/** Returns an expression that denotes a specified subvector. */
public STPExpr extract(int high_bit_no, int low_bit_no, int encodingSize) {
STPExpr cached = cachedExtract.get(high_bit_no, low_bit_no);
if (cached != null) return cached;
ExtractExpr exp = new ExtractExpr(getSolver(), this, high_bit_no, low_bit_no, encodingSize);
cachedExtract.put(high_bit_no, low_bit_no, exp);
return exp;
}
private Regexp internalGetBoundedRegexp(Grammar g, String startSymbol, int bound) {
if (regexpCache.containsKeys(startSymbol, bound)) return regexpCache.get(startSymbol, bound);
// removing epsilons may not succeed for start symbol. We check if that's the case.
boolean canGenerateEmptyString = g.containsEpsilonProduction(startSymbol);
List<Regexp> x = new ArrayList<Regexp>();
for (GrammarProduction prod : g.getRule(startSymbol).getProductions()) {
List<GrammarProductionElement> elems = prod.getElements();
if (canGenerateEmptyString
|| elems.size()
<= bound) { // uses the fact that every symbol (other than start) produces at least
// one terminal
List<List<Integer>> distros = new ArrayList<List<Integer>>(distributions(bound, elems));
distrosLoop:
for (int j = 0; j < distros.size(); j++) {
List<Integer> distro = distros.get(j);
Regexp[] exps = new Regexp[distro.size()];
for (int i = 0; i < elems.size(); i++) {
GrammarProductionElement elem = elems.get(i);
int sizeForElem = distro.get(i);
if (terms_are_single_char) {
if (sizeForElem > 1
&& (elem.getKind() == GrammarElementKind.GTERMINAL
|| elem.getKind() == GrammarElementKind.GSPECIAL)) {
continue
distrosLoop; // no way you can generate a string longer than 1 from a terminal
}
if (sizeForElem == 1 && elem.getKind() == GrammarElementKind.GTERMINAL) {
TerminalElement te = (TerminalElement) elem;
exps[i] = HampiConstraints.constRegexp(te.getNameNoQuotes());
} else if (sizeForElem == 1 && elem.getKind() == GrammarElementKind.GSPECIAL) {
SpecialElement spec = (SpecialElement) elem;
exps[i] = HampiConstraints.constRegexp(spec.getNameNoDelimiters());
} else if (elem.getKind() == GrammarElementKind.GNONTERMINAL) {
NonterminalElement nt = (NonterminalElement) elem;
if (bounds.containsKey(nt)
&& bounds.get(nt)
< sizeForElem) { // cannot generate a string longer than the upper bound on
// all strings generatable from the nonterminal
continue distrosLoop;
}
Regexp subRegexp = internalGetBoundedRegexp(g, nt.getName(), sizeForElem);
if (subRegexp != null) {
exps[i] = subRegexp;
} else {
continue distrosLoop;
}
} else throw new IllegalStateException("expected a nonterminal or special" + elem);
} else {
if (elem.getKind() == GrammarElementKind.GSPECIAL)
throw new UnsupportedOperationException("not implemented yet");
if (elem.getKind() == GrammarElementKind.GTERMINAL) {
TerminalElement term = (TerminalElement) elem;
if (term.getNameNoQuotes().length() != sizeForElem) {
continue distrosLoop; // no way you can generate a string this long
} else {
exps[i] = HampiConstraints.constRegexp(term.getNameNoQuotes());
}
} else if (elem.getKind() == GrammarElementKind.GNONTERMINAL) {
NonterminalElement nt = (NonterminalElement) elem;
if (bounds.containsKey(nt)
&& bounds.get(nt)
< sizeForElem) { // cannot generate a string longer than the upper bound on
// all strings generatable from the nonterminal
continue distrosLoop;
}
Regexp subRegexp = internalGetBoundedRegexp(g, nt.getName(), sizeForElem);
if (subRegexp != null) {
exps[i] = subRegexp;
} else {
continue distrosLoop;
}
} else throw new IllegalStateException("expected a nonterminal or special" + elem);
}
}
Regexp e;
if (exps.length == 1) {
e = exps[0];
} else {
e = HampiConstraints.concatRegexp(exps);
}
if (!x.contains(e)) {
x.add(e);
}
}
}
}
Regexp result;
if (x.isEmpty() && !canGenerateEmptyString) {
result = null;
} else if (x.isEmpty() && canGenerateEmptyString) {
Hampi h = new Hampi();
result = h.constRegexp("");
} else if (x.size() == 1) {
result = x.get(0);
} else {
Hampi h = new Hampi();
result = h.orRegexp(x.toArray(new Regexp[x.size()]));
}
regexpCache.put(startSymbol, bound, result);
return result;
}