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deferred addition of basic string axioms

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no longer crashes the solver and got our first correct UNSAT!
This commit is contained in:
Murphy Berzish 2015-09-26 21:02:56 -04:00
parent 4d5a0ea53f
commit f6affe64d0
2 changed files with 51 additions and 9 deletions
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53
src/smt/theory_str.cpp
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@ -117,6 +117,20 @@ app * theory_str::mk_strlen(app * e) {
}
}
bool theory_str::can_propagate() {
return !m_basicstr_axiom_todo.empty();
}
void theory_str::propagate() {
TRACE("t_str_detail", tout << "trying to propagate..." << std::endl;);
while (can_propagate()) {
for (unsigned i = 0; i < m_basicstr_axiom_todo.size(); ++i) {
instantiate_basic_string_axioms(m_basicstr_axiom_todo[i]);
}
m_basicstr_axiom_todo.reset();
}
}
/*
* Instantiate an axiom of the following form:
* Length(Concat(x, y)) = Length(x) + Length(y)
@ -165,17 +179,32 @@ void theory_str::instantiate_concat_axiom(enode * cat) {
* Add axioms that are true for any string variable:
* 1. Length(x) >= 0
* 2. Length(x) == 0 <=> x == ""
* If the term is a string constant, we can assert something stronger:
* Length(x) == strlen(x)
*/
void theory_str::instantiate_basic_string_axioms(enode * str) {
// generate a stronger axiom for constant strings
if (m_strutil.is_string(str->get_owner())) {
// TODO
} else {
// TODO keep track of which enodes we have added axioms for, so we don't add the same ones twice?
app * a_str = str->get_owner();
context & ctx = get_context();
ast_manager & m = get_manager();
// TODO keep track of which enodes we have added axioms for, so we don't add the same ones twice?
context & ctx = get_context();
ast_manager & m = get_manager();
// generate a stronger axiom for constant strings
app * a_str = str->get_owner();
if (m_strutil.is_string(str->get_owner())) {
expr_ref len_str(m);
len_str = mk_strlen(a_str);
SASSERT(len_str);
const char * strconst = 0;
m_strutil.is_string(str->get_owner(), & strconst);
TRACE("t_str_detail", tout << "instantiating constant string axioms for \"" << strconst << "\"" << std::endl;);
int l = strlen(strconst);
expr_ref len(m_autil.mk_numeral(rational(l), true), m);
literal lit(mk_eq(len_str, len, false));
ctx.mark_as_relevant(lit);
ctx.mk_th_axiom(get_id(), 1, &lit);
} else {
// TODO find out why these are crashing the SMT solver
// build axiom 1: Length(a_str) >= 0
@ -233,7 +262,13 @@ void theory_str::attach_new_th_var(enode * n) {
ctx.attach_th_var(n, this, v);
TRACE("t_str_detail", tout << "new theory var: " << mk_ismt2_pp(n->get_owner(), get_manager()) << " := v#" << v << std::endl;);
// probably okay...note however that this seems to miss constants and functions
//instantiate_basic_string_axioms(n);
m_basicstr_axiom_todo.push_back(n);
}
void theory_str::reset_eh() {
TRACE("t_str", tout << "resetting" << std::endl;);
m_basicstr_axiom_todo.reset();
pop_scope_eh(0);
}
void theory_str::init_search_eh() {