mirror of
https://github.com/Z3Prover/z3
synced 2026-04-03 10:28:57 +00:00
1317 lines
51 KiB
C++
1317 lines
51 KiB
C++
/*++
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Copyright (c) 2026 Microsoft Corporation
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Module Name:
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theory_nseq.cpp
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Abstract:
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ZIPT string solver theory for Z3.
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Implementation of theory_nseq.
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Author:
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Clemens Eisenhofer 2026-03-01
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Nikolaj Bjorner (nbjorner) 2026-03-01
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--*/
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#include "smt/theory_nseq.h"
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#include "smt/smt_context.h"
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#include "smt/smt_justification.h"
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#include "util/statistics.h"
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#include "util/trail.h"
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namespace smt {
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theory_nseq::theory_nseq(context& ctx) :
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theory(ctx, ctx.get_manager().mk_family_id("seq")),
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m_seq(m),
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m_autil(m),
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m_th_rewriter(m),
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m_rewriter(m),
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m_arith_value(m),
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m_egraph(m),
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m_sgraph(m, m_egraph),
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m_context_solver(m),
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m_core_solver(m),
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m_nielsen(m_sgraph, m_context_solver, m_core_solver),
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m_axioms(m_th_rewriter),
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m_regex(m_sgraph),
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m_model(m, m_seq, m_rewriter, m_sgraph),
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m_relevant_lengths(m)
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{
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std::function<void(expr_ref_vector const&)> add_clause =
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[&](expr_ref_vector const &clause) {
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literal_vector lits;
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for (auto const &e : clause) {
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auto lit = mk_literal(e);
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if (lit == false_literal)
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continue;
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if (lit == true_literal)
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return;
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if (ctx.get_assignment(lit) == l_true)
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return;
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ctx.mark_as_relevant(lit);
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lits.push_back(lit);
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}
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// TODO - add validation, trace axioms
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ctx.mk_th_axiom(get_id(), lits.size(), lits.data());
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};
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std::function < void(expr* e)> set_phase = [&](expr* e) {
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literal lit = mk_literal(e);
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ctx.force_phase(lit);
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};
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std::function < void(void)> ensure_digit_axiom = [this, add_clause]() {
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if (!m_digits_initialized) {
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for (unsigned i = 0; i < 10; ++i) {
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expr_ref cnst(m_seq.mk_char('0' + i), m);
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expr_ref_vector clause(m);
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clause.push_back(m.mk_eq(m_axioms.sk().mk_digit2int(cnst), m_autil.mk_int(i)));
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add_clause(clause);
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}
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get_context().push_trail(value_trail<bool>(m_digits_initialized));
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m_digits_initialized = true;
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}
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};
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std::function<void(expr *)> mark_no_diseq = [&](expr *e) {
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m_no_diseq_set.insert(e);
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ctx.push_trail(insert_obj_trail(m_no_diseq_set, e));
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};
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m_axioms.set_add_clause(add_clause);
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m_axioms.set_phase(set_phase);
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m_axioms.set_ensure_digits(ensure_digit_axiom);
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m_axioms.set_mark_no_diseq(mark_no_diseq);
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std::function<sat::literal(expr*)> literal_if_false = [&](expr* e) {
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bool is_not = m.is_not(e, e);
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TRACE(seq, tout << "literal_if_false: " << mk_pp(e, m) << " internalized - " << ctx.e_internalized(e) << "\n");
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if (!ctx.e_internalized(e))
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return sat::null_literal;
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literal lit = ctx.get_literal(e);
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if (is_not)
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lit.neg();
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if (ctx.get_assignment(lit) == l_false) {
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TRACE(seq, tout << "literal_if_false: " << lit << " " << mk_pp(e, m) << " is assigned false\n");
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return lit;
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}
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TRACE(seq, tout << "literal_if_false: " << mk_pp(e, m) << " is assigned " << ctx.get_assignment(lit) << "\n");
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return sat::null_literal;
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};
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m_nielsen.set_literal_if_false(literal_if_false);
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}
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// -----------------------------------------------------------------------
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// Initialization
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// -----------------------------------------------------------------------
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void theory_nseq::init() {
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m_arith_value.init(&get_context());
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}
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// -----------------------------------------------------------------------
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// Internalization
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// -----------------------------------------------------------------------
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bool theory_nseq::internalize_atom(app* atom, bool /*gate_ctx*/) {
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// std::cout << "internalize_atom: " << mk_pp(atom, m) << std::endl;
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// str.in_re atoms are boolean predicates: register as bool_var
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// so that assign_eh fires when the SAT solver assigns them.
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// Following theory_seq: create a bool_var directly without an enode
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// for the str.in_re predicate (avoids needing to internalize the regex arg).
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if (m_seq.str.is_in_re(atom)) {
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expr* str_arg = atom->get_arg(0);
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mk_var(ensure_enode(str_arg));
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if (!ctx.b_internalized(atom)) {
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bool_var bv = ctx.mk_bool_var(atom);
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ctx.set_var_theory(bv, get_id());
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ctx.mark_as_relevant(bv);
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}
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get_snode(str_arg);
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return true;
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}
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return internalize_term(atom);
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}
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theory_var theory_nseq::mk_var(enode* n) {
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expr* o = n->get_expr();
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if (!m_seq.is_seq(o) && !m_seq.is_re(o) && !m_seq.str.is_nth_u(o))
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return null_theory_var;
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if (is_attached_to_var(n))
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return n->get_th_var(get_id());
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theory_var v = theory::mk_var(n);
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get_context().attach_th_var(n, this, v);
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get_context().mark_as_relevant(n);
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return v;
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}
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bool theory_nseq::internalize_term(app* term) {
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// std::cout << "internalize_term: " << mk_pp(term, m) << std::endl;
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// ensure ALL children are internalized (following theory_seq pattern)
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for (auto arg : *term) {
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mk_var(ensure_enode(arg));
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}
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if (ctx.e_internalized(term)) {
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mk_var(ctx.get_enode(term));
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return true;
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}
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if (m.is_bool(term)) {
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bool_var bv = ctx.mk_bool_var(term);
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ctx.set_var_theory(bv, get_id());
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ctx.mark_as_relevant(bv);
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}
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enode* en;
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if (ctx.e_internalized(term))
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en = ctx.get_enode(term);
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else
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en = ctx.mk_enode(term, false, m.is_bool(term), true);
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mk_var(en);
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// register in our private sgraph
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get_snode(term);
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// track higher-order terms for lazy unfolding
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expr* ho_f = nullptr, *ho_s = nullptr, *ho_b = nullptr, *ho_i = nullptr;
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if (m_seq.str.is_map(term, ho_f, ho_s) ||
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m_seq.str.is_mapi(term, ho_f, ho_i, ho_s) ||
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m_seq.str.is_foldl(term, ho_f, ho_b, ho_s) ||
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m_seq.str.is_foldli(term, ho_f, ho_i, ho_b, ho_s)) {
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ctx.push_trail(restore_vector(m_ho_terms));
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m_ho_terms.push_back(term);
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ensure_length_var(ho_s);
