Examples with ATNState org.antlr.v4.runtime.atn.ATNState used on opensource projects

Example 26 with ATNState

use of org.antlr.v4.runtime.atn.ATNState in project antlr4 by tunnelvisionlabs.

the class LeftRecursionDetector method check.

public void check() {
    for (RuleStartState start : atn.ruleToStartState) {
        // System.out.print("check "+start.rule.name);
        rulesVisitedPerRuleCheck.clear();
        rulesVisitedPerRuleCheck.add(start);
        // FASerializer ser = new FASerializer(atn.g, start);
        // System.out.print(":\n"+ser+"\n");
        check(g.getRule(start.ruleIndex), start, new HashSet<ATNState>());
    }
    // System.out.println("cycles="+listOfRecursiveCycles);
    if (!listOfRecursiveCycles.isEmpty()) {
        g.tool.errMgr.leftRecursionCycles(g.fileName, listOfRecursiveCycles);
    }
}

Example 27 with ATNState

use of org.antlr.v4.runtime.atn.ATNState in project antlr4 by tunnelvisionlabs.

the class ParserATNSimulator method computeStartState.

@NotNull
protected SimulatorState computeStartState(DFA dfa, ParserRuleContext globalContext, boolean useContext) {
    DFAState s0 = dfa.isPrecedenceDfa() ? dfa.getPrecedenceStartState(parser.getPrecedence(), useContext) : useContext ? dfa.s0full.get() : dfa.s0.get();
    if (s0 != null) {
        if (!useContext) {
            return new SimulatorState(globalContext, s0, useContext, globalContext);
        }
        s0.setContextSensitive(atn);
    }
    final int decision = dfa.decision;
    @NotNull final ATNState p = dfa.atnStartState;
    int previousContext = 0;
    ParserRuleContext remainingGlobalContext = globalContext;
    // always at least the implicit call to start rule
    PredictionContext initialContext = useContext ? PredictionContext.EMPTY_FULL : PredictionContext.EMPTY_LOCAL;
    PredictionContextCache contextCache = new PredictionContextCache();
    if (useContext) {
        if (!enable_global_context_dfa) {
            while (remainingGlobalContext != null) {
                if (remainingGlobalContext.isEmpty()) {
                    previousContext = PredictionContext.EMPTY_FULL_STATE_KEY;
                    remainingGlobalContext = null;
                } else {
                    previousContext = getReturnState(remainingGlobalContext);
                    initialContext = initialContext.appendContext(previousContext, contextCache);
                    remainingGlobalContext = remainingGlobalContext.getParent();
                }
            }
        }
        while (s0 != null && s0.isContextSensitive() && remainingGlobalContext != null) {
            DFAState next;
            remainingGlobalContext = skipTailCalls(remainingGlobalContext);
            if (remainingGlobalContext.isEmpty()) {
                next = s0.getContextTarget(PredictionContext.EMPTY_FULL_STATE_KEY);
                previousContext = PredictionContext.EMPTY_FULL_STATE_KEY;
                remainingGlobalContext = null;
            } else {
                previousContext = getReturnState(remainingGlobalContext);
                next = s0.getContextTarget(previousContext);
                initialContext = initialContext.appendContext(previousContext, contextCache);
                remainingGlobalContext = remainingGlobalContext.getParent();
            }
            if (next == null) {
                break;
            }
            s0 = next;
        }
    }
    if (s0 != null && !s0.isContextSensitive()) {
        return new SimulatorState(globalContext, s0, useContext, remainingGlobalContext);
    }
    ATNConfigSet configs = new ATNConfigSet();
    while (true) {
        ATNConfigSet reachIntermediate = new ATNConfigSet();
        int n = p.getNumberOfTransitions();
        for (int ti = 0; ti < n; ti++) {
            // for each transition
            ATNState target = p.transition(ti).target;
            reachIntermediate.add(ATNConfig.create(target, ti + 1, initialContext));
        }
        boolean hasMoreContext = remainingGlobalContext != null;
        if (!hasMoreContext) {
            configs.setOutermostConfigSet(true);
        }
        final boolean collectPredicates = true;
        closure(reachIntermediate, configs, collectPredicates, hasMoreContext, contextCache, false);
        boolean stepIntoGlobal = configs.getDipsIntoOuterContext();
        DFAState next;
        if (useContext && !enable_global_context_dfa) {
            s0 = addDFAState(dfa, configs, contextCache);
            break;
        } else if (s0 == null) {
            if (!dfa.isPrecedenceDfa()) {
                AtomicReference<DFAState> reference = useContext ? dfa.s0full : dfa.s0;
                next = addDFAState(dfa, configs, contextCache);
                if (!reference.compareAndSet(null, next)) {
                    next = reference.get();
                }
            } else {
                /* If this is a precedence DFA, we use applyPrecedenceFilter
					 * to convert the computed start state to a precedence start
					 * state. We then use DFA.setPrecedenceStartState to set the
					 * appropriate start state for the precedence level rather
					 * than simply setting DFA.s0.
					 */
                configs = applyPrecedenceFilter(configs, globalContext, contextCache);
                next = addDFAState(dfa, configs, contextCache);
                dfa.setPrecedenceStartState(parser.getPrecedence(), useContext, next);
            }
        } else {
            if (dfa.isPrecedenceDfa()) {
                configs = applyPrecedenceFilter(configs, globalContext, contextCache);
            }
            next = addDFAState(dfa, configs, contextCache);
            s0.setContextTarget(previousContext, next);
        }
        s0 = next;
        if (!useContext || !stepIntoGlobal) {
            break;
        }
        // TODO: make sure it distinguishes empty stack states
        next.setContextSensitive(atn);
        configs.clear();
        remainingGlobalContext = skipTailCalls(remainingGlobalContext);
        int nextContextElement = getReturnState(remainingGlobalContext);
        if (remainingGlobalContext.isEmpty()) {
            remainingGlobalContext = null;
        } else {
            remainingGlobalContext = remainingGlobalContext.getParent();
        }
        if (nextContextElement != PredictionContext.EMPTY_FULL_STATE_KEY) {
            initialContext = initialContext.appendContext(nextContextElement, contextCache);
        }
        previousContext = nextContextElement;
    }
    return new SimulatorState(globalContext, s0, useContext, remainingGlobalContext);
}

