrie!=NULL) {
+            uprv_free(trie->newTrie->data);
+            uprv_free(trie->newTrie);
+        }
+        uprv_free(trie);
+    }
+}
+
+U_CAPI int32_t U_EXPORT2
+utrie2_getVersion(const void *data, int32_t length, UBool anyEndianOk) {
+    uint32_t signature;
+    if(length<16 || data==NULL || (U_POINTER_MASK_LSB(data, 3)!=0)) {
+        return 0;
+    }
+    signature=*(const uint32_t *)data;
+    if(signature==UTRIE2_SIG) {
+        return 2;
+    }
+    if(anyEndianOk && signature==UTRIE2_OE_SIG) {
+        return 2;
+    }
+    if(signature==UTRIE_SIG) {
+        return 1;
+    }
+    if(anyEndianOk && signature==UTRIE_OE_SIG) {
+        return 1;
+    }
+    return 0;
+}
+
+U_CAPI UBool U_EXPORT2
+utrie2_isFrozen(const UTrie2 *trie) {
+    return (UBool)(trie->newTrie==NULL);
+}
+
+U_CAPI int32_t U_EXPORT2
+utrie2_serialize(const UTrie2 *trie,
+                 void *data, int32_t capacity,
+                 UErrorCode *pErrorCode) {
+    /* argument check */
+    if(U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+
+    if( trie==NULL || trie->memory==NULL || trie->newTrie!=NULL ||
+        capacity<0 || (capacity>0 && (data==NULL || (U_POINTER_MASK_LSB(data, 3)!=0)))
+    ) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    if(capacity>=trie->length) {
+        uprv_memcpy(data, trie->memory, trie->length);
+    } else {
+        *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
+    }
+    return trie->length;
+}
+
+U_CAPI int32_t U_EXPORT2
+utrie2_swap(const UDataSwapper *ds,
+            const void *inData, int32_t length, void *outData,
+            UErrorCode *pErrorCode) {
+    const UTrie2Header *inTrie;
+    UTrie2Header trie;
+    int32_t dataLength, size;
+    UTrie2ValueBits valueBits;
+
+    if(U_FAILURE(*pErrorCode)) {
+        return 0;
+    }
+    if(ds==NULL || inData==NULL || (length>=0 && outData==NULL)) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return 0;
+    }
+
+    /* setup and swapping */
+    if(length>=0 && length<(int32_t)sizeof(UTrie2Header)) {
+        *pErrorCode=U_INDEX_OUTOFBOUNDS_ERROR;
+        return 0;
+    }
+
+    inTrie=(const UTrie2Header *)inData;
+    trie.signature=ds->readUInt32(inTrie->signature);
+    trie.options=ds->readUInt16(inTrie->options);
+    trie.indexLength=ds->readUInt16(inTrie->indexLength);
+    trie.shiftedDataLength=ds->readUInt16(inTrie->shiftedDataLength);
+
+    valueBits=(UTrie2ValueBits)(trie.options&UTRIE2_OPTIONS_VALUE_BITS_MASK);
+    dataLength=(int32_t)trie.shiftedDataLength<<UTRIE2_INDEX_SHIFT;
+
+    if( trie.signature!=UTRIE2_SIG ||
+        valueBits<0 || UTRIE2_COUNT_VALUE_BITS<=valueBits ||
+        trie.indexLength<UTRIE2_INDEX_1_OFFSET ||
+        dataLength<UTRIE2_DATA_START_OFFSET
+    ) {
+        *pErrorCode=U_INVALID_FORMAT_ERROR; /* not a UTrie */
+        return 0;
+    }
+
+    size=sizeof(UTrie2Header)+trie.indexLength*2;
+    switch(valueBits) {
+    case UTRIE2_16_VALUE_BITS:
+        size+=dataLength*2;
+        break;
+    case UTRIE2_32_VALUE_BITS:
+        size+=dataLength*4;
+        break;
+    default:
+        *pErrorCode=U_INVALID_FORMAT_ERROR;
+        return 0;
+    }
+
+    if(length>=0) {
+        UTrie2Header *outTrie;
+
+        if(length<size) {
+            *pErrorCode=U_INDEX_OUTOFBOUNDS_ERROR;
+            return 0;
+        }
+
+        outTrie=(UTrie2Header *)outData;
+
+        /* swap the header */
+        ds->swapArray32(ds, &inTrie->signature, 4, &outTrie->signature, pErrorCode);
+        ds->swapArray16(ds, &inTrie->options, 12, &outTrie->options, pErrorCode);
+
+        /* swap the index and the data */
+        switch(valueBits) {
+        case UTRIE2_16_VALUE_BITS:
+            ds->swapArray16(ds, inTrie+1, (trie.indexLength+dataLength)*2, outTrie+1, pErrorCode);
+            break;
+        case UTRIE2_32_VALUE_BITS:
+            ds->swapArray16(ds, inTrie+1, trie.indexLength*2, outTrie+1, pErrorCode);
+            ds->swapArray32(ds, (const uint16_t *)(inTrie+1)+trie.indexLength, dataLength*4,
+                                     (uint16_t *)(outTrie+1)+trie.indexLength, pErrorCode);
+            break;
+        default:
+            *pErrorCode=U_INVALID_FORMAT_ERROR;
+            return 0;
+        }
+    }
+
+    return size;
+}
+
+// utrie2_swapAnyVersion() should be defined here but lives in utrie2_builder.c
+// to avoid a dependency from utrie2.cpp on utrie.c.