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}
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expr* v;
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if (m_seq.str.is_length(term, v)) {
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ctx.push_trail(restore_vector(m_relevant_lengths));
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m_relevant_lengths.push_back(term);
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}
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return true;
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}
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// -----------------------------------------------------------------------
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// Equality / disequality notifications
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// -----------------------------------------------------------------------
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void theory_nseq::new_eq_eh(theory_var v1, theory_var v2) {
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expr* e1 = get_enode(v1)->get_expr();
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expr* e2 = get_enode(v2)->get_expr();
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TRACE(seq, tout << mk_pp(e1, m) << " == " << mk_pp(e2, m) << "\n");
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if (m_seq.is_re(e1)) {
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push_unhandled_pred();
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return;
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}
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if (!m_seq.is_seq(e1) || !m_seq.is_seq(e2))
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return;
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euf::snode* s1 = get_snode(e1);
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euf::snode* s2 = get_snode(e2);
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if (s1 && s2) {
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seq::dep_tracker dep = nullptr;
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ctx.push_trail(restore_vector(m_prop_queue));
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m_prop_queue.push_back(eq_item(s1, s2, get_enode(v1), get_enode(v2), dep));
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}
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}
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void theory_nseq::new_diseq_eh(theory_var v1, theory_var v2) {
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expr* e1 = get_enode(v1)->get_expr();
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expr* e2 = get_enode(v2)->get_expr();
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TRACE(seq, tout << mk_pp(e1, m) << " != " << mk_pp(e2, m) << "\n");
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if (m_seq.is_re(e1))
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// regex disequality: nseq cannot verify language non-equivalence
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push_unhandled_pred();
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else if (m_seq.is_seq(e1) && !m_no_diseq_set.contains(e1) && !m_no_diseq_set.contains(e2))
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m_axioms.diseq_axiom(e1, e2);
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else
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;
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}
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// -----------------------------------------------------------------------
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// Boolean assignment notification
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// -----------------------------------------------------------------------
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void theory_nseq::assign_eh(bool_var v, bool is_true) {
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expr* e = ctx.bool_var2expr(v);
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// std::cout << "assigned " << mk_pp(e, m) << " = " << is_true << std::endl;
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expr *s = nullptr, *re = nullptr, *a = nullptr, *b = nullptr;
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TRACE(seq, tout << (is_true ? "" : "¬") << mk_bounded_pp(e, m, 3) << "\n";);
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if (m_seq.str.is_in_re(e, s, re)) {
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euf::snode* sn_str = get_snode(s);
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euf::snode* sn_re = get_snode(re);
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if (!sn_str || !sn_re)
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return;
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literal lit(v, !is_true);
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seq::dep_tracker dep = nullptr;
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if (is_true) {
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ctx.push_trail(restore_vector(m_prop_queue));
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m_prop_queue.push_back(mem_item(sn_str, sn_re, lit, nullptr, m_next_mem_id++, dep));
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}
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else {
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// ¬(str ∈ R) ≡ str ∈ complement(R): store as a positive membership
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// so the Nielsen graph sees it uniformly; the original negative literal
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// is kept in mem_source for conflict reporting.
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expr_ref re_compl(m_seq.re.mk_complement(re), m);
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euf::snode* sn_re_compl = get_snode(re_compl.get());
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ctx.push_trail(restore_vector(m_prop_queue));
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m_prop_queue.push_back(mem_item(sn_str, sn_re_compl, lit, nullptr, m_next_mem_id++, dep));
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}
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}
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else if (m_seq.str.is_prefix(e)) {
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if (is_true)
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m_axioms.prefix_true_axiom(e);
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else
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m_axioms.prefix_axiom(e);
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}
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else if (m_seq.str.is_suffix(e)) {
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if (is_true)
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m_axioms.suffix_true_axiom(e);
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else
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m_axioms.suffix_axiom(e);
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}
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else if (m_seq.str.is_contains(e)) {
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if (is_true)
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m_axioms.contains_true_axiom(e);
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else
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m_axioms.not_contains_axiom(e);
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}
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else if (m_seq.str.is_lt(e) || m_seq.str.is_le(e)) {
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// axioms added via relevant_eh → dequeue_axiom
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}
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else if (m_axioms.sk().is_eq(e, a, b) && is_true) {
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enode* n1 = ensure_enode(a);
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enode* n2 = ensure_enode(b);
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auto v1 = mk_var(n1);
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auto v2 = mk_var(n2);
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if (n1->get_root() != n2->get_root()) {
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literal lit(v, false);
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ctx.mark_as_relevant(n1);
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ctx.mark_as_relevant(n2);
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TRACE(seq, tout << "is-eq " << mk_pp(a, m) << " == " << mk_pp(b, m) << "\n");
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justification* js = ctx.mk_justification(
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ext_theory_eq_propagation_justification(
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get_id(), ctx, 1, &lit, 0, nullptr, n1, n2));
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ctx.assign_eq(n1, n2, eq_justification(js));
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new_eq_eh(v1, v2);
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}
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}
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else if (m_seq.is_skolem(e) ||
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m_seq.str.is_nth_i(e) ||
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m_seq.str.is_nth_u(e) ||
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m_seq.str.is_is_digit(e) ||
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m_seq.str.is_foldl(e) ||
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m_seq.str.is_foldli(e)) {
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// no-op: handled by other mechanisms
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}
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else if (is_app(e) && to_app(e)->get_family_id() == m_seq.get_family_id())
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push_unhandled_pred();
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}
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// -----------------------------------------------------------------------
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// Scope management
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// -----------------------------------------------------------------------
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void theory_nseq::push_scope_eh() {
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theory::push_scope_eh();
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m_sgraph.push();
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}
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void theory_nseq::pop_scope_eh(unsigned num_scopes) {
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theory::pop_scope_eh(num_scopes);
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m_sgraph.pop(num_scopes);
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}
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void theory_nseq::push_unhandled_pred() {
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ctx.push_trail(value_trail<unsigned>(m_num_unhandled_bool));
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++m_num_unhandled_bool;
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}
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// -----------------------------------------------------------------------
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// Propagation: eager eq/diseq/literal dispatch
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// -----------------------------------------------------------------------
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bool theory_nseq::can_propagate() {
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return m_prop_qhead < m_prop_queue.size();
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}
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void theory_nseq::propagate() {
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if (m_prop_qhead == m_prop_queue.size())
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return;
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ctx.push_trail(value_trail(m_prop_qhead));
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while (m_prop_qhead < m_prop_queue.size() && !ctx.inconsistent()) {
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auto const& item = m_prop_queue[m_prop_qhead++];
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if (std::holds_alternative<eq_item>(item))
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propagate_eq(std::get<eq_item>(item));
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else if (std::holds_alternative<mem_item>(item))
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propagate_pos_mem(std::get<mem_item>(item));
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else if (std::holds_alternative<axiom_item>(item))
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dequeue_axiom(std::get<axiom_item>(item).e);
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else {
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UNREACHABLE();
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}
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}
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}
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void theory_nseq::propagate_eq(tracked_str_eq const& eq) {
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// When s1 = s2 is learned, ensure len(s1) and len(s2) are
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// internalized so congruence closure propagates len(s1) = len(s2).
