private ParseDelta enter() {
return ParseDelta
// Start the left.
.builder(first)
// Push this so that we can remember to do b if a passes.
.push()
.build();
}
private ParseDelta exitPass() {
// Continue to the next entry.
return ParseDelta.builder(second).build();
}
/**
* Executes A and then B on the remaining input.
*
* <p>This matches the minimal language {∀a∈A,%forall;b%isin;concatenation(a, b)}.
*/
public final class SeqCombinator extends BinaryCombinator {
/** */
public SeqCombinator(Supplier<NodeMetadata> mds, Combinator first, Combinator second) {
super(mds, first, second);
}
@Override
protected SeqCombinator unfold(
NodeMetadata newMetadata,
Function<ProdName, ProdName> renamer,
Combinator newFirst,
Combinator newSecond) {
if (newMetadata.equals(this.md) && this.first == newFirst && this.second == newSecond) {
return this;
}
return new SeqCombinator(Suppliers.ofInstance(newMetadata), newFirst, newSecond);
}
@Override
public ParseDelta enter(Parse p) {
return enter();
}
@Override
public ParseDelta exit(Parse p, Success s) {
switch (s) {
case FAIL:
return EXIT_FAIL;
case PASS:
return exitPass();
}
throw new AssertionError(s);
}
@Override
public final ImmutableList<ParseDelta> epsilonTransition(
TransitionType tt, Language lang, OutputContext ctx) {
switch (tt) {
case ENTER:
return ImmutableList.of(enter());
case EXIT_PASS:
return ImmutableList.of(exitPass());
case EXIT_FAIL:
return ImmutableList.of(EXIT_FAIL);
}
throw new AssertionError(tt);
}
private ParseDelta enter() {
return ParseDelta
// Start the left.
.builder(first)
// Push this so that we can remember to do b if a passes.
.push()
.build();
}
private static final ParseDelta EXIT_FAIL = ParseDelta.fail().build();
private ParseDelta exitPass() {
// Continue to the next entry.
return ParseDelta.builder(second).build();
}
@Override
public Precedence precedence() {
return Precedence.SEQUENCE;
}
@Override
protected String getVizTypeClassName() {
return "seq";
}
@Override
protected void visualizeBody(DetailLevel lvl, VizOutput out) throws IOException {
writeBinaryOperator(
first,
second,
precedence(),
Predicates.instanceOf(SeqCombinator.class),
STRING_COALESCING_INFIXER,
lvl,
out);
}
@Override
public Frequency consumesInput(Language lang) {
Frequency ff = lang.lali.consumesInput(first);
switch (ff) {
case NEVER:
return lang.lali.consumesInput(second);
case ALWAYS:
return ff;
case SOMETIMES:
Frequency sf = lang.lali.consumesInput(second);
switch (sf) {
case ALWAYS:
case SOMETIMES:
return sf;
case NEVER:
return Frequency.SOMETIMES;
}
throw new AssertionError(sf.name());
}
throw new AssertionError(ff.name());
}
@Override
public ImmutableRangeSet<Integer> lookahead(Language lang) {
Frequency ff = lang.lali.consumesInput(first);
switch (ff) {
case NEVER:
return lang.lali.lookahead(second);
case ALWAYS:
return lang.lali.lookahead(first);
case SOMETIMES:
TreeRangeSet<Integer> r = TreeRangeSet.create();
r.addAll(lang.lali.lookahead(first));
r.addAll(lang.lali.lookahead(second));
return ImmutableRangeSet.copyOf(r);
}
throw new AssertionError(ff.name());
}
@Override
public boolean reachesWithoutConsuming(Combinator target, Language lang) {
// Check whether target is reachable from any member.
return super.reachesWithoutConsuming(target, lang)
|| first.reachesWithoutConsuming(target, lang)
|| (lang.lali.consumesInput(first) != Frequency.ALWAYS
&& second.reachesWithoutConsuming(target, lang));
}
/** Finds sequences of characters that */
private static final Infixer STRING_COALESCING_INFIXER = new StringCoalescingInfixer();
}
