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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.Token;
     31 import org.antlr.runtime.CommonToken;
     32 
     33 public class TreePatternParser {
     34 	protected TreePatternLexer tokenizer;
     35 	protected int ttype;
     36 	protected TreeWizard wizard;
     37 	protected TreeAdaptor adaptor;
     38 
     39 	public TreePatternParser(TreePatternLexer tokenizer, TreeWizard wizard, TreeAdaptor adaptor) {
     40 		this.tokenizer = tokenizer;
     41 		this.wizard = wizard;
     42 		this.adaptor = adaptor;
     43 		ttype = tokenizer.nextToken(); // kickstart
     44 	}
     45 
     46 	public Object pattern() {
     47 		if ( ttype==TreePatternLexer.BEGIN ) {
     48 			return parseTree();
     49 		}
     50 		else if ( ttype==TreePatternLexer.ID ) {
     51 			Object node = parseNode();
     52 			if ( ttype==TreePatternLexer.EOF ) {
     53 				return node;
     54 			}
     55 			return null; // extra junk on end
     56 		}
     57 		return null;
     58 	}
     59 
     60 	public Object parseTree() {
     61 		if ( ttype != TreePatternLexer.BEGIN ) {
     62 			throw new RuntimeException("no BEGIN");
     63 		}
     64 		ttype = tokenizer.nextToken();
     65 		Object root = parseNode();
     66 		if ( root==null ) {
     67 			return null;
     68 		}
     69 		while ( ttype==TreePatternLexer.BEGIN ||
     70 				ttype==TreePatternLexer.ID ||
     71 				ttype==TreePatternLexer.PERCENT ||
     72 				ttype==TreePatternLexer.DOT )
     73 		{
     74 			if ( ttype==TreePatternLexer.BEGIN ) {
     75 				Object subtree = parseTree();
     76 				adaptor.addChild(root, subtree);
     77 			}
     78 			else {
     79 				Object child = parseNode();
     80 				if ( child==null ) {
     81 					return null;
     82 				}
     83 				adaptor.addChild(root, child);
     84 			}
     85 		}
     86 		if ( ttype != TreePatternLexer.END ) {
     87 			throw new RuntimeException("no END");
     88 		}
     89 		ttype = tokenizer.nextToken();
     90 		return root;
     91 	}
     92 
     93 	public Object parseNode() {
     94 		// "%label:" prefix
     95 		String label = null;
     96 		if ( ttype == TreePatternLexer.PERCENT ) {
     97 			ttype = tokenizer.nextToken();
     98 			if ( ttype != TreePatternLexer.ID ) {
     99 				return null;
    100 			}
    101 			label = tokenizer.sval.toString();
    102 			ttype = tokenizer.nextToken();
    103 			if ( ttype != TreePatternLexer.COLON ) {
    104 				return null;
    105 			}
    106 			ttype = tokenizer.nextToken(); // move to ID following colon
    107 		}
    108 
    109 		// Wildcard?
    110 		if ( ttype == TreePatternLexer.DOT ) {
    111 			ttype = tokenizer.nextToken();
    112 			Token wildcardPayload = new CommonToken(0, ".");
    113 			TreeWizard.TreePattern node =
    114 				new TreeWizard.WildcardTreePattern(wildcardPayload);
    115 			if ( label!=null ) {
    116 				node.label = label;
    117 			}
    118 			return node;
    119 		}
    120 
    121 		// "ID" or "ID[arg]"
    122 		if ( ttype != TreePatternLexer.ID ) {
    123 			return null;
    124 		}
    125 		String tokenName = tokenizer.sval.toString();
    126 		ttype = tokenizer.nextToken();
    127 		if ( tokenName.equals("nil") ) {
    128 			return adaptor.nil();
    129 		}
    130 		String text = tokenName;
    131 		// check for arg
    132 		String arg = null;
    133 		if ( ttype == TreePatternLexer.ARG ) {
    134 			arg = tokenizer.sval.toString();
    135 			text = arg;
    136 			ttype = tokenizer.nextToken();
    137 		}
    138 
    139 		// create node
    140 		int treeNodeType = wizard.getTokenType(tokenName);
    141 		if ( treeNodeType==Token.INVALID_TOKEN_TYPE ) {
    142 			return null;
    143 		}
    144 		Object node;
    145 		node = adaptor.create(treeNodeType, text);
    146 		if ( label!=null && node.getClass()==TreeWizard.TreePattern.class ) {
    147 			((TreeWizard.TreePattern)node).label = label;
    148 		}
    149 		if ( arg!=null && node.getClass()==TreeWizard.TreePattern.class ) {
    150 			((TreeWizard.TreePattern)node).hasTextArg = true;
    151 		}
    152 		return node;
    153 	}
    154 }
    155