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java.lang.Objectjava.lang.Throwable
java.lang.Exception
org.antlr.runtime.RecognitionException
public class RecognitionException
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.
Field Summary | |
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boolean |
approximateLineInfo
If you are parsing a tree node stream, you will encounter som imaginary nodes w/o line/col info. |
int |
c
The current char when an error occurred. |
int |
charPositionInLine
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int |
index
What is index of token/char were we looking at when the error occurred? |
IntStream |
input
What input stream did the error occur in? |
int |
line
Track the line at which the error occurred in case this is generated from a lexer. |
java.lang.Object |
node
If this is a tree parser exception, node is set to the node with the problem. |
Token |
token
The current Token when an error occurred. |
Constructor Summary | |
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RecognitionException()
Used for remote debugger deserialization |
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RecognitionException(IntStream input)
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Method Summary | |
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protected void |
extractInformationFromTreeNodeStream(IntStream input)
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int |
getUnexpectedType()
Return the token type or char of the unexpected input element |
Methods inherited from class java.lang.Throwable |
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fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
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public transient IntStream input
public int index
public Token token
public java.lang.Object node
public int c
public int line
public int charPositionInLine
public boolean approximateLineInfo
Constructor Detail |
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public RecognitionException()
public RecognitionException(IntStream input)
Method Detail |
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protected void extractInformationFromTreeNodeStream(IntStream input)
public int getUnexpectedType()
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