Class: ParserInterpreter

Inherits:
Parser show all
Defined in:
lib/antlr4/ParserInterpreter.rb

Overview

A parser simulator that mimics what ANTLR’s generated

parser code does. A ParserATNSimulator is used to make
predictions via adaptivePredict but this class moves a pointer through the
ATN to simulate parsing. ParserATNSimulator just
makes us efficient rather than having to backtrack, for example.

This properly creates parse trees even for left recursive rules.

We rely on the left recursive rule invocation and special predicate
transitions to make left recursive rules work.

See TestParserInterpreter for examples.

Instance Attribute Summary collapse

Attributes inherited from Parser

#buildParseTrees, #ctx, #errHandler, #input, #parseListeners, #precedenceStack, #syntaxErrors, #tracer

Attributes inherited from Recognizer

#listeners, #ruleIndexMapCache, #state, #tokenTypeMapCache

Instance Method Summary collapse

Methods inherited from Parser

#addContextToParseTree, #addParseListener, #compileParseTreePattern, #consume, #dumpDFA, #enterOuterAlt, #enterRule, #exitRule, #getATNWithBypassAlts, #getCurrentToken, #getDFAStrings, #getExpectedTokens, #getExpectedTokensWithinCurrentRule, #getInputStream, #getInvokingContext, #getParseListeners, #getPrecedence, #getRuleIndex, #getRuleInvocationStack, #getSourceName, #getTokenFactory, #getTokenStream, #inContext, #isExpectedToken, #match, #matchWildcard, #notifyErrorListeners, #precpred, #pushNewRecursionContext, #removeParseListener, #removeParseListeners, #reset, #setInputStream, #setTokenFactory, #setTokenStream, #setTrace, #triggerEnterRuleEvent, #triggerExitRuleEvent, #unrollRecursionContexts

Methods inherited from Recognizer

#addErrorListener, #checkVersion, #extractVersion, #getErrorHeader, #getErrorListenerDispatch, #getRuleIndexMap, #getState, #getTokenErrorDisplay, #getTokenType, #getTokenTypeMap, #precpred, #sempred

Constructor Details

#initialize(grammarFileName, tokenNames, ruleNames, atn, input) ⇒ ParserInterpreter

Returns a new instance of ParserInterpreter.



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# File 'lib/antlr4/ParserInterpreter.rb', line 20

def initialize(grammarFileName, tokenNames, ruleNames, atn, input)
    super(input)
    self.grammarFileName = grammarFileName
    self.atn = atn
    self.tokenNames = tokenNames
    self.ruleNames = ruleNames
    self.decisionToDFA = atn.decisionToState.map {|state| DFA.new(state) }
    self.sharedContextCache = PredictionContextCache.new()
    self.parentContextStack = Array.new
    # identify the ATN states where pushNewRecursionContext must be called
    self.pushRecursionContextStates = Set.new()
    atn.states.each do |state|
        next if not state.kind_of? StarLoopEntryState
        if state.precedenceRuleDecision
            self.pushRecursionContextStates.add(state.stateNumber)
        end
    end
    # get atn simulator that knows how to do predictions
    self.interp = ParserATNSimulator.new(self, atn, self.decisionToDFA, self.sharedContextCache)
end

Instance Attribute Details

#atn ⇒ Object

Returns the value of attribute atn.



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# File 'lib/antlr4/ParserInterpreter.rb', line 17

def atn
  @atn
end

#decisionToDFA ⇒ Object

Returns the value of attribute decisionToDFA.



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# File 'lib/antlr4/ParserInterpreter.rb', line 18

def decisionToDFA
  @decisionToDFA
end

#grammarFileName ⇒ Object

Returns the value of attribute grammarFileName.



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# File 'lib/antlr4/ParserInterpreter.rb', line 17

def grammarFileName
  @grammarFileName
end

#interp ⇒ Object

Returns the value of attribute interp.



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# File 'lib/antlr4/ParserInterpreter.rb', line 19

def interp
  @interp
end

#parentContextStack ⇒ Object

Returns the value of attribute parentContextStack.



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# File 'lib/antlr4/ParserInterpreter.rb', line 17

def parentContextStack
  @parentContextStack
end

#pushRecursionContextStates ⇒ Object

Returns the value of attribute pushRecursionContextStates.



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# File 'lib/antlr4/ParserInterpreter.rb', line 19

def pushRecursionContextStates
  @pushRecursionContextStates
end

#ruleNames ⇒ Object

Returns the value of attribute ruleNames.



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# File 'lib/antlr4/ParserInterpreter.rb', line 18

def ruleNames
  @ruleNames
end

#sharedContextCache ⇒ Object

Returns the value of attribute sharedContextCache.



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# File 'lib/antlr4/ParserInterpreter.rb', line 18

def sharedContextCache
  @sharedContextCache
end

#tokenNames ⇒ Object

Returns the value of attribute tokenNames.



