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https://github.com/Z3Prover/z3
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Rewrite term_graph::project and term_graph::solve
This commit is contained in:
parent
771d3b1349
commit
144d8df5d5
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@ -614,205 +614,244 @@ namespace qe {
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m_cg_table.reset();
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}
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expr* term_graph::mk_pure(term& t) {
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expr* e = nullptr;
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if (m_term2app.find(t.get_id(), e)) return e;
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e = t.get_expr();
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if (!is_app(e)) return nullptr;
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app* a = ::to_app(e);
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expr_ref_vector kids(m);
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for (term* ch : term::children(t)) {
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if (!m_term2app.find(ch->get_root().get_id(), e)) return nullptr;
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kids.push_back(e);
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}
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expr* result = m.mk_app(a->get_decl(), kids.size(), kids.c_ptr());
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m_pinned.push_back(result);
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m_term2app.insert(t.get_id(), result);
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return result;
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}
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namespace {
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class projector {
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term_graph &m_tg;
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ast_manager &m;
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u_map<expr*> m_term2app;
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u_map<expr*> m_root2rep;
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u_map<bool> m_decls;
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bool m_exclude;
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void term_graph::project_core(func_decl_ref_vector const& decls,
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bool exclude,
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expr_ref_vector &result) {
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u_map<bool> _decls;
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for (func_decl* f : decls) _decls.insert(f->get_id(), true);
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// - propagate representatives up over parents.
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// use work-list + marking to propagate.
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// - produce equalities over represented classes.
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// - produce other literals over represented classes
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// (walk disequalities in m_lits and represent lhs/rhs over decls or excluding decls)
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expr_ref_vector m_pinned; // tracks expr in the maps
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obj_hashtable<expr> eqs;
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expr_ref eq(m);
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ptr_vector<term> worklist;
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for (term * t : m_terms) {
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worklist.push_back(t);
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t->set_mark(true);
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}
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while (!worklist.empty()) {
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term* t = worklist.back();
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worklist.pop_back();
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t->set_mark(false);
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if (m_term2app.contains(t->get_id()))
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continue;
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if (!t->is_theory() && exclude == _decls.contains(t->get_decl_id()))
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continue;
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term& root = t->get_root();
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bool has_rep = m_term2app.contains(root.get_id());
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expr* pure = mk_pure(*t);
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if (!pure) continue;
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// ensure that the root has a representative
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// either by looking up cached version,
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// computing it for the first time, or
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// inheriting pure.
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expr* rep = nullptr;
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if (root.is_theory() || exclude != _decls.contains(root.get_decl_id())) {
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rep = mk_pure(root);
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}
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else if (has_rep) {
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rep = m_term2app.find(root.get_id());
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}
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else {
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rep = pure;
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m_term2app.insert(root.get_id(), pure);
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}
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bool update_rep = false;
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// AG: can rep be null at this point?
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// AG: why mk_pure(root) is guaranteed to return non-null?
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// Add equations between pure and rep,
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// optionally swap the roles of rep and pure if
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// pure makes a better representative.
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if (rep != pure) {
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if (m.is_unique_value(rep) && !m.is_unique_value(pure)) {
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m_term2app.insert(root.get_id(), pure);
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update_rep = true;
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expr* mk_pure(term& t) {
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expr* e = nullptr;
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if (m_term2app.find(t.get_id(), e)) return e;
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e = t.get_expr();
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if (!is_app(e)) return nullptr;
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app* a = ::to_app(e);
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expr_ref_buffer kids(m);
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for (term* ch : term::children(t)) {
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if (!m_root2rep.find(ch->get_root().get_id(), e)) return nullptr;
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kids.push_back(e);
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}
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eq = m.mk_eq(rep, pure);
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if (!eqs.contains(eq)) {
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eqs.insert(eq);
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result.push_back(eq);
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expr* pure = m.mk_app(a->get_decl(), kids.size(), kids.c_ptr());
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m_pinned.push_back(pure);
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m_term2app.insert(t.get_id(), pure);
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return pure;
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}
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bool is_better_rep(expr *t1, expr *t2) {
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if (!t2) return t1;
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return m.is_unique_value(t1) && !m.is_unique_value(t2);
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}
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void purify() {
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// - propagate representatives up over parents.
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// use work-list + marking to propagate.
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// - produce equalities over represented classes.