+
+/* enumeration -------------------------------------------------------------- */
+
+#define MIN_VALUE(a, b) ((a)<(b) ? (a) : (b))
+
+/* default UTrie2EnumValue() returns the input value itself */
+static uint32_t U_CALLCONV
+enumSameValue(const void * /*context*/, uint32_t value) {
+    return value;
+}
+
+/**
+ * Enumerate all ranges of code points with the same relevant values.
+ * The values are transformed from the raw trie entries by the enumValue function.
+ *
+ * Currently requires start<limit and both start and limit must be multiples
+ * of UTRIE2_DATA_BLOCK_LENGTH.
+ *
+ * Optimizations:
+ * - Skip a whole block if we know that it is filled with a single value,
+ *   and it is the same as we visited just before.
+ * - Handle the null block specially because we know a priori that it is filled
+ *   with a single value.
+ */
+static void
+enumEitherTrie(const UTrie2 *trie,
+               UChar32 start, UChar32 limit,
+               UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange, const void *context) {
+    const uint32_t *data32;
+    const uint16_t *idx;
+
+    uint32_t value, prevValue, initialValue;
+    UChar32 c, prev, highStart;
+    int32_t j, i2Block, prevI2Block, index2NullOffset, block, prevBlock, nullBlock;
+
+    if(enumRange==NULL) {
+        return;
+    }
+    if(enumValue==NULL) {
+        enumValue=enumSameValue;
+    }
+
+    if(trie->newTrie==NULL) {
+        /* frozen trie */
+        idx=trie->index;
+        U_ASSERT(idx!=NULL); /* the following code assumes trie->newTrie is not NULL when idx is NULL */
+        data32=trie->data32;
+
+        index2NullOffset=trie->index2NullOffset;
+        nullBlock=trie->dataNullOffset;
+    } else {
+        /* unfrozen, mutable trie */
+        idx=NULL;
+        data32=trie->newTrie->data;
+        U_ASSERT(data32!=NULL); /* the following code assumes idx is not NULL when data32 is NULL */
+
+        index2NullOffset=trie->newTrie->index2NullOffset;
+        nullBlock=trie->newTrie->dataNullOffset;
+    }
+
+    highStart=trie->highStart;
+
+    /* get the enumeration value that corresponds to an initial-value trie data entry */
+    initialValue=enumValue(context, trie->initialValue);
+
+    /* set variables for previous range */
+    prevI2Block=-1;
+    prevBlock=-1;
+    prev=start;
+    prevValue=0;
+
+    /* enumerate index-2 blocks */
+    for(c=start; c<limit && c<highStart;) {
+        /* Code point limit for iterating inside this i2Block. */
+        UChar32 tempLimit=c+UTRIE2_CP_PER_INDEX_1_ENTRY;
+        if(limit<tempLimit) {
+            tempLimit=limit;
+        }
+        if(c<=0xffff) {
+            if(!U_IS_SURROGATE(c)) {
+                i2Block=c>>UTRIE2_SHIFT_2;
+            } else if(U_IS_SURROGATE_LEAD(c)) {
+                /*
+                 * Enumerate values for lead surrogate code points, not code units:
+                 * This special block has half the normal length.
+                 */
+                i2Block=UTRIE2_LSCP_INDEX_2_OFFSET;
+                tempLimit=MIN_VALUE(0xdc00, limit);
+            } else {
+                /*
+                 * Switch back to the normal part of the index-2 table.
+                 * Enumerate the second half of the surrogates block.
+                 */
+                i2Block=0xd800>>UTRIE2_SHIFT_2;
+                tempLimit=MIN_VALUE(0xe000, limit);
+            }
+        } else {
+            /* supplementary code points */
+            if(idx!=NULL) {
+                i2Block=idx[(UTRIE2_INDEX_1_OFFSET-UTRIE2_OMITTED_BMP_INDEX_1_LENGTH)+
+                              (c>>UTRIE2_SHIFT_1)];
+            } else {
+                i2Block=trie->newTrie->index1[c>>UTRIE2_SHIFT_1];
+            }
+            if(i2Block==prevI2Block && (c-prev)>=UTRIE2_CP_PER_INDEX_1_ENTRY) {
+                /*
+                 * The index-2 block is the same as the previous one, and filled with prevValue.
