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With inspiration from other libraries
/*
* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
package org.antlr.v4.runtime.tree.pattern;
import org.antlr.v4.runtime.misc.MultiMap;
import org.antlr.v4.runtime.tree.ParseTree;
import java.util.Collections;
import java.util.List;
/**
* Represents the result of matching a {@link ParseTree} against a tree pattern.
*/
public class ParseTreeMatch {
/**
* This is the backing field for {@link #getTree()}.
*/
private final ParseTree tree;
/**
* This is the backing field for {@link #getPattern()}.
*/
private final ParseTreePattern pattern;
/**
* This is the backing field for {@link #getLabels()}.
*/
private final MultiMap labels;
/**
* This is the backing field for {@link #getMismatchedNode()}.
*/
private final ParseTree mismatchedNode;
/**
* Constructs a new instance of {@link ParseTreeMatch} from the specified
* parse tree and pattern.
*
* @param tree The parse tree to match against the pattern.
* @param pattern The parse tree pattern.
* @param labels A mapping from label names to collections of
* {@link ParseTree} objects located by the tree pattern matching process.
* @param mismatchedNode The first node which failed to match the tree
* pattern during the matching process.
*
* @exception IllegalArgumentException if {@code tree} is {@code null}
* @exception IllegalArgumentException if {@code pattern} is {@code null}
* @exception IllegalArgumentException if {@code labels} is {@code null}
*/
public ParseTreeMatch(ParseTree tree, ParseTreePattern pattern, MultiMap labels, ParseTree mismatchedNode) {
if (tree == null) {
throw new IllegalArgumentException("tree cannot be null");
}
if (pattern == null) {
throw new IllegalArgumentException("pattern cannot be null");
}
if (labels == null) {
throw new IllegalArgumentException("labels cannot be null");
}
this.tree = tree;
this.pattern = pattern;
this.labels = labels;
this.mismatchedNode = mismatchedNode;
}
/**
* Get the last node associated with a specific {@code label}.
*
* For example, for pattern {@code }, {@code get("id")} returns the
* node matched for that {@code ID}. If more than one node
* matched the specified label, only the last is returned. If there is
* no node associated with the label, this returns {@code null}.
*
* Pattern tags like {@code } and {@code } without labels are
* considered to be labeled with {@code ID} and {@code expr}, respectively.
*
* @param label The label to check.
*
* @return The last {@link ParseTree} to match a tag with the specified
* label, or {@code null} if no parse tree matched a tag with the label.
*/
public ParseTree get(String label) {
List parseTrees = labels.get(label);
if ( parseTrees==null || parseTrees.size()==0 ) {
return null;
}
return parseTrees.get( parseTrees.size()-1 ); // return last if multiple
}
/**
* Return all nodes matching a rule or token tag with the specified label.
*
* If the {@code label} is the name of a parser rule or token in the
* grammar, the resulting list will contain both the parse trees matching
* rule or tags explicitly labeled with the label and the complete set of
* parse trees matching the labeled and unlabeled tags in the pattern for
* the parser rule or token. For example, if {@code label} is {@code "foo"},
* the result will contain all of the following.
*
*
* - Parse tree nodes matching tags of the form {@code
} and
* {@code }.
* - Parse tree nodes matching tags of the form {@code
}.
* - Parse tree nodes matching tags of the form {@code
}.
*
*
* @param label The label.
*
* @return A collection of all {@link ParseTree} nodes matching tags with
* the specified {@code label}. If no nodes matched the label, an empty list
* is returned.
*/
public List getAll(String label) {
List nodes = labels.get(label);
if ( nodes==null ) {
return Collections.emptyList();
}
return nodes;
}
/**
* Return a mapping from label → [list of nodes].
*
* The map includes special entries corresponding to the names of rules and
* tokens referenced in tags in the original pattern. For additional
* information, see the description of {@link #getAll(String)}.
*
* @return A mapping from labels to parse tree nodes. If the parse tree
* pattern did not contain any rule or token tags, this map will be empty.
*/
public MultiMap getLabels() {
return labels;
}
/**
* Get the node at which we first detected a mismatch.
*
* @return the node at which we first detected a mismatch, or {@code null}
* if the match was successful.
*/
public ParseTree getMismatchedNode() {
return mismatchedNode;
}
/**
* Gets a value indicating whether the match operation succeeded.
*
* @return {@code true} if the match operation succeeded; otherwise,
* {@code false}.
*/
public boolean succeeded() {
return mismatchedNode == null;
}
/**
* Get the tree pattern we are matching against.
*
* @return The tree pattern we are matching against.
*/
public ParseTreePattern getPattern() {
return pattern;
}
/**
* Get the parse tree we are trying to match to a pattern.
*
* @return The {@link ParseTree} we are trying to match to a pattern.
*/
public ParseTree getTree() {
return tree;
}
/**
* {@inheritDoc}
*/
@Override
public String toString() {
return String.format(
"Match %s; found %d labels",
succeeded() ? "succeeded" : "failed",
getLabels().size());
}
}