345 lines
11 KiB
C++
345 lines
11 KiB
C++
// Copyright (C) 2017 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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// edits.cpp
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// created: 2017feb08 Markus W. Scherer
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#include "unicode/utypes.h"
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#include "unicode/edits.h"
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#include "cmemory.h"
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#include "uassert.h"
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U_NAMESPACE_BEGIN
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namespace {
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// 0000uuuuuuuuuuuu records u+1 unchanged text units.
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const int32_t MAX_UNCHANGED_LENGTH = 0x1000;
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const int32_t MAX_UNCHANGED = MAX_UNCHANGED_LENGTH - 1;
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// 0wwwcccccccccccc with w=1..6 records ccc+1 replacements of w:w text units.
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// No length change.
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const int32_t MAX_SHORT_WIDTH = 6;
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const int32_t MAX_SHORT_CHANGE_LENGTH = 0xfff;
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const int32_t MAX_SHORT_CHANGE = 0x6fff;
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// 0111mmmmmmnnnnnn records a replacement of m text units with n.
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// m or n = 61: actual length follows in the next edits array unit.
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// m or n = 62..63: actual length follows in the next two edits array units.
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// Bit 30 of the actual length is in the head unit.
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// Trailing units have bit 15 set.
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const int32_t LENGTH_IN_1TRAIL = 61;
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const int32_t LENGTH_IN_2TRAIL = 62;
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} // namespace
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Edits::~Edits() {
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if(array != stackArray) {
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uprv_free(array);
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}
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}
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void Edits::reset() {
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length = delta = 0;
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}
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void Edits::addUnchanged(int32_t unchangedLength) {
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if(U_FAILURE(errorCode) || unchangedLength == 0) { return; }
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if(unchangedLength < 0) {
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errorCode = U_ILLEGAL_ARGUMENT_ERROR;
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return;
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}
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// Merge into previous unchanged-text record, if any.
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int32_t last = lastUnit();
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if(last < MAX_UNCHANGED) {
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int32_t remaining = MAX_UNCHANGED - last;
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if (remaining >= unchangedLength) {
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setLastUnit(last + unchangedLength);
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return;
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}
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setLastUnit(MAX_UNCHANGED);
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unchangedLength -= remaining;
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}
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// Split large lengths into multiple units.
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while(unchangedLength >= MAX_UNCHANGED_LENGTH) {
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append(MAX_UNCHANGED);
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unchangedLength -= MAX_UNCHANGED_LENGTH;
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}
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// Write a small (remaining) length.
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if(unchangedLength > 0) {
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append(unchangedLength - 1);
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}
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}
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void Edits::addReplace(int32_t oldLength, int32_t newLength) {
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if(U_FAILURE(errorCode)) { return; }
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if(oldLength == newLength && 0 < oldLength && oldLength <= MAX_SHORT_WIDTH) {
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// Replacement of short oldLength text units by same-length new text.
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// Merge into previous short-replacement record, if any.
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int32_t last = lastUnit();
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if(MAX_UNCHANGED < last && last < MAX_SHORT_CHANGE &&
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(last >> 12) == oldLength && (last & 0xfff) < MAX_SHORT_CHANGE_LENGTH) {
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setLastUnit(last + 1);
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return;
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}
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append(oldLength << 12);
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return;
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}
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if(oldLength < 0 || newLength < 0) {
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errorCode = U_ILLEGAL_ARGUMENT_ERROR;
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return;
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}
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if (oldLength == 0 && newLength == 0) {
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return;
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}
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int32_t newDelta = newLength - oldLength;
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if (newDelta != 0) {
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if ((newDelta > 0 && delta >= 0 && newDelta > (INT32_MAX - delta)) ||
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(newDelta < 0 && delta < 0 && newDelta < (INT32_MIN - delta))) {
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// Integer overflow or underflow.
