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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
// Description: The root node of a TextContainer.
//
using System;
using MS.Internal;
using System.Collections;
using System.Windows.Threading;
namespace System.Windows.Documents
{
// All TextContainers contain a single TextTreeRootNode, which contains all other
// nodes. The root node is special because it contains tree-global data,
// and TextPositions may never reference its BeforeStart/AfterEnd edges.
// Because of the restrictions on TextPointer, the root node may never
// be removed from the tree.
internal class TextTreeRootNode : TextTreeNode
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
// Creates a TextTreeRootNode instance.
internal TextTreeRootNode(TextContainer tree)
{
_tree = tree;
#if REFCOUNT_DEAD_TEXTPOINTERS
_deadPositionList = new ArrayList(0);
#endif // REFCOUNT_DEAD_TEXTPOINTERS
// Root node has two imaginary element edges to match TextElementNode semantics.
_symbolCount = 2;
// CaretUnitBoundaryCache always starts unset.
_caretUnitBoundaryCacheOffset = -1;
}
#endregion Constructors
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region Public Methods
#if DEBUG
// Debug-only ToString override.
public override string ToString()
{
return ("RootNode Id=" + this.DebugId + " SymbolCount=" + _symbolCount);
}
#endif // DEBUG
#endregion Public Methods
//------------------------------------------------------
//
// Internal Methods
//
//------------------------------------------------------
#region Internal Methods
// Returns a shallow copy of this node.
// This should never be called for the root node, since it is never
// involved in delete operations.
internal override TextTreeNode Clone()
{
Invariant.Assert(false, "Unexpected call to TextTreeRootNode.Clone!");
return null;
}
// Returns the TextPointerContext of the node.
// If node is TextTreeTextElementNode, this method returns ElementStart
// if direction == Forward, otherwise ElementEnd if direction == Backward.
internal override TextPointerContext GetPointerContext(LogicalDirection direction)
{
// End-of-tree is "None".
return TextPointerContext.None;
}
#endregion Internal methods
//------------------------------------------------------
//
// Internal Properties
//
//------------------------------------------------------
#region Internal Properties
// The root node never has a parent node.
internal override SplayTreeNode ParentNode
{
get
{
return null;
}
set
{
Invariant.Assert(false, "Can't set ParentNode on TextContainer root!");
}
}
// Root node of a contained tree, if any.
internal override SplayTreeNode ContainedNode
{
get
{
return _containedNode;
}
set
{
_containedNode = (TextTreeNode)value;
}
}
// The root node never has sibling nodes, so the LeftSymbolCount is a
// constant zero.
internal override int LeftSymbolCount
{
get
{
return 0;
}
set
{
Invariant.Assert(false, "TextContainer root is never a sibling!");
}
}
// The root node never has sibling nodes, so the LeftCharCount is a
// constant zero.
internal override int LeftCharCount
{
get
{
return 0;
}
set
{
Invariant.Assert(false, "TextContainer root is never a sibling!");
}
}
// The root node never has siblings, so it never has child nodes.
internal override SplayTreeNode LeftChildNode
{
get
{
return null;
}
set
{
Invariant.Assert(false, "TextContainer root never has sibling nodes!");
}
}
// The root node never has siblings, so it never has child nodes.
internal override SplayTreeNode RightChildNode
{
get
{
return null;
}
set
{
Invariant.Assert(false, "TextContainer root never has sibling nodes!");
}
}
// The tree generation. Incremented whenever the tree content changes.
internal override uint Generation
{
get
{
return _generation;
}
set
{
_generation = value;
}
}
// Like the Generation property, but this counter is only updated when
// an edit that might affect TextPositions occurs. In practice, inserts
// do not bother TextPositions, but deletions do.
internal uint PositionGeneration
{
get
{
return _positionGeneration;
}
set
{
_positionGeneration = value;
}
}
// Incremeneted whenever a layout property value changes on a TextElement.
internal uint LayoutGeneration
{
get
{
return _layoutGeneration;
}
set
{
_layoutGeneration = value;
// Invalidate the caret unit boundary cache on layout update.
