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

Example 41 with ATNState

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

the class LexerATNFactory method action.

protected Handle action(GrammarAST node, LexerAction lexerAction) {
    ATNState left = newState(node);
    ATNState right = newState(node);
    boolean isCtxDependent = false;
    int lexerActionIndex = getLexerActionIndex(lexerAction);
    ActionTransition a = new ActionTransition(right, currentRule.index, lexerActionIndex, isCtxDependent);
    left.addTransition(a);
    node.atnState = left;
    Handle h = new Handle(left, right);
    return h;
}

Example 42 with ATNState

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

the class LexerATNFactory method stringLiteral.

/**
 * For a lexer, a string is a sequence of char to match.  That is,
 *  "fog" is treated as 'f' 'o' 'g' not as a single transition in
 *  the DFA.  Machine== o-'f'->o-'o'->o-'g'->o and has n+1 states
 *  for n characters.
 */
@Override
public Handle stringLiteral(TerminalAST stringLiteralAST) {
    String chars = stringLiteralAST.getText();
    ATNState left = newState(stringLiteralAST);
    ATNState right;
    String s = CharSupport.getStringFromGrammarStringLiteral(chars);
    if (s == null) {
        // the lexer will already have given an error
        return new Handle(left, left);
    }
    int n = s.length();
    ATNState prev = left;
    right = null;
    for (int i = 0; i < n; ) {
        right = newState(stringLiteralAST);
        int codePoint = s.codePointAt(i);
        prev.addTransition(CodePointTransitions.createWithCodePoint(right, codePoint));
        prev = right;
        i += Character.charCount(codePoint);
    }
    stringLiteralAST.atnState = left;
    return new Handle(left, right);
}

Example 43 with ATNState

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

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 44 with ATNState

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

the class LeftRecursionDetector method check.

/**
 * From state s, look for any transition to a rule that is currently
 *  being traced.  When tracing r, visitedPerRuleCheck has r
 *  initially.  If you reach a rule stop state, return but notify the
 *  invoking rule that the called rule is nullable. This implies that
 *  invoking rule must look at follow transition for that invoking state.
 *
 *  The visitedStates tracks visited states within a single rule so
 *  we can avoid epsilon-loop-induced infinite recursion here.  Keep
 *  filling the cycles in listOfRecursiveCycles and also, as a
 *  side-effect, set leftRecursiveRules.
 */
public boolean check(Rule enclosingRule, ATNState s, Set<ATNState> visitedStates) {
    if (s instanceof RuleStopState)
        return true;
    if (visitedStates.contains(s))
        return false;
    visitedStates.add(s);
    // System.out.println("visit "+s);
    int n = s.getNumberOfTransitions();
    boolean stateReachesStopState = false;
    for (int i = 0; i < n; i++) {
        Transition t = s.transition(i);
        if (t instanceof RuleTransition) {
            RuleTransition rt = (RuleTransition) t;
            Rule r = g.getRule(rt.ruleIndex);
            if (rulesVisitedPerRuleCheck.contains((RuleStartState) t.target)) {
                addRulesToCycle(enclosingRule, r);
            } else {
                // must visit if not already visited; mark target, pop when done
                rulesVisitedPerRuleCheck.add((RuleStartState) t.target);
                // send new visitedStates set per rule invocation
                boolean nullable = check(r, t.target, new HashSet<ATNState>());
                // we're back from visiting that rule
                rulesVisitedPerRuleCheck.remove((RuleStartState) t.target);
                if (nullable) {
                    stateReachesStopState |= check(enclosingRule, rt.followState, visitedStates);
                }
            }
        } else if (t.isEpsilon()) {
            stateReachesStopState |= check(enclosingRule, t.target, visitedStates);
        }
    // else ignore non-epsilon transitions
    }
    return stateReachesStopState;
}

Example 45 with ATNState

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

the class ATNOptimizer method optimizeSets.

private static void optimizeSets(Grammar g, ATN atn) {
    if (g.isParser()) {
        // parser codegen doesn't currently support SetTransition
        return;
    }
    int removedStates = 0;
    List<DecisionState> decisions = atn.decisionToState;
    for (DecisionState decision : decisions) {
        if (decision.ruleIndex >= 0) {
            Rule rule = g.getRule(decision.ruleIndex);
            if (Character.isLowerCase(rule.name.charAt(0))) {
                // parser codegen doesn't currently support SetTransition
                continue;
            }
        }
        IntervalSet setTransitions = new IntervalSet();
        for (int i = 0; i < decision.getNumberOfTransitions(); i++) {
            Transition epsTransition = decision.transition(i);
            if (!(epsTransition instanceof EpsilonTransition)) {
                continue;
            }
            if (epsTransition.target.getNumberOfTransitions() != 1) {
                continue;
            }
            Transition transition = epsTransition.target.transition(0);
            if (!(transition.target instanceof BlockEndState)) {
                continue;
            }
            if (transition instanceof NotSetTransition) {
                // TODO: not yet implemented
                continue;
            }
            if (transition instanceof AtomTransition || transition instanceof RangeTransition || transition instanceof SetTransition) {
                setTransitions.add(i);
            }
        }
        // due to min alt resolution policies, can only collapse sequential alts
        for (int i = setTransitions.getIntervals().size() - 1; i >= 0; i--) {
            Interval interval = setTransitions.getIntervals().get(i);
            if (interval.length() <= 1) {
                continue;
            }
            ATNState blockEndState = decision.transition(interval.a).target.transition(0).target;
            IntervalSet matchSet = new IntervalSet();
            for (int j = interval.a; j <= interval.b; j++) {
                Transition matchTransition = decision.transition(j).target.transition(0);
                if (matchTransition instanceof NotSetTransition) {
                    throw new UnsupportedOperationException("Not yet implemented.");
                }
                IntervalSet set = matchTransition.label();
                List<Interval> intervals = set.getIntervals();
                int n = intervals.size();
                for (int k = 0; k < n; k++) {
                    Interval setInterval = intervals.get(k);
                    int a = setInterval.a;
                    int b = setInterval.b;
                    if (a != -1 && b != -1) {
                        for (int v = a; v <= b; v++) {
                            if (matchSet.contains(v)) {
                                // TODO: Token is missing (i.e. position in source will not be displayed).
                                g.tool.errMgr.grammarError(ErrorType.CHARACTERS_COLLISION_IN_SET, g.fileName, null, CharSupport.getANTLRCharLiteralForChar(v), CharSupport.getIntervalSetEscapedString(matchSet));
                                break;
                            }
                        }
                    }
                }
                matchSet.addAll(set);
            }
            Transition newTransition;
            if (matchSet.getIntervals().size() == 1) {
                if (matchSet.size() == 1) {
                    newTransition = CodePointTransitions.createWithCodePoint(blockEndState, matchSet.getMinElement());
                } else {
                    Interval matchInterval = matchSet.getIntervals().get(0);
                    newTransition = CodePointTransitions.createWithCodePointRange(blockEndState, matchInterval.a, matchInterval.b);
                }
            } else {
                newTransition = new SetTransition(blockEndState, matchSet);
            }
            decision.transition(interval.a).target.setTransition(0, newTransition);
            for (int j = interval.a + 1; j <= interval.b; j++) {
                Transition removed = decision.removeTransition(interval.a + 1);
                atn.removeState(removed.target);
                removedStates++;
            }
        }
    }
// System.out.println("ATN optimizer removed " + removedStates + " states by collapsing sets.");
}