Added: TX2UtCustomBTree base class
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@ -50,6 +50,8 @@ type
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procedure Clear();
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procedure Push(const ANode: PX2UtBTreeNode);
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function Pop(): PX2UtBTreeNode;
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procedure Reverse();
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end;
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{
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@ -57,20 +59,21 @@ type
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:: This class implements a binary tree of pointer values.
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}
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TX2UtBTree = class(TObject)
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TX2UtCustomBTree = class(TObject)
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private
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FRoot: PX2UtBTreeNode;
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FCursor: PX2UtBTreeNode;
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FIsReset: Boolean;
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FParent: TX2UtBTreeStack;
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protected
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function GetItem(Index: Cardinal): Pointer;
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procedure SetItem(Index: Cardinal; const Value: Pointer);
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function GetCurrentIndex(): Cardinal;
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function GetCurrentValue(): Pointer;
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protected
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function LookupNode(const AIndex: Cardinal;
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const ACreate: Boolean = True): PX2UtBTreeNode; virtual;
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const ACreate: Boolean = False;
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const ACursor: Boolean = False): PX2UtBTreeNode; virtual;
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procedure NewNode(const AParent: PX2UtBTreeNode;
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var ANode: PX2UtBTreeNode;
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@ -84,17 +87,33 @@ type
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property Root: PX2UtBTreeNode read FRoot;
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property IsReset: Boolean read FIsReset write FIsReset;
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property Parent: TX2UtBTreeStack read FParent;
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//:$ Gets or sets an item.
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property Items[Index: Cardinal]: Pointer read GetItem
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write SetItem; default;
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//:$ Returns the index at the current cursor location.
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property CurrentIndex: Cardinal read GetCurrentIndex;
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//:$ Returns the value at the current cursor location.
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property CurrentValue: Pointer read GetCurrentValue;
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public
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constructor Create();
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destructor Destroy(); override;
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//:$ Clears the tree
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//:$ Clears the tree.
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procedure Clear();
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//:$ Deletes a node from the tree
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//:$ Deletes a node from the tree.
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procedure Delete(const AIndex: Cardinal);
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//:$ Resets the node cursor
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//:$ Checks if an index exists in the tree.
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//:: If the ASetCursor parameter is set to True, the cursor will be
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//:: positioned at the item if it is found.
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function Exists(const AIndex: Cardinal; const ASetCursor: Boolean = False): Boolean;
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//:$ Resets the node cursor.
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//:: The node cursor can be used to traverse through the binary tree.
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//:: Call Reset first, followed by Next to get the first item. You can
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//:: continue to call Next until it returns false. The CurrentIndex and
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@ -103,27 +122,29 @@ type
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//:! until the next Reset call.
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procedure Reset();
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//:$ Moves the node cursor to the next node
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//:$ Moves the node cursor to the next node.
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//:! The order in which nodes are traversed is from top to bottom, left
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//:! to right. Do not depend on the binary tree to sort the output.
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function Next(): Boolean;
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end;
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//:$ Gets or sets an item.
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property Items[Index: Cardinal]: Pointer read GetItem
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write SetItem; default;
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{
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:$ Binary tree implementation
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//:$ Returns the index at the current cursor location
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property CurrentIndex: Cardinal read GetCurrentIndex;
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//:$ Returns the value at the current cursor location
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property CurrentValue: Pointer read GetCurrentValue;
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:: This class exposes TX2UtCustomBTree's properties
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}
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TX2UtBTree = class(TX2UtCustomBTree)
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public
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property Items;
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property CurrentIndex;
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property CurrentValue;
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end;
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{
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:$ Binary tree implementation for integer values
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}
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TX2UtIntegerBTree = class(TX2UtBTree)
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private
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protected
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function GetItem(Index: Cardinal): Integer;
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procedure SetItem(Index: Cardinal; const Value: Integer);
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function GetCurrentValue(): Integer;
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@ -140,7 +161,7 @@ type
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:$ Binary tree implementation for string values
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}
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TX2UtStringBTree = class(TX2UtBTree)
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private
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protected
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function GetItem(Index: Cardinal): String;
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procedure SetItem(Index: Cardinal; const Value: String);
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function GetCurrentValue(): String;
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@ -166,10 +187,7 @@ const
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CStackSize = 32;
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type
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PStringRecord = ^TStringRecord;
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TStringRecord = record
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Value: String;
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end;
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PString = ^String;
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{======================== TX2UtBTreeStack
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@ -215,10 +233,30 @@ begin
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end;
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{============================= TX2UtBTree
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procedure TX2UtBTreeStack.Reverse;
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var
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iCount: Integer;
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iIndex: Integer;
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pSwap: PX2UtBTreeNode;
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begin
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if FPosition = -1 then
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exit;
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iCount := (FPosition + 1) div 2;
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for iIndex := 0 to iCount - 1 do
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begin
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pSwap := FItems[iIndex];
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FItems[iIndex] := FItems[FPosition - iIndex];
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FItems[FPosition - iIndex] := pSwap;
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end;
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end;
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{======================= TX2UtCustomBTree
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Initialization
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========================================}
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constructor TX2UtBTree.Create;
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constructor TX2UtCustomBTree.Create;
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begin
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inherited;
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@ -226,7 +264,7 @@ begin
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FParent := TX2UtBTreeStack.Create();
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end;
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destructor TX2UtBTree.Destroy;
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destructor TX2UtCustomBTree.Destroy;
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begin
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FreeAndNil(FParent);
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DeleteNode(FRoot);
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@ -235,10 +273,10 @@ begin
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end;
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{============================= TX2UtBTree
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{======================= TX2UtCustomBTree
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Tree Management
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========================================}
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function TX2UtBTree.LookupNode;
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function TX2UtCustomBTree.LookupNode;
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var
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pNode: PX2UtBTreeNode;
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@ -250,7 +288,15 @@ begin
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begin
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InitNode(pNode);
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pNode^.Index := AIndex;
