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104 lines
3.5 KiB
104 lines
3.5 KiB
//
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// TreeVisitor.m
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// ANTLR
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//
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// Created by Alan Condit on 6/18/10.
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// [The "BSD licence"]
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// Copyright (c) 2010 Alan Condit
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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// 1. Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// 3. The name of the author may not be used to endorse or promote products
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// derived from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#import "TreeVisitor.h"
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#import "CommonTreeAdaptor.h"
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@implementation TreeVisitor
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+ (TreeVisitor *)newTreeVisitor:(id<TreeAdaptor>)anAdaptor
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{
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return [[TreeVisitor alloc] initWithAdaptor:anAdaptor];
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}
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+ (TreeVisitor *)newTreeVisitor
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{
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return [[TreeVisitor alloc] init];
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}
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- (id)init
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{
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if ((self = [super init]) != nil) {
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adaptor = [[CommonTreeAdaptor newTreeAdaptor] retain];
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}
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return self;
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}
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- (id)initWithAdaptor:(id<TreeAdaptor>)anAdaptor
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{
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if ((self = [super init]) != nil) {
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adaptor = [anAdaptor retain];
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}
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return self;
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}
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- (void) dealloc
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{
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#ifdef DEBUG_DEALLOC
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NSLog( @"called dealloc in TreeVisitor" );
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#endif
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if ( adaptor ) [adaptor release];
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[super dealloc];
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}
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/** Visit every node in tree t and trigger an action for each node
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* before/after having visited all of its children.
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* Execute both actions even if t has no children.
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* If a child visit yields a new child, it can update its
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* parent's child list or just return the new child. The
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* child update code works even if the child visit alters its parent
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* and returns the new tree.
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*
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* Return result of applying post action to this node.
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*/
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- (id<BaseTree>)visit:(id<BaseTree>)t Action:(TreeVisitorAction *)action
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{
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// System.out.println("visit "+((Tree)t).toStringTree());
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BOOL isNil = [adaptor isNil:t];
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if ( action != nil && !isNil ) {
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t = [action pre:(id<BaseTree>)t]; // if rewritten, walk children of new t
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}
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for (int i=0; i < [adaptor getChildCount:t]; i++) {
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id<BaseTree> child = [adaptor getChild:t At:i];
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id<BaseTree> visitResult = [self visit:child Action:action];
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id<BaseTree> childAfterVisit = [adaptor getChild:t At:i];
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if ( visitResult != childAfterVisit ) { // result & child differ?
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[adaptor setChild:t At:i Child:visitResult];
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}
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}
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if ( action != nil && !isNil ) t = [action post:(id<BaseTree>)t];
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return t;
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}
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@synthesize adaptor;
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@end
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