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# File 'lib/antlr4/ParserInterpreter.rb', line 18

def tokenNames
  @tokenNames
end

Instance Method Details

#enterRecursionRule(localctx, state, ruleIndex, precedence) ⇒ Object 



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# File 'lib/antlr4/ParserInterpreter.rb', line 77

def enterRecursionRule(localctx, state, ruleIndex, precedence)
    self.parentContextStack.push([self.ctx, localctx.invokingState])
    super(localctx, state, ruleIndex, precedence)
end

#getATNState ⇒ Object 



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# File 'lib/antlr4/ParserInterpreter.rb', line 81

def getATNState
    return self.atn.states[self.state]
end

#parse(startRuleIndex) ⇒ Object

Begin parsing at startRuleIndex#



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# File 'lib/antlr4/ParserInterpreter.rb', line 41

def parse(startRuleIndex)
    startRuleStartState = self.atn.ruleToStartState[startRuleIndex]
    rootContext = InterpreterRuleContext.new(nil, ATNState::INVALID_STATE_NUMBER, startRuleIndex)
    if startRuleStartState.isPrecedenceRule
        self.enterRecursionRule(rootContext, startRuleStartState.stateNumber, startRuleIndex, 0)
    else
        self.enterRule(rootContext, startRuleStartState.stateNumber, startRuleIndex)
    end
    while true
        p = self.getATNState()
        if p.stateType==ATNState::RULE_STOP 
            # pop; return from rule
            if self.ctx.length==0
                if startRuleStartState.isPrecedenceRule
                    result = self.ctx
                    parentContext = self.parentContextStack.pop()
                    self.unrollRecursionContexts(parentContext.a)
                    return result
                else
                    self.exitRule()
                    return rootContext
                end
            end
            self.visitRuleStopState(p)
        else
            begin
                self.visitState(p)
            rescue RecognitionException => e
                self.state = self.atn.ruleToStopState[p.ruleIndex].stateNumber
                self.ctx.exception = e
                self.errHandler.reportError(self, e)
                self.errHandler.recover(self, e)
            end
        end
    end
end

#visitRuleStopState(p) ⇒ Object

p:ATNState)



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# File 'lib/antlr4/ParserInterpreter.rb', line 137

def visitRuleStopState(p) # p:ATNState)
    ruleStartState = self.atn.ruleToStartState[p.ruleIndex]
    if ruleStartState.isPrecedenceRule then
        parentContext = self.parentContextStack.pop()
        self.unrollRecursionContexts(parentContext.a)
        self.state = parentContext[1]
    else
        self.exitRule()
    end
    ruleTransition = self.atn.states[self.state].transitions[0]
    self.state = ruleTransition.followState.stateNumber
end

#visitState(p) ⇒ Object 



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# File 'lib/antlr4/ParserInterpreter.rb', line 85

def visitState(p)
    edge = 0
    if p.transitions.length() > 1
        self.errHandler.sync(self)
        edge = self.interp.adaptivePredict(self.input, p.decision, self.ctx)
    else
        edge = 1
    end

    transition = p.transitions[edge - 1]
    tt = transition.serializationType
    if tt==Transition::EPSILON then

        if self.pushRecursionContextStates[p.stateNumber] and not transition.target.kind_of? LoopEndState
            t = self.parentContextStack[-1]
            ctx = InterpreterRuleContext.new(t[0], t[1], self.ctx.ruleIndex)
            self.pushNewRecursionContext(ctx, self.atn.ruleToStartState[p.ruleIndex].stateNumber, self.ctx.ruleIndex)
        end
    elsif tt==Transition::ATOM
        self.match(transition.label)
    elsif [ Transition::RANGE, Transition::SET, Transition::NOT_SET].member? tt 
        if not transition.matches(self.input.LA(1), Token::MIN_USER_TOKEN_TYPE, 0xFFFF)
            self.errHandler.recoverInline(self)
        end
        self.matchWildcard()
    elsif tt==Transition::WILDCARD
        self.matchWildcard()
    elsif tt==Transition::RULE
        ruleStartState = transition.target
        ruleIndex = ruleStartState.ruleIndex
        ctx = InterpreterRuleContext(self.ctx, p.stateNumber, ruleIndex)
        if ruleStartState.isPrecedenceRule
            self.enterRecursionRule(ctx, ruleStartState.stateNumber, ruleIndex, transition.precedence)
        else
            self.enterRule(ctx, transition.target.stateNumber, ruleIndex)
        end
    elsif tt==Transition::PREDICATE
        if not self.sempred(self.ctx, transition.ruleIndex, transition.predIndex)
            raise FailedPredicateException.new(self)
        end
    elsif tt==Transition::ACTION
        self.action(self.ctx, transition.ruleIndex, transition.actionIndex)
    elsif tt==Transition::PRECEDENCE
        if not self.precpred(self.ctx, transition.precedence)
            msg = "precpred(ctx, #{transition.precedence})"
            raise FailedPredicateException.new(self, msg)
        end
    else
        raise UnsupportedOperationException.new("Unrecognized ATN transition type.")
    end
    self.state = transition.target.stateNumber
end