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Result := pRoot;
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Result := pNode;
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if ACursor then
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begin
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Parent.Clear();
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IsReset := False;
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Cursor := pNode;
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end;
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exit;
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end;
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@ -292,10 +338,24 @@ begin
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end;
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end;
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end;
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if ACursor and Assigned(Result) then
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begin
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// Trace parents
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pNode := Result^.Parent;
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while Assigned(pNode) do
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begin
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Parent.Push(pNode);
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pNode := pNode^.Parent;
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end;
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// Parents are now in reverse order
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Parent.Reverse();
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end;
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end;
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procedure TX2UtBTree.NewNode;
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procedure TX2UtCustomBTree.NewNode;
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begin
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New(ANode);
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FillChar(ANode^, SizeOf(TX2UtBTreeNode), #0);
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@ -306,12 +366,12 @@ begin
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InitNode(ANode);
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end;
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procedure TX2UtBTree.InitNode;
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procedure TX2UtCustomBTree.InitNode;
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begin
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// Reserved for descendants
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end;
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procedure TX2UtBTree.DeleteNode;
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procedure TX2UtCustomBTree.DeleteNode;
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begin
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if Assigned(ANode^.Left) then
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DeleteNode(ANode^.Left);
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@ -332,39 +392,45 @@ begin
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end;
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procedure TX2UtBTree.Clear;
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procedure TX2UtCustomBTree.Clear;
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begin
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DeleteNode(FRoot);
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NewNode(nil, FRoot, False);
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end;
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procedure TX2UtBTree.Delete;
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procedure TX2UtCustomBTree.Delete;
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var
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pItem: PX2UtBTreeNode;
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begin
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pItem := LookupNode(AIndex, False);
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pItem := LookupNode(AIndex);
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if Assigned(pItem) then
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DeleteNode(pItem);
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end;
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function TX2UtCustomBTree.Exists;
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begin
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Result := Assigned(LookupNode(AIndex, False, True));
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end;
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{============================= TX2UtBTree
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{======================= TX2UtCustomBTree
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Tree Traversing
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========================================}
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procedure TX2UtBTree.ClearCursor;
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procedure TX2UtCustomBTree.ClearCursor;
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begin
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Cursor := nil;
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end;
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procedure TX2UtBTree.Reset;
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procedure TX2UtCustomBTree.Reset;
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begin
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Cursor := Root;
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IsReset := True;
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end;
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function TX2UtBTree.Next;
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function TX2UtCustomBTree.Next;
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var
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pParent: PX2UtBTreeNode;
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pCurrent: PX2UtBTreeNode;
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@ -418,7 +484,7 @@ begin
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end;
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end;
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function TX2UtBTree.GetCurrentIndex;
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function TX2UtCustomBTree.GetCurrentIndex;
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begin
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if Assigned(Cursor) and (not IsReset) then
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Result := Cursor^.Index
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@ -426,7 +492,7 @@ begin
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raise EX2UtBTreeInvalidCursor.Create(RSInvalidCursor);
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end;
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function TX2UtBTree.GetCurrentValue;
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function TX2UtCustomBTree.GetCurrentValue;
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begin
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if Assigned(Cursor) and (not IsReset) then
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Result := Cursor^.Value
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@ -435,26 +501,26 @@ begin
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end;
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{============================= TX2UtBTree
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{======================= TX2UtCustomBTree
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Items
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========================================}
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function TX2UtBTree.GetItem;
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function TX2UtCustomBTree.GetItem;
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var
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pItem: PX2UtBTreeNode;
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begin
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Result := nil;
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pItem := LookupNode(Index, False);
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pItem := LookupNode(Index);
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if Assigned(pItem) then
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Result := pItem^.Value;
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end;
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procedure TX2UtBTree.SetItem;
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procedure TX2UtCustomBTree.SetItem;
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var
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pItem: PX2UtBTreeNode;
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begin
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pItem := LookupNode(Index);
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pItem := LookupNode(Index, True);
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if Assigned(pItem) then
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pItem^.Value := Value;
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end;
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@ -488,9 +554,9 @@ var
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begin
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Result := '';
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pItem := LookupNode(Index, False);
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pItem := LookupNode(Index);
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if Assigned(pItem) then
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Result := PStringRecord(pItem^.Value)^.Value;
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Result := PString(pItem^.Value)^;
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end;
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procedure TX2UtStringBTree.SetItem;
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@ -498,35 +564,35 @@ var
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pItem: PX2UtBTreeNode;
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begin
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pItem := LookupNode(Index);
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pItem := LookupNode(Index, True);
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if Assigned(pItem) then
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PStringRecord(pItem^.Value)^.Value := Value;
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PString(pItem^.Value)^ := Value;
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end;
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function TX2UtStringBTree.GetCurrentValue;
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var
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pValue: PStringRecord;
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pValue: PString;
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begin
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Result := '';
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pValue := inherited GetCurrentValue();
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if Assigned(pValue) then
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Result := pValue^.Value;
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Result := pValue^;
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end;
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procedure TX2UtStringBTree.DeleteNode;
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begin
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Dispose(PStringRecord(ANode^.Value));
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inherited;
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end;
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procedure TX2UtStringBTree.InitNode;
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begin
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inherited;
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New(PStringRecord(ANode^.Value));
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New(PString(ANode^.Value));
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end;
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procedure TX2UtStringBTree.DeleteNode;
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begin
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Dispose(PString(ANode^.Value));
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inherited;
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end;
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end.
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