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errorCode = U_INDEX_OUTOFBOUNDS_ERROR;
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return;
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}
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delta += newDelta;
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}
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int32_t head = 0x7000;
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if (oldLength < LENGTH_IN_1TRAIL && newLength < LENGTH_IN_1TRAIL) {
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head |= oldLength << 6;
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head |= newLength;
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append(head);
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} else if ((capacity - length) >= 5 || growArray()) {
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int32_t limit = length + 1;
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if(oldLength < LENGTH_IN_1TRAIL) {
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head |= oldLength << 6;
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} else if(oldLength <= 0x7fff) {
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head |= LENGTH_IN_1TRAIL << 6;
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array[limit++] = (uint16_t)(0x8000 | oldLength);
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} else {
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head |= (LENGTH_IN_2TRAIL + (oldLength >> 30)) << 6;
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array[limit++] = (uint16_t)(0x8000 | (oldLength >> 15));
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array[limit++] = (uint16_t)(0x8000 | oldLength);
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}
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if(newLength < LENGTH_IN_1TRAIL) {
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head |= newLength;
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} else if(newLength <= 0x7fff) {
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head |= LENGTH_IN_1TRAIL;
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array[limit++] = (uint16_t)(0x8000 | newLength);
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} else {
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head |= LENGTH_IN_2TRAIL + (newLength >> 30);
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array[limit++] = (uint16_t)(0x8000 | (newLength >> 15));
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array[limit++] = (uint16_t)(0x8000 | newLength);
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}
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array[length] = (uint16_t)head;
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length = limit;
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}
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}
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void Edits::append(int32_t r) {
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if(length < capacity || growArray()) {
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array[length++] = (uint16_t)r;
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}
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}
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UBool Edits::growArray() {
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int32_t newCapacity;
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if (array == stackArray) {
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newCapacity = 2000;
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} else if (capacity == INT32_MAX) {
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errorCode = U_BUFFER_OVERFLOW_ERROR;
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return FALSE;
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} else if (capacity >= (INT32_MAX / 2)) {
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newCapacity = INT32_MAX;
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} else {
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newCapacity = 2 * capacity;
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}
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// Grow by at least 5 units so that a maximal change record will fit.
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if ((newCapacity - capacity) < 5) {
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errorCode = U_BUFFER_OVERFLOW_ERROR;
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return FALSE;
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}
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uint16_t *newArray = (uint16_t *)uprv_malloc((size_t)newCapacity * 2);
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if (newArray == NULL) {
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errorCode = U_MEMORY_ALLOCATION_ERROR;
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return FALSE;
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}
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uprv_memcpy(newArray, array, (size_t)length * 2);
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if (array != stackArray) {
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uprv_free(array);
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}
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array = newArray;
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capacity = newCapacity;
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return TRUE;
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}
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UBool Edits::copyErrorTo(UErrorCode &outErrorCode) {
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if (U_FAILURE(outErrorCode)) { return TRUE; }
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if (U_SUCCESS(errorCode)) { return FALSE; }
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outErrorCode = errorCode;
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return TRUE;
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}
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UBool Edits::hasChanges() const {
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if (delta != 0) {
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return TRUE;
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}
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for (int32_t i = 0; i < length; ++i) {
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if (array[i] > MAX_UNCHANGED) {
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return TRUE;
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}
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}
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return FALSE;
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}
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Edits::Iterator::Iterator(const uint16_t *a, int32_t len, UBool oc, UBool crs) :
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array(a), index(0), length(len), remaining(0),
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onlyChanges_(oc), coarse(crs),
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changed(FALSE), oldLength_(0), newLength_(0),
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srcIndex(0), replIndex(0), destIndex(0) {}
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int32_t Edits::Iterator::readLength(int32_t head) {
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if (head < LENGTH_IN_1TRAIL) {
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return head;
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} else if (head < LENGTH_IN_2TRAIL) {
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U_ASSERT(index < length);
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U_ASSERT(array[index] >= 0x8000);
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return array[index++] & 0x7fff;
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} else {
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U_ASSERT((index + 2) <= length);
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U_ASSERT(array[index] >= 0x8000);
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U_ASSERT(array[index + 1] >= 0x8000);
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int32_t len = ((head & 1) << 30) |
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((int32_t)(array[index] & 0x7fff) << 15) |
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(array[index + 1] & 0x7fff);
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index += 2;
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return len;
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}
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}
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void Edits::Iterator::updateIndexes() {
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srcIndex += oldLength_;
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if (changed) {
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replIndex += newLength_;
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}
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destIndex += newLength_;
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}
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UBool Edits::Iterator::noNext() {
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// No change beyond the string.
