The Tor Browser: accessible/src/base/TextUpdater.cpp@6474c204b198 (annotated)

accessible/src/base/TextUpdater.cpp@6474c204b198 (annotated)

accessible/src/base/TextUpdater.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- 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);
 }

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accessible/src/base/TextUpdater.cpp@6474c204b198 (annotated)

accessible/src/base/TextUpdater.cpp