scuffed-code/icu4c/source/common/edits.cpp

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// © 2017 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
// edits.cpp
// created: 2017feb08 Markus W. Scherer
#include "unicode/utypes.h"
#include "unicode/edits.h"
#include "cmemory.h"
#include "uassert.h"
U_NAMESPACE_BEGIN
namespace {
// 0000uuuuuuuuuuuu records u+1 unchanged text units.
const int32_t MAX_UNCHANGED_LENGTH = 0x1000;
const int32_t MAX_UNCHANGED = MAX_UNCHANGED_LENGTH - 1;
// 0wwwcccccccccccc with w=1..6 records ccc+1 replacements of w:w text units.
// No length change.
const int32_t MAX_SHORT_WIDTH = 6;
const int32_t MAX_SHORT_CHANGE_LENGTH = 0xfff;
const int32_t MAX_SHORT_CHANGE = 0x6fff;
// 0111mmmmmmnnnnnn records a replacement of m text units with n.
// m or n = 61: actual length follows in the next edits array unit.
// m or n = 62..63: actual length follows in the next two edits array units.
// Bit 30 of the actual length is in the head unit.
// Trailing units have bit 15 set.
const int32_t LENGTH_IN_1TRAIL = 61;
const int32_t LENGTH_IN_2TRAIL = 62;
} // namespace
void Edits::releaseArray() U_NOEXCEPT {
if (array != stackArray) {
uprv_free(array);
}
}
Edits &Edits::copyArray(const Edits &other) {
if (U_FAILURE(errorCode_)) {
length = delta = numChanges = 0;
return *this;
}
if (length > capacity) {
uint16_t *newArray = (uint16_t *)uprv_malloc((size_t)length * 2);
if (newArray == nullptr) {
length = delta = numChanges = 0;
errorCode_ = U_MEMORY_ALLOCATION_ERROR;
return *this;
}
releaseArray();
array = newArray;
capacity = length;
}
if (length > 0) {
uprv_memcpy(array, other.array, (size_t)length * 2);
}
return *this;
}
Edits &Edits::moveArray(Edits &src) U_NOEXCEPT {
if (U_FAILURE(errorCode_)) {
length = delta = numChanges = 0;
return *this;
}
releaseArray();
if (length > STACK_CAPACITY) {
array = src.array;
capacity = src.capacity;
src.array = src.stackArray;
src.capacity = STACK_CAPACITY;
src.reset();
return *this;
}
array = stackArray;
capacity = STACK_CAPACITY;
if (length > 0) {
uprv_memcpy(array, src.array, (size_t)length * 2);
}
return *this;
}
Edits &Edits::operator=(const Edits &other) {
length = other.length;
delta = other.delta;
numChanges = other.numChanges;
errorCode_ = other.errorCode_;
return copyArray(other);
}
Edits &Edits::operator=(Edits &&src) U_NOEXCEPT {
length = src.length;
delta = src.delta;
numChanges = src.numChanges;
errorCode_ = src.errorCode_;
return moveArray(src);
}
Edits::~Edits() {
releaseArray();
}
void Edits::reset() U_NOEXCEPT {
length = delta = numChanges = 0;
errorCode_ = U_ZERO_ERROR;
}
void Edits::addUnchanged(int32_t unchangedLength) {
if(U_FAILURE(errorCode_) || unchangedLength == 0) { return; }
if(unchangedLength < 0) {
errorCode_ = U_ILLEGAL_ARGUMENT_ERROR;
return;
}
// Merge into previous unchanged-text record, if any.
int32_t last = lastUnit();
if(last < MAX_UNCHANGED) {
int32_t remaining = MAX_UNCHANGED - last;
if (remaining >= unchangedLength) {
setLastUnit(last + unchangedLength);
return;
}
setLastUnit(MAX_UNCHANGED);
unchangedLength -= remaining;
}
// Split large lengths into multiple units.
while(unchangedLength >= MAX_UNCHANGED_LENGTH) {
append(MAX_UNCHANGED);
unchangedLength -= MAX_UNCHANGED_LENGTH;
}
// Write a small (remaining) length.
if(unchangedLength > 0) {
append(unchangedLength - 1);
}
}
void Edits::addReplace(int32_t oldLength, int32_t newLength) {
if(U_FAILURE(errorCode_)) { return; }
if(oldLength == newLength && 0 < oldLength && oldLength <= MAX_SHORT_WIDTH) {
// Replacement of short oldLength text units by same-length new text.