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ensure_length_var(eq.m_l->get_expr());
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ensure_length_var(eq.m_r->get_expr());
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}
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void theory_nseq::propagate_pos_mem(tracked_str_mem const& mem) {
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if (!mem.m_str || !mem.m_regex)
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return;
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// regex is ∅ → conflict
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if (m_regex.is_empty_regex(mem.m_regex)) {
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enode_pair_vector eqs;
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literal_vector lits;
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lits.push_back(mem.lit);
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set_conflict(eqs, lits);
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return;
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}
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// empty string in non-nullable regex → conflict
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if (mem.m_str->is_empty() && !mem.m_regex->is_nullable()) {
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enode_pair_vector eqs;
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literal_vector lits;
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lits.push_back(mem.lit);
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set_conflict(eqs, lits);
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return;
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}
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// ensure length term exists for the string argument
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expr* s_expr = mem.m_str->get_expr();
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if (s_expr)
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ensure_length_var(s_expr);
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if (!get_fparams().m_nseq_regex_factorization)
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return;
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// Boolean Closure Propagations
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expr* re_expr = mem.m_regex->get_expr();
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if (m_seq.re.is_intersection(re_expr)) {
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for (expr* arg : *to_app(re_expr)) {
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expr_ref in_r(m_seq.re.mk_in_re(s_expr, arg), m);
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literal_vector lits;
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lits.push_back(~mem.lit);
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lits.push_back(mk_literal(in_r));
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ctx.mk_th_axiom(get_id(), lits.size(), lits.data());
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}
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}
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else if (m_seq.re.is_union(re_expr)) {
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literal_vector lits;
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lits.push_back(~mem.lit);
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for (expr* arg : *to_app(re_expr)) {
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expr_ref in_r(m_seq.re.mk_in_re(s_expr, arg), m);
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lits.push_back(mk_literal(in_r));
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}
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ctx.mk_th_axiom(get_id(), lits.size(), lits.data());
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}
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else if (m_seq.re.is_complement(re_expr)) {
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expr* arg = to_app(re_expr)->get_arg(0);
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expr_ref in_r(m_seq.re.mk_in_re(s_expr, arg), m);
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literal_vector lits;
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lits.push_back(~mem.lit);
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lits.push_back(~mk_literal(in_r));
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ctx.mk_th_axiom(get_id(), lits.size(), lits.data());
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}
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}
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void theory_nseq::ensure_length_var(expr* e) {
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if (!e || !m_seq.is_seq(e))
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return;
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expr_ref len(m_seq.str.mk_length(e), m);
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if (!ctx.e_internalized(len))
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ctx.internalize(len, false);
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}
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// -----------------------------------------------------------------------
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// Axiom enqueue / dequeue (follows theory_seq::enque_axiom / deque_axiom)
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// -----------------------------------------------------------------------
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void theory_nseq::enqueue_axiom(expr* e) {
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if (m_axiom_set.contains(e))
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return;
|
|
m_axiom_set.insert(e);
|
|
ctx.push_trail(insert_obj_trail<expr>(m_axiom_set, e));
|
|
ctx.push_trail(restore_vector(m_prop_queue));
|
|
m_prop_queue.push_back(axiom_item{e});
|
|
}
|
|
|
|
void theory_nseq::dequeue_axiom(expr* n) {
|
|
TRACE(seq, tout << "dequeue_axiom: " << mk_bounded_pp(n, m, 2) << "\n";);
|
|
if (m_seq.str.is_length(n))
|
|
m_axioms.length_axiom(n);
|
|
else if (m_seq.str.is_index(n))
|
|
m_axioms.indexof_axiom(n);
|
|
else if (m_seq.str.is_last_index(n))
|
|
m_axioms.last_indexof_axiom(n);
|
|
else if (m_seq.str.is_replace(n))
|
|
m_axioms.replace_axiom(n);
|
|
else if (m_seq.str.is_replace_all(n))
|
|
m_axioms.replace_all_axiom(n);
|
|
else if (m_seq.str.is_extract(n))
|
|
m_axioms.extract_axiom(n);
|
|
else if (m_seq.str.is_at(n))
|
|
m_axioms.at_axiom(n);
|
|
else if (m_seq.str.is_nth_i(n))
|
|
m_axioms.nth_axiom(n);
|
|
else if (m_seq.str.is_itos(n))
|
|
m_axioms.itos_axiom(n);
|
|
else if (m_seq.str.is_stoi(n))
|
|
m_axioms.stoi_axiom(n);
|
|
else if (m_seq.str.is_lt(n))
|
|
m_axioms.lt_axiom(n);
|
|
else if (m_seq.str.is_le(n))
|
|
m_axioms.le_axiom(n);
|
|
else if (m_seq.str.is_unit(n))
|
|
m_axioms.unit_axiom(n);
|
|
else if (m_seq.str.is_is_digit(n))
|
|
m_axioms.is_digit_axiom(n);
|
|
else if (m_seq.str.is_from_code(n))
|
|
m_axioms.str_from_code_axiom(n);
|
|
else if (m_seq.str.is_to_code(n))
|
|
m_axioms.str_to_code_axiom(n);
|
|
}
|
|
|
|
void theory_nseq::relevant_eh(app* n) {
|
|
if (m_seq.str.is_length(n) ||
|
|
m_seq.str.is_index(n) ||
|
|
m_seq.str.is_last_index(n) ||
|
|
m_seq.str.is_replace(n) ||
|
|
m_seq.str.is_replace_all(n)||
|
|
m_seq.str.is_extract(n) ||
|
|
m_seq.str.is_at(n) ||
|
|
m_seq.str.is_nth_i(n) ||
|
|
m_seq.str.is_itos(n) ||
|
|
m_seq.str.is_stoi(n) ||
|
|
m_seq.str.is_lt(n) ||
|
|
m_seq.str.is_le(n) ||
|
|
m_seq.str.is_unit(n) ||
|
|
m_seq.str.is_is_digit(n) ||
|
|
m_seq.str.is_from_code(n) ||
|
|
m_seq.str.is_to_code(n))
|
|
enqueue_axiom(n);
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Final check: build Nielsen graph and search
|
|
// -----------------------------------------------------------------------
|
|
|
|
void theory_nseq::populate_nielsen_graph() {
|
|
m_nielsen.reset();
|
|
|
|
unsigned num_eqs = 0, num_mems = 0;
|
|
|
|
// transfer string equalities and regex memberships from prop_queue to nielsen graph root
|
|
for (auto const& item : m_prop_queue) {
|
|
if (std::holds_alternative<eq_item>(item)) {
|
|
auto const& eq = std::get<eq_item>(item);
|
|
m_nielsen.add_str_eq(eq.m_lhs, eq.m_rhs, eq.m_l, eq.m_r);
|
|
++num_eqs;
|
|
}
|
|
else if (std::holds_alternative<mem_item>(item)) {
|
|
auto const& mem = std::get<mem_item>(item);
|
|
int triv = m_regex.check_trivial(mem);
|
|
if (triv > 0) {
|
|
++num_mems;
|
|
continue; // trivially satisfied, skip
|
|
}
|
|
if (triv < 0) {
|
|
// trivially unsat: add anyway so solve() detects conflict
|
|
m_nielsen.add_str_mem(mem.m_str, mem.m_regex, mem.lit);
|
|
++num_mems;
|
|
continue;
|
|
}
|
|
// pre-process: consume ground prefix characters
|
|
vector<seq::str_mem> processed;
|
|
if (!m_regex.process_str_mem(mem, processed)) {
|
|
// conflict during ground prefix consumption
|
|
m_nielsen.add_str_mem(mem.m_str, mem.m_regex, mem.lit);
|
|
++num_mems;
|
|
continue;
|
|
}
|
|
for (auto const& pm : processed)
|
|
m_nielsen.add_str_mem(pm.m_str, pm.m_regex, mem.lit);
|
|
++num_mems;
|
|
}
|
|
}
|
|
|
|
TRACE(seq, tout << "nseq populate: " << num_eqs << " eqs, "
|
|
<< num_mems << " mems -> nielsen root\n");
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: populating graph with "
|
|
<< num_eqs << " eqs, " << num_mems << " mems\n";);
|
|
}
|
|
|
|
final_check_status theory_nseq::final_check_eh(unsigned /*final_check_round*/) {
|
|
// Always assert non-negativity for all string theory vars,
|
|
// even when there are no string equations/memberships.
