|
1
|
|
|
<?php |
|
2
|
|
|
|
|
3
|
|
|
declare(strict_types=1); |
|
4
|
|
|
|
|
5
|
|
|
namespace Antlr\Antlr4\Runtime\Tree; |
|
6
|
|
|
|
|
7
|
|
|
class AbstractParseTreeVisitor implements ParseTreeVisitor |
|
8
|
|
|
{ |
|
9
|
|
|
/** |
|
10
|
|
|
* {@inheritdoc} |
|
11
|
|
|
* |
|
12
|
|
|
* The default implementation calls {@see ParseTree::accept()} on the specified tree. |
|
13
|
|
|
* |
|
14
|
|
|
* @return mixed |
|
15
|
|
|
*/ |
|
16
|
7 |
|
public function visit(ParseTree $tree) |
|
17
|
|
|
{ |
|
18
|
7 |
|
return $tree->accept($this); |
|
19
|
|
|
} |
|
20
|
|
|
|
|
21
|
|
|
/** |
|
22
|
|
|
* {@inheritdoc} |
|
23
|
|
|
* |
|
24
|
|
|
* The default implementation initializes the aggregate result to |
|
25
|
|
|
* {@see AbstractParseTreeVisitor::defaultResult()}. Before visiting each |
|
26
|
|
|
* child, it calls {@see AbstractParseTreeVisitor::shouldVisitNextChild()}; |
|
27
|
|
|
* if the result is `false` no more children are visited and the current |
|
28
|
|
|
* aggregate result is returned. After visiting a child, the aggregate |
|
29
|
|
|
* result is updated by calling {@see AbstractParseTreeVisitor::aggregateResult()} |
|
30
|
|
|
* with the previous aggregate result and the result of visiting the child. |
|
31
|
|
|
* |
|
32
|
|
|
* The default implementation is not safe for use in visitors that modify |
|
33
|
|
|
* the tree structure. Visitors that modify the tree should override this |
|
34
|
|
|
* method to behave properly in respect to the specific algorithm in use. |
|
35
|
|
|
* |
|
36
|
|
|
* @return mixed |
|
37
|
|
|
*/ |
|
38
|
7 |
|
public function visitChildren(RuleNode $node) |
|
39
|
|
|
{ |
|
40
|
7 |
|
$result = $this->defaultResult(); |
|
|
|
|
|
|
41
|
|
|
|
|
42
|
7 |
|
$n = $node->getChildCount(); |
|
43
|
|
|
|
|
44
|
7 |
|
for ($i=0; $i < $n; $i++) { |
|
45
|
5 |
|
if (!$this->shouldVisitNextChild($node, $result)) { |
|
46
|
|
|
break; |
|
47
|
|
|
} |
|
48
|
|
|
|
|
49
|
|
|
/** @var ParseTree $child */ |
|
50
|
5 |
|
$child = $node->getChild($i); |
|
51
|
|
|
|
|
52
|
5 |
|
$childResult = $child->accept($this); |
|
53
|
|
|
|
|
54
|
5 |
|
$result = $this->aggregateResult($result, $childResult); |
|
55
|
|
|
} |
|
56
|
|
|
|
|
57
|
7 |
|
return $result; |
|
58
|
|
|
} |
|
59
|
|
|
|
|
60
|
|
|
/** |
|
61
|
|
|
* {@inheritdoc} |
|
62
|
|
|
* |
|
63
|
|
|
* The default implementation returns the result of |
|
64
|
|
|
* {@see AbstractParseTreeVisitor::defaultResult()}. |
|
65
|
|
|
* |
|
66
|
|
|
* @return mixed |
|
67
|
|
|
*/ |
|
68
|
1 |
|
public function visitTerminal(TerminalNode $node) |
|
69
|
|
|
{ |
|
70
|
1 |
|
return $this->defaultResult(); |
|
|
|
|
|
|
71
|
|
|
} |
|
72
|
|
|
|
|
73
|
|
|
/** |
|
74
|
|
|
* {@inheritdoc} |
|
75
|
|
|
* |
|
76
|
|
|
* The default implementation returns the result of |
|
77
|
|
|
* {@see AbstractParseTreeVisitor::defaultResult()}. |
|
78
|
|
|
* |
|
79
|
|
|
* @return mixed |
|
80
|
|
|
*/ |
|
81
|
|
|
public function visitErrorNode(ErrorNode $tree) |
|
82
|
|
|
{ |
|
83
|
|
|
return $this->defaultResult(); |
|
|
|
|
|
|
84
|
|
|
} |
|
85
|
|
|
|
|
86
|
|
|
/** |
|
87
|
|
|
* Gets the default value returned by visitor methods. This value is |
|
88
|
|
|
* returned by the default implementations of |
|
89
|
|
|
* {@see AbstractParseTreeVisitor::visitTerminal()}, |
|
90
|
|
|
* {@see AbstractParseTreeVisitor::visitErrorNode()}. |
|
91
|
|
|
* The default implementation of {@see AbstractParseTreeVisitor::visitChildren()} |
|
92
|
|
|
* initializes its aggregate result to this value. |
|
93
|
|
|
* |
|
94
|
|
|
* The base implementation returns `null`. |
|
95
|
|
|
* |
|
96
|
