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

Example 96 with ATNState

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

the class ParserATNFactory method epsilon.

/**
 * From an empty alternative build {@code o-e->o}.
 */
@NotNull
@Override
public Handle epsilon(@NotNull GrammarAST node) {
    ATNState left = newState(node);
    ATNState right = newState(node);
    epsilon(left, right);
    node.atnState = left;
    return new Handle(left, right);
}

Example 97 with ATNState

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

the class ParserATNFactory method epsilon.

protected void epsilon(ATNState a, @NotNull ATNState b, boolean prepend) {
    for (Transition t : a.getTransitions()) {
        if (t.getSerializationType() != Transition.EPSILON) {
            continue;
        }
        if (t.target == b && ((EpsilonTransition) t).outermostPrecedenceReturn() == -1) {
            // This transition was already added
            return;
        }
    }
    if (a != null) {
        int index = prepend ? 0 : a.getNumberOfTransitions();
        a.addTransition(index, new EpsilonTransition(b));
    }
}

Example 98 with ATNState

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

the class ParserATNFactory method addEOFTransitionToStartRules.

/**
 * Add an EOF transition to any rule end ATNState that points to nothing
 *  (i.e., for all those rules not invoked by another rule).  These
 *  are start symbols then.
 *
 *  Return the number of grammar entry points; i.e., how many rules are
 *  not invoked by another rule (they can only be invoked from outside).
 *  These are the start rules.
 */
public int addEOFTransitionToStartRules() {
    int n = 0;
    // one unique EOF target for all rules
    ATNState eofTarget = newState(null);
    for (Rule r : g.rules.values()) {
        ATNState stop = atn.ruleToStopState[r.index];
        if (stop.getNumberOfTransitions() > 0)
            continue;
        n++;
        Transition t = new AtomTransition(eofTarget, Token.EOF);
        stop.addTransition(t);
    }
    return n;
}

Example 99 with ATNState

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

the class ParserATNFactory method createATN.

@NotNull
@Override
public ATN createATN() {
    _createATN(g.rules.values());
    assert atn.maxTokenType == g.getMaxTokenType();
    addRuleFollowLinks();
    addEOFTransitionToStartRules();
    ATNOptimizer.optimize(g, atn);
    for (Tuple3<? extends Rule, ? extends ATNState, ? extends ATNState> pair : preventEpsilonClosureBlocks) {
        LL1Analyzer analyzer = new LL1Analyzer(atn);
        ATNState blkStart = pair.getItem2();
        ATNState blkStop = pair.getItem3();
        IntervalSet lookahead = analyzer.LOOK(blkStart, blkStop, PredictionContext.EMPTY_LOCAL);
        if (lookahead.contains(org.antlr.v4.runtime.Token.EPSILON)) {
            ErrorType errorType = pair.getItem1() instanceof LeftRecursiveRule ? ErrorType.EPSILON_LR_FOLLOW : ErrorType.EPSILON_CLOSURE;
            g.tool.errMgr.grammarError(errorType, g.fileName, ((GrammarAST) pair.getItem1().ast.getChild(0)).getToken(), pair.getItem1().name);
        }
    }
    optionalCheck: for (Tuple3<? extends Rule, ? extends ATNState, ? extends ATNState> pair : preventEpsilonOptionalBlocks) {
        int bypassCount = 0;
        for (int i = 0; i < pair.getItem2().getNumberOfTransitions(); i++) {
            ATNState startState = pair.getItem2().transition(i).target;
            if (startState == pair.getItem3()) {
                bypassCount++;
                continue;
            }
            LL1Analyzer analyzer = new LL1Analyzer(atn);
            if (analyzer.LOOK(startState, pair.getItem3(), PredictionContext.EMPTY_LOCAL).contains(org.antlr.v4.runtime.Token.EPSILON)) {
                g.tool.errMgr.grammarError(ErrorType.EPSILON_OPTIONAL, g.fileName, ((GrammarAST) pair.getItem1().ast.getChild(0)).getToken(), pair.getItem1().name);
                continue optionalCheck;
            }
        }
        if (bypassCount != 1) {
            throw new UnsupportedOperationException("Expected optional block with exactly 1 bypass alternative.");
        }
    }
    return atn;
}

Example 100 with ATNState

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

the class ParserATNFactory method block.

/**
 * From {@code A|B|..|Z} alternative block build
 *
 * <pre>
 *  o-&gt;o-A-&gt;o-&gt;o (last ATNState is BlockEndState pointed to by all alts)
 *  |          ^
 *  |-&gt;o-B-&gt;o--|
 *  |          |
 *  ...        |
 *  |          |
 *  |-&gt;o-Z-&gt;o--|
 * </pre>
 *
 * So start node points at every alternative with epsilon transition and
 * every alt right side points at a block end ATNState.
 * <p>
 * Special case: only one alternative: don't make a block with alt
 * begin/end.
 * <p>
 * Special case: if just a list of tokens/chars/sets, then collapse to a
 * single edged o-set-&gt;o graph.
 * <p>
 * TODO: Set alt number (1..n) in the states?
 */
@NotNull
@Override
public Handle block(@NotNull BlockAST blkAST, @NotNull GrammarAST ebnfRoot, @NotNull List<Handle> alts) {
    if (ebnfRoot == null) {
        if (alts.size() == 1) {
            Handle h = alts.get(0);
            blkAST.atnState = h.left;
            return h;
        }
        BlockStartState start = newState(BasicBlockStartState.class, blkAST);
        if (alts.size() > 1)
            atn.defineDecisionState(start);
        return makeBlock(start, blkAST, alts);
    }
    switch(ebnfRoot.getType()) {
        case ANTLRParser.OPTIONAL:
            BlockStartState start = newState(BasicBlockStartState.class, blkAST);
            atn.defineDecisionState(start);
            Handle h = makeBlock(start, blkAST, alts);
            return optional(ebnfRoot, h);
        case ANTLRParser.CLOSURE:
            BlockStartState star = newState(StarBlockStartState.class, ebnfRoot);
            if (alts.size() > 1)
                atn.defineDecisionState(star);
            h = makeBlock(star, blkAST, alts);
            return star(ebnfRoot, h);
        case ANTLRParser.POSITIVE_CLOSURE:
            PlusBlockStartState plus = newState(PlusBlockStartState.class, ebnfRoot);
            if (alts.size() > 1)
                atn.defineDecisionState(plus);
            h = makeBlock(plus, blkAST, alts);
            return plus(ebnfRoot, h);
    }
    return null;
}