|
|
if (assert_nonneg_for_all_vars()) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: nonneg assertions added, FC_CONTINUE\n";);
|
|
return FC_CONTINUE;
|
|
}
|
|
|
|
// Check if there are any eq/mem items in the propagation queue.
|
|
bool has_eq_or_mem = any_of(m_prop_queue, [](auto const &item) {
|
|
return std::holds_alternative<eq_item>(item) || std::holds_alternative<mem_item>(item);
|
|
});
|
|
|
|
// there is nothing to do for the string solver, as there are no string constraints
|
|
if (!has_eq_or_mem && m_ho_terms.empty() && !has_unhandled_preds()) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: empty state+ho, FC_DONE (no solve)\n";);
|
|
m_nielsen.reset();
|
|
m_nielsen.create_root();
|
|
m_nielsen.set_sat_node(m_nielsen.root());
|
|
TRACE(seq, display(tout << "empty nielsen\n"));
|
|
return FC_DONE;
|
|
}
|
|
|
|
// All literals that were needed to build a model could be assigned to true.
|
|
// There is an existing nielsen graph with a satisfying assignment.
|
|
if (!m_nielsen_literals.empty() && m_nielsen.sat_node() != nullptr &&
|
|
all_of(m_nielsen_literals, [&](auto lit) { return l_true == ctx.get_assignment(lit); })) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: satifiable state revisited\n");
|
|
return FC_DONE;
|
|
}
|
|
|
|
// unfold higher-order terms when sequence structure is known
|
|
if (unfold_ho_terms()) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: unfolded ho_terms, FC_CONTINUE\n";);
|
|
return FC_CONTINUE;
|
|
}
|
|
|
|
if (!has_eq_or_mem && !has_unhandled_preds()) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: empty state (after ho), FC_DONE (no solve)\n";);
|
|
m_nielsen.reset();
|
|
m_nielsen.create_root();
|
|
m_nielsen.set_sat_node(m_nielsen.root());
|
|
TRACE(seq, display(tout << "empty nielsen\n"));
|
|
return FC_DONE;
|
|
}
|
|
|
|
populate_nielsen_graph();
|
|
|
|
// assert length constraints derived from string equalities
|
|
if (assert_length_constraints()) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: length constraints asserted, FC_CONTINUE\n";);
|
|
return FC_CONTINUE;
|
|
}
|
|
|
|
++m_num_final_checks;
|
|
|
|
m_nielsen.set_max_search_depth(get_fparams().m_nseq_max_depth);
|
|
m_nielsen.set_max_nodes(get_fparams().m_nseq_max_nodes);
|
|
m_nielsen.set_parikh_enabled(get_fparams().m_nseq_parikh);
|
|
m_nielsen.set_signature_split(get_fparams().m_nseq_signature);
|
|
m_nielsen.set_regex_factorization(get_fparams().m_nseq_regex_factorization);
|
|
|
|
// Regex membership pre-check: before running DFS, check intersection
|
|
// emptiness for each variable's regex constraints. This handles
|
|
// regex-only problems that the DFS cannot efficiently solve.
|
|
if (get_fparams().m_nseq_regex_precheck) {
|
|
switch (check_regex_memberships_precheck()) {
|
|
case l_true:
|
|
// conflict was asserted inside check_regex_memberships_precheck
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: regex precheck UNSAT\n";);
|
|
return FC_CONTINUE;
|
|
case l_false:
|
|
// all regex constraints satisfiable, no word eqs → SAT
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: regex precheck SAT\n";);
|
|
m_nielsen.set_sat_node(m_nielsen.root());
|
|
if (!check_length_coherence())
|
|
return FC_CONTINUE;
|
|
TRACE(seq, display(tout << "pre-check done\n"));
|
|
return FC_DONE;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: calling solve()\n";);
|
|
|
|
// here the actual Nielsen solving happens
|
|
auto result = m_nielsen.solve();
|
|
|
|
#ifdef Z3DEBUG
|
|
// Examining the Nielsen graph is probably the best way of debugging
|
|
std::string dot = m_nielsen.to_dot();
|
|
IF_VERBOSE(1, verbose_stream() << dot << "\n";);
|
|
// std::cout << "Got: " << (result == seq::nielsen_graph::search_result::sat ? "sat" : (result == seq::nielsen_graph::search_result::unsat ? "unsat" : "unknown")) << std::endl;
|
|
#endif
|
|
|
|
if (result == seq::nielsen_graph::search_result::unsat) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: solve UNSAT\n";);
|
|
explain_nielsen_conflict();
|
|
return FC_CONTINUE;
|
|
}
|
|
|
|
if (result == seq::nielsen_graph::search_result::sat) {
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: solve SAT, sat_node="
|
|
<< (m_nielsen.sat_node() ? "set" : "null") << "\n";);
|
|
// Nielsen found a consistent assignment for positive constraints.