// Merge into previous short-replacement record, if any.
++numChanges;
int32_t last = lastUnit();
if(MAX_UNCHANGED < last && last < MAX_SHORT_CHANGE &&
(last >> 12) == oldLength && (last & 0xfff) < MAX_SHORT_CHANGE_LENGTH) {
setLastUnit(last + 1);
return;
}
append(oldLength << 12);
return;
}
if(oldLength < 0 || newLength < 0) {
errorCode_ = U_ILLEGAL_ARGUMENT_ERROR;
return;
}
if (oldLength == 0 && newLength == 0) {
return;
}
++numChanges;
int32_t newDelta = newLength - oldLength;
if (newDelta != 0) {
if ((newDelta > 0 && delta >= 0 && newDelta > (INT32_MAX - delta)) ||
(newDelta < 0 && delta < 0 && newDelta < (INT32_MIN - delta))) {
// Integer overflow or underflow.
errorCode_ = U_INDEX_OUTOFBOUNDS_ERROR;
return;
}
delta += newDelta;
}
int32_t head = 0x7000;
if (oldLength < LENGTH_IN_1TRAIL && newLength < LENGTH_IN_1TRAIL) {
head |= oldLength << 6;
head |= newLength;
append(head);
} else if ((capacity - length) >= 5 || growArray()) {
int32_t limit = length + 1;
if(oldLength < LENGTH_IN_1TRAIL) {
head |= oldLength << 6;
} else if(oldLength <= 0x7fff) {
head |= LENGTH_IN_1TRAIL << 6;
array[limit++] = (uint16_t)(0x8000 | oldLength);
} else {
head |= (LENGTH_IN_2TRAIL + (oldLength >> 30)) << 6;
array[limit++] = (uint16_t)(0x8000 | (oldLength >> 15));
array[limit++] = (uint16_t)(0x8000 | oldLength);
}
if(newLength < LENGTH_IN_1TRAIL) {
head |= newLength;
} else if(newLength <= 0x7fff) {
head |= LENGTH_IN_1TRAIL;
array[limit++] = (uint16_t)(0x8000 | newLength);
} else {
head |= LENGTH_IN_2TRAIL + (newLength >> 30);
array[limit++] = (uint16_t)(0x8000 | (newLength >> 15));
array[limit++] = (uint16_t)(0x8000 | newLength);
}
array[length] = (uint16_t)head;
length = limit;
}
}
void Edits::append(int32_t r) {
if(length < capacity || growArray()) {
array[length++] = (uint16_t)r;
}
}
UBool Edits::growArray() {
int32_t newCapacity;
if (array == stackArray) {
newCapacity = 2000;
} else if (capacity == INT32_MAX) {
// Not U_BUFFER_OVERFLOW_ERROR because that could be confused on a string transform API
// with a result-string-buffer overflow.
errorCode_ = U_INDEX_OUTOFBOUNDS_ERROR;
return FALSE;
} else if (capacity >= (INT32_MAX / 2)) {
newCapacity = INT32_MAX;
} else {
newCapacity = 2 * capacity;
}
// Grow by at least 5 units so that a maximal change record will fit.
if ((newCapacity - capacity) < 5) {
errorCode_ = U_INDEX_OUTOFBOUNDS_ERROR;
return FALSE;
}
uint16_t *newArray = (uint16_t *)uprv_malloc((size_t)newCapacity * 2);
if (newArray == NULL) {
errorCode_ = U_MEMORY_ALLOCATION_ERROR;
return FALSE;
}
uprv_memcpy(newArray, array, (size_t)length * 2);
releaseArray();
array = newArray;
capacity = newCapacity;
return TRUE;
}
UBool Edits::copyErrorTo(UErrorCode &outErrorCode) {
if (U_FAILURE(outErrorCode)) { return TRUE; }
if (U_SUCCESS(errorCode_)) { return FALSE; }
outErrorCode = errorCode_;
return TRUE;
}
Edits &Edits::mergeAndAppend(const Edits &ab, const Edits &bc, UErrorCode &errorCode) {
if (copyErrorTo(errorCode)) { return *this; }
// Picture string a --(Edits ab)--> string b --(Edits bc)--> string c.
