Examples with DFAState org.antlr.v4.runtime.dfa.DFAState used on opensource projects

Example 6 with DFAState

use of org.antlr.v4.runtime.dfa.DFAState 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 7 with DFAState

use of org.antlr.v4.runtime.dfa.DFAState in project antlr4 by tunnelvisionlabs.

the class ParserATNSimulator method addDFAEdge.

@NotNull
protected DFAState addDFAEdge(@NotNull DFA dfa, @NotNull DFAState fromState, int t, IntegerList contextTransitions, @NotNull ATNConfigSet toConfigs, PredictionContextCache contextCache) {
    assert contextTransitions == null || contextTransitions.isEmpty() || dfa.isContextSensitive();
    DFAState from = fromState;
    DFAState to = addDFAState(dfa, toConfigs, contextCache);
    if (contextTransitions != null) {
        for (int context : contextTransitions.toArray()) {
            if (context == PredictionContext.EMPTY_FULL_STATE_KEY) {
                if (from.configs.isOutermostConfigSet()) {
                    continue;
                }
            }
            from.setContextSensitive(atn);
            from.setContextSymbol(t);
            DFAState next = from.getContextTarget(context);
            if (next != null) {
                from = next;
                continue;
            }
            next = addDFAContextState(dfa, from.configs, context, contextCache);
            assert context != PredictionContext.EMPTY_FULL_STATE_KEY || next.configs.isOutermostConfigSet();
            from.setContextTarget(context, next);
            from = next;
        }
    }
    if (debug)
        System.out.println("EDGE " + from + " -> " + to + " upon " + getTokenName(t));
    addDFAEdge(from, t, to);
    if (debug)
        System.out.println("DFA=\n" + dfa.toString(parser != null ? parser.getVocabulary() : VocabularyImpl.EMPTY_VOCABULARY, parser != null ? parser.getRuleNames() : null));
    return to;
}

Example 8 with DFAState

use of org.antlr.v4.runtime.dfa.DFAState in project antlr4 by tunnelvisionlabs.

the class LexerATNSimulator method execATN.

protected int execATN(@NotNull CharStream input, @NotNull DFAState ds0) {
    // System.out.println("enter exec index "+input.index()+" from "+ds0.configs);
    if (debug) {
        System.out.format(Locale.getDefault(), "start state closure=%s\n", ds0.configs);
    }
    if (ds0.isAcceptState()) {
        // allow zero-length tokens
        captureSimState(prevAccept, input, ds0);
    }
    int t = input.LA(1);
    @NotNull DFAState // s is current/from DFA state
    s = ds0;
    while (true) {
        // while more work
        if (debug) {
            System.out.format(Locale.getDefault(), "execATN loop starting closure: %s\n", s.configs);
        }
        // As we move src->trg, src->trg, we keep track of the previous trg to
        // avoid looking up the DFA state again, which is expensive.
        // If the previous target was already part of the DFA, we might
        // be able to avoid doing a reach operation upon t. If s!=null,
        // it means that semantic predicates didn't prevent us from
        // creating a DFA state. Once we know s!=null, we check to see if
        // the DFA state has an edge already for t. If so, we can just reuse
        // it's configuration set; there's no point in re-computing it.
        // This is kind of like doing DFA simulation within the ATN
        // simulation because DFA simulation is really just a way to avoid
        // computing reach/closure sets. Technically, once we know that
        // we have a previously added DFA state, we could jump over to
        // the DFA simulator. But, that would mean popping back and forth
        // a lot and making things more complicated algorithmically.
        // This optimization makes a lot of sense for loops within DFA.
        // A character will take us back to an existing DFA state
        // that already has lots of edges out of it. e.g., .* in comments.
        DFAState target = getExistingTargetState(s, t);
        if (target == null) {
            target = computeTargetState(input, s, t);
        }
        if (target == ERROR) {
            break;
        }
        // end of the token.
        if (t != IntStream.EOF) {
            consume(input);
        }
        if (target.isAcceptState()) {
            captureSimState(prevAccept, input, target);
            if (t == IntStream.EOF) {
                break;
            }
        }
        t = input.LA(1);
        // flip; current DFA target becomes new src/from state
        s = target;
    }
    return failOrAccept(prevAccept, input, s.configs, t);
}

Example 9 with DFAState

use of org.antlr.v4.runtime.dfa.DFAState in project antlr4 by tunnelvisionlabs.

the class LexerATNSimulator method match.

public int match(@NotNull CharStream input, int mode) {
    match_calls++;
    this.mode = mode;
    int mark = input.mark();
    try {
        this.startIndex = input.index();
        this.prevAccept.reset();
        DFAState s0 = atn.modeToDFA[mode].s0.get();
        if (s0 == null) {
            return matchATN(input);
        } else {
            return execATN(input, s0);
        }
    } finally {
        input.release(mark);
    }
}

Example 10 with DFAState

use of org.antlr.v4.runtime.dfa.DFAState in project antlr4 by tunnelvisionlabs.

the class DFASerializer method getStateString.

String getStateString(DFAState s) {
    if (s == ATNSimulator.ERROR) {
        return "ERROR";
    }
    int n = s.stateNumber;
    String stateStr = "s" + n;
    if (s.isAcceptState()) {
        if (s.predicates != null) {
            stateStr = ":s" + n + "=>" + Arrays.toString(s.predicates);
        } else {
            stateStr = ":s" + n + "=>" + s.getPrediction();
        }
    }
    if (s.isContextSensitive()) {
        stateStr += "*";
        for (ATNConfig config : s.configs) {
            if (config.getReachesIntoOuterContext()) {
                stateStr += "*";
                break;
            }
        }
    }
    return stateStr;
}