|
|
SASSERT(has_eq_or_mem); // we should have axiomatized them
|
|
|
|
if (!add_nielsen_assumptions())
|
|
return FC_CONTINUE;
|
|
|
|
if (!check_length_coherence())
|
|
return FC_CONTINUE;
|
|
|
|
CTRACE(seq, !has_unhandled_preds(), display(tout << "done\n"));
|
|
if (!has_unhandled_preds())
|
|
return FC_DONE;
|
|
}
|
|
|
|
TRACE(seq, display(tout << "unknown\n"));
|
|
IF_VERBOSE(1, verbose_stream() << "nseq final_check: solve UNKNOWN, FC_GIVEUP\n";);
|
|
return FC_GIVEUP;
|
|
}
|
|
|
|
|
|
bool theory_nseq::add_nielsen_assumptions() {
|
|
bool has_undef = false;
|
|
m_nielsen_literals.reset();
|
|
struct reset_vector : public trail {
|
|
sat::literal_vector &v;
|
|
reset_vector(sat::literal_vector &v) : v(v) {}
|
|
void undo() override {
|
|
v.reset();
|
|
}
|
|
};
|
|
ctx.push_trail(reset_vector(m_nielsen_literals));
|
|
for (auto const& c : m_nielsen.sat_node()->constraints()) {
|
|
bool was_internalized = ctx.e_internalized(c.fml);
|
|
auto lit = mk_literal(c.fml);
|
|
m_nielsen_literals.push_back(lit);
|
|
switch (ctx.get_assignment(lit)) {
|
|
case l_true:
|
|
break;
|
|
case l_undef:
|
|
has_undef = true;
|
|
ctx.force_phase(lit);
|
|
IF_VERBOSE(2, verbose_stream() <<
|
|
"nseq final_check: adding nielsen assumption " << c.fml << "\n";);
|
|
TRACE(seq, tout << "assign: " << c.fml << "\n");
|
|
break;
|
|
case l_false:
|
|
// this should not happen because nielsen checks for this before returning a satisfying path.
|
|
IF_VERBOSE(0, verbose_stream()
|
|
<< "nseq final_check: nielsen assumption " << c.fml << " is false\n";);
|
|
ctx.force_phase(lit);
|
|
if (!was_internalized) {
|
|
has_undef = true;
|
|
ctx.force_phase(lit);
|
|
break;
|
|
}
|
|
TRACE(seq, tout << "assigned to false: " << c.fml << "\n");
|
|
UNREACHABLE();
|
|
break;
|
|
}
|
|
}
|
|
if (has_undef)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Conflict explanation
|
|
// -----------------------------------------------------------------------
|
|
|
|
void theory_nseq::explain_nielsen_conflict() {
|
|
enode_pair_vector eqs;
|
|
literal_vector lits;
|
|
for (seq::dep_source const& d : m_nielsen.conflict_sources()) {
|
|
if (std::holds_alternative<enode_pair>(d))
|
|
eqs.push_back(std::get<enode_pair>(d));
|
|
else
|
|
lits.push_back(std::get<sat::literal>(d));
|
|
}
|
|
++m_num_conflicts;
|
|
set_conflict(eqs, lits);
|
|
|
|
#ifdef Z3DEBUG
|
|
#if 1
|
|
std::vector<std::pair<unsigned, unsigned>> confl;
|
|
for (auto& lit : lits) {
|
|
std::cout << mk_pp(ctx.literal2expr(lit), m) << "\n-----------\n";
|
|
}
|
|
for (auto& eq : eqs) {
|
|
std::cout << mk_pp(eq.first->get_expr(), m) << " == " << mk_pp(eq.second->get_expr(), m) << "\n-----------\n";
|
|
}
|
|
std::cout << std::endl;
|
|
#endif
|
|
#endif
|
|
|
|
#ifdef Z3DEBUG
|
|
std::cout << "Conflict with " << lits.size() << " literals and " << eqs.size() << " equalities" << std::endl;
|
|
std::cout << "The root node contained " << m_nielsen.root()->str_mems().size() << " memberships and " << m_nielsen.root()->str_eqs().size() << " equalities" << std::endl;
|
|
#endif
|
|
}
|
|
|
|
void theory_nseq::set_conflict(enode_pair_vector const& eqs, literal_vector const& lits) {
|
|
TRACE(seq, tout << "nseq conflict: " << eqs.size() << " eqs, " << lits.size() << " lits\n";);
|
|
ctx.set_conflict(
|
|
ctx.mk_justification(
|
|
ext_theory_conflict_justification(
|
|
get_id(), ctx, lits.size(), lits.data(), eqs.size(), eqs.data(), 0, nullptr)));
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Model generation
|
|
// -----------------------------------------------------------------------
|
|
|
|
void theory_nseq::init_model(model_generator& mg) {
|
|
m_model.init(mg, m_nielsen);
|
|
}
|
|
|
|
model_value_proc* theory_nseq::mk_value(enode* n, model_generator& mg) {
|
|
return m_model.mk_value(n, mg);
|
|
}
|
|
|
|
void theory_nseq::finalize_model(model_generator& mg) {
|
|
m_model.finalize(mg);
|
|
}
|
|
|
|
void theory_nseq::validate_model(proto_model& mdl) {
|
|
for (auto const& item : m_prop_queue)
|
|
if (std::holds_alternative<mem_item>(item))
|
|
m_model.validate_regex(std::get<mem_item>(item), mdl);
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Statistics / display
|
|
// -----------------------------------------------------------------------
|
|
|
|
void theory_nseq::collect_statistics(::statistics& st) const {
|
|
st.update("nseq conflicts", m_num_conflicts);
|
|
st.update("nseq final checks", m_num_final_checks);
|
|
st.update("nseq length axioms", m_num_length_axioms);
|
|
st.update("nseq ho unfolds", m_num_ho_unfolds);
|
|
m_nielsen.collect_statistics(st);
|
|
}
|
|
|
|
void theory_nseq::display(std::ostream& out) const {
|
|
unsigned num_eqs = 0, num_mems = 0;
|
|
for (auto const& item : m_prop_queue) {
|
|
if (std::holds_alternative<eq_item>(item)) ++num_eqs;
|
|
else if (std::holds_alternative<mem_item>(item)) ++num_mems;
|
|
}
|
|
out << "theory_nseq\n";
|
|
out << " str_eqs: " << num_eqs << "\n";
|
|
out << " str_mems: " << num_mems << "\n";
|
|
out << " prop_queue: " << m_prop_qhead << "/" << m_prop_queue.size() << "\n";
|
|
out << " ho_terms: " << m_ho_terms.size() << "\n";
|
|
for (auto const &item : m_prop_queue) {
|
|
if (std::holds_alternative<eq_item>(item)) {
|
|
auto const& eq = std::get<eq_item>(item);
|
|
out << " eq: " << mk_bounded_pp(eq.m_l->get_expr(), m, 3)
|
|
<< " = " << mk_bounded_pp(eq.m_r->get_expr(), m, 3) << "\n";
|
|
}
|
|
else if (std::holds_alternative<mem_item>(item)) {
|
|
auto const& mem = std::get<mem_item>(item);
|
|
out << " mem: " << mk_bounded_pp(mem.m_str->get_expr(), m, 3)
|
|
<< " in " << mk_bounded_pp(mem.m_regex->get_expr(), m, 3)
|
|
<< " (lit: " << mem.lit << ")\n";
|
|
}
|
|
else if (std::holds_alternative<axiom_item>(item)) {
|
|
auto const& ax = std::get<axiom_item>(item);
|
|
out << " axiom: " << mk_bounded_pp(ax.e, m, 3) << "\n";
|
|
}
|
|
}
|
|
m_nielsen.display(out);
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Factory / clone
|
|
// -----------------------------------------------------------------------
|
|
|
|
theory* theory_nseq::mk_fresh(context* ctx) {
|
|
return alloc(theory_nseq, *ctx);
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Higher-order term unfolding (seq.map, seq.foldl, etc.)
