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 */
28package org.antlr.runtime;
29
30import org.antlr.runtime.tree.*;
31
32/** The root of the ANTLR exception hierarchy.
33 *
34 *  To avoid English-only error messages and to generally make things
35 *  as flexible as possible, these exceptions are not created with strings,
36 *  but rather the information necessary to generate an error.  Then
37 *  the various reporting methods in Parser and Lexer can be overridden
38 *  to generate a localized error message.  For example, MismatchedToken
39 *  exceptions are built with the expected token type.
40 *  So, don't expect getMessage() to return anything.
41 *
42 *  Note that as of Java 1.4, you can access the stack trace, which means
43 *  that you can compute the complete trace of rules from the start symbol.
44 *  This gives you considerable context information with which to generate
45 *  useful error messages.
46 *
47 *  ANTLR generates code that throws exceptions upon recognition error and
48 *  also generates code to catch these exceptions in each rule.  If you
49 *  want to quit upon first error, you can turn off the automatic error
50 *  handling mechanism using rulecatch action, but you still need to
51 *  override methods mismatch and recoverFromMismatchSet.
52 *
53 *  In general, the recognition exceptions can track where in a grammar a
54 *  problem occurred and/or what was the expected input.  While the parser
55 *  knows its state (such as current input symbol and line info) that
56 *  state can change before the exception is reported so current token index
57 *  is computed and stored at exception time.  From this info, you can
58 *  perhaps print an entire line of input not just a single token, for example.
59 *  Better to just say the recognizer had a problem and then let the parser
60 *  figure out a fancy report.
61 */
62public class RecognitionException extends Exception {
63	/** What input stream did the error occur in? */
64	public transient IntStream input;
65
66	/** What is index of token/char were we looking at when the error occurred? */
67	public int index;
68
69	/** The current Token when an error occurred.  Since not all streams
70	 *  can retrieve the ith Token, we have to track the Token object.
71	 *  For parsers.  Even when it's a tree parser, token might be set.
72	 */
73	public Token token;
74
75	/** If this is a tree parser exception, node is set to the node with
76	 *  the problem.
77	 */
78	public Object node;
79
80	/** The current char when an error occurred. For lexers. */
81	public int c;
82
83	/** Track the line at which the error occurred in case this is
84	 *  generated from a lexer.  We need to track this since the
85	 *  unexpected char doesn't carry the line info.
86	 */
87	public int line;
88
89	public int charPositionInLine;
90
91	/** If you are parsing a tree node stream, you will encounter som
92	 *  imaginary nodes w/o line/col info.  We now search backwards looking
93	 *  for most recent token with line/col info, but notify getErrorHeader()
94	 *  that info is approximate.
95	 */
96	public boolean approximateLineInfo;
97
98	/** Used for remote debugger deserialization */
99	public RecognitionException() {
100	}
101
102	public RecognitionException(IntStream input) {
103		this.input = input;
104		this.index = input.index();
105		if ( input instanceof TokenStream ) {
106			this.token = ((TokenStream)input).LT(1);
107			this.line = token.getLine();
108			this.charPositionInLine = token.getCharPositionInLine();
109		}
110		if ( input instanceof TreeNodeStream ) {
111			extractInformationFromTreeNodeStream(input);
112		}
113		else if ( input instanceof CharStream ) {
114			this.c = input.LA(1);
115			this.line = ((CharStream)input).getLine();
116			this.charPositionInLine = ((CharStream)input).getCharPositionInLine();
117		}
118		else {
119			this.c = input.LA(1);
120		}
121	}
122
123	protected void extractInformationFromTreeNodeStream(IntStream input) {
124		TreeNodeStream nodes = (TreeNodeStream)input;
125		this.node = nodes.LT(1);
126		TreeAdaptor adaptor = nodes.getTreeAdaptor();
127		Token payload = adaptor.getToken(node);
128		if ( payload!=null ) {
129			this.token = payload;
130			if ( payload.getLine()<= 0 ) {
131				// imaginary node; no line/pos info; scan backwards
132				int i = -1;
133				Object priorNode = nodes.LT(i);
134				while ( priorNode!=null ) {
135					Token priorPayload = adaptor.getToken(priorNode);
136					if ( priorPayload!=null && priorPayload.getLine()>0 ) {
137						// we found the most recent real line / pos info
138						this.line = priorPayload.getLine();
139						this.charPositionInLine = priorPayload.getCharPositionInLine();
140						this.approximateLineInfo = true;
141						break;
142					}
143					--i;
144					priorNode = nodes.LT(i);
145				}
146			}
147			else { // node created from real token
148				this.line = payload.getLine();
149				this.charPositionInLine = payload.getCharPositionInLine();
150			}
151		}
152		else if ( this.node instanceof Tree) {
153			this.line = ((Tree)this.node).getLine();
154			this.charPositionInLine = ((Tree)this.node).getCharPositionInLine();
155			if ( this.node instanceof CommonTree) {
156				this.token = ((CommonTree)this.node).token;
157			}
158		}
159		else {
160			int type = adaptor.getType(this.node);
161			String text = adaptor.getText(this.node);
162			this.token = new CommonToken(type, text);
163		}
164	}
165
166	/** Return the token type or char of the unexpected input element */
167	public int getUnexpectedType() {
168		if ( input instanceof TokenStream ) {
169			return token.getType();
170		}
171		else if ( input instanceof TreeNodeStream ) {
172			TreeNodeStream nodes = (TreeNodeStream)input;
173			TreeAdaptor adaptor = nodes.getTreeAdaptor();
174			return adaptor.getType(node);
175		}
176		else {
177			return c;
178		}
179	}
180}
181