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changed = FALSE;
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oldLength_ = newLength_ = 0;
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return FALSE;
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}
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UBool Edits::Iterator::next(UBool onlyChanges, UErrorCode &errorCode) {
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if (U_FAILURE(errorCode)) { return FALSE; }
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// We have an errorCode in case we need to start guarding against integer overflows.
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// It is also convenient for caller loops if we bail out when an error was set elsewhere.
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updateIndexes();
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if (remaining > 0) {
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// Fine-grained iterator: Continue a sequence of equal-length changes.
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--remaining;
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return TRUE;
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}
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if (index >= length) {
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return noNext();
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}
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int32_t u = array[index++];
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if (u <= MAX_UNCHANGED) {
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// Combine adjacent unchanged ranges.
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changed = FALSE;
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oldLength_ = u + 1;
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while (index < length && (u = array[index]) <= MAX_UNCHANGED) {
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++index;
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oldLength_ += u + 1;
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}
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newLength_ = oldLength_;
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if (onlyChanges) {
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updateIndexes();
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if (index >= length) {
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return noNext();
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}
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// already fetched u > MAX_UNCHANGED at index
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++index;
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} else {
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return TRUE;
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}
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}
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changed = TRUE;
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if (u <= MAX_SHORT_CHANGE) {
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if (coarse) {
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int32_t w = u >> 12;
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int32_t len = (u & 0xfff) + 1;
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oldLength_ = newLength_ = len * w;
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} else {
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// Split a sequence of equal-length changes that was compressed into one unit.
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oldLength_ = newLength_ = u >> 12;
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remaining = u & 0xfff;
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return TRUE;
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}
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} else {
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U_ASSERT(u <= 0x7fff);
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oldLength_ = readLength((u >> 6) & 0x3f);
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newLength_ = readLength(u & 0x3f);
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if (!coarse) {
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return TRUE;
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}
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}
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// Combine adjacent changes.
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while (index < length && (u = array[index]) > MAX_UNCHANGED) {
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++index;
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if (u <= MAX_SHORT_CHANGE) {
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int32_t w = u >> 12;
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int32_t len = (u & 0xfff) + 1;
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len = len * w;
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oldLength_ += len;
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newLength_ += len;
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} else {
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U_ASSERT(u <= 0x7fff);
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int32_t oldLen = readLength((u >> 6) & 0x3f);
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int32_t newLen = readLength(u & 0x3f);
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oldLength_ += oldLen;
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newLength_ += newLen;
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}
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}
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return TRUE;
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}
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UBool Edits::Iterator::findSourceIndex(int32_t i, UErrorCode &errorCode) {
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if (U_FAILURE(errorCode) || i < 0) { return FALSE; }
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if (i < srcIndex) {
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// Reset the iterator to the start.
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index = remaining = oldLength_ = newLength_ = srcIndex = replIndex = destIndex = 0;
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} else if (i < (srcIndex + oldLength_)) {
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// The index is in the current span.
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return TRUE;
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}
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while (next(FALSE, errorCode)) {
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if (i < (srcIndex + oldLength_)) {
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// The index is in the current span.
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return TRUE;
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}
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if (remaining > 0) {
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// Is the index in one of the remaining compressed edits?
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// srcIndex is the start of the current span, before the remaining ones.
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int32_t len = (remaining + 1) * oldLength_;
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if (i < (srcIndex + len)) {
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int32_t n = (i - srcIndex) / oldLength_; // 1 <= n <= remaining
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len = n * oldLength_;
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srcIndex += len;
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replIndex += len;
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destIndex += len;
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remaining -= n;
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return TRUE;
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}
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// Make next() skip all of these edits at once.
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oldLength_ = newLength_ = len;
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remaining = 0;
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}
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}
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return FALSE;
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}
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U_NAMESPACE_END
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