|
|
// -----------------------------------------------------------------------
|
|
|
|
bool theory_nseq::unfold_ho_terms() {
|
|
if (m_ho_terms.empty())
|
|
return false;
|
|
|
|
bool progress = false;
|
|
|
|
for (app* term : m_ho_terms) {
|
|
expr* f = nullptr, *s = nullptr, *b = nullptr, *idx = nullptr;
|
|
|
|
if (!m_seq.str.is_map(term, f, s) &&
|
|
!m_seq.str.is_mapi(term, f, idx, s) &&
|
|
!m_seq.str.is_foldl(term, f, b, s) &&
|
|
!m_seq.str.is_foldli(term, f, idx, b, s))
|
|
continue;
|
|
|
|
if (!ctx.e_internalized(s))
|
|
continue;
|
|
|
|
// Find a structural representative in s's equivalence class
|
|
enode* s_root = ctx.get_enode(s)->get_root();
|
|
expr* repr = nullptr;
|
|
enode* curr = s_root;
|
|
do {
|
|
expr* e = curr->get_expr();
|
|
expr *a1, *a2;
|
|
if (m_seq.str.is_empty(e) ||
|
|
m_seq.str.is_unit(e, a1) ||
|
|
m_seq.str.is_concat(e, a1, a2)) {
|
|
repr = e;
|
|
break;
|
|
}
|
|
curr = curr->get_next();
|
|
} while (curr != s_root);
|
|
|
|
if (!repr)
|
|
continue;
|
|
|
|
// Build ho_term with structural seq arg, then rewrite
|
|
expr_ref ho_repr(m);
|
|
if (m_seq.str.is_map(term))
|
|
ho_repr = m_seq.str.mk_map(f, repr);
|
|
else if (m_seq.str.is_mapi(term))
|
|
ho_repr = m_seq.str.mk_mapi(f, idx, repr);
|
|
else if (m_seq.str.is_foldl(term))
|
|
ho_repr = m_seq.str.mk_foldl(f, b, repr);
|
|
else
|
|
ho_repr = m_seq.str.mk_foldli(f, idx, b, repr);
|
|
|
|
expr_ref rewritten(m);
|
|
br_status st = m_rewriter.mk_app_core(
|
|
to_app(ho_repr)->get_decl(),
|
|
to_app(ho_repr)->get_num_args(),
|
|
to_app(ho_repr)->get_args(),
|
|
rewritten);
|
|
|
|
if (st == BR_FAILED)
|
|
continue;
|
|
|
|
// Internalize both the structural ho_term and its rewrite
|
|
if (!ctx.e_internalized(ho_repr))
|
|
ctx.internalize(ho_repr, false);
|
|
if (!ctx.e_internalized(rewritten))
|
|
ctx.internalize(rewritten, false);
|
|
|
|
enode* ho_en = ctx.get_enode(ho_repr);
|
|
enode* res_en = ctx.get_enode(rewritten);
|
|
|
|
if (ho_en->get_root() == res_en->get_root())
|
|
continue;
|
|
|
|
// Assert tautological axiom: ho_repr = rewritten
|
|
// Congruence closure merges map(f,s) with map(f,repr)
|
|
// since s = repr in the E-graph.
|
|
expr_ref eq_expr(m.mk_eq(ho_repr, rewritten), m);
|
|
if (!ctx.b_internalized(eq_expr))
|
|
ctx.internalize(eq_expr, true);
|
|
literal eq_lit = ctx.get_literal(eq_expr);
|
|
if (ctx.get_assignment(eq_lit) != l_true) {
|
|
ctx.mk_th_axiom(get_id(), 1, &eq_lit);
|
|
TRACE(seq, tout << "nseq ho unfold: "
|
|
<< mk_bounded_pp(ho_repr, m, 3) << " = "
|
|
<< mk_bounded_pp(rewritten, m, 3) << "\n";);
|
|
++m_num_ho_unfolds;
|
|
progress = true;
|
|
}
|
|
}
|
|
|
|
// For map/mapi: propagate length preservation
|
|
for (app* term : m_ho_terms) {
|
|
expr* f = nullptr, *s = nullptr, *idx = nullptr;
|
|
bool is_map = m_seq.str.is_map(term, f, s);
|
|
bool is_mapi = !is_map && m_seq.str.is_mapi(term, f, idx, s);
|
|
if (!is_map && !is_mapi)
|
|
continue;
|
|
if (!m_seq.is_seq(term))
|
|
continue;
|
|
|
|
// len(map(f, s)) = len(s)
|
|
expr_ref len_map(m_seq.str.mk_length(term), m);
|
|
expr_ref len_s(m_seq.str.mk_length(s), m);
|
|
expr_ref len_eq(m.mk_eq(len_map, len_s), m);
|
|
if (!ctx.b_internalized(len_eq))
|
|
ctx.internalize(len_eq, true);
|
|
literal len_lit = ctx.get_literal(len_eq);
|
|
if (ctx.get_assignment(len_lit) != l_true) {
|
|
ctx.mk_th_axiom(get_id(), 1, &len_lit);
|
|
++m_num_length_axioms;
|
|
progress = true;
|
|
}
|
|
}
|
|
|
|
return progress;
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Helpers
|
|
// -----------------------------------------------------------------------
|
|
|
|
euf::snode* theory_nseq::get_snode(expr* e) {
|
|
return m_sgraph.mk(e);
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Arithmetic value queries
|
|
// -----------------------------------------------------------------------
|
|
|
|
bool theory_nseq::get_num_value(expr* e, rational& val) const {
|
|
return m_arith_value.get_value_equiv(e, val) && val.is_int();
|
|
}
|
|
|
|
bool theory_nseq::lower_bound(expr* e, rational& lo) const {
|
|
bool is_strict = true;
|
|
return m_arith_value.get_lo(e, lo, is_strict) && !is_strict && lo.is_int();
|
|
}
|
|
|
|
bool theory_nseq::upper_bound(expr* e, rational& hi) const {
|
|
bool is_strict = true;
|
|
return m_arith_value.get_up(e, hi, is_strict) && !is_strict && hi.is_int();
|
|
}
|
|
|
|
bool theory_nseq::get_length(expr* e, rational& val) {
|
|
rational val1;
|
|
expr* e1 = nullptr;
|
|
expr* e2 = nullptr;
|
|
ptr_vector<expr> todo;
|
|
todo.push_back(e);
|
|
val.reset();
|
|
zstring s;
|
|
while (!todo.empty()) {
|
|
expr* c = todo.back();
|
|
todo.pop_back();
|
|
if (m_seq.str.is_concat(c, e1, e2)) {
|
|
todo.push_back(e1);
|
|
todo.push_back(e2);
|
|
}
|
|
else if (m_seq.str.is_unit(c))
|
|
val += rational(1);
|
|
else if (m_seq.str.is_empty(c))
|
|
continue;
|
|
else if (m_seq.str.is_string(c, s))
|
|
val += rational(s.length());
|
|
else {
|
|
expr_ref len(m_seq.str.mk_length(c), m);
|
|
if (m_arith_value.get_value(len, val1) && !val1.is_neg())
|
|
val += val1;
|
|
else
|
|
return false;
|
|
}
|
|
}
|
|
return val.is_int();
|
|
}
|
|
|
|
void theory_nseq::add_length_axiom(literal lit) {
|
|
ctx.mark_as_relevant(lit);
|
|
ctx.mk_th_axiom(get_id(), 1, &lit);
|
|
++m_num_length_axioms;
|
|
}
|
|
|
|
bool theory_nseq::propagate_length_lemma(literal lit, seq::length_constraint const& lc) {
