Class: DiagnosticErrorListener

Inherits:
ErrorListener show all
Defined in:
lib/antlr4/error/DiagnosticErrorListener.rb

Overview

This implementation of ANTLRErrorListener can be used to identify certain potential correctness and performance problems in grammars. “Reports” are made by calling Parser#notifyErrorListeners with the appropriate message.

<ul> <li>Ambiguities: These are cases where more than one path through the grammar can match the input.</li> <li>Weak context sensitivity: These are cases where full-context prediction resolved an SLL conflict to a unique alternative which equaled the minimum alternative of the SLL conflict.</li> <li>Strong (forced) context sensitivity: These are cases where the full-context prediction resolved an SLL conflict to a unique alternative, and the minimum alternative of the SLL conflict was found to not be a truly viable alternative. Two-stage parsing cannot be used for inputs where this situation occurs.</li> </ul>

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from ErrorListener

#syntaxError

Constructor Details

#initialize(exactOnly = true) ⇒ DiagnosticErrorListener

Returns a new instance of DiagnosticErrorListener.



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# File 'lib/antlr4/error/DiagnosticErrorListener.rb', line 55

def initialize(exactOnly=true)
    # whether all ambiguities or only exact ambiguities are reported.
    @exactOnly = exactOnly
end

Instance Attribute Details

#exactOnly ⇒ Object

Returns the value of attribute exactOnly.



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# File 'lib/antlr4/error/DiagnosticErrorListener.rb', line 54

def exactOnly
  @exactOnly
end

Instance Method Details

#getConflictingAlts(reportedAlts, configs) ⇒ Object

Computes the set of conflicting or ambiguous alternatives from a configuration set, if that information was not already provided by the parser.

reported by the parser. returns the set of alternatives represented in configs.

Parameters:

  • reportedAlts —

    The set of conflicting or ambiguous alternatives, as

  • configs —

    The conflicting or ambiguous configuration set.



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# File 'lib/antlr4/error/DiagnosticErrorListener.rb', line 125

def getConflictingAlts(reportedAlts, configs)
    if not reportedAlts.nil? then
        return reportedAlts
    end

    result = Set.new
    for config in configs
        result.add(config.alt)
    end
    return result
end

#getDecisionDescription(recognizer, dfa) ⇒ Object 



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# File 'lib/antlr4/error/DiagnosticErrorListener.rb', line 97

def getDecisionDescription(recognizer, dfa)
    decision = dfa.decision
    ruleIndex = dfa.atnStartState.ruleIndex

    ruleNames = recognizer.ruleNames
    if ruleIndex < 0 or ruleIndex >= ruleNames.length
        return decision.to_s
    end

    ruleName = ruleNames[ruleIndex]
    if ruleName.nil? or ruleName.zero? then
        return decision.to_s
    end

    return "#{decision} (#{ruleName})"
end

#reportAmbiguity(recognizer, dfa, startIndex, stopIndex, exact, ambigAlts, configs) ⇒ Object 



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# File 'lib/antlr4/error/DiagnosticErrorListener.rb', line 60

def reportAmbiguity(recognizer, dfa, startIndex, stopIndex, exact, ambigAlts, configs)
    return if self.exactOnly and not exact

    StringIO.open { |buf| 
        buf.write("reportAmbiguity d=")
        buf.write(self.getDecisionDescription(recognizer, dfa))
        buf.write(": ambigAlts=")
        buf.write(self.getConflictingAlts(ambigAlts, configs).to_s)
        buf.write(", input='")
        buf.write(recognizer.getTokenStream().getText(startIndex, stopIndex)) # getText
        buf.write("'")
        recognizer.notifyErrorListeners(buf.string())
    }
end

#reportAttemptingFullContext(recognizer, dfa, startIndex, stopIndex, conflictingAlts, configs) ⇒ Object 



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# File 'lib/antlr4/error/DiagnosticErrorListener.rb', line 75

def reportAttemptingFullContext(recognizer, dfa, startIndex, stopIndex, conflictingAlts, configs)
    StringIO.open {|buf|
        buf.write("reportAttemptingFullContext d=")
        buf.write(self.getDecisionDescription(recognizer, dfa))
        buf.write(", input='")
        buf.write(recognizer.getTokenStream().getText(startIndex, stopIndex))
        buf.write("'")
        recognizer.notifyErrorListeners(buf.string())
    }
end

#reportContextSensitivity(recognizer, dfa, startIndex, stopIndex, prediction, configs) ⇒ Object 



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# File 'lib/antlr4/error/DiagnosticErrorListener.rb', line 86

def reportContextSensitivity(recognizer, dfa, startIndex, stopIndex, prediction, configs)
    StringIO.open {|buf|
        buf.write("reportContextSensitivity d=")
        buf.write(self.getDecisionDescription(recognizer, dfa))
        buf.write(", input='")
        buf.write(recognizer.getTokenStream().getText(startIndex, stopIndex))
        buf.write("'")
        recognizer.notifyErrorListeners(buf.string())
  }
end