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seq

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2015-12-10 02:38:56 -08:00
parent d81186eaca
commit 30580a012a
3 changed files with 36 additions and 18 deletions
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4
src/ast/rewriter/seq_rewriter.cpp
View file

@ -72,6 +72,10 @@ br_status seq_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * con
SASSERT(num_args == 2);
return mk_seq_suffix(args[0], args[1], result);
case OP_SEQ_INDEX:
if (num_args == 2) {
expr_ref arg3(m_autil.mk_int(0), m());
return mk_seq_index(args[0], args[1], arg3, result);
}
SASSERT(num_args == 3);
return mk_seq_index(args[0], args[1], args[2], result);
case OP_SEQ_REPLACE:

2
src/ast/seq_decl_plugin.h
View file

@ -220,7 +220,7 @@ public:
MATCH_TERNARY(is_extract);
MATCH_BINARY(is_contains);
MATCH_BINARY(is_at);
MATCH_BINARY(is_index);
MATCH_TERNARY(is_index);
MATCH_TERNARY(is_replace);
MATCH_BINARY(is_prefix);
MATCH_BINARY(is_suffix);

48
src/smt/theory_seq.cpp
View file

@ -745,33 +745,47 @@ void theory_seq::tightest_prefix(expr* s, expr* x, literal lit) {
}
/*
let i = Index(s, t)
let i = Index(s, t, offset)
(!contains(s, t) -> i = -1)
(s = empty -> i = 0)
(contains(s, t) & s != empty -> t = xsy)
(contains(s, t) -> tightest_prefix(s, x))
if offset = 0:
(!contains(s, t) -> i = -1)
(s = empty -> i = 0)
(contains(s, t) & s != empty -> t = xsy)
(contains(s, t) -> tightest_prefix(s, x))
if 0 <= offset < len(t):
t = zt' & len(z) == offset
add above constraints with t'
if offset >= len(t):
i = -1
if offset < 0:
?
optional lemmas:
(len(s) > len(t) -> i = -1)
(len(s) <= len(t) -> i <= len(t)-len(s))
*/
void theory_seq::add_indexof_axiom(expr* i) {
expr* s, *t;
VERIFY(m_util.str.is_index(i, s, t));
expr_ref fml(m), emp(m), minus_one(m), zero(m), xsy(m);
expr_ref x = mk_skolem(m_contains_left_sym, s, t);
expr_ref y = mk_skolem(m_contains_right_sym, s, t);
expr* s, *t, *offset;
rational r;
VERIFY(m_util.str.is_index(i, s, t, offset));
expr_ref emp(m), minus_one(m), zero(m), xsy(m);
minus_one = m_autil.mk_int(-1);
zero = m_autil.mk_int(0);
emp = m_util.str.mk_empty(m.get_sort(s));
xsy = m_util.str.mk_concat(x,s,y);
literal cnt = mk_literal(m_util.str.mk_contains(s, t));
literal eq_empty = mk_eq(s, emp, false);
add_axiom(cnt, mk_eq(i, minus_one, false));
add_axiom(~eq_empty, mk_eq(i, zero, false));
add_axiom(~cnt, eq_empty, mk_eq(t, xsy, false));
tightest_prefix(s, x, ~cnt);
if (m_autil.is_numeral(offset, r) && r.is_zero()) {
expr_ref x = mk_skolem(m_contains_left_sym, s, t);
expr_ref y = mk_skolem(m_contains_right_sym, s, t);
xsy = m_util.str.mk_concat(x,s,y);
literal cnt = mk_literal(m_util.str.mk_contains(s, t));
literal eq_empty = mk_eq(s, emp, false);
add_axiom(cnt, mk_eq(i, minus_one, false));
add_axiom(~eq_empty, mk_eq(i, zero, false));
add_axiom(~cnt, eq_empty, mk_eq(t, xsy, false));
tightest_prefix(s, x, ~cnt);
}
else {
// TBD
}
}
/*