1//
2//  ANTLRTreeVisitor.m
3//  ANTLR
4//
5//  Created by Alan Condit on 6/18/10.
6// [The "BSD licence"]
7// Copyright (c) 2010 Alan Condit
8// All rights reserved.
9//
10// Redistribution and use in source and binary forms, with or without
11// modification, are permitted provided that the following conditions
12// are met:
13// 1. Redistributions of source code must retain the above copyright
14//    notice, this list of conditions and the following disclaimer.
15// 2. Redistributions in binary form must reproduce the above copyright
16//    notice, this list of conditions and the following disclaimer in the
17//    documentation and/or other materials provided with the distribution.
18// 3. The name of the author may not be used to endorse or promote products
19//    derived from this software without specific prior written permission.
20//
21// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24// IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31
32#import "ANTLRTreeVisitor.h"
33#import "ANTLRCommonTreeAdaptor.h"
34
35@implementation ANTLRTreeVisitor
36
37+ (ANTLRTreeVisitor *)newANTLRTreeVisitor:(id<ANTLRTreeAdaptor>)anAdaptor
38{
39    return [[ANTLRTreeVisitor alloc] initWithAdaptor:anAdaptor];
40}
41
42+ (ANTLRTreeVisitor *)newANTLRTreeVisitor
43{
44    return [[ANTLRTreeVisitor alloc] init];
45}
46
47
48- (id)init
49{
50    if ((self = [super init]) != nil) {
51        adaptor = [[ANTLRCommonTreeAdaptor newTreeAdaptor] retain];
52    }
53    return self;
54}
55
56- (id)initWithAdaptor:(id<ANTLRTreeAdaptor>)anAdaptor
57{
58    if ((self = [super init]) != nil) {
59        adaptor = [anAdaptor retain];
60    }
61    return self;
62}
63
64- (void) dealloc
65{
66#ifdef DEBUG_DEALLOC
67    NSLog( @"called dealloc in ANTLRTreeVisitor" );
68#endif
69    if ( adaptor ) [adaptor release];
70    [super dealloc];
71}
72
73/** Visit every node in tree t and trigger an action for each node
74 *  before/after having visited all of its children.
75 *  Execute both actions even if t has no children.
76 *  If a child visit yields a new child, it can update its
77 *  parent's child list or just return the new child.  The
78 *  child update code works even if the child visit alters its parent
79 *  and returns the new tree.
80 *
81 *  Return result of applying post action to this node.
82 */
83- (ANTLRTreeVisitor *)visit:(ANTLRCommonTree *)t Action:(ANTLRTreeVisitorAction *)action
84{
85    // System.out.println("visit "+((Tree)t).toStringTree());
86    BOOL isNil = [adaptor isNil:t];
87    if ( action != nil && !isNil ) {
88        t = [action pre:(ANTLRTreeVisitorAction *)t]; // if rewritten, walk children of new t
89    }
90    for (int i=0; i < [adaptor getChildCount:t]; i++) {
91        ANTLRCommonTree *child = [adaptor getChild:t At:i];
92        ANTLRCommonTree *visitResult = [self visit:child Action:action];
93        ANTLRCommonTree *childAfterVisit = [adaptor getChild:t At:i];
94        if ( visitResult !=  childAfterVisit ) { // result & child differ?
95            [adaptor setChild:t At:i Child:visitResult];
96        }
97    }
98    if ( action != nil && !isNil ) t = [action post:(ANTLRTreeVisitorAction *)t];
99    return t;
100}
101
102@synthesize adaptor;
103@end
104