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update generation of empty sequence to take sort argument, fix mk_concat substitution

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2026-03-13 10:00:23 -07:00
parent e384e8f3d4
commit df9df50a71
6 changed files with 146 additions and 121 deletions
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18
src/ast/euf/euf_sgraph.cpp
View file

@ -461,21 +461,23 @@ namespace euf {
return mk(u);
}
snode* sgraph::mk_empty() {
expr_ref e(m_seq.str.mk_empty(m_str_sort), m);
snode* sgraph::mk_empty_seq(sort* s) {
expr_ref e(m_seq.str.mk_empty(s), m);
return mk(e);
}
snode* sgraph::mk_concat(snode* a, snode* b) {
if (a->is_empty()) return b;
if (b->is_empty()) return a;
expr_ref e(m_seq.str.mk_concat(a->get_expr(), b->get_expr()), m);
return mk(e);
if (m_seq.is_re(a->get_expr()))
return mk(expr_ref(m_seq.re.mk_concat(a->get_expr(), b->get_expr()), m));
else
return mk(expr_ref(m_seq.str.mk_concat(a->get_expr(), b->get_expr()), m));
}
snode* sgraph::drop_first(snode* n) {
if (n->is_empty() || n->is_token())
return mk_empty();
return mk_empty_seq(n->get_sort());
SASSERT(n->is_concat());
snode* l = n->arg(0);
snode* r = n->arg(1);
@ -486,7 +488,7 @@ namespace euf {
snode* sgraph::drop_last(snode* n) {
if (n->is_empty() || n->is_token())
return mk_empty();
return mk_empty_seq(n->get_sort());
SASSERT(n->is_concat());
snode* l = n->arg(0);
snode* r = n->arg(1);
@ -497,7 +499,7 @@ namespace euf {
snode* sgraph::drop_left(snode* n, unsigned count) {
if (count == 0 || n->is_empty()) return n;
if (count >= n->length()) return mk_empty();
if (count >= n->length()) return mk_empty_seq(n->get_sort());
for (unsigned i = 0; i < count; ++i)
n = drop_first(n);
return n;
@ -505,7 +507,7 @@ namespace euf {
snode* sgraph::drop_right(snode* n, unsigned count) {
if (count == 0 || n->is_empty()) return n;
if (count >= n->length()) return mk_empty();
if (count >= n->length()) return mk_empty_seq(n->get_sort());
for (unsigned i = 0; i < count; ++i)
n = drop_last(n);
return n;

2
src/ast/euf/euf_sgraph.h
View file

@ -128,7 +128,7 @@ namespace euf {
// factory methods for creating snodes with corresponding expressions
snode* mk_var(symbol const& name);
snode* mk_char(unsigned ch);
snode* mk_empty();
snode *mk_empty_seq(sort *s);
snode* mk_concat(snode* a, snode* b);
// drop operations: remove tokens from the front/back of a concat tree

4
src/ast/euf/euf_snode.h
View file

@ -143,6 +143,10 @@ namespace euf {
}
}
sort *get_sort() const {
return m_expr ? m_expr->get_sort() : nullptr;
}
// analogous to ZIPT's Str.First / Str.Last
snode const* first() const {
snode const* s = this;