Introduce previousPositionOf() for VisiblePosition

Source/core/editing/commands/DeleteSelectionCommand.cpp

 /*
  * Copyright (C) 2005 Apple Computer, 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 211 matching lines @@
 
         // skip smart delete if the selection to delete already starts or ends with whitespace
         Position pos = VisiblePosition(m_upstreamStart, m_selectionToDelete.affinity()).deepEquivalent();
         bool skipSmartDelete = trailingWhitespacePosition(pos, VP_DEFAULT_AFFINITY, ConsiderNonCollapsibleWhitespace).isNotNull();
         if (!skipSmartDelete)
             skipSmartDelete = leadingWhitespacePosition(m_downstreamEnd, VP_DEFAULT_AFFINITY, ConsiderNonCollapsibleWhitespace).isNotNull();
 
         // extend selection upstream if there is whitespace there
         bool hasLeadingWhitespaceBeforeAdjustment = leadingWhitespacePosition(m_upstreamStart, m_selectionToDelete.affinity(), ConsiderNonCollapsibleWhitespace).isNotNull();
         if (!skipSmartDelete && hasLeadingWhitespaceBeforeAdjustment) {
-            VisiblePosition visiblePos = VisiblePosition(m_upstreamStart, VP_DEFAULT_AFFINITY).previous();
+            VisiblePosition visiblePos = previousPositionOf(VisiblePosition(m_upstreamStart, VP_DEFAULT_AFFINITY));
             pos = visiblePos.deepEquivalent();
             // Expand out one character upstream for smart delete and recalculate
             // positions based on this change.
             m_upstreamStart = mostBackwardCaretPosition(pos);
             m_downstreamStart = mostForwardCaretPosition(pos);
             m_leadingWhitespace = leadingWhitespacePosition(m_upstreamStart, visiblePos.affinity());
 
             setStartingSelectionOnSmartDelete(m_upstreamStart, m_upstreamEnd);
         }
 
@@ skipping 134 matching lines @@
         LayoutObject* r = node->layoutObject();
         if (r && r->isTableCell() && toLayoutTableCell(r)->contentHeight() <= 0) {
             Position firstEditablePosition = firstEditablePositionInNode(node.get());
             if (firstEditablePosition.isNotNull())
                 insertBlockPlaceholder(firstEditablePosition);
         }
         return;
     }
 
     if (node == m_startBlock) {
-        VisiblePosition previous = VisiblePosition(firstPositionInNode(m_startBlock.get())).previous();
+        VisiblePosition previous = previousPositionOf(VisiblePosition(firstPositionInNode(m_startBlock.get())));
         if (previous.isNotNull() && !isEndOfBlock(previous))
             m_needPlaceholder = true;
     }
     if (node == m_endBlock) {
         VisiblePosition next = VisiblePosition(lastPositionInNode(m_endBlock.get())).next();
         if (next.isNotNull() && !isStartOfBlock(next))
             m_needPlaceholder = true;
     }
 
     // FIXME: Update the endpoints of the range being deleted.
@@ skipping 411 matching lines @@
         if (Element* table = isLastPositionBeforeTable(m_selectionToDelete.visibleStart())) {
             if (m_selectionToDelete.end().anchorNode()->isDescendantOf(table))
                 m_needPlaceholder = false;
         }
     }
 
 
     // set up our state
     initializePositionData();
 
-    bool lineBreakBeforeStart = lineBreakExistsAtVisiblePosition(VisiblePosition(m_upstreamStart).previous());
+    bool lineBreakBeforeStart = lineBreakExistsAtVisiblePosition(previousPositionOf(VisiblePosition(m_upstreamStart)));
 
-    // Delete any text that may hinder our ability to fixup whitespace after the delete
+    // Delete any text that may hinder our ability to fixup whitespace after the
+    // delete
     deleteInsignificantTextDownstream(m_trailingWhitespace);
 
     saveTypingStyleState();
 
     // deleting just a BR is handled specially, at least because we do not
     // want to replace it with a placeholder BR!
     if (handleSpecialCaseBRDelete()) {
         calculateTypingStyleAfterDelete();
         setEndingSelection(VisibleSelection(m_endingPosition, affinity, endingSelection().isDirectional()));
         clearTransientState();
@@ skipping 67 matching lines @@
     visitor->trace(m_deleteIntoBlockquoteStyle);
     visitor->trace(m_startRoot);
     visitor->trace(m_endRoot);
     visitor->trace(m_startTableRow);
     visitor->trace(m_endTableRow);
     visitor->trace(m_temporaryPlaceholder);
     CompositeEditCommand::trace(visitor);
 }
 
 } // namespace blink