src/org/antlr/runtime/tree/TreeParser.java

/*
 [The "BSD license"]
 Copyright (c) 2005-2009 Terence Parr
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
 3. The name of the author may not be used to endorse or promote products
     derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.antlr.runtime.tree;

import org.antlr.runtime.*;

import java.util.regex.Pattern;
import java.util.regex.Matcher;

/** 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 {
	public static final int DOWN = Token.DOWN;
	public static final int UP = Token.UP;

    // precompiled regex used by inContext
    static String dotdot = ".*[^.]\\.\\.[^.].*";
    static String doubleEtc = ".*\\.\\.\\.\\s+\\.\\.\\..*";
    static Pattern dotdotPattern = Pattern.compile(dotdot);
    static Pattern doubleEtcPattern = Pattern.compile(doubleEtc);

	protected TreeNodeStream input;

	public TreeParser(TreeNodeStream input) {
		super(); // highlight that we go to super to set state object
		setTreeNodeStream(input);
	}

	public TreeParser(TreeNodeStream input, RecognizerSharedState state) {
		super(state); // share the state object with another parser
		setTreeNodeStream(input);
    }

	public void reset() {
		super.reset(); // reset all recognizer state variables
		if ( input!=null ) {
			input.seek(0); // rewind the input
		}
	}

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

	public TreeNodeStream getTreeNodeStream() {
		return input;
	}

	public String getSourceName() {
		return input.getSourceName();
	}

	protected Object getCurrentInputSymbol(IntStream input) {
		return ((TreeNodeStream)input).LT(1);
	}

	protected Object getMissingSymbol(IntStream input,
									  RecognitionException e,
									  int expectedTokenType,
									  BitSet follow)
	{
		String tokenText =
			"<missing "+getTokenNames()[expectedTokenType]+">";
        TreeAdaptor adaptor = ((TreeNodeStream)e.input).getTreeAdaptor();
        return adaptor.create(new CommonToken(expectedTokenType, tokenText));
	}

    /** Match '.' in tree parser has special meaning.  Skip node or
	 *  entire tree if node has children.  If children, scan until
	 *  corresponding UP node.
	 */
	public void matchAny(IntStream ignore) { // ignore stream, copy of input
		state.errorRecovery = false;
		state.failed = false;
		Object look = input.LT(1);
		if ( input.getTreeAdaptor().getChildCount(look)==0 ) {
			input.consume(); // not subtree, consume 1 node and return
			return;
		}
		// current node is a subtree, skip to corresponding UP.
		// must count nesting level to get right UP
		int level=0;
		int tokenType = input.getTreeAdaptor().getType(look);
		while ( tokenType!=Token.EOF && !(tokenType==UP && level==0) ) {
			input.consume();
			look = input.LT(1);
			tokenType = input.getTreeAdaptor().getType(look);
			if ( tokenType == DOWN ) {
				level++;
			}
			else if ( tokenType == UP ) {
				level--;
			}
		}
		input.consume(); // consume UP
	}

    /** We have DOWN/UP nodes in the stream that have no line info; override.
	 *  plus we want to alter the exception type.  Don't try to recover
	 *  from tree parser errors inline...
     */
    protected Object recoverFromMismatchedToken(IntStream input,
                                                int ttype,
                                                BitSet follow)
        throws RecognitionException
    {
        throw new MismatchedTreeNodeException(ttype, (TreeNodeStream)input);
    }

    /** Prefix error message with the grammar name because message is
	 *  always intended for the programmer because the parser built
	 *  the input tree not the user.
	 */
	public String getErrorHeader(RecognitionException e) {
		return getGrammarFileName()+": node from "+
			   (e.approximateLineInfo?"after ":"")+"line "+e.line+":"+e.charPositionInLine;
	}

	/** Tree parsers parse nodes they usually have a token object as
	 *  payload. Set the exception token and do the default behavior.
	 */
	public String getErrorMessage(RecognitionException e, String[] tokenNames) {
		if ( this instanceof TreeParser ) {
			TreeAdaptor adaptor = ((TreeNodeStream)e.input).getTreeAdaptor();
			e.token = adaptor.getToken(e.node);
			if ( e.token==null ) { // could be an UP/DOWN node
				e.token = new CommonToken(adaptor.getType(e.node),
										  adaptor.getText(e.node));
			}
		}
		return super.getErrorMessage(e, tokenNames);
	}

	public void traceIn(String ruleName, int ruleIndex)  {
		super.traceIn(ruleName, ruleIndex, input.LT(1));
	}

	public void traceOut(String ruleName, int ruleIndex)  {
		super.traceOut(ruleName, ruleIndex, input.LT(1));
	}
}