org.antlr.runtime.RecognitionException Class Reference
Public Member Functions | |
| RecognitionException () | |
| RecognitionException (IntStream input) | |
| int | getUnexpectedType () |
Public Attributes | |
| transient IntStream | input |
| int | index |
| Token | token |
| Object | node |
| int | c |
| int | line |
| int | charPositionInLine |
| boolean | approximateLineInfo |
Protected Member Functions | |
| void | extractInformationFromTreeNodeStream (IntStream input) |
Detailed Description
The root of the ANTLR exception hierarchy.To avoid English-only error messages and to generally make things as flexible as possible, these exceptions are not created with strings, but rather the information necessary to generate an error. Then the various reporting methods in Parser and Lexer can be overridden to generate a localized error message. For example, MismatchedToken exceptions are built with the expected token type. So, don't expect getMessage() to return anything.
Note that as of Java 1.4, you can access the stack trace, which means that you can compute the complete trace of rules from the start symbol. This gives you considerable context information with which to generate useful error messages.
ANTLR generates code that throws exceptions upon recognition error and also generates code to catch these exceptions in each rule. If you want to quit upon first error, you can turn off the automatic error handling mechanism using rulecatch action, but you still need to override methods mismatch and recoverFromMismatchSet.
In general, the recognition exceptions can track where in a grammar a problem occurred and/or what was the expected input. While the parser knows its state (such as current input symbol and line info) that state can change before the exception is reported so current token index is computed and stored at exception time. From this info, you can perhaps print an entire line of input not just a single token, for example. Better to just say the recognizer had a problem and then let the parser figure out a fancy report.
Definition at line 62 of file RecognitionException.java.
Constructor & Destructor Documentation
| org.antlr.runtime.RecognitionException.RecognitionException | ( | ) |
Used for remote debugger deserialization
Definition at line 99 of file RecognitionException.java.
| org.antlr.runtime.RecognitionException.RecognitionException | ( | IntStream | input | ) |
Definition at line 102 of file RecognitionException.java.
Member Function Documentation
| void org.antlr.runtime.RecognitionException.extractInformationFromTreeNodeStream | ( | IntStream | input | ) | [protected] |
Definition at line 123 of file RecognitionException.java.
| int org.antlr.runtime.RecognitionException.getUnexpectedType | ( | ) |
Return the token type or char of the unexpected input element
Definition at line 167 of file RecognitionException.java.
Member Data Documentation
What input stream did the error occur in?
Definition at line 64 of file RecognitionException.java.
What is index of token/char were we looking at when the error occurred?
Definition at line 67 of file RecognitionException.java.
If this is a tree parser exception, node is set to the node with the problem.
Definition at line 78 of file RecognitionException.java.
The current char when an error occurred. For lexers.
Definition at line 81 of file RecognitionException.java.
Track the line at which the error occurred in case this is generated from a lexer. We need to track this since the unexpected char doesn't carry the line info.
Definition at line 87 of file RecognitionException.java.
Definition at line 89 of file RecognitionException.java.
If you are parsing a tree node stream, you will encounter som imaginary nodes w/o line/col info. We now search backwards looking for most recent token with line/col info, but notify getErrorHeader() that info is approximate.
Definition at line 96 of file RecognitionException.java.
The documentation for this class was generated from the following file:
- /Users/parrt/antlr/code/antlr/main/runtime/Java/src/org/antlr/runtime/RecognitionException.java