Example 28 with ATNState

use of org.antlr.v4.runtime.atn.ATNState in project antlr4 by tunnelvisionlabs.

the class Parser method getExpectedTokensWithinCurrentRule.

@NotNull
public IntervalSet getExpectedTokensWithinCurrentRule() {
    ATN atn = getInterpreter().atn;
    ATNState s = atn.states.get(getState());
    return atn.nextTokens(s);
}

Example 29 with ATNState

use of org.antlr.v4.runtime.atn.ATNState in project antlr4 by tunnelvisionlabs.

the class ParserInterpreter method visitState.

protected void visitState(ATNState p) {
    int predictedAlt = 1;
    if (p.getNumberOfTransitions() > 1) {
        predictedAlt = visitDecisionState((DecisionState) p);
    }
    Transition transition = p.transition(predictedAlt - 1);
    switch(transition.getSerializationType()) {
        case Transition.EPSILON:
            if (pushRecursionContextStates.get(p.stateNumber) && !(transition.target instanceof LoopEndState)) {
                // We are at the start of a left recursive rule's (...)* loop
                // and we're not taking the exit branch of loop.
                InterpreterRuleContext localctx = createInterpreterRuleContext(_parentContextStack.peek().getItem1(), _parentContextStack.peek().getItem2(), _ctx.getRuleIndex());
                pushNewRecursionContext(localctx, atn.ruleToStartState[p.ruleIndex].stateNumber, _ctx.getRuleIndex());
            }
            break;
        case Transition.ATOM:
            match(((AtomTransition) transition).label);
            break;
        case Transition.RANGE:
        case Transition.SET:
        case Transition.NOT_SET:
            if (!transition.matches(_input.LA(1), Token.MIN_USER_TOKEN_TYPE, 65535)) {
                recoverInline();
            }
            matchWildcard();
            break;
        case Transition.WILDCARD:
            matchWildcard();
            break;
        case Transition.RULE:
            RuleStartState ruleStartState = (RuleStartState) transition.target;
            int ruleIndex = ruleStartState.ruleIndex;
            InterpreterRuleContext newctx = createInterpreterRuleContext(_ctx, p.stateNumber, ruleIndex);
            if (ruleStartState.isPrecedenceRule) {
                enterRecursionRule(newctx, ruleStartState.stateNumber, ruleIndex, ((RuleTransition) transition).precedence);
            } else {
                enterRule(newctx, transition.target.stateNumber, ruleIndex);
            }
            break;
        case Transition.PREDICATE:
            PredicateTransition predicateTransition = (PredicateTransition) transition;
            if (!sempred(_ctx, predicateTransition.ruleIndex, predicateTransition.predIndex)) {
                throw new FailedPredicateException(this);
            }
            break;
        case Transition.ACTION:
            ActionTransition actionTransition = (ActionTransition) transition;
            action(_ctx, actionTransition.ruleIndex, actionTransition.actionIndex);
            break;
        case Transition.PRECEDENCE:
            if (!precpred(_ctx, ((PrecedencePredicateTransition) transition).precedence)) {
                throw new FailedPredicateException(this, String.format("precpred(_ctx, %d)", ((PrecedencePredicateTransition) transition).precedence));
            }
            break;
        default:
            throw new UnsupportedOperationException("Unrecognized ATN transition type.");
    }
    setState(transition.target.stateNumber);
}

Example 30 with ATNState

use of org.antlr.v4.runtime.atn.ATNState in project antlr4 by tunnelvisionlabs.

the class DefaultErrorStrategy method getErrorRecoverySet.

