treeparser.java

ANTLR(ANother Tool for Language Recognition)它是这样的一种工具

package org.antlr.runtime.tree;

import org.antlr.runtime.*;

import java.util.List;
import java.util.ArrayList;

/** A parser for a stream of tree nodes.  "tree grammars" result in a subclass
 *  of this.  All the error reporting and recovery is shared with Parser via
 *  the BaseRecognizer superclass.
*/
public class TreeParser extends BaseRecognizer {
	protected TreeNodeStream input;

	public TreeParser(TreeNodeStream input) {
		setTreeNodeStream(input);
	}

	/** Set the input stream and reset the parser */
	public void setTreeNodeStream(TreeNodeStream input) {
		this.input = input;
		reset();
	}

	public TreeNodeStream getTreeNodeStream() {
		return input;
	}

	/** Convert a List<RuleReturnScope> to List<StringTemplate> by copying
	 *  out the .st property.  Useful when converting from
	 *  list labels to template attributes:
	 *
	 *    a : ids+=rule -> foo(ids={toTemplates($ids)})
	 *      ;
	 */
	public List toTemplates(List retvals) {
		if ( retvals==null ) return null;
		List strings = new ArrayList(retvals.size());
		for (int i=0; i<retvals.size(); i++) {
			strings.add(((TreeRuleReturnScope)retvals.get(i)).getTemplate());
		}
		return strings;
	}

	/** We have DOWN/UP nodes in the stream that have no line info; override.
	 *  plus we want to alter the exception type.
	 */
	protected void mismatch(IntStream input, int ttype, BitSet follow)
		throws RecognitionException
	{
		MismatchedTreeNodeException mte =
			new MismatchedTreeNodeException(ttype, (TreeNodeStream)input);
		recoverFromMismatchedToken(input, mte, ttype, follow);
	}

}