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filter length limits to be non-skolems and under concat/""/unit

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This commit is contained in:
Nikolaj Bjorner 2022-09-15 07:41:00 -07:00
parent af258d1720
commit 088898834c
3 changed files with 43 additions and 7 deletions
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18
src/ast/rewriter/seq_skolem.cpp
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@ -26,10 +26,14 @@ skolem::skolem(ast_manager& m, th_rewriter& rw):
m_suffix = "seq.s.prefix";
m_accept = "aut.accept";
m_tail = "seq.tail";
m_left = "seq.left";
m_right = "seq.right";
m_seq_first = "seq.first";
m_seq_last = "seq.last";
m_indexof_left = "seq.idx.l";
m_indexof_right = "seq.idx.r";
m_lindexof_left = "seq.lidx.l";
m_lindexof_right = "seq.lidx.r";
m_aut_step = "aut.step";
m_pre = "seq.pre"; // (seq.pre s l): prefix of string s of length l
m_post = "seq.post"; // (seq.post s l): suffix of string s of length k, based on extract starting at index i of length l
@ -155,6 +159,20 @@ bool skolem::is_tail(expr* e, expr*& s, expr*& idx) const {
return is_tail(e) && (s = to_app(e)->get_arg(0), idx = to_app(e)->get_arg(1), true);
}
bool skolem::is_left_or_right(expr* e, expr*& x, expr*& y, expr*& z) {
if (!is_skolem(m_left, e) && !is_skolem(m_right, e))
return false;
x = nullptr;
y = nullptr;
z = nullptr;
unsigned sz = to_app(e)->get_num_args();
if (sz > 0) x = to_app(e)->get_arg(0);
if (sz > 1) y = to_app(e)->get_arg(1);
if (sz > 2) z = to_app(e)->get_arg(2);
return true;
}
bool skolem::is_eq(expr* e, expr*& a, expr*& b) const {
return is_skolem(m_eq, e) && (a = to_app(e)->get_arg(0), b = to_app(e)->get_arg(1), true);
}