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Merge pull request #1517 from mtrberzi/issue1379

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Handle third argument of str.indexof in Z3str3
This commit is contained in:
Nikolaj Bjorner 2018-03-08 14:19:01 -08:00 • committed by GitHub
commit 4f9d198c51
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2 changed files with 58 additions and 26 deletions
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82
src/smt/theory_str.cpp
View file

@ -641,7 +641,6 @@ namespace smt {
}
app * theory_str::mk_indexof(expr * haystack, expr * needle) {
// TODO check meaning of the third argument here
app * indexof = u.str.mk_index(haystack, needle, mk_int(0));
m_trail.push_back(indexof);
// immediately force internalization so that axiom setup does not fail
@ -844,14 +843,7 @@ namespace smt {
instantiate_axiom_Contains(e);
} else if (u.str.is_index(a)) {
instantiate_axiom_Indexof(e);
/* TODO NEXT: Indexof2/Lastindexof rewrite?
} else if (is_Indexof2(e)) {
instantiate_axiom_Indexof2(e);
} else if (is_LastIndexof(e)) {
instantiate_axiom_LastIndexof(e);
*/
} else if (u.str.is_extract(a)) {
// TODO check semantics of substr vs. extract
instantiate_axiom_Substr(e);
} else if (u.str.is_replace(a)) {
instantiate_axiom_Replace(e);
@ -1232,27 +1224,37 @@ namespace smt {
context & ctx = get_context();
ast_manager & m = get_manager();
app * expr = e->get_owner();
if (axiomatized_terms.contains(expr)) {
TRACE("str", tout << "already set up Indexof axiom for " << mk_pp(expr, m) << std::endl;);
app * ex = e->get_owner();
if (axiomatized_terms.contains(ex)) {
TRACE("str", tout << "already set up str.indexof axiom for " << mk_pp(ex, m) << std::endl;);
return;
}
axiomatized_terms.insert(expr);
SASSERT(ex->get_num_args() == 3);
// if the third argument is exactly the integer 0, we can use this "simple" indexof;
// otherwise, we call the "extended" version
expr * startingPosition = ex->get_arg(2);
rational startingInteger;
if (!m_autil.is_numeral(startingPosition, startingInteger) || !startingInteger.is_zero()) {
// "extended" indexof term with prefix
instantiate_axiom_Indexof_extended(e);
return;
}
axiomatized_terms.insert(ex);
TRACE("str", tout << "instantiate Indexof axiom for " << mk_pp(expr, m) << std::endl;);
TRACE("str", tout << "instantiate str.indexof axiom for " << mk_pp(ex, m) << std::endl;);
expr_ref x1(mk_str_var("x1"), m);
expr_ref x2(mk_str_var("x2"), m);
expr_ref indexAst(mk_int_var("index"), m);
expr_ref condAst(mk_contains(expr->get_arg(0), expr->get_arg(1)), m);
expr_ref condAst(mk_contains(ex->get_arg(0), ex->get_arg(1)), m);
SASSERT(condAst);
// -----------------------
// true branch
expr_ref_vector thenItems(m);
// args[0] = x1 . args[1] . x2
thenItems.push_back(ctx.mk_eq_atom(expr->get_arg(0), mk_concat(x1, mk_concat(expr->get_arg(1), x2))));
thenItems.push_back(ctx.mk_eq_atom(ex->get_arg(0), mk_concat(x1, mk_concat(ex->get_arg(1), x2))));
// indexAst = |x1|
thenItems.push_back(ctx.mk_eq_atom(indexAst, mk_strlen(x1)));
// args[0] = x3 . x4
@ -1260,11 +1262,11 @@ namespace smt {
// /\ ! contains(x3, args[1])
expr_ref x3(mk_str_var("x3"), m);
expr_ref x4(mk_str_var("x4"), m);
expr_ref tmpLen(m_autil.mk_add(indexAst, mk_strlen(expr->get_arg(1)), mk_int(-1)), m);
expr_ref tmpLen(m_autil.mk_add(indexAst, mk_strlen(ex->get_arg(1)), mk_int(-1)), m);
SASSERT(tmpLen);
thenItems.push_back(ctx.mk_eq_atom(expr->get_arg(0), mk_concat(x3, x4)));
thenItems.push_back(ctx.mk_eq_atom(ex->get_arg(0), mk_concat(x3, x4)));
thenItems.push_back(ctx.mk_eq_atom(mk_strlen(x3), tmpLen));
thenItems.push_back(mk_not(m, mk_contains(x3, expr->get_arg(1))));
thenItems.push_back(mk_not(m, mk_contains(x3, ex->get_arg(1))));
expr_ref thenBranch(m.mk_and(thenItems.size(), thenItems.c_ptr()), m);
SASSERT(thenBranch);
@ -1276,26 +1278,42 @@ namespace smt {
