Introduce previousPositionOf() for VisiblePosition

Source/core/editing/commands/TypingCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2007, 2008 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 285 matching lines @@
     if (!frame->spellChecker().isContinuousSpellCheckingEnabled())
         return;
 
     frame->spellChecker().cancelCheck();
 
     // Take a look at the selection that results after typing and determine whether we need to spellcheck.
     // Since the word containing the current selection is never marked, this does a check to
     // see if typing made a new word that is not in the current selection. Basically, you
     // get this by being at the end of a word and typing a space.
     VisiblePosition start(endingSelection().start(), endingSelection().affinity());
-    VisiblePosition previous = start.previous();
+    VisiblePosition previous = previousPositionOf(start);
 
     VisiblePosition p1 = startOfWord(previous, LeftWordIfOnBoundary);
 
     if (commandType == InsertParagraphSeparator) {
         VisiblePosition p2 = nextWordPosition(start);
         VisibleSelection words(p1, endOfWord(p2));
         frame->spellChecker().markMisspellingsAfterLineBreak(words);
     } else if (previous.isNotNull()) {
         VisiblePosition p2 = startOfWord(start, LeftWordIfOnBoundary);
         if (p1.deepEquivalent() != p2.deepEquivalent())
@@ skipping 114 matching lines @@
 
         m_smartDelete = false;
 
         OwnPtrWillBeRawPtr<FrameSelection> selection = FrameSelection::create();
         selection->setSelection(endingSelection());
         selection->modify(FrameSelection::AlterationExtend, DirectionBackward, granularity);
         if (killRing && selection->isCaret() && granularity != CharacterGranularity)
             selection->modify(FrameSelection::AlterationExtend, DirectionBackward, CharacterGranularity);
 
         VisiblePosition visibleStart(endingSelection().visibleStart());
-        if (visibleStart.previous(CannotCrossEditingBoundary).isNull()) {
+        if (previousPositionOf(visibleStart, CannotCrossEditingBoundary).isNull()) {
             // When the caret is at the start of the editable area in an empty list item, break out of the list item.
             if (breakOutOfEmptyListItem()) {
                 typingAddedToOpenCommand(DeleteKey);
                 return;
             }
             // When there are no visible positions in the editing root, delete its entire contents.
             if (visibleStart.next(CannotCrossEditingBoundary).isNull() && makeEditableRootEmpty()) {
                 typingAddedToOpenCommand(DeleteKey);
                 return;
             }
         }
 
         // If we have a caret selection at the beginning of a cell, we have nothing to do.
         Node* enclosingTableCell = enclosingNodeOfType(visibleStart.deepEquivalent(), &isTableCell);
         if (enclosingTableCell && visibleStart.deepEquivalent() == VisiblePosition(firstPositionInNode(enclosingTableCell)).deepEquivalent())
             return;
 
         // If the caret is at the start of a paragraph after a table, move content into the last table cell.
-        if (isStartOfParagraph(visibleStart) && isFirstPositionAfterTable(visibleStart.previous(CannotCrossEditingBoundary))) {
+        if (isStartOfParagraph(visibleStart) && isFirstPositionAfterTable(previousPositionOf(visibleStart, CannotCrossEditingBoundary))) {
             // Unless the caret is just before a table.  We don't want to move a table into the last table cell.
             if (isLastPositionBeforeTable(visibleStart))
                 return;
             // Extend the selection backward into the last cell, then deletion will handle the move.
             selection->modify(FrameSelection::AlterationExtend, DirectionBackward, granularity);
         // If the caret is just after a table, select the table and don't delete anything.
         } else if (Element* table = isFirstPositionAfterTable(visibleStart)) {
             setEndingSelection(VisibleSelection(positionBeforeNode(table), endingSelection().start(), TextAffinity::Downstream, endingSelection().isDirectional()));
             typingAddedToOpenCommand(DeleteKey);
             return;
@@ skipping 155 matching lines @@
     ASSERT_NOT_REACHED();
     m_preservesTypingStyle = false;
 }
 
 bool TypingCommand::isTypingCommand() const
 {
     return true;
 }
 
 } // namespace blink