+                 * Only possible for supplementary code points because the linear-BMP index-2
+                 * table creates unique i2Block values.
+                 */
+                c+=UTRIE2_CP_PER_INDEX_1_ENTRY;
+                continue;
+            }
+        }
+        prevI2Block=i2Block;
+        if(i2Block==index2NullOffset) {
+            /* this is the null index-2 block */
+            if(prevValue!=initialValue) {
+                if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
+                    return;
+                }
+                prevBlock=nullBlock;
+                prev=c;
+                prevValue=initialValue;
+            }
+            c+=UTRIE2_CP_PER_INDEX_1_ENTRY;
+        } else {
+            /* enumerate data blocks for one index-2 block */
+            int32_t i2, i2Limit;
+            i2=(c>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK;
+            if((c>>UTRIE2_SHIFT_1)==(tempLimit>>UTRIE2_SHIFT_1)) {
+                i2Limit=(tempLimit>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK;
+            } else {
+                i2Limit=UTRIE2_INDEX_2_BLOCK_LENGTH;
+            }
+            for(; i2<i2Limit; ++i2) {
+                if(idx!=NULL) {
+                    block=(int32_t)idx[i2Block+i2]<<UTRIE2_INDEX_SHIFT;
+                } else {
+                    block=trie->newTrie->index2[i2Block+i2];
+                }
+                if(block==prevBlock && (c-prev)>=UTRIE2_DATA_BLOCK_LENGTH) {
+                    /* the block is the same as the previous one, and filled with prevValue */
+                    c+=UTRIE2_DATA_BLOCK_LENGTH;
+                    continue;
+                }
+                prevBlock=block;
+                if(block==nullBlock) {
+                    /* this is the null data block */
+                    if(prevValue!=initialValue) {
+                        if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
+                            return;
+                        }
+                        prev=c;
+                        prevValue=initialValue;
+                    }
+                    c+=UTRIE2_DATA_BLOCK_LENGTH;
+                } else {
+                    for(j=0; j<UTRIE2_DATA_BLOCK_LENGTH; ++j) {
+                        value=enumValue(context, data32!=NULL ? data32[block+j] : idx[block+j]);
+                        if(value!=prevValue) {
+                            if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
+                                return;
+                            }
+                            prev=c;
+                            prevValue=value;
+                        }
+                        ++c;
+                    }
+                }
+            }
+        }
+    }
+
+    if(c>limit) {
+        c=limit;  /* could be higher if in the index2NullOffset */
+    } else if(c<limit) {
+        /* c==highStart<limit */
+        uint32_t highValue;
+        if(idx!=NULL) {
+            highValue=
+                data32!=NULL ?
+                    data32[trie->highValueIndex] :
+                    idx[trie->highValueIndex];
+        } else {
+            highValue=trie->newTrie->data[trie->newTrie->dataLength-UTRIE2_DATA_GRANULARITY];
+        }
+        value=enumValue(context, highValue);
+        if(value!=prevValue) {
+            if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
+                return;
+            }
+            prev=c;
+            prevValue=value;
+        }
+        c=limit;
+    }
+
+    /* deliver last range */
+    enumRange(context, prev, c-1, prevValue);
+}
+
+U_CAPI void U_EXPORT2
+utrie2_enum(const UTrie2 *trie,
+            UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange, const void *context) {
+    enumEitherTrie(trie, 0, 0x110000, enumValue, enumRange, context);
+}
+
+U_CAPI void U_EXPORT2
+utrie2_enumForLeadSurrogate(const UTrie2 *trie, UChar32 lead,
+                            UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange,
+                            const void *context) {
+    if(!U16_IS_LEAD(lead)) {
+        return;
+    }
+    lead=(lead-0xd7c0)<<10;   /* start code point */
+    enumEitherTrie(trie, lead, lead+0x400, enumValue, enumRange, context);
+}
+
+/* C++ convenience wrappers ------------------------------------------------- */
+
+U_NAMESPACE_BEGIN
+
+uint16_t BackwardUTrie2StringIterator::previous16() {
+    codePointLimit=codePointStart;
+    if(start>=codePointStart) {
+        codePoint=U_SENTINEL;
+        return 0;
+    }
+    uint16_t result;
+    UTRIE2_U16_PREV16(trie, start, codePointStart, codePoint, result);
+    return result;
+}
+
+uint16_t ForwardUTrie2StringIterator::next16() {
+    codePointStart=codePointLimit;
+    if(codePointLimit==limit) {
+        codePoint=U_SENTINEL;
+        return 0;
+    }
+    uint16_t result;
+    UTRIE2_U16_NEXT16(trie, codePointLimit, limit, codePoint, result);
+    return result;
+}
+
+U_NAMESPACE_END