_caretUnitBoundaryCacheOffset = -1;
}
}
// Cached symbol offset. The root node is always at offset zero.
internal override int SymbolOffsetCache
{
get
{
return 0;
}
set
{
Invariant.Assert(value == 0, "Bad SymbolOffsetCache on TextContainer root!");
}
}
// The count of all symbols in the tree, including two edge symbols for
// the root node itself.
internal override int SymbolCount
{
get
{
return _symbolCount;
}
set
{
Invariant.Assert(value >= 2, "Bad _symbolCount on TextContainer root!");
_symbolCount = value;
}
}
// The count of all chars in the tree.
internal override int IMECharCount
{
get
{
return _imeCharCount;
}
set
{
Invariant.Assert(value >= 0, "IMECharCount may never be negative!");
_imeCharCount = value;
}
}
// Count of TextPositions referencing the node's BeforeStart
// edge. We don't bother to actually track this for the root node
// since it is only useful in delete operations and the root node
// is never deleted.
internal override bool BeforeStartReferenceCount
{
get
{
return false;
}
set
{
Invariant.Assert(!value, "Root node BeforeStart edge can never be referenced!");
}
}
// Count of TextPositions referencing the node's AfterStart
// edge. We don't bother to actually track this for the root node
// since it is only useful in delete operations and the root node
// is never deleted.
internal override bool AfterStartReferenceCount
{
get
{
return false;
}
set
{
// We can ignore the value because the TextContainer root is never removed.
}
}
// Count of TextPositions referencing the node's BeforeEnd
// edge. We don't bother to actually track this for the root node
// since it is only useful in delete operations and the root node
// is never deleted.
internal override bool BeforeEndReferenceCount
{
get
{
return false;
}
set
{
// We can ignore the value because the TextContainer root is never removed.
}
}
// Count of TextPositions referencing the node's AfterEnd
// edge. We don't bother to actually track this for the root node
// since it is only useful in delete operations and the root node
// is never deleted.
internal override bool AfterEndReferenceCount
{
get
{
return false;
}
set
{
Invariant.Assert(!value, "Root node AfterEnd edge can never be referenced!");
}
}
// The owning TextContainer.
internal TextContainer TextContainer
{
get
{
return _tree;
}
}
// A tree of TextTreeTextBlocks, used to store raw text for the entire
// tree.
internal TextTreeRootTextBlock RootTextBlock
{
get
{
return _rootTextBlock;
}
set
{
_rootTextBlock = value;
}
}
#if REFCOUNT_DEAD_TEXTPOINTERS
// A list of positions ready to be garbage collected. The TextPointer
// finalizer adds positions to this list.
internal ArrayList DeadPositionList
{
get
{
return _deadPositionList;
}
set
{
_deadPositionList = value;
}
}
#endif // REFCOUNT_DEAD_TEXTPOINTERS
// Structure that allows for dispatcher processing to be
// enabled after a call to Dispatcher.DisableProcessing.
internal DispatcherProcessingDisabled DispatcherProcessingDisabled
{
get
{
return _processingDisabled;
}
set
{
_processingDisabled = value;
}
}
// Cached TextView.IsAtCaretUnitBoundary calculation for CaretUnitBoundaryCacheOffset.
internal bool CaretUnitBoundaryCache
{
get
{
return _caretUnitBoundaryCache;
}
set
{
_caretUnitBoundaryCache = value;
}
}
// Symbol offset of CaretUnitBoundaryCache, or -1 if the cache is empty.
internal int CaretUnitBoundaryCacheOffset
{
get
{
return _caretUnitBoundaryCacheOffset;
}
set
{
_caretUnitBoundaryCacheOffset = value;
}
}
#endregion Internal Properties
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
#region Private Fields
// The owning TextContainer.
private readonly TextContainer _tree;
// Root node of a contained tree, if any.
private TextTreeNode _containedNode;
// The count of all symbols in the tree, including two edge symbols for
// the root node itself.
private int _symbolCount;
// The count of all chars in the tree.
private int _imeCharCount;
// The tree generation. Incremented whenever the tree content changes.
private uint _generation;
// Like _generation, but only updated when a change could affect positions.
private uint _positionGeneration;
// Like _generation, but only updated when on a TextElement layout property change.
private uint _layoutGeneration;
// A tree of TextTreeTextBlocks, used to store raw text for the entire TextContainer.
private TextTreeRootTextBlock _rootTextBlock;
#if REFCOUNT_DEAD_TEXTPOINTERS
// A list of positions ready to be garbage collected. The TextPointer
// finalizer adds positions to this list.
private ArrayList _deadPositionList;
#endif // REFCOUNT_DEAD_TEXTPOINTERS
// Cached TextView.IsAtCaretUnitBoundary calculation for _caretUnitBoundaryCacheOffset.
private bool _caretUnitBoundaryCache;
// Symbol offset of _caretUnitBoundaryCache, or -1 if the cache is empty.
private int _caretUnitBoundaryCacheOffset;
// Structure that allows for dispatcher processing to be
// enabled after a call to Dispatcher.DisableProcessing.
private DispatcherProcessingDisabled _processingDisabled;
#endregion Private Fields
}
}
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