The Tor Browser: comparison accessible/src/base/TextUpdater.cpp

--1:000000000000
+:33757ae5ea71
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "TextUpdater.h"
+#include "Accessible-inl.h"
+#include "DocAccessible-inl.h"
+#include "TextLeafAccessible.h"
+#include <algorithm>
+using namespace mozilla::a11y;
+void
+TextUpdater::Run(DocAccessible* aDocument, TextLeafAccessible* aTextLeaf,
+const nsAString& aNewText)
+{
+NS_ASSERTION(aTextLeaf, "No text leaf accessible?");
+const nsString& oldText = aTextLeaf->Text();
+uint32_t oldLen = oldText.Length(), newLen = aNewText.Length();
+uint32_t minLen = std::min(oldLen, newLen);
+// Skip coinciding begin substrings.
+uint32_t skipStart = 0;
+for (; skipStart < minLen; skipStart++) {
+if (aNewText[skipStart] != oldText[skipStart])
+break;
+}
+// The text was changed. Do update.
+if (skipStart != minLen || oldLen != newLen) {
+TextUpdater updater(aDocument, aTextLeaf);
+updater.DoUpdate(aNewText, oldText, skipStart);
+}
+}
+void
+TextUpdater::DoUpdate(const nsAString& aNewText, const nsAString& aOldText,
+uint32_t aSkipStart)
+{
+Accessible* parent = mTextLeaf->Parent();
+if (!parent)
+return;
+mHyperText = parent->AsHyperText();
+if (!mHyperText) {
+NS_ERROR("Text leaf parent is not hypertext!");
+return;
+}
+// Get the text leaf accessible offset and invalidate cached offsets after it.
+mTextOffset = mHyperText->GetChildOffset(mTextLeaf, true);
+NS_ASSERTION(mTextOffset != -1,
+"Text leaf hasn't offset within hyper text!");
+uint32_t oldLen = aOldText.Length(), newLen = aNewText.Length();
+uint32_t minLen = std::min(oldLen, newLen);
+// Trim coinciding substrings from the end.
+uint32_t skipEnd = 0;
+while (minLen - skipEnd > aSkipStart &&
+aNewText[newLen - skipEnd - 1] == aOldText[oldLen - skipEnd - 1]) {
+skipEnd++;
+}
+uint32_t strLen1 = oldLen - aSkipStart - skipEnd;
+uint32_t strLen2 = newLen - aSkipStart - skipEnd;
+const nsAString& str1 = Substring(aOldText, aSkipStart, strLen1);
+const nsAString& str2 = Substring(aNewText, aSkipStart, strLen2);
+// Increase offset of the text leaf on skipped characters amount.
+mTextOffset += aSkipStart;
+// It could be single insertion or removal or the case of long strings. Do not
+// calculate the difference between long strings and prefer to fire pair of
+// insert/remove events as the old string was replaced on the new one.
+if (strLen1 == 0 || strLen2 == 0 ||
+strLen1 > kMaxStrLen || strLen2 > kMaxStrLen) {
+if (strLen1 > 0) {
+// Fire text change event for removal.
+nsRefPtr<AccEvent> textRemoveEvent =
+new AccTextChangeEvent(mHyperText, mTextOffset, str1, false);
+mDocument->FireDelayedEvent(textRemoveEvent);
+}
+if (strLen2 > 0) {
+// Fire text change event for insertion.
+nsRefPtr<AccEvent> textInsertEvent =
+new AccTextChangeEvent(mHyperText, mTextOffset, str2, true);
+mDocument->FireDelayedEvent(textInsertEvent);
+}
+mDocument->MaybeNotifyOfValueChange(mHyperText);
+// Update the text.
+mTextLeaf->SetText(aNewText);
+return;
+}
+// Otherwise find the difference between strings and fire events.
+// Note: we can skip initial and final coinciding characters since they don't
+// affect the Levenshtein distance.
+// Compute the flat structured matrix need to compute the difference.
+uint32_t len1 = strLen1 + 1, len2 = strLen2 + 1;
+uint32_t* entries = new uint32_t[len1 * len2];
+for (uint32_t colIdx = 0; colIdx < len1; colIdx++)
+entries[colIdx] = colIdx;
+uint32_t* row = entries;
+for (uint32_t rowIdx = 1; rowIdx < len2; rowIdx++) {
+uint32_t* prevRow = row;
+row += len1;
+row[0] = rowIdx;
+for (uint32_t colIdx = 1; colIdx < len1; colIdx++) {
+if (str1[colIdx - 1] != str2[rowIdx - 1]) {
+uint32_t left = row[colIdx - 1];
+uint32_t up = prevRow[colIdx];
+uint32_t upleft = prevRow[colIdx - 1];
+row[colIdx] = std::min(upleft, std::min(left, up)) + 1;
+} else {
+row[colIdx] = prevRow[colIdx - 1];
+}
+}
+}
+// Compute events based on the difference.
+nsTArray<nsRefPtr<AccEvent> > events;
+ComputeTextChangeEvents(str1, str2, entries, events);
+delete [] entries;
+// Fire events.
+for (int32_t idx = events.Length() - 1; idx >= 0; idx--)
+mDocument->FireDelayedEvent(events[idx]);
+mDocument->MaybeNotifyOfValueChange(mHyperText);
+// Update the text.
+mTextLeaf->SetText(aNewText);
+}
+void
+TextUpdater::ComputeTextChangeEvents(const nsAString& aStr1,
+const nsAString& aStr2,
+uint32_t* aEntries,
+nsTArray<nsRefPtr<AccEvent> >& aEvents)
+{
+int32_t colIdx = aStr1.Length(), rowIdx = aStr2.Length();
+// Point at which strings last matched.
+int32_t colEnd = colIdx;
+int32_t rowEnd = rowIdx;
+int32_t colLen = colEnd + 1;
+uint32_t* row = aEntries + rowIdx * colLen;
+uint32_t dist = row[colIdx]; // current Levenshtein distance
+while (rowIdx && colIdx) { // stop when we can't move diagonally
+if (aStr1[colIdx - 1] == aStr2[rowIdx - 1]) { // match
+if (rowIdx < rowEnd) { // deal with any pending insertion
+FireInsertEvent(Substring(aStr2, rowIdx, rowEnd - rowIdx),
+rowIdx, aEvents);
+}
+if (colIdx < colEnd) { // deal with any pending deletion
+FireDeleteEvent(Substring(aStr1, colIdx, colEnd - colIdx),
+rowIdx, aEvents);
+}
+colEnd = --colIdx; // reset the match point
+rowEnd = --rowIdx;
+row -= colLen;
+continue;
+}
+--dist;
+if (dist == row[colIdx - 1 - colLen]) { // substitution
+--colIdx;
+--rowIdx;
+row -= colLen;
+continue;
+}
+if (dist == row[colIdx - colLen]) { // insertion
+--rowIdx;
+row -= colLen;
+continue;
+}
+if (dist == row[colIdx - 1]) { // deletion
+--colIdx;
+continue;
+}
+NS_NOTREACHED("huh?");
+return;
+}
+if (rowEnd)
+FireInsertEvent(Substring(aStr2, 0, rowEnd), 0, aEvents);
+if (colEnd)
+FireDeleteEvent(Substring(aStr1, 0, colEnd), 0, aEvents);
+}

The Tor Browser / file comparison

comparison: accessible/src/base/TextUpdater.cpp

accessible/src/base/TextUpdater.cpp