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add regex support for reverse and left/right derivative rewriting (#4477)

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* partial work on adding 'reverse' (broken code)

* new op codes for derivative and reverse + associated rewrite rules

* incorporate reverses and derivatives in rewriter + some fixes

* enable rewriting str.in_re constraints with right derivative
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calebstanford-msr 2020-05-29 16:00:37 -04:00 • committed by GitHub
parent 3d9d52f742
commit c939195c10
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 254 additions and 110 deletions
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19
src/smt/seq_regex.cpp
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@ -216,10 +216,9 @@ namespace smt {
return false;
// (accept s i R) & len(s) > i => (accept s (+ i 1) D(nth(s, i), R)) or conds
expr_ref head = th.mk_nth(s, i);
d = seq_rw().derivative(head, d);
if (!d)
throw default_exception("unable to expand derivative");
expr_ref head = th.mk_nth(s, i);
d = re().mk_derivative(head, r);
rewrite(d);
literal acc_next = th.mk_literal(sk().mk_accept(s, a().mk_int(idx + 1), d));
conds.push_back(~lit);
@ -339,9 +338,9 @@ namespace smt {
return;
literal null_lit = th.mk_literal(is_nullable);
expr_ref hd = mk_first(r);
expr_ref d = seq_rw().derivative(hd, r);
if (!d)
throw default_exception("derivative was not defined");
expr_ref d(m);
d = re().mk_derivative(hd, r);
rewrite(d);
literal_vector lits;
lits.push_back(~lit);
if (null_lit != false_literal)
@ -382,9 +381,9 @@ namespace smt {
}
th.add_axiom(~lit, ~th.mk_literal(is_nullable));
expr_ref hd = mk_first(r);
expr_ref d = seq_rw().derivative(hd, r);
if (!d)
throw default_exception("derivative was not defined");
expr_ref d(m);
d = re().mk_derivative(hd, r);
rewrite(d);
literal_vector lits;
expr_ref_pair_vector cofactors(m);
seq_rw().get_cofactors(d, cofactors);