dom.pp: Customized memory management, fixes 17 test cases and all memory leaks in testsuite:

* Every node created by Document.CreateXXX method is now guaranteed to be destroyed with the
  document, whether it is part of the tree or not. Therefore, DOM methods which remove nodes
  from the tree (namely, TDOMNode.RemoveChild, TDOMNode.ReplaceChild,
  TDOMElement.SetAttributeNode and TDOMElement.SetAttributeNodeNS) no longer need to destroy
  their return value and are now conformant to the specs.
* Nodes are allocated in arrays of instances (emulates 'placement new operator' in C++ terms).
  Allocation and freeing are as fast as possible (just assigns a couple of pointers).
* Behaviour of nodes that are created by direct call to constructor is unchanged.

git-svn-id: trunk@13185 -

packages/fcl-xml/src/dom.pp

@@ -928,9 +928,7 @@ end;
 
 function TDOMNode.RemoveChild(OldChild: TDOMNode): TDOMNode;
 begin
-  DetachChild(OldChild);
+  Result := DetachChild(OldChild);
-  OldChild.Free;
-  Result:=nil;
 end;
 
 function TDOMNode.AppendChild(NewChild: TDOMNode): TDOMNode;
@@ -1248,8 +1246,7 @@ begin
   InsertBefore(NewChild, OldChild);
   if Assigned(OldChild) then
     RemoveChild(OldChild);
-  // TODO: per DOM spec, must return OldChild, but OldChild is destroyed
+  Result := OldChild;
-  Result := NewChild;
 end;
 
 function TDOMNode_WithChildren.DetachChild(OldChild: TDOMNode): TDOMNode;
@@ -1352,7 +1349,8 @@ end;
 procedure TDOMNode_WithChildren.SetTextContent(const AValue: DOMString);
 begin
   Changing;
-  FreeChildren;
+  while Assigned(FFirstChild) do
+    DetachChild(FFirstChild);
   if AValue <> '' then
     AppendChild(FOwnerDocument.CreateTextNode(AValue));
 end;
@@ -1972,31 +1970,36 @@ function TDOMDocument.CreateElement(const tagName: DOMString): TDOMElement;
 begin
   if not IsXmlName(tagName, FXML11) then
     raise EDOMError.Create(INVALID_CHARACTER_ERR, 'DOMDocument.CreateElement');
-  Result := TDOMElement.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMElement);
+  Result.Create(Self);
   Result.FNSI.QName := FNames.FindOrAdd(DOMPChar(tagName), Length(tagName));
   // TODO: attach default attributes
 end;
 
 function TDOMDocument.CreateElementBuf(Buf: DOMPChar; Length: Integer): TDOMElement;
 begin
-  Result := TDOMElement.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMElement);
+  Result.Create(Self);
   Result.FNSI.QName := FNames.FindOrAdd(Buf, Length);
 end;
 
 function TDOMDocument.CreateDocumentFragment: TDOMDocumentFragment;
 begin
-  Result := TDOMDocumentFragment.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMDocumentFragment);
+  Result.Create(Self);
 end;
 
 function TDOMDocument.CreateTextNode(const data: DOMString): TDOMText;
 begin
-  Result := TDOMText.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMText);
+  Result.Create(Self);
   Result.FNodeValue := data;
 end;
 
 function TDOMDocument.CreateTextNodeBuf(Buf: DOMPChar; Length: Integer; IgnWS: Boolean): TDOMText;
 begin
-  Result := TDOMText.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMText);
+  Result.Create(Self);
   SetString(Result.FNodeValue, Buf, Length);
   if IgnWS then
     Include(Result.FFlags, nfIgnorableWS);
@@ -2005,13 +2008,15 @@ end;
 
 function TDOMDocument.CreateComment(const data: DOMString): TDOMComment;
 begin
-  Result := TDOMComment.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMComment);
+  Result.Create(Self);
   Result.FNodeValue := data;
 end;
 
 function TDOMDocument.CreateCommentBuf(Buf: DOMPChar; Length: Integer): TDOMComment;
 begin
-  Result := TDOMComment.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMComment);
+  Result.Create(Self);
   SetString(Result.FNodeValue, Buf, Length);
 end;
 
@@ -2033,20 +2038,23 @@ function TDOMDocument.CreateAttribute(const name: DOMString): TDOMAttr;
 begin
   if not IsXmlName(name, FXML11) then
     raise EDOMError.Create(INVALID_CHARACTER_ERR, 'DOMDocument.CreateAttribute');
-  Result := TDOMAttr.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMAttr);
+  Result.Create(Self);
   Result.FNSI.QName := FNames.FindOrAdd(DOMPChar(name), Length(name));
   Include(Result.FFlags, nfSpecified);
 end;
 
 function TDOMDocument.CreateAttributeBuf(Buf: DOMPChar; Length: Integer): TDOMAttr;
 begin
-  Result := TDOMAttr.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMAttr);
+  Result.Create(Self);
   Result.FNSI.QName := FNames.FindOrAdd(buf, Length);
   Include(Result.FFlags, nfSpecified);
 end;
 
 function TDOMDocument.CreateAttributeDef(Buf: DOMPChar; Length: Integer): TDOMAttrDef;
 begin
+// not using custom allocation here
   Result := TDOMAttrDef.Create(Self);
   Result.FNSI.QName := FNames.FindOrAdd(Buf, Length);
 end;
@@ -2183,7 +2191,8 @@ end;
 function TXMLDocument.CreateCDATASection(const data: DOMString):
   TDOMCDATASection;
 begin
-  Result := TDOMCDATASection.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMCDATASection);
+  Result.Create(Self);
   Result.FNodeValue := data;
 end;
 
@@ -2192,7 +2201,8 @@ function TXMLDocument.CreateProcessingInstruction(const target,
 begin
   if not IsXmlName(target, FXML11) then
     raise EDOMError.Create(INVALID_CHARACTER_ERR, 'XMLDocument.CreateProcessingInstruction');
-  Result := TDOMProcessingInstruction.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMProcessingInstruction);
+  Result.Create(Self);
   Result.FTarget := target;
   Result.FNodeValue := data;
 end;
@@ -2205,7 +2215,8 @@ var
 begin
   if not IsXmlName(name, FXML11) then
     raise EDOMError.Create(INVALID_CHARACTER_ERR, 'XMLDocument.CreateEntityReference');
-  Result := TDOMEntityReference.Create(Self);
+  TDOMNode(Result) := Alloc(TDOMEntityReference);
+  Result.Create(Self);
   Result.FName := name;
   dType := DocType;
   if Assigned(dType) then
@@ -2459,25 +2470,11 @@ end;
 function TDOMElement.SetAttributeNode(NewAttr: TDOMAttr): TDOMAttr;
 begin
   Result := Attributes.SetNamedItem(NewAttr) as TDOMAttr;
-
-  // TODO -cConformance: here goes inconsistency with DOM 2 - same as in TDOMNode.RemoveChild
-  if Assigned(Result) and (Result <> NewAttr) then
-  begin
-    Result.Free;
-    Result := nil;
-  end;  
 end;
 
 function TDOMElement.SetAttributeNodeNS(NewAttr: TDOMAttr): TDOMAttr;
 begin
   Result := Attributes.SetNamedItemNS(NewAttr) as TDOMAttr;
-
-  // TODO -cConformance: here goes inconsistency with DOM 2 - same as in TDOMNode.RemoveChild
-  if Assigned(Result) and (Result <> NewAttr) then
-  begin
-    Result.Free;
-    Result := nil;
-  end;  
 end;