Class ProxyErrorListener
- java.lang.Object
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- org.antlr.v4.runtime.ProxyErrorListener
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- All Implemented Interfaces:
ANTLRErrorListener
public class ProxyErrorListener extends Object implements ANTLRErrorListener
This implementation ofANTLRErrorListener
dispatches all calls to a collection of delegate listeners. This reduces the effort required to support multiple listeners.- Author:
- Sam Harwell
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Constructor Summary
Constructors Constructor Description ProxyErrorListener(Collection<? extends ANTLRErrorListener> delegates)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
reportAmbiguity(Parser recognizer, DFA dfa, int startIndex, int stopIndex, boolean exact, BitSet ambigAlts, ATNConfigSet configs)
This method is called by the parser when a full-context prediction results in an ambiguity.void
reportAttemptingFullContext(Parser recognizer, DFA dfa, int startIndex, int stopIndex, BitSet conflictingAlts, ATNConfigSet configs)
This method is called when an SLL conflict occurs and the parser is about to use the full context information to make an LL decision.void
reportContextSensitivity(Parser recognizer, DFA dfa, int startIndex, int stopIndex, int prediction, ATNConfigSet configs)
This method is called by the parser when a full-context prediction has a unique result.void
syntaxError(Recognizer<?,?> recognizer, Object offendingSymbol, int line, int charPositionInLine, String msg, RecognitionException e)
Upon syntax error, notify any interested parties.
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Constructor Detail
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ProxyErrorListener
public ProxyErrorListener(Collection<? extends ANTLRErrorListener> delegates)
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Method Detail
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syntaxError
public void syntaxError(Recognizer<?,?> recognizer, Object offendingSymbol, int line, int charPositionInLine, String msg, RecognitionException e)
Description copied from interface:ANTLRErrorListener
Upon syntax error, notify any interested parties. This is not how to recover from errors or compute error messages.ANTLRErrorStrategy
specifies how to recover from syntax errors and how to compute error messages. This listener's job is simply to emit a computed message, though it has enough information to create its own message in many cases.The
RecognitionException
is non-null for all syntax errors except when we discover mismatched token errors that we can recover from in-line, without returning from the surrounding rule (via the single token insertion and deletion mechanism).- Specified by:
syntaxError
in interfaceANTLRErrorListener
- Parameters:
recognizer
- What parser got the error. From this object, you can access the context as well as the input stream.offendingSymbol
- The offending token in the input token stream, unless recognizer is a lexer (then it's null). If no viable alternative error,e
has token at which we started production for the decision.line
- The line number in the input where the error occurred.charPositionInLine
- The character position within that line where the error occurred.msg
- The message to emit.e
- The exception generated by the parser that led to the reporting of an error. It is null in the case where the parser was able to recover in line without exiting the surrounding rule.
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reportAmbiguity
public void reportAmbiguity(Parser recognizer, DFA dfa, int startIndex, int stopIndex, boolean exact, BitSet ambigAlts, ATNConfigSet configs)
Description copied from interface:ANTLRErrorListener
This method is called by the parser when a full-context prediction results in an ambiguity.Each full-context prediction which does not result in a syntax error will call either
ANTLRErrorListener.reportContextSensitivity(org.antlr.v4.runtime.Parser, org.antlr.v4.runtime.dfa.DFA, int, int, int, org.antlr.v4.runtime.atn.ATNConfigSet)
orANTLRErrorListener.reportAmbiguity(org.antlr.v4.runtime.Parser, org.antlr.v4.runtime.dfa.DFA, int, int, boolean, java.util.BitSet, org.antlr.v4.runtime.atn.ATNConfigSet)
.When
ambigAlts
is not null, it contains the set of potentially viable alternatives identified by the prediction algorithm. WhenambigAlts
is null, useATNConfigSet.getAlts()
to obtain the represented alternatives from theconfigs
argument.When
exact
istrue
, all of the potentially viable alternatives are truly viable, i.e. this is reporting an exact ambiguity. Whenexact
isfalse
, at least two of the potentially viable alternatives are viable for the current input, but the prediction algorithm terminated as soon as it determined that at least the minimum potentially viable alternative is truly viable.When the
PredictionMode.LL_EXACT_AMBIG_DETECTION
prediction mode is used, the parser is required to identify exact ambiguities soexact
will always betrue
.This method is not used by lexers.