expr_ref breakdownAssert(m.mk_ite(condAst, thenBranch, elseBranch), m);
SASSERT(breakdownAssert);
expr_ref reduceToIndex(ctx.mk_eq_atom(expr, indexAst), m);
expr_ref reduceToIndex(ctx.mk_eq_atom(ex, indexAst), m);
SASSERT(reduceToIndex);
expr_ref finalAxiom(m.mk_and(breakdownAssert, reduceToIndex), m);
SASSERT(finalAxiom);
assert_axiom(finalAxiom);
{
// heuristic: integrate with str.contains information
// (but don't introduce it if it isn't already in the instance)
expr_ref haystack(ex->get_arg(0), m), needle(ex->get_arg(1), m), startIdx(ex->get_arg(2), m);
expr_ref zeroAst(mk_int(0), m);
// (H contains N) <==> (H indexof N, i) >= 0
expr_ref premise(u.str.mk_contains(haystack, needle), m);
ctx.internalize(premise, false);
expr_ref conclusion(m_autil.mk_ge(ex, zeroAst), m);
expr_ref containsAxiom(ctx.mk_eq_atom(premise, conclusion), m);
SASSERT(containsAxiom);
// we can't assert this during init_search as it breaks an invariant if the instance becomes inconsistent
m_delayed_axiom_setup_terms.push_back(containsAxiom);
}
}
void theory_str::instantiate_axiom_Indexof2(enode * e) {
void theory_str::instantiate_axiom_Indexof_extended(enode * e) {
context & ctx = get_context();
ast_manager & m = get_manager();
app * expr = e->get_owner();
if (axiomatized_terms.contains(expr)) {
TRACE("str", tout << "already set up Indexof2 axiom for " << mk_pp(expr, m) << std::endl;);
TRACE("str", tout << "already set up extended str.indexof axiom for " << mk_pp(expr, m) << std::endl;);
return;
}
SASSERT(expr->get_num_args() == 3);
axiomatized_terms.insert(expr);
TRACE("str", tout << "instantiate Indexof2 axiom for " << mk_pp(expr, m) << std::endl;);
TRACE("str", tout << "instantiate extended str.indexof axiom for " << mk_pp(expr, m) << std::endl;);
// -------------------------------------------------------------------------------
// if (arg[2] >= length(arg[0])) // ite2
@ -1327,7 +1345,7 @@ namespace smt {
ite2ElseItems.push_back(ctx.mk_eq_atom(indexAst, mk_indexof(suffix, expr->get_arg(1))));
ite2ElseItems.push_back(ctx.mk_eq_atom(expr->get_arg(2), prefixLen));
ite2ElseItems.push_back(ite3);
expr_ref ite2Else(m.mk_and(ite2ElseItems.size(), ite2ElseItems.c_ptr()), m);
expr_ref ite2Else(mk_and(ite2ElseItems), m);
SASSERT(ite2Else);
expr_ref ite2(m.mk_ite(
@ -1350,6 +1368,20 @@ namespace smt {
expr_ref reduceTerm(ctx.mk_eq_atom(expr, resAst), m);
SASSERT(reduceTerm);
assert_axiom(reduceTerm);
{
// heuristic: integrate with str.contains information
// (but don't introduce it if it isn't already in the instance)
expr_ref haystack(expr->get_arg(0), m), needle(expr->get_arg(1), m), startIdx(expr->get_arg(2), m);
// (H contains N) <==> (H indexof N, i) >= 0
expr_ref premise(u.str.mk_contains(haystack, needle), m);
ctx.internalize(premise, false);
expr_ref conclusion(m_autil.mk_ge(expr, zeroAst), m);
expr_ref containsAxiom(ctx.mk_eq_atom(premise, conclusion), m);
SASSERT(containsAxiom);
// we can't assert this during init_search as it breaks an invariant if the instance becomes inconsistent
m_delayed_axiom_setup_terms.push_back(containsAxiom);
}
}
void theory_str::instantiate_axiom_LastIndexof(enode * e) {
@ -8731,8 +8763,8 @@ namespace smt {
context & ctx = get_context();
ast_manager & m = get_manager();
expr_ref_vector assignments(m);
ctx.get_assignments(assignments);
//expr_ref_vector assignments(m);
//ctx.get_assignments(assignments);
if (opt_VerifyFinalCheckProgress) {
finalCheckProgressIndicator = false;

2
src/smt/theory_str.h
View file

@ -447,7 +447,7 @@ protected:
void instantiate_axiom_suffixof(enode * e);
void instantiate_axiom_Contains(enode * e);
void instantiate_axiom_Indexof(enode * e);
void instantiate_axiom_Indexof2(enode * e);
void instantiate_axiom_Indexof_extended(enode * e);
void instantiate_axiom_LastIndexof(enode * e);
void instantiate_axiom_Substr(enode * e);
void instantiate_axiom_Replace(enode * e);