|
|
// unconditional constraints: assert as theory axiom
|
|
if (lc.m_kind == seq::length_kind::nonneg) {
|
|
add_length_axiom(lit);
|
|
return true;
|
|
}
|
|
|
|
// conditional constraints: propagate with justification from dep_tracker
|
|
enode_pair_vector eqs;
|
|
literal_vector lits;
|
|
seq::deps_to_lits(lc.m_dep, eqs, lits);
|
|
|
|
ctx.mark_as_relevant(lit);
|
|
justification* js = ctx.mk_justification(
|
|
ext_theory_propagation_justification(
|
|
get_id(), ctx,
|
|
lits.size(), lits.data(),
|
|
eqs.size(), eqs.data(),
|
|
lit));
|
|
ctx.assign(lit, js);
|
|
|
|
TRACE(seq, tout << "nseq length propagation: " << mk_pp(lc.m_expr, m)
|
|
<< " (" << eqs.size() << " eqs, " << lits.size() << " lits)\n";);
|
|
++m_num_length_axioms;
|
|
return true;
|
|
}
|
|
|
|
bool theory_nseq::assert_nonneg_for_all_vars() {
|
|
arith_util arith(m);
|
|
bool new_axiom = false;
|
|
unsigned nv = get_num_vars();
|
|
for (unsigned v = 0; v < nv; ++v) {
|
|
expr* e = get_enode(v)->get_expr();
|
|
if (!m_seq.is_seq(e))
|
|
continue;
|
|
expr_ref len_var(m_seq.str.mk_length(e), m);
|
|
expr_ref ge_zero(arith.mk_ge(len_var, arith.mk_int(0)), m);
|
|
if (!ctx.b_internalized(ge_zero))
|
|
ctx.internalize(ge_zero, true);
|
|
literal lit = ctx.get_literal(ge_zero);
|
|
if (ctx.get_assignment(lit) != l_true) {
|
|
add_length_axiom(lit);
|
|
new_axiom = true;
|
|
}
|
|
}
|
|
return new_axiom;
|
|
}
|
|
|
|
bool theory_nseq::assert_length_constraints() {
|
|
vector<seq::length_constraint> constraints;
|
|
m_nielsen.generate_length_constraints(constraints);
|
|
|
|
bool new_axiom = false;
|
|
for (auto const& lc : constraints) {
|
|
expr* e = lc.m_expr;
|
|
if (!ctx.b_internalized(e))
|
|
ctx.internalize(e, true);
|
|
literal lit = ctx.get_literal(e);
|
|
if (ctx.get_assignment(lit) != l_true) {
|
|
TRACE(seq, tout << "nseq length lemma: " << mk_pp(e, m) << "\n";);
|
|
propagate_length_lemma(lit, lc);
|
|
new_axiom = true;
|
|
}
|
|
}
|
|
return new_axiom;
|
|
}
|
|
|
|
// -----------------------------------------------------------------------
|
|
// Regex membership pre-check
|
|
// For each variable with regex membership constraints, check intersection
|
|
// emptiness before DFS. Mirrors ZIPT's per-variable regex evaluation.
|
|
//
|
|
// Returns:
|
|
// l_true — conflict asserted (empty intersection for some variable)
|
|
// l_false — all variables satisfiable and no word eqs/diseqs → SAT
|
|
// l_undef — inconclusive, proceed to DFS
|
|
// -----------------------------------------------------------------------
|
|
|
|
lbool theory_nseq::check_regex_memberships_precheck() {
|
|
// Collect mem items from the propagation queue into a local pointer array
|
|
// so that indices into the array remain stable during this function.
|
|
ptr_vector<tracked_str_mem const> mems;
|
|
for (auto const& item : m_prop_queue)
|
|
if (std::holds_alternative<mem_item>(item))
|
|
mems.push_back(&std::get<mem_item>(item));
|
|
|
|
if (mems.empty())
|
|
return l_undef;
|
|
|
|
// Group membership indices by variable snode id.
|
|
// Only consider memberships whose string snode is a plain variable (s_var).
|
|
u_map<unsigned_vector> var_to_mems;
|
|
bool all_primitive = true;
|
|
|
|
for (unsigned i = 0; i < mems.size(); ++i) {
|
|
auto const& mem = *mems[i];
|
|
SASSERT(mem.m_str && mem.m_regex);
|
|
if (mem.is_primitive()) {
|
|
auto& vec = var_to_mems.insert_if_not_there(mem.m_str->id(), unsigned_vector());
|
|
vec.push_back(i);
|
|
}
|
|
else
|
|
all_primitive = false;
|
|
}
|
|
|
|
if (var_to_mems.empty())
|
|
return l_undef;
|
|
|
|
// Check if there are any eq items in the queue (needed for SAT condition below).
|
|
bool has_eqs = false;
|
|
for (auto const& item : m_prop_queue)
|
|
if (std::holds_alternative<eq_item>(item)) { has_eqs = true; break; }
|
|
|
|
bool any_undef = false;
|
|
|
|
// Check intersection emptiness for each variable.
|
|
for (auto& kv : var_to_mems) {
|
|
unsigned var_id = kv.m_key;
|
|
unsigned_vector const& mem_indices = kv.m_value;
|
|
ptr_vector<euf::snode> regexes;
|
|
for (unsigned i : mem_indices) {
|
|
euf::snode* re = mems[i]->m_regex;
|
|
if (re)
|
|
regexes.push_back(re);
|
|
}
|
|
if (regexes.empty())
|
|
continue;
|
|
|
|
// Use a bounded BFS (50 states) for the pre-check to keep it fast.
|
|
// If the BFS times out (l_undef), we fall through to DFS.
|
|
lbool result = m_regex.check_intersection_emptiness(regexes, 50);
|
|
|
|
if (result == l_true) {
|
|
// Intersection is empty → the memberships on this variable are
|
|
// jointly unsatisfiable. Assert a conflict from all their literals.
|
|
enode_pair_vector eqs;
|
|
literal_vector lits;
|
|
for (unsigned i : mem_indices) {
|
|
SASSERT(ctx.get_assignment(mems[i]->lit) == l_true); // we already stored the polarity of the literal
|
|
lits.push_back(mems[i]->lit);
|
|
}
|
|
TRACE(seq, tout << "nseq regex precheck: empty intersection for var "
|
|
<< var_id << ", conflict with " << lits.size() << " lits\n";);
|
|
set_conflict(eqs, lits);
|
|
return l_true; // conflict asserted
|
|
}
|
|
if (result == l_undef)
|
|
any_undef = true;
|
|
// l_false = non-empty intersection, this variable's constraints are satisfiable
|
|
}
|
|
|
|
if (any_undef)
|
|
return l_undef; // cannot fully determine; let DFS decide
|
|
|
|
// All variables' regex intersections are non-empty.
