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      1 /*
      2  [The "BSD license"]
      3  Copyright (c) 2005-2009 Terence Parr
      4  All rights reserved.
      5 
      6  Redistribution and use in source and binary forms, with or without
      7  modification, are permitted provided that the following conditions
      8  are met:
      9  1. Redistributions of source code must retain the above copyright
     10      notice, this list of conditions and the following disclaimer.
     11  2. Redistributions in binary form must reproduce the above copyright
     12      notice, this list of conditions and the following disclaimer in the
     13      documentation and/or other materials provided with the distribution.
     14  3. The name of the author may not be used to endorse or promote products
     15      derived from this software without specific prior written permission.
     16 
     17  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 package org.antlr.runtime.tree;
     29 
     30 import org.antlr.runtime.*;
     31 
     32 import java.util.regex.Pattern;
     33 import java.util.regex.Matcher;
     34 
     35 /** A parser for a stream of tree nodes.  "tree grammars" result in a subclass
     36  *  of this.  All the error reporting and recovery is shared with Parser via
     37  *  the BaseRecognizer superclass.
     38 */
     39 public class TreeParser extends BaseRecognizer {
     40 	public static final int DOWN = Token.DOWN;
     41 	public static final int UP = Token.UP;
     42 
     43     // precompiled regex used by inContext
     44     static String dotdot = ".*[^.]\\.\\.[^.].*";
     45     static String doubleEtc = ".*\\.\\.\\.\\s+\\.\\.\\..*";
     46     static Pattern dotdotPattern = Pattern.compile(dotdot);
     47     static Pattern doubleEtcPattern = Pattern.compile(doubleEtc);
     48 
     49 	protected TreeNodeStream input;
     50 
     51 	public TreeParser(TreeNodeStream input) {
     52 		super(); // highlight that we go to super to set state object
     53 		setTreeNodeStream(input);
     54 	}
     55 
     56 	public TreeParser(TreeNodeStream input, RecognizerSharedState state) {
     57 		super(state); // share the state object with another parser
     58 		setTreeNodeStream(input);
     59     }
     60 
     61 	public void reset() {
     62 		super.reset(); // reset all recognizer state variables
     63 		if ( input!=null ) {
     64 			input.seek(0); // rewind the input
     65 		}
     66 	}
     67 
     68 	/** Set the input stream */
     69 	public void setTreeNodeStream(TreeNodeStream input) {
     70 		this.input = input;
     71 	}
     72 
     73 	public TreeNodeStream getTreeNodeStream() {
     74 		return input;
     75 	}
     76 
     77 	public String getSourceName() {
     78 		return input.getSourceName();
     79 	}
     80 
     81 	protected Object getCurrentInputSymbol(IntStream input) {
     82 		return ((TreeNodeStream)input).LT(1);
     83 	}
     84 
     85 	protected Object getMissingSymbol(IntStream input,
     86 									  RecognitionException e,
     87 									  int expectedTokenType,
     88 									  BitSet follow)
     89 	{
     90 		String tokenText =
     91 			"<missing "+getTokenNames()[expectedTokenType]+">";
     92         TreeAdaptor adaptor = ((TreeNodeStream)e.input).getTreeAdaptor();
     93         return adaptor.create(new CommonToken(expectedTokenType, tokenText));
     94 	}
     95 
     96     /** Match '.' in tree parser has special meaning.  Skip node or
     97 	 *  entire tree if node has children.  If children, scan until
     98 	 *  corresponding UP node.
     99 	 */
    100 	public void matchAny(IntStream ignore) { // ignore stream, copy of input
    101 		state.errorRecovery = false;
    102 		state.failed = false;
    103 		Object look = input.LT(1);
    104 		if ( input.getTreeAdaptor().getChildCount(look)==0 ) {
    105 			input.consume(); // not subtree, consume 1 node and return
    106 			return;
    107 		}
    108 		// current node is a subtree, skip to corresponding UP.
    109 		// must count nesting level to get right UP
    110 		int level=0;
    111 		int tokenType = input.getTreeAdaptor().getType(look);
    112 		while ( tokenType!=Token.EOF && !(tokenType==UP && level==0) ) {
    113 			input.consume();
    114 			look = input.LT(1);
    115 			tokenType = input.getTreeAdaptor().getType(look);
    116 			if ( tokenType == DOWN ) {
    117 				level++;
    118 			}
    119 			else if ( tokenType == UP ) {
    120 				level--;
    121 			}
    122 		}
    123 		input.consume(); // consume UP
    124 	}
    125 
    126     /** We have DOWN/UP nodes in the stream that have no line info; override.
    127 	 *  plus we want to alter the exception type.  Don't try to recover
    128 	 *  from tree parser errors inline...
    129      */
    130     protected Object recoverFromMismatchedToken(IntStream input,
    131                                                 int ttype,
    132                                                 BitSet follow)
    133         throws RecognitionException
    134     {
    135         throw new MismatchedTreeNodeException(ttype, (TreeNodeStream)input);
    136     }
    137 
    138     /** Prefix error message with the grammar name because message is
    139 	 *  always intended for the programmer because the parser built
    140 	 *  the input tree not the user.
    141 	 */
    142 	public String getErrorHeader(RecognitionException e) {
    143 		return getGrammarFileName()+": node from "+
    144 			   (e.approximateLineInfo?"after ":"")+"line "+e.line+":"+e.charPositionInLine;
    145 	}
    146 
    147 	/** Tree parsers parse nodes they usually have a token object as
    148 	 *  payload. Set the exception token and do the default behavior.
    149 	 */
    150 	public String getErrorMessage(RecognitionException e, String[] tokenNames) {
    151 		if ( this instanceof TreeParser ) {
    152 			TreeAdaptor adaptor = ((TreeNodeStream)e.input).getTreeAdaptor();
    153 			e.token = adaptor.getToken(e.node);
    154 			if ( e.token==null ) { // could be an UP/DOWN node
    155 				e.token = new CommonToken(adaptor.getType(e.node),
    156 										  adaptor.getText(e.node));
    157 			}
    158 		}
    159 		return super.getErrorMessage(e, tokenNames);
    160 	}
    161 
    162 	public void traceIn(String ruleName, int ruleIndex)  {
    163 		super.traceIn(ruleName, ruleIndex, input.LT(1));
    164 	}
    165 
    166 	public void traceOut(String ruleName, int ruleIndex)  {
    167 		super.traceOut(ruleName, ruleIndex, input.LT(1));
    168 	}
    169 }
    170