- Specified by:
reportAmbiguity
in interfaceANTLRErrorListener
- Parameters:
recognizer
- the parser instancedfa
- the DFA for the current decisionstartIndex
- the input index where the decision startedstopIndex
- the input input where the ambiguity was identifiedexact
-true
if the ambiguity is exactly known, otherwisefalse
. This is alwaystrue
whenPredictionMode.LL_EXACT_AMBIG_DETECTION
is used.ambigAlts
- the potentially ambiguous alternatives, ornull
to indicate that the potentially ambiguous alternatives are the complete set of represented alternatives inconfigs
configs
- the ATN configuration set where the ambiguity was identified
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reportAttemptingFullContext
public void reportAttemptingFullContext(Parser recognizer, DFA dfa, int startIndex, int stopIndex, BitSet conflictingAlts, ATNConfigSet configs)
Description copied from interface:ANTLRErrorListener
This method is called when an SLL conflict occurs and the parser is about to use the full context information to make an LL decision.If one or more configurations in
configs
contains a semantic predicate, the predicates are evaluated before this method is called. The subset of alternatives which are still viable after predicates are evaluated is reported inconflictingAlts
.This method is not used by lexers.
- Specified by:
reportAttemptingFullContext
in interfaceANTLRErrorListener
- Parameters:
recognizer
- the parser instancedfa
- the DFA for the current decisionstartIndex
- the input index where the decision startedstopIndex
- the input index where the SLL conflict occurredconflictingAlts
- The specific conflicting alternatives. If this isnull
, the conflicting alternatives are all alternatives represented inconfigs
. At the moment, conflictingAlts is non-null (for the reference implementation, but Sam's optimized version can see this as null).configs
- the ATN configuration set where the SLL conflict was detected
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reportContextSensitivity
public void reportContextSensitivity(Parser recognizer, DFA dfa, int startIndex, int stopIndex, int prediction, ATNConfigSet configs)
Description copied from interface:ANTLRErrorListener
This method is called by the parser when a full-context prediction has a unique result.Each full-context prediction which does not result in a syntax error will call either
ANTLRErrorListener.reportContextSensitivity(org.antlr.v4.runtime.Parser, org.antlr.v4.runtime.dfa.DFA, int, int, int, org.antlr.v4.runtime.atn.ATNConfigSet)
orANTLRErrorListener.reportAmbiguity(org.antlr.v4.runtime.Parser, org.antlr.v4.runtime.dfa.DFA, int, int, boolean, java.util.BitSet, org.antlr.v4.runtime.atn.ATNConfigSet)
.For prediction implementations that only evaluate full-context predictions when an SLL conflict is found (including the default
ParserATNSimulator
implementation), this method reports cases where SLL conflicts were resolved to unique full-context predictions, i.e. the decision was context-sensitive. This report does not necessarily indicate a problem, and it may appear even in completely unambiguous grammars.configs
may have more than one represented alternative if the full-context prediction algorithm does not evaluate predicates before beginning the full-context prediction. In all cases, the final prediction is passed as theprediction
argument.Note that the definition of "context sensitivity" in this method differs from the concept in
DecisionInfo.contextSensitivities
. This method reports all instances where an SLL conflict occurred but LL parsing produced a unique result, whether or not that unique result matches the minimum alternative in the SLL conflicting set.This method is not used by lexers.
- Specified by:
reportContextSensitivity
in interfaceANTLRErrorListener
- Parameters:
recognizer
- the parser instancedfa
- the DFA for the current decisionstartIndex
- the input index where the decision startedstopIndex
- the input index where the context sensitivity was finally determinedprediction
- the unambiguous result of the full-context predictionconfigs
- the ATN configuration set where the unambiguous prediction was determined
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