// Parallel iteration over both Edits.
Iterator abIter = ab.getFineIterator();
Iterator bcIter = bc.getFineIterator();
UBool abHasNext = TRUE, bcHasNext = TRUE;
// Copy iterator state into local variables, so that we can modify and subdivide spans.
// ab old & new length, bc old & new length
int32_t aLength = 0, ab_bLength = 0, bc_bLength = 0, cLength = 0;
// When we have different-intermediate-length changes, we accumulate a larger change.
int32_t pending_aLength = 0, pending_cLength = 0;
for (;;) {
// At this point, for each of the two iterators:
// Either we are done with the locally cached current edit,
// and its intermediate-string length has been reset,
// or we will continue to work with a truncated remainder of this edit.
//
// If the current edit is done, and the iterator has not yet reached the end,
// then we fetch the next edit. This is true for at least one of the iterators.
//
// Normally it does not matter whether we fetch from ab and then bc or vice versa.
// However, the result is observably different when
// ab deletions meet bc insertions at the same intermediate-string index.
// Some users expect the bc insertions to come first, so we fetch from bc first.
if (bc_bLength == 0) {
if (bcHasNext && (bcHasNext = bcIter.next(errorCode))) {
bc_bLength = bcIter.oldLength();
cLength = bcIter.newLength();
if (bc_bLength == 0) {
// insertion
if (ab_bLength == 0 || !abIter.hasChange()) {
addReplace(pending_aLength, pending_cLength + cLength);
pending_aLength = pending_cLength = 0;
} else {
pending_cLength += cLength;
}
continue;
}
}
// else see if the other iterator is done, too.
}
if (ab_bLength == 0) {
if (abHasNext && (abHasNext = abIter.next(errorCode))) {
aLength = abIter.oldLength();
ab_bLength = abIter.newLength();
if (ab_bLength == 0) {
// deletion
if (bc_bLength == bcIter.oldLength() || !bcIter.hasChange()) {
addReplace(pending_aLength + aLength, pending_cLength);
pending_aLength = pending_cLength = 0;
} else {
pending_aLength += aLength;
}
continue;
}
} else if (bc_bLength == 0) {
// Both iterators are done at the same time:
// The intermediate-string lengths match.
break;
} else {
// The ab output string is shorter than the bc input string.
if (!copyErrorTo(errorCode)) {
errorCode = U_ILLEGAL_ARGUMENT_ERROR;
}
return *this;
}
}
if (bc_bLength == 0) {
// The bc input string is shorter than the ab output string.
if (!copyErrorTo(errorCode)) {
errorCode = U_ILLEGAL_ARGUMENT_ERROR;
}
return *this;
}
// Done fetching: ab_bLength > 0 && bc_bLength > 0
// The current state has two parts:
// - Past: We accumulate a longer ac edit in the "pending" variables.
// - Current: We have copies of the current ab/bc edits in local variables.
// At least one side is newly fetched.
// One side might be a truncated remainder of an edit we fetched earlier.
if (!abIter.hasChange() && !bcIter.hasChange()) {
// An unchanged span all the way from string a to string c.
if (pending_aLength != 0 || pending_cLength != 0) {
addReplace(pending_aLength, pending_cLength);
pending_aLength = pending_cLength = 0;
}
int32_t unchangedLength = aLength <= cLength ? aLength : cLength;
addUnchanged(unchangedLength);
ab_bLength = aLength -= unchangedLength;
bc_bLength = cLength -= unchangedLength;
// At least one of the unchanged spans is now empty.
continue;
}
if (!abIter.hasChange() && bcIter.hasChange()) {
// Unchanged a->b but changed b->c.
if (ab_bLength >= bc_bLength) {
// Split the longer unchanged span into change + remainder.
addReplace(pending_aLength + bc_bLength, pending_cLength + cLength);
pending_aLength = pending_cLength = 0;
aLength = ab_bLength -= bc_bLength;
bc_bLength = 0;
continue;
}
// Handle the shorter unchanged span below like a change.