/*  Compute the error recovery set for the current rule.  During
	 *  rule invocation, the parser pushes the set of tokens that can
	 *  follow that rule reference on the stack; this amounts to
	 *  computing FIRST of what follows the rule reference in the
	 *  enclosing rule. See LinearApproximator.FIRST().
	 *  This local follow set only includes tokens
	 *  from within the rule; i.e., the FIRST computation done by
	 *  ANTLR stops at the end of a rule.
	 *
	 *  EXAMPLE
	 *
	 *  When you find a "no viable alt exception", the input is not
	 *  consistent with any of the alternatives for rule r.  The best
	 *  thing to do is to consume tokens until you see something that
	 *  can legally follow a call to r *or* any rule that called r.
	 *  You don't want the exact set of viable next tokens because the
	 *  input might just be missing a token--you might consume the
	 *  rest of the input looking for one of the missing tokens.
	 *
	 *  Consider grammar:
	 *
	 *  a : '[' b ']'
	 *    | '(' b ')'
	 *    ;
	 *  b : c '^' INT ;
	 *  c : ID
	 *    | INT
	 *    ;
	 *
	 *  At each rule invocation, the set of tokens that could follow
	 *  that rule is pushed on a stack.  Here are the various
	 *  context-sensitive follow sets:
	 *
	 *  FOLLOW(b1_in_a) = FIRST(']') = ']'
	 *  FOLLOW(b2_in_a) = FIRST(')') = ')'
	 *  FOLLOW(c_in_b) = FIRST('^') = '^'
	 *
	 *  Upon erroneous input "[]", the call chain is
	 *
	 *  a -> b -> c
	 *
	 *  and, hence, the follow context stack is:
	 *
	 *  depth     follow set       start of rule execution
	 *    0         <EOF>                    a (from main())
	 *    1          ']'                     b
	 *    2          '^'                     c
	 *
	 *  Notice that ')' is not included, because b would have to have
	 *  been called from a different context in rule a for ')' to be
	 *  included.
	 *
	 *  For error recovery, we cannot consider FOLLOW(c)
	 *  (context-sensitive or otherwise).  We need the combined set of
	 *  all context-sensitive FOLLOW sets--the set of all tokens that
	 *  could follow any reference in the call chain.  We need to
	 *  resync to one of those tokens.  Note that FOLLOW(c)='^' and if
	 *  we resync'd to that token, we'd consume until EOF.  We need to
	 *  sync to context-sensitive FOLLOWs for a, b, and c: {']','^'}.
	 *  In this case, for input "[]", LA(1) is ']' and in the set, so we would
	 *  not consume anything. After printing an error, rule c would
	 *  return normally.  Rule b would not find the required '^' though.
	 *  At this point, it gets a mismatched token error and throws an
	 *  exception (since LA(1) is not in the viable following token
	 *  set).  The rule exception handler tries to recover, but finds
	 *  the same recovery set and doesn't consume anything.  Rule b
	 *  exits normally returning to rule a.  Now it finds the ']' (and
	 *  with the successful match exits errorRecovery mode).
	 *
	 *  So, you can see that the parser walks up the call chain looking
	 *  for the token that was a member of the recovery set.
	 *
	 *  Errors are not generated in errorRecovery mode.
	 *
	 *  ANTLR's error recovery mechanism is based upon original ideas:
	 *
	 *  "Algorithms + Data Structures = Programs" by Niklaus Wirth
	 *
	 *  and
	 *
	 *  "A note on error recovery in recursive descent parsers":
	 *  http://portal.acm.org/citation.cfm?id=947902.947905
	 *
	 *  Later, Josef Grosch had some good ideas:
	 *
	 *  "Efficient and Comfortable Error Recovery in Recursive Descent
	 *  Parsers":
	 *  ftp://www.cocolab.com/products/cocktail/doca4.ps/ell.ps.zip
	 *
	 *  Like Grosch I implement context-sensitive FOLLOW sets that are combined
	 *  at run-time upon error to avoid overhead during parsing.
	 */
@NotNull
protected IntervalSet getErrorRecoverySet(@NotNull Parser recognizer) {
    ATN atn = recognizer.getInterpreter().atn;
    RuleContext ctx = recognizer._ctx;
    IntervalSet recoverSet = new IntervalSet();
    while (ctx != null && ctx.invokingState >= 0) {
        // compute what follows who invoked us
        ATNState invokingState = atn.states.get(ctx.invokingState);
        RuleTransition rt = (RuleTransition) invokingState.transition(0);
        IntervalSet follow = atn.nextTokens(rt.followState);
        recoverSet.addAll(follow);
        ctx = ctx.parent;
    }
    recoverSet.remove(Token.EPSILON);
    // System.out.println("recover set "+recoverSet.toString(recognizer.getTokenNames()));
    return recoverSet;
}