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unit TreeWalker;
{(*}
(*------------------------------------------------------------------------------
Delphi Code formatter source code
The Original Code is SimpleTreeWalker, released March 2004.
The Initial Developer of the Original Code is Anthony Steele.
Portions created by Anthony Steele are Copyright (C) 1999-2008 Anthony Steele.
All Rights Reserved.
Contributor(s):
Anthony Steele.
The contents of this file are subject to the Mozilla Public License Version 1.1
(the "License"). you may not use this file except in compliance with the License.
You may obtain a copy of the License at http://www.mozilla.org/NPL/
Software distributed under the License is distributed on an "AS IS" basis,
WITHOUT WARRANTY OF ANY KIND, either express or implied.
See the License for the specific language governing rights and limitations
under the License.
Alternatively, the contents of this file may be used under the terms of
the GNU General Public License Version 2 or later (the "GPL")
See http://www.gnu.org/licenses/gpl.html
------------------------------------------------------------------------------*)
{*)}
{$I JcfGlobal.inc}
interface
{ AFS 1 March 04
Simpler, hopefully faster approach to visiting the tree
Code is in neither the visitor or the tree
but uses both
The tree is a root node with children
The visitor is a process which is applied to each node in turn
This is how all processes that transform the program input to output
are applied. So it is key to the second phase of the program,
The first being generating the parse tree
}
uses ParseTreeNode, BaseVisitor;
type
TTreeWalker = class(TObject)
private
{ flags about the current visitor's needs
Almost all visitors use the infix walk of leaf nodes
Few look at the interior nodes }
{ does it do the prefix walk of interior nodes? }
fbHasPreVisit: Boolean;
{ does it do the postfix walk of interior nodes? }
fbHasPostVisit: Boolean;
{ does it visit the leaves - almost all do }
fbHasSourceTokenVisit: Boolean;
{ flag set true when a a visitor request that the current item be deleted,
and the index is thereafter wrong }
fbRecalcIndex: Boolean;
fcVisitor: TBaseTreeNodeVisitor;
procedure InitialiseFlags;
procedure VisitTree(const pcNode: TParseTreeNode);
public
procedure Visit(const pcRoot: TParseTreeNode; const pcVisitor: TBaseTreeNodeVisitor);
end;
implementation
uses
{ delphi } SysUtils;
procedure TTreeWalker.InitialiseFlags;
begin
{ read these once only for speed }
fbHasPreVisit := fcVisitor.HasPreVisit;
fbHasPostVisit := fcVisitor.HasPostVisit;
fbHasSourceTokenVisit := fcVisitor.HasSourceTokenVisit;
end;
procedure TTreeWalker.VisitTree(const pcNode: TParseTreeNode);
const
{ if a node has more than this number of direct children, then something is very wrong
can have lots in some "header" units that just list a lot of consts
AFS 8 Oct 2006 upped it for Sourceforge bug 1558885 }
MAX_NODE_CHILDREN = 4194304;
var
liLoop: Integer;
lcChildNode: TParseTreeNode;
liNewIndex: Integer;
begin
if pcNode.IsLeaf then
begin
if fbHasSourceTokenVisit then
fbRecalcIndex := fcVisitor.VisitSourceToken(pcNode);
end
else
begin
{ not leaf - visit children }
if fbHasPreVisit then
fcVisitor.PreVisitParseTreeNode(pcNode);
if pcNode.ChildNodeCount > MAX_NODE_CHILDREN then
begin
// some parse or insert process has gone bezerk
raise Exception.Create('Too many child nodes ' + IntToStr(pcNode.ChildNodeCount));
end;
liLoop := 0;
while liLoop < pcNode.ChildNodeCount do
begin
lcChildNode := pcNode.ChildNodes[liLoop];
VisitTree(lcChildNode);
{ fbRecalcIndex flag is for speed
need to deal with shifting indexes when an item is moved or deleted
but only then. The rest of the time it just slows us down }
if fbRecalcIndex then
begin
{ has this node been moved or removed?
if so, don't increment counter, as the next item will now be in this slot }
liNewIndex := pcNode.IndexOfChild(lcChildNode);
fbRecalcIndex := False;
if liNewIndex >= 0 then
// proceed to next one
liLoop := liNewIndex + 1;
{ else case is that liNewIndex is -1 as the current item has been deleted.
Stay at same index as the next item will now be in this slot }
end
else
inc(liLoop);
end;
if fbHasPostVisit then
fcVisitor.PostVisitParseTreeNode(pcNode);
end;
end;
procedure TTreeWalker.Visit(const pcRoot: TParseTreeNode; const pcVisitor: TBaseTreeNodeVisitor);
begin
Assert(pcRoot <> nil);
Assert(pcVisitor <> nil);
fcVisitor := pcVisitor;
InitialiseFlags;
VisitTree(pcRoot);
end;
end.
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