1/*
2 [The "BSD licence"]
3 Copyright (c) 2005-2007 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*/
28package org.antlr.runtime.tree {
29	import org.antlr.runtime.*;
30
31	/** A parser for a stream of tree nodes.  "tree grammars" result in a subclass
32	 *  of this.  All the error reporting and recovery is shared with Parser via
33	 *  the BaseRecognizer superclass.
34	*/
35	public class TreeParser extends BaseRecognizer {
36		public static const DOWN:int = TokenConstants.DOWN;
37		public static const UP:int = TokenConstants.UP;
38
39		protected var input:TreeNodeStream;
40
41		public function TreeParser(input:TreeNodeStream, state:RecognizerSharedState = null) {
42			super(state);
43			treeNodeStream = input;
44		}
45
46		public override function reset():void {
47			super.reset(); // reset all recognizer state variables
48			if ( input!=null ) {
49				input.seek(0); // rewind the input
50			}
51		}
52
53		/** Set the input stream */
54		public function set treeNodeStream(input:TreeNodeStream):void {
55			this.input = input;
56		}
57
58		public function get treeNodeStream():TreeNodeStream {
59			return input;
60		}
61
62		public override function get sourceName():String {
63			return input.sourceName;
64		}
65
66		protected override function getCurrentInputSymbol(input:IntStream):Object {
67			return TreeNodeStream(input).LT(1);
68		}
69
70		protected override function getMissingSymbol(input:IntStream,
71										   e:RecognitionException,
72										   expectedTokenType:int,
73										   follow:BitSet):Object {
74			var tokenText:String =
75				"<missing "+tokenNames[expectedTokenType]+">";
76			return CommonTree.createFromToken(new CommonToken(expectedTokenType, tokenText));
77		}
78
79		/** Match '.' in tree parser has special meaning.  Skip node or
80		 *  entire tree if node has children.  If children, scan until
81		 *  corresponding UP node.
82		 */
83		public function matchAny(ignore:IntStream):void { // ignore stream, copy of this.input
84			state.errorRecovery = false;
85			state.failed = false;
86			var look:Object = input.LT(1);
87			if ( input.treeAdaptor.getChildCount(look)==0 ) {
88				input.consume(); // not subtree, consume 1 node and return
89				return;
90			}
91			// current node is a subtree, skip to corresponding UP.
92			// must count nesting level to get right UP
93			var level:int=0;
94			var tokenType:int = input.treeAdaptor.getType(look);
95			while ( tokenType!=TokenConstants.EOF && !(tokenType==UP && level==0) ) {
96				input.consume();
97				look = input.LT(1);
98				tokenType = input.treeAdaptor.getType(look);
99				if ( tokenType == DOWN ) {
100					level++;
101				}
102				else if ( tokenType == UP ) {
103					level--;
104				}
105			}
106			input.consume(); // consume UP
107		}
108
109		/** We have DOWN/UP nodes in the stream that have no line info; override.
110		 *  plus we want to alter the exception type. Don't try to recover
111	 	 *  from tree parser errors inline...
112		 */
113		protected override function mismatch(input:IntStream, ttype:int, follow:BitSet):void {
114			throw new MismatchedTreeNodeException(ttype, TreeNodeStream(input));
115		}
116
117		/** Prefix error message with the grammar name because message is
118		 *  always intended for the programmer because the parser built
119		 *  the input tree not the user.
120		 */
121		public override function getErrorHeader(e:RecognitionException):String {
122			return grammarFileName+": node from "+
123				   (e.approximateLineInfo?"after ":"")+"line "+e.line+":"+e.charPositionInLine;
124		}
125
126		/** Tree parsers parse nodes they usually have a token object as
127		 *  payload. Set the exception token and do the default behavior.
128		 */
129		public override function getErrorMessage(e:RecognitionException, tokenNames:Array):String {
130			if ( this is TreeParser ) {
131				var adaptor:TreeAdaptor = TreeNodeStream(e.input).treeAdaptor;
132				e.token = adaptor.getToken(e.node);
133				if ( e.token==null ) { // could be an UP/DOWN node
134					e.token = new CommonToken(adaptor.getType(e.node),
135											  adaptor.getText(e.node));
136				}
137			}
138			return super.getErrorMessage(e, tokenNames);
139		}
140
141	   public function set treeAdaptor(adaptor:TreeAdaptor):void {
142            // do nothing, implemented in generated code
143        }
144
145        public function get treeAdaptor():TreeAdaptor {
146            // implementation provided in generated code
147            return null;
148        }
149
150		public function traceIn(ruleName:String, ruleIndex:int):void  {
151			super.traceInSymbol(ruleName, ruleIndex, input.LT(1));
152		}
153
154		public function traceOut(ruleName:String, ruleIndex:int):void  {
155			super.traceOutSymbol(ruleName, ruleIndex, input.LT(1));
156		}
157	}
158
159}