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// - produce other literals over represented classes
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// (walk disequalities in m_lits and represent
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// lhs/rhs over decls or excluding decls)
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ptr_vector<term> worklist;
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for (term * t : m_tg.m_terms) {
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worklist.push_back(t);
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t->set_mark(true);
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}
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while (!worklist.empty()) {
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term* t = worklist.back();
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worklist.pop_back();
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t->set_mark(false);
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if (m_term2app.contains(t->get_id()))
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continue;
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if (!t->is_theory() && is_projected(*t))
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continue;
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expr* pure = mk_pure(*t);
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if (!pure) continue;
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m_term2app.insert(t->get_id(), pure);
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expr* rep = nullptr;
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// ensure that the root has a representative
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m_root2rep.find(t->get_root().get_id(), rep);
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// update rep with pure if it is better
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if (pure != rep && is_better_rep(pure, rep)) {
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m_root2rep.insert(t->get_root().get_id(), pure);
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for (term * p : term::parents(t->get_root())) {
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m_term2app.remove(p->get_id());
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if (!p->is_marked()) {
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p->set_mark(true);
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worklist.push_back(p);
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}
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}
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}
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}
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// Here we could also walk equivalence classes that
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// contain interpreted values by sort and extract
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// disequalities bewteen non-unique value
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// representatives. these disequalities are implied
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// and can be mined using other means, such as theory
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// aware core minimization
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m_tg.reset_marks();
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}
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void solve() {
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ptr_vector<term> worklist;
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for (term * t : m_tg.m_terms) {
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// skip pure terms
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if (m_term2app.contains(t->get_id())) continue;
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worklist.push_back(t);
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t->set_mark(true);
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}
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while (!worklist.empty()) {
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term* t = worklist.back();
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worklist.pop_back();
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t->set_mark(false);
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if (m_term2app.contains(t->get_id()))
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continue;
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expr* pure = mk_pure(*t);
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if (!pure) continue;
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m_term2app.insert(t->get_id(), pure);
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expr* rep = nullptr;
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// ensure that the root has a representative
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m_root2rep.find(t->get_root().get_id(), rep);
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if (!rep) {
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m_root2rep.insert(t->get_root().get_id(), pure);
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for (term * p : term::parents(t->get_root())) {
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SASSERT(!m_term2app.contains(p->get_id()));
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if (!p->is_marked()) {
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p->set_mark(true);
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worklist.push_back(p);
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}
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}
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}
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}
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m_tg.reset_marks();
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}
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bool find_app(term &t, expr *&res) {
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return m_root2rep.find(t.get_root().get_id(), res);
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}
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bool find_app(expr *lit, expr *&res) {
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return m_root2rep.find(m_tg.get_term(lit)->get_root().get_id(), res);
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}
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void mk_lits(expr_ref_vector &res) {
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expr *e = nullptr;
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for (auto *lit : m_tg.m_lits) {
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if (!m.is_eq(lit) && find_app(lit, e))
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res.push_back(e);
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}
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}
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// update the worklist if this is the first
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// representative or pure was swapped into rep.
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if (!has_rep || update_rep) {
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for (term * p : term::parents(root)) {
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if (update_rep) m_term2app.remove(p->get_id());
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if (!p->is_marked()) {
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p->set_mark(true);
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worklist.push_back(p);
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void mk_pure_equalities(const term &t, expr_ref_vector &res) {
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expr *rep = nullptr;
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if (!m_root2rep.find(t.get_id(), rep)) return;
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for (term *it = &t.get_next(); it != &t; it = &it->get_next()) {
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expr* member = mk_pure(*it);
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if (member)
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res.push_back (m.mk_eq (rep, member));
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}
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}
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bool is_projected(const term &t) {
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return m_exclude == m_decls.contains(t.get_decl_id());
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}
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void mk_unpure_equalities(const term &t, expr_ref_vector &res) {
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expr *rep = nullptr;
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if (!m_root2rep.find(t.get_id(), rep)) return;
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for (term *it = &t.get_next(); it != &t; it = &it->get_next()) {
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expr* member = mk_pure(*it);
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SASSERT(member);
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if (!is_projected(*it) || !is_solved_eq(rep, member)) {
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res.push_back(m.mk_eq(rep, member));
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}
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}
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}
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}
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// Here we could also walk equivalence classes that contain interpreted values by sort and
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// extract disequalities bewteen non-unique value representatives.