|
|
* @return mixed |
|
97
|
|
|
*/ |
|
98
|
7 |
|
protected function defaultResult() |
|
99
|
|
|
{ |
|
100
|
7 |
|
return null; |
|
101
|
|
|
} |
|
102
|
|
|
|
|
103
|
|
|
/** |
|
104
|
|
|
* Aggregates the results of visiting multiple children of a node. After |
|
105
|
|
|
* either all children are visited or |
|
106
|
|
|
* {@see AbstractParseTreeVisitor::shouldVisitNextChild()} returns `false`, |
|
107
|
|
|
* the aggregate value is returned as the result of |
|
108
|
|
|
* {@see AbstractParseTreeVisitor::visitChildren()}. |
|
109
|
|
|
* |
|
110
|
|
|
* The default implementation returns `nextResult`, meaning |
|
111
|
|
|
* {@see AbstractParseTreeVisitor::visitChildren()} will return the result |
|
112
|
|
|
* of the last child visited (or return the initial value if the node has |
|
113
|
|
|
* no children). |
|
114
|
|
|
* |
|
115
|
|
|
* @param mixed $aggregate The previous aggregate value. In the default |
|
116
|
|
|
* implementation, the aggregate value is initialized |
|
117
|
|
|
* to {@see AbstractParseTreeVisitor::defaultResult()}, |
|
118
|
|
|
* which is passed as the `aggregate` argument to |
|
119
|
|
|
* this method after the first child node is visited. |
|
120
|
|
|
* @param mixed $nextResult The result of the immediately preceeding call to |
|
121
|
|
|
* visit a child node. |
|
122
|
|
|
* |
|
123
|
|
|
* @return mixed |
|
124
|
|
|
*/ |
|
125
|
5 |
|
protected function aggregateResult($aggregate, $nextResult) |
|
|
|
|
|
|
126
|
|
|
{ |
|
127
|
5 |
|
return $nextResult; |
|
128
|
|
|
} |
|
129
|
|
|
|
|
130
|
|
|
/** |
|
131
|
|
|
* This method is called after visiting each child in |
|
132
|
|
|
* {@see AbstractParseTreeVisitor::visitChildren()}. This method is first |
|
133
|
|
|
* called before the first child is visited; at that point `currentResult` |
|
134
|
|
|
* will be the initial value (in the default implementation, the initial |
|
135
|
|
|
* value is returned by a call to {@see AbstractParseTreeVisitor::defaultResult()}. |
|
136
|
|
|
* This method is not called after the last child is visited. |
|
137
|
|
|
* |
|
138
|
|
|
* The default implementation always returns `true`, indicating that |
|
139
|
|
|
* `visitChildren` should only return after all children are visited. |
|
140
|
|
|
* One reason to override this method is to provide a "short circuit" |
|
141
|
|
|
* evaluation option for situations where the result of visiting a single |
|
142
|
|
|
* child has the potential to determine the result of the visit operation as |
|
143
|
|
|
* a whole. |
|
144
|
|
|
* |
|
145
|
|
|
* @param RuleNode $node The {@see RuleNode} whose children are |
|
146
|
|
|
* currently being visited. |
|
147
|
|
|
* @param mixed $currentResult The current aggregate result of the children |
|
148
|
|
|
* visited to the current point. |
|
149
|
|
|
* |
|
150
|
|
|
* @return bool `true` to continue visiting children. Otherwise return `false` |
|
151
|
|
|
* to stop visiting children and immediately return the current |
|
152
|
|
|
* aggregate result from {@see AbstractParseTreeVisitor::visitChildren()}. |
|
153
|
|
|
*/ |
|
154
|
5 |
|
protected function shouldVisitNextChild(RuleNode $node, $currentResult) : bool |
|
|
|
|
|
|
155
|
|
|
{ |
|
156
|
5 |
|
return true; |
|
157
|
|
|
} |
|
158
|
|
|
} |
|
159
|
|
|
|
This check looks for function or method calls that always return null and whose return value is assigned to a variable.
The method
getObject()can return nothing but null, so it makes no sense to assign that value to a variable.The reason is most likely that a function or method is imcomplete or has been reduced for debug purposes.