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

Example 6 with BlockStartState

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

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?
	 */
@Override
public Handle block(BlockAST blkAST, GrammarAST ebnfRoot, 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;
}

Example 7 with BlockStartState

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

the class ParserATNFactory method optional.

/**
	 * From {@code (A)?} build either:
	 *
	 * <pre>
	 *  o--A-&gt;o
	 *  |     ^
	 *  o----&gt;|
	 * </pre>
	 *
	 * or, if {@code A} is a block, just add an empty alt to the end of the
	 * block
	 */
@Override
public Handle optional(GrammarAST optAST, Handle blk) {
    BlockStartState blkStart = (BlockStartState) blk.left;
    ATNState blkEnd = blk.right;
    preventEpsilonOptionalBlocks.add(new Triple<Rule, ATNState, ATNState>(currentRule, blkStart, blkEnd));
    boolean greedy = ((QuantifierAST) optAST).isGreedy();
    blkStart.nonGreedy = !greedy;
    epsilon(blkStart, blk.right, !greedy);
    optAST.atnState = blk.left;
    return blk;
}

Example 8 with BlockStartState

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

the class ParserATNFactory method makeBlock.

protected Handle makeBlock(BlockStartState start, BlockAST blkAST, List<Handle> alts) {
    BlockEndState end = newState(BlockEndState.class, blkAST);
    start.endState = end;
    for (Handle alt : alts) {
        // hook alts up to decision block
        epsilon(start, alt.left);
        epsilon(alt.right, end);
        // no back link in ATN so must walk entire alt to see if we can
        // strip out the epsilon to 'end' state
        TailEpsilonRemover opt = new TailEpsilonRemover(atn);
        opt.visit(alt.left);
    }
    Handle h = new Handle(start, end);
    //		FASerializer ser = new FASerializer(g, h.left);
    //		System.out.println(blkAST.toStringTree()+":\n"+ser);
    blkAST.atnState = start;
    return h;
}