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// these disequalities are implied and can be mined using other means, such as
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// theory aware core minimization
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reset_marks();
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void mk_equalities(bool pure, expr_ref_vector &res) {
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for (term *t : m_tg.m_terms) {
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if (!t->is_root()) continue;
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if (!m_root2rep.contains(t->get_id())) continue;
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if (pure)
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mk_pure_equalities(*t, res);
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else
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mk_unpure_equalities(*t, res);
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}
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}
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void mk_pure_equalities(expr_ref_vector &res) {
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return mk_equalities(true, res);
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}
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void mk_unpure_equalities(expr_ref_vector &res) {
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return mk_equalities(false, res);
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}
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bool is_solved_eq(expr *_lhs, expr* _rhs) {
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if (!is_app(_lhs) || !is_app(_rhs)) return false;
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app *lhs, *rhs;
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lhs = ::to_app(_lhs);
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rhs = ::to_app(_rhs);
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if (rhs->get_num_args() > 0) return false;
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if (rhs->get_family_id() != null_family_id) return false;
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return !occurs(rhs, lhs);
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}
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public:
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projector(term_graph &tg) : m_tg(tg), m(m_tg.m), m_pinned(m) {}
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void reset() {
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m_tg.reset_marks();
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m_term2app.reset();
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m_root2rep.reset();
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m_decls.reset();
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m_pinned.reset();
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}
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expr_ref_vector project(func_decl_ref_vector const &decls, bool exclude) {
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expr_ref_vector res(m);
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m_exclude = exclude;
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for (auto *d : decls) {m_decls.insert(d->get_id(), true);}
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purify();
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mk_lits(res);
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mk_pure_equalities(res);
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reset();
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return res;
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}
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expr_ref_vector solve(func_decl_ref_vector const &decls, bool exclude) {
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expr_ref_vector res(m);
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m_exclude = exclude;
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purify();
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solve();
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mk_lits(res);
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mk_unpure_equalities(res);
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reset();
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return res;
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}
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};
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}
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expr_ref_vector term_graph::project(func_decl_ref_vector const& decls, bool exclude) {
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expr_ref_vector result(m);
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m_term2app.reset();
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m_pinned.reset();
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project_core(decls, exclude, result);
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// walk other predicates than equalities
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for (expr* e : m_lits) {
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if (!m.is_eq(e) && m_term2app.find(get_term(e)->get_root().get_id(), e)) {
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result.push_back(e);
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}
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}
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m_term2app.reset();
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m_pinned.reset();
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return result;
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projector p(*this);
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return p.project(decls, exclude);
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}
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bool term_graph::is_solved_eq(expr *_lhs, expr* _rhs) {
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if (!is_app(_lhs) || !is_app(_rhs)) return false;
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app *lhs, *rhs;
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lhs = ::to_app(_lhs);
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rhs = ::to_app(_rhs);
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if (rhs->get_num_args() > 0) return false;
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if (rhs->get_family_id() != null_family_id) return false;
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return !occurs(rhs, lhs);
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}
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void term_graph::solve_core(func_decl_ref_vector const &decls, bool exclude,
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expr_ref_vector &result) {
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u_map<bool> _decls;
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for (func_decl* f : decls) _decls.insert(f->get_id(), true);
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obj_hashtable<expr> eqs;
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expr_ref eq(m);
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ptr_vector<term> worklist;
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for (term * t : m_terms) {
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worklist.push_back(t);
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t->set_mark(true);
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}
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while (!worklist.empty()) {
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term* t = worklist.back();
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worklist.pop_back();
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t->set_mark(false);
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if (m_term2app.contains(t->get_id()))
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continue;
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term &root = t->get_root();
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bool has_rep = m_term2app.contains(root.get_id());
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expr *pure = mk_pure(*t);
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if (!pure) continue;
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if (has_rep) {
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// add equality if needed
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expr* rep = m_term2app.find(root.get_id());
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if (exclude != _decls.contains(t->get_decl_id()) || !is_solved_eq(rep, pure)) {
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eq = m.mk_eq(rep, pure);
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if (!eqs.contains(eq)) {
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eqs.insert(eq);
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result.push_back(eq);
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}
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}
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}
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else {
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// let pure be the representative
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m_term2app.insert(root.get_id(), pure);
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// schedule parents of root to be processed again
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for (term * p : term::parents(root)) {
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if (!p->is_marked()) {
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p->set_mark(true);
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worklist.push_back(p);
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}
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}
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SASSERT(false);
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// TBD: deal with root
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}
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}
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reset_marks();
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}
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expr_ref_vector term_graph::solve(func_decl_ref_vector const &decls, bool exclude) {
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expr_ref_vector result(m);
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m_term2app.reset();
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m_pinned.reset();
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project_core(decls, exclude, result);
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solve_core(decls, exclude, result);
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// walk other predicates than equalities
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for (expr* e : m_lits) {
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if (!m.is_eq(e) && m_term2app.find(get_term(e)->get_root().get_id(), e)) {
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result.push_back(e);
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}
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}
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m_term2app.reset();
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m_pinned.reset();
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return result;
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projector p(*this);
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return p.solve(decls, exclude);
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}
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}
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@ -26,6 +26,8 @@ namespace qe {
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class term;
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namespace {class projector;}
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class term_graph_plugin {
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family_id m_id;
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public:
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@ -40,6 +42,7 @@ namespace qe {
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class term_graph {
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friend class projector;
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struct term_hash { unsigned operator()(term const* t) const; };
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struct term_eq { bool operator()(term const* a, term const* b) const; };
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ast_manager & m;
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