add the pdd evaluator and a unit test for it

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

src/math/dd/pdd_eval.h

@@ -0,0 +1,42 @@
+/*++
+Copyright (c) 2019 Microsoft Corporation
+
+Module Name:
+
+    dd_pdd.cpp
+
+Abstract:
+
+    Poly DD package 
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2019-12-23
+    Lev Nachmanson (levnach) 2019-12-23
+
+Revision History:
+
+--*/
+#include "math/dd/dd_pdd.h"
+
+namespace dd {
+// calculates the value of a pdd expression based on the given values of the variables
+class pdd_eval {
+    pdd_manager& m;
+    
+    std::function<rational (unsigned)> m_var2val;
+    
+public:
+    
+    pdd_eval(pdd_manager& m): m(m) {}
+    
+    void operator=(std::function<rational (unsigned)>& i2v) { m_var2val = i2v; }
+
+    rational operator()(pdd const& p) {
+        if (p.is_val()) {
+            return p.val();
+        }
+        return (*this)(p.hi()) * m_var2val(p.var()) + (*this)(p.lo());
+    }
+};
+}

src/test/pdd.cpp

@@ -1,7 +1,8 @@
 #include "math/dd/dd_pdd.h"
+#include "math/dd/pdd_eval.h"
 
 namespace dd {
-    static void test1() {
+static void test1() {
     pdd_manager m(3);
     pdd v0 = m.mk_var(0);
     pdd v1 = m.mk_var(1);
@@ -46,9 +47,9 @@ namespace dd {
     c2 = (v0*v1*(v2 + v0)) + v2;
     c3 = c2.reduce(c1);
     std::cout << c1 << " " << c2 << " reduce: " << c3 << "\n";
-    }
+}
 
-    static void test2() {
+static void test2() {
     std::cout << "\ntest2\n";
     // a(b^2)cd + abc + bcd + bc + cd + 3 reduce by  bc
     pdd_manager m(4);
@@ -65,9 +66,9 @@ namespace dd {
     pdd r_fe = m.