|
|
// If there are no word equations, variables are independent and
|
|
// each can be assigned a witness string → SAT.
|
|
if (all_primitive && !has_eqs && !has_unhandled_preds()) {
|
|
TRACE(seq, tout << "nseq regex precheck: all intersections non-empty, "
|
|
<< "no word eqs → SAT\n";);
|
|
return l_false; // signals SAT (non-empty / satisfiable)
|
|
}
|
|
|
|
return l_undef; // mixed constraints; let DFS decide
|
|
}
|
|
|
|
bool theory_nseq::check_length_coherence() {
|
|
if (m_relevant_lengths.empty())
|
|
return true;
|
|
|
|
SASSERT(m_nielsen.sat_node());
|
|
|
|
auto const& mems = m_nielsen.sat_node()->str_mems();
|
|
if (mems.empty())
|
|
return true;
|
|
|
|
u_map<unsigned_vector> var_to_mems;
|
|
for (unsigned i = 0; i < mems.size(); ++i) {
|
|
auto const& mem = mems[i];
|
|
if (mem.is_primitive() && mem.m_str) {
|
|
auto& vec = var_to_mems.insert_if_not_there(mem.m_str->id(), unsigned_vector());
|
|
vec.push_back(i);
|
|
}
|
|
}
|
|
|
|
if (var_to_mems.empty())
|
|
return true;
|
|
|
|
for (expr* len_expr : m_relevant_lengths) {
|
|
expr* s = nullptr;
|
|
VERIFY(m_seq.str.is_length(len_expr, s));
|
|
|
|
euf::snode* s_node = m_sgraph.find(s);
|
|
SASSERT(s_node);
|
|
|
|
unsigned var_id = s_node->id();
|
|
if (!var_to_mems.contains(var_id))
|
|
continue;
|
|
|
|
rational val_l;
|
|
VERIFY(m_arith_value.get_value(len_expr, val_l));
|
|
|
|
SASSERT(val_l.is_unsigned());
|
|
|
|
// unless we intervene, the integer solver will take this length
|
|
// so check if we really want this value
|
|
const unsigned l = val_l.get_unsigned();
|
|
|
|
unsigned_vector const& mem_indices = var_to_mems[var_id];
|
|
ptr_vector<euf::snode> regexes;
|
|
for (const unsigned i : mem_indices) {
|
|
euf::snode* re = mems[i].m_regex;
|
|
if (re)
|
|
regexes.push_back(re);
|
|
}
|
|
|
|
SASSERT(!regexes.empty());
|
|
sort* ele_sort;
|
|
VERIFY(m_seq.is_seq(m_sgraph.get_str_sort(), ele_sort));
|
|
unsigned g = 1;
|
|
if (m_gradient_cache.contains(s))
|
|
g = m_gradient_cache[s];
|
|
else
|
|
m_gradient_cache.insert(s, 1);
|
|
|
|
expr_ref allchar(m_seq.re.mk_full_char(m_seq.re.mk_re(m_sgraph.get_str_sort())), m);
|
|
expr_ref l_expr(m_autil.mk_int(l), m);
|
|
expr_ref loop_l(m_seq.re.mk_loop_proper(allchar.get(), l, l), m);
|
|
|
|
euf::snode* sigmal_node = get_snode(loop_l.get());
|
|
regexes.push_back(sigmal_node);
|
|
SASSERT(regexes.size() > 1);
|
|
|
|
lbool result = m_regex.check_intersection_emptiness(regexes);
|
|
|
|
if (result == l_true) {
|
|
// TODO: Incorporate that we might know the maximum length generated by a regex [in those cases, the gradients will never work]
|
|
// It is empty. Try gradient.
|
|
regexes.pop_back(); // Remove loop_l
|
|
|
|
expr_ref loop_g(m_seq.re.mk_loop_proper(allchar.get(), g, g), m);
|
|
expr_ref star_g(m_seq.re.mk_star(loop_g.get()), m);
|
|
expr_ref sigmal_g_expr(m_seq.re.mk_concat(loop_l.get(), star_g.get()), m);
|
|
|
|
euf::snode* sigmal_g_node = get_snode(sigmal_g_expr.get());
|
|
regexes.push_back(sigmal_g_node);
|
|
|
|
lbool result_g = m_regex.check_intersection_emptiness(regexes);
|
|
|
|
expr_ref prop_expr(m);
|
|
if (result_g == l_true) {
|
|
// Block the whole gradient
|
|
expr_ref g_expr(m_autil.mk_int(g), m);
|
|
expr_ref len_lt_l(m_autil.mk_lt(len_expr, l_expr), m);
|
|
expr_ref len_minus_l(m_autil.mk_sub(len_expr, l_expr), m);
|
|
expr_ref not_divides(m.mk_not(m_autil.mk_divides(g_expr, len_minus_l)), m);
|
|
prop_expr = m.mk_or(len_lt_l, not_divides);
|
|
m_th_rewriter(prop_expr); // the divisibility predicate needs to be rewritten as it won't happen automatically
|
|
|
|
m_gradient_cache[s] = 1; // Reset gradient cache
|
|
}
|
|
else {
|
|
prop_expr = m.mk_not(m.mk_eq(len_expr, l_expr));
|
|
m_gradient_cache[s] = g + 1; // Increment gradient cache
|
|
}
|
|
|
|
if (!ctx.b_internalized(prop_expr))
|
|
ctx.internalize(prop_expr, true);
|
|
literal lit_prop = ctx.get_literal(prop_expr);
|
|
|
|
enode_pair_vector eqs;
|
|
literal_vector dep_lits;
|
|
for (unsigned idx : mem_indices) {
|
|
if (mems[idx].m_dep)
|
|
seq::deps_to_lits(mems[idx].m_dep, eqs, dep_lits);
|
|
}
|
|
|
|
ctx.mark_as_relevant(lit_prop);
|
|
justification* js = ctx.mk_justification(
|
|
ext_theory_propagation_justification(
|
|
get_id(), ctx,
|
|
dep_lits.size(), dep_lits.data(),
|
|
eqs.size(), eqs.data(),
|
|
lit_prop));
|
|
|
|
ctx.assign(lit_prop, js);
|
|
|
|
TRACE(seq, tout << "nseq length coherence check: length " << l << " with gradient " << g << " is incompatible for " << mk_pp(s, m) << ", propagated " << mk_pp(prop_expr, m) << "\n";);
|
|
IF_VERBOSE(1, verbose_stream() << "nseq length coherence check: length " << l << " with gradient " << g << " is incompatible for " << mk_pp(s, m) << ", propagated " << mk_pp(prop_expr, m) << "\n";);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
}
|