Examples with LL1Analyzer org.antlr.v4.runtime.atn.LL1Analyzer used on opensource projects

Example 1 with LL1Analyzer

use of org.antlr.v4.runtime.atn.LL1Analyzer in project antlr4 by antlr.

the class ATN method nextTokens.

/** Compute the set of valid tokens that can occur starting in state {@code s}.
	 *  If {@code ctx} is null, the set of tokens will not include what can follow
	 *  the rule surrounding {@code s}. In other words, the set will be
	 *  restricted to tokens reachable staying within {@code s}'s rule.
	 */
public IntervalSet nextTokens(ATNState s, RuleContext ctx) {
    LL1Analyzer anal = new LL1Analyzer(this);
    IntervalSet next = anal.LOOK(s, ctx);
    return next;
}

Example 2 with LL1Analyzer

use of org.antlr.v4.runtime.atn.LL1Analyzer in project antlr4 by antlr.

the class ParserATNFactory method createATN.

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

Example 3 with LL1Analyzer

use of org.antlr.v4.runtime.atn.LL1Analyzer in project antlr4 by antlr.

the class AnalysisPipeline method processParser.

protected void processParser() {
    g.decisionLOOK = new ArrayList<IntervalSet[]>(g.atn.getNumberOfDecisions() + 1);
    for (DecisionState s : g.atn.decisionToState) {
        g.tool.log("LL1", "\nDECISION " + s.decision + " in rule " + g.getRule(s.ruleIndex).name);
        IntervalSet[] look;
        if (s.nonGreedy) {
            // nongreedy decisions can't be LL(1)
            look = new IntervalSet[s.getNumberOfTransitions() + 1];
        } else {
            LL1Analyzer anal = new LL1Analyzer(g.atn);
            look = anal.getDecisionLookahead(s);
            g.tool.log("LL1", "look=" + Arrays.toString(look));
        }
        assert s.decision + 1 >= g.decisionLOOK.size();
        Utils.setSize(g.decisionLOOK, s.decision + 1);
        g.decisionLOOK.set(s.decision, look);
        g.tool.log("LL1", "LL(1)? " + disjoint(look));
    }
}

Example 4 with LL1Analyzer

use of org.antlr.v4.runtime.atn.LL1Analyzer in project antlr4 by antlr.

the class AnalysisPipeline method processLexer.

protected void processLexer() {
    // make sure all non-fragment lexer rules must match at least one symbol
    for (Rule rule : g.rules.values()) {
        if (rule.isFragment()) {
            continue;
        }
        LL1Analyzer analyzer = new LL1Analyzer(g.atn);
        IntervalSet look = analyzer.LOOK(g.atn.ruleToStartState[rule.index], null);
        if (look.contains(Token.EPSILON)) {
            g.tool.errMgr.grammarError(ErrorType.EPSILON_TOKEN, g.fileName, ((GrammarAST) rule.ast.getChild(0)).getToken(), rule.name);
        }
    }
}