implement user scopes for sat solver

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/test/main.cpp

@@ -219,6 +219,7 @@ int main(int argc, char ** argv) {
     TST(sorting_network);
     TST(theory_pb);
     TST(simplex);
+    TST(sat_user_scope);
     //TST_ARGV(hs);
 }
 

src/test/sat_user_scope.cpp

@@ -0,0 +1,102 @@
+#include "sat_solver.h"
+#include "util.h"
+
+typedef sat::literal_vector clause_t;
+typedef vector<clause_t> clauses_t;
+typedef vector<clauses_t> trail_t;
+
+// [ [c1, c2, ..], [ ...] ]
+
+static unsigned s_num_vars = 6;
+static unsigned s_num_clauses_per_frame = 8;
+static unsigned s_num_frames = 7;
+
+static void add_literal(random_gen& r, clause_t& c) {
+    c.push_back(sat::literal(r(s_num_vars) + 1, r(2) == 0));
+}
+
+static clause_t& last_clause(trail_t& t) {
+    return t.back().back();
+}
+
+static void add_clause(sat::solver& s, random_gen& r, trail_t& t) {
+    t.back().push_back(sat::literal_vector());
+    clause_t& cls = last_clause(t);
+    for (unsigned i = 0; i < 3; ++i) {
+        add_literal(r, cls);
+    }
+    s.mk_clause(cls.size(), cls.c_ptr());
+}
+
+static void display_state(std::ostream& out, sat::solver& s, trail_t& t) {
+    s.display(out);
+}
+
+static void pop_user_scope(sat::solver& s, trail_t& t) {
+    std::cout << "pop\n";
+    s.user_pop(1);
+    t.pop_back();
+}
+
+static void push_user_scope(sat::solver& s, trail_t& t) {
+    std::cout << "push\n";
+    s.user_push();
+    t.push_back(clauses_t());
+}
+
+static void init_vars(sat::solver& s) {
+    for (unsigned i = 0; i <= s_num_vars; ++i) {
+        s.mk_var();
+    }
+}
+
+static void check_coherence(sat::solver& s1, trail_t& t) {
+    params_ref p;
+    sat::solver s2(p, 0);
+    init_vars(s2);
+    sat::literal_vector cls;
+    for (unsigned i = 0; i < t.size(); ++i) {
+        clauses_t& clss = t[i];
+        for (unsigned j = 0; j < clss.size(); ++j) {
+            cls.reset();
+            cls.append(clss[j]);
+            s2.mk_clause(cls.size(), cls.c_ptr());
+        }
+    }
+    lbool is_sat1 = s1.check();
+    lbool is_sat2 = s2.check();
+    if (is_sat1 != is_sat2) {
+        s1.display(std::cout);
+        s2.display(std::cout);
+    }
+    std::cout << is_sat1 << "\n";
+    SASSERT(is_sat1 == is_sat2);
+}
+
+void tst_sat_user_scope() {
+    random_gen r(0);
+    trail_t trail;
+    params_ref p;
+    sat::solver s(p, 0);  // incremental solver
+    init_vars(s);
+    while (true) {
+        for (unsigned i = 0; i < s_num_frames; ++i) {
+            // push 3 frames, pop 2
+            for (unsigned k = 0; k < 3; ++k) {
+                push_user_scope(s, trail);
+                for (unsigned j = 0; j < s_num_clauses_per_frame; ++j) {
+                    add_clause(s, r, trail);
+                }
+                check_coherence(s, trail);
+            }
+            for (unsigned k = 0; k < 2; ++k) {
+                pop_user_scope(s, trail);
+                check_coherence(s, trail);
+            }
+        }
+        for (unsigned i = 0; i < s_num_frames; ++i) {
+            pop_user_scope(s, trail);
+            check_coherence(s, trail);
+        }
+    }
+}