} else if (abIter.hasChange() && !bcIter.hasChange()) {
// Changed a->b and then unchanged b->c.
if (ab_bLength <= bc_bLength) {
// Split the longer unchanged span into change + remainder.
addReplace(pending_aLength + aLength, pending_cLength + ab_bLength);
pending_aLength = pending_cLength = 0;
cLength = bc_bLength -= ab_bLength;
ab_bLength = 0;
continue;
}
// Handle the shorter unchanged span below like a change.
} else { // both abIter.hasChange() && bcIter.hasChange()
if (ab_bLength == bc_bLength) {
// Changes on both sides up to the same position. Emit & reset.
addReplace(pending_aLength + aLength, pending_cLength + cLength);
pending_aLength = pending_cLength = 0;
ab_bLength = bc_bLength = 0;
continue;
}
}
// Accumulate the a->c change, reset the shorter side,
// keep a remainder of the longer one.
pending_aLength += aLength;
pending_cLength += cLength;
if (ab_bLength < bc_bLength) {
bc_bLength -= ab_bLength;
cLength = ab_bLength = 0;
} else { // ab_bLength > bc_bLength
ab_bLength -= bc_bLength;
aLength = bc_bLength = 0;
}
}
if (pending_aLength != 0 || pending_cLength != 0) {
addReplace(pending_aLength, pending_cLength);
}
copyErrorTo(errorCode);
return *this;
}
Edits::Iterator::Iterator(const uint16_t *a, int32_t len, UBool oc, UBool crs) :
array(a), index(0), length(len), remaining(0),
onlyChanges_(oc), coarse(crs),
changed(FALSE), oldLength_(0), newLength_(0),
srcIndex(0), replIndex(0), destIndex(0) {}
int32_t Edits::Iterator::readLength(int32_t head) {
if (head < LENGTH_IN_1TRAIL) {
return head;
} else if (head < LENGTH_IN_2TRAIL) {
U_ASSERT(index < length);
U_ASSERT(array[index] >= 0x8000);
return array[index++] & 0x7fff;
} else {
U_ASSERT((index + 2) <= length);
U_ASSERT(array[index] >= 0x8000);
U_ASSERT(array[index + 1] >= 0x8000);
int32_t len = ((head & 1) << 30) |
((int32_t)(array[index] & 0x7fff) << 15) |
(array[index + 1] & 0x7fff);
index += 2;
return len;
}
}
void Edits::Iterator::updateIndexes() {
srcIndex += oldLength_;
if (changed) {
replIndex += newLength_;
}
destIndex += newLength_;
}
UBool Edits::Iterator::noNext() {
// No change beyond the string.
changed = FALSE;
oldLength_ = newLength_ = 0;
return FALSE;
}
UBool Edits::Iterator::next(UBool onlyChanges, UErrorCode &errorCode) {
if (U_FAILURE(errorCode)) { return FALSE; }
// We have an errorCode in case we need to start guarding against integer overflows.
// It is also convenient for caller loops if we bail out when an error was set elsewhere.
updateIndexes();
if (remaining > 0) {
// Fine-grained iterator: Continue a sequence of equal-length changes.
--remaining;
return TRUE;
}
if (index >= length) {
return noNext();
}
int32_t u = array[index++];
if (u <= MAX_UNCHANGED) {
// Combine adjacent unchanged ranges.
changed = FALSE;
oldLength_ = u + 1;
while (index < length && (u = array[index]) <= MAX_UNCHANGED) {
++index;
oldLength_ += u + 1;
}
newLength_ = oldLength_;
if (onlyChanges) {
updateIndexes();
if (index >= length) {
return noNext();
}
// already fetched u > MAX_UNCHANGED at index
++index;
} else {
return TRUE;
}
}
changed = TRUE;
if (u <= MAX_SHORT_CHANGE) {
if (coarse) {
int32_t w = u >> 12;
int32_t len = (u & 0xfff) + 1;
oldLength_ = newLength_ = len * w;
} else {
// Split a sequence of equal-length changes that was compressed into one unit.
oldLength_ = newLength_ = u >> 12;
remaining = u & 0xfff;
return TRUE;
}
} else {
U_ASSERT(u <= 0x7fff);
oldLength_ = readLength((u >> 6) & 0x3f);
newLength_ = readLength(u & 0x3f);
if (!coarse) {
return TRUE;
}
}
// Combine adjacent changes.
while (index < length && (u = array[index]) > MAX_UNCHANGED) {
++index;
if (u <= MAX_SHORT_CHANGE) {
int32_t w = u >> 12;
int32_t len = (u & 0xfff) + 1;
len = len * w;
oldLength_ += len;
newLength_ += len;
} else {
U_ASSERT(u <= 0x7fff);
int32_t oldLen = readLength((u >> 6) & 0x3f);
int32_t newLen = readLength(u & 0x3f);
oldLength_ += oldLen;
newLength_ += newLen;
}
}
return TRUE;
}
int32_t Edits::Iterator::findIndex(int32_t i, UBool findSource, UErrorCode &errorCode) {
if (U_FAILURE(errorCode) || i < 0) { return -1; }
int32_t spanStart, spanLength;
if (findSource) { // find source index
spanStart = srcIndex;
spanLength = oldLength_;
} else { // find destination index
spanStart = destIndex;
spanLength = newLength_;
}
if (i < spanStart) {
// Reset the iterator to the start.
index = remaining = oldLength_ = newLength_ = srcIndex = replIndex = destIndex = 0;
} else if (i < (spanStart + spanLength)) {
// The index is in the current span.
return 0;
}
while (next(FALSE, errorCode)) {
if (findSource) {
spanStart = srcIndex;
spanLength = oldLength_;
} else {
spanStart = destIndex;
spanLength = newLength_;
}
if (i < (spanStart + spanLength)) {
// The index is in the current span.
return 0;
}
if (remaining > 0) {
// Is the index in one of the remaining compressed edits?
// spanStart is the start of the current span, before the remaining ones.
int32_t len = (remaining + 1) * spanLength;
if (i < (spanStart + len)) {
int32_t n = (i - spanStart) / spanLength; // 1 <= n <= remaining
len = n * spanLength;
srcIndex += len;
replIndex += len;
destIndex += len;
remaining -= n;
return 0;
}
// Make next() skip all of these edits at once.
oldLength_ = newLength_ = len;
remaining = 0;
}
}
return 1;
}
int32_t Edits::Iterator::destinationIndexFromSourceIndex(int32_t i, UErrorCode &errorCode) {
int32_t where = findIndex(i, TRUE, errorCode);
if (where < 0) {
// Error or before the string.
return 0;
}
if (where > 0 || i == srcIndex) {
// At or after string length, or at start of the found span.
return destIndex;
}
if (changed) {
// In a change span, map to its end.
return destIndex + newLength_;
} else {
// In an unchanged span, offset 1:1 within it.
return destIndex + (i - srcIndex);
}
}
int32_t Edits::Iterator::sourceIndexFromDestinationIndex(int32_t i, UErrorCode &errorCode) {
int32_t where = findIndex(i, FALSE, errorCode);
if (where < 0) {
// Error or before the string.
return 0;
}
if (where > 0 || i == destIndex) {
// At or after string length, or at start of the found span.
return srcIndex;
}
if (changed) {
// In a change span, map to its end.
return srcIndex + oldLength_;
} else {
// In an unchanged span, offset within it.
return srcIndex + (i - destIndex);
}
}
U_NAMESPACE_END