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

Example 26 with RuleTransition

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

the class ATN method getExpectedTokens.

/**
 * Computes the set of input symbols which could follow ATN state number
 * {@code stateNumber} in the specified full {@code context}. This method
 * considers the complete parser context, but does not evaluate semantic
 * predicates (i.e. all predicates encountered during the calculation are
 * assumed true). If a path in the ATN exists from the starting state to the
 * {@link RuleStopState} of the outermost context without matching any
 * symbols, {@link Token#EOF} is added to the returned set.
 *
 * <p>If {@code context} is {@code null}, it is treated as
 * {@link ParserRuleContext#EMPTY}.</p>
 *
 * <p>Note that this does NOT give you the set of all tokens that could
 * appear at a given token position in the input phrase.  In other words, it
 * does not answer:</p>
 *
 * <quote>"Given a specific partial input phrase, return the set of all
 * tokens that can follow the last token in the input phrase."</quote>
 *
 * <p>The big difference is that with just the input, the parser could land
 * right in the middle of a lookahead decision. Getting all
 * <em>possible</em> tokens given a partial input stream is a separate
 * computation. See https://github.com/antlr/antlr4/issues/1428</p>
 *
 * <p>For this function, we are specifying an ATN state and call stack to
 * compute what token(s) can come next and specifically: outside of a
 * lookahead decision. That is what you want for error reporting and
 * recovery upon parse error.</p>
 *
 * @param stateNumber the ATN state number
 * @param context the full parse context
 * @return The set of potentially valid input symbols which could follow the
 * specified state in the specified context.
 * @throws IllegalArgumentException if the ATN does not contain a state with
 * number {@code stateNumber}
 */
@NotNull
public IntervalSet getExpectedTokens(int stateNumber, @Nullable RuleContext context) {
    if (stateNumber < 0 || stateNumber >= states.size()) {
        throw new IllegalArgumentException("Invalid state number.");
    }
    RuleContext ctx = context;
    ATNState s = states.get(stateNumber);
    IntervalSet following = nextTokens(s);
    if (!following.contains(Token.EPSILON)) {
        return following;
    }
    IntervalSet expected = new IntervalSet();
    expected.addAll(following);
    expected.remove(Token.EPSILON);
    while (ctx != null && ctx.invokingState >= 0 && following.contains(Token.EPSILON)) {
        ATNState invokingState = states.get(ctx.invokingState);
        RuleTransition rt = (RuleTransition) invokingState.transition(0);
        following = nextTokens(rt.followState);
        expected.addAll(following);
        expected.remove(Token.EPSILON);
        ctx = ctx.parent;
    }
    if (following.contains(Token.EPSILON)) {
        expected.add(Token.EOF);
    }
    return expected;
}

Example 27 with RuleTransition

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

the class ATNPrinter method asString.

public String asString() {
    if (start == null)
        return null;
    marked = new HashSet<ATNState>();
    work = new ArrayList<ATNState>();
    work.add(start);
    StringBuilder buf = new StringBuilder();
    ATNState s;
    while (!work.isEmpty()) {
        s = work.remove(0);
        if (marked.contains(s))
            continue;
        int n = s.getNumberOfTransitions();
        // System.out.println("visit "+s+"; edges="+n);
        marked.add(s);
        for (int i = 0; i < n; i++) {
            Transition t = s.transition(i);
            if (!(s instanceof RuleStopState)) {
                // don't add follow states to work
                if (t instanceof RuleTransition)
                    work.add(((RuleTransition) t).followState);
                else
                    work.add(t.target);
            }
            buf.append(getStateString(s));
            if (t instanceof EpsilonTransition) {
                buf.append("->").append(getStateString(t.target)).append('\n');
            } else if (t instanceof RuleTransition) {
                buf.append("-").append(g.getRule(((RuleTransition) t).ruleIndex).name).append("->").append(getStateString(t.target)).append('\n');
            } else if (t instanceof ActionTransition) {
                ActionTransition a = (ActionTransition) t;
                buf.append("-").append(a.toString()).append("->").append(getStateString(t.target)).append('\n');
            } else if (t instanceof SetTransition) {
                SetTransition st = (SetTransition) t;
                boolean not = st instanceof NotSetTransition;
                if (g.isLexer()) {
                    buf.append("-").append(not ? "~" : "").append(st.toString()).append("->").append(getStateString(t.target)).append('\n');
                } else {
                    buf.append("-").append(not ? "~" : "").append(st.label().toString(g.getVocabulary())).append("->").append(getStateString(t.target)).append('\n');
                }
            } else if (t instanceof AtomTransition) {
                AtomTransition a = (AtomTransition) t;
                String label = g.getTokenDisplayName(a.label);
                buf.append("-").append(label).append("->").append(getStateString(t.target)).append('\n');
            } else {
                buf.append("-").append(t.toString()).append("->").append(getStateString(t.target)).append('\n');
            }
        }
    }
    return buf.toString();
}

Example 28 with RuleTransition

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

the class ParserATNFactory method elemList.

@NotNull
public Handle elemList(@NotNull List<Handle> els) {
    int n = els.size();
    for (int i = 0; i < n - 1; i++) {
        // hook up elements (visit all but last)
        Handle el = els.get(i);
        // if el is of form o-x->o for x in {rule, action, pred, token, ...}
        // and not last in alt
        Transition tr = null;
        if (el.left.getNumberOfTransitions() == 1)
            tr = el.left.transition(0);
        boolean isRuleTrans = tr instanceof RuleTransition;
        if (el.left.getStateType() == ATNState.BASIC && el.right.getStateType() == ATNState.BASIC && tr != null && (isRuleTrans && ((RuleTransition) tr).followState == el.right || tr.target == el.right)) {
            // we can avoid epsilon edge to next el
            if (isRuleTrans)
                ((RuleTransition) tr).followState = els.get(i + 1).left;
            else
                tr.target = els.get(i + 1).left;
            // we skipped over this state
            atn.removeState(el.right);
        } else {
            // need epsilon if previous block's right end node is complicated
            epsilon(el.right, els.get(i + 1).left);
        }
    }
    Handle first = els.get(0);
    Handle last = els.get(n - 1);
    if (first == null || last == null) {
        g.tool.errMgr.toolError(ErrorType.INTERNAL_ERROR, "element list has first|last == null");
    }
    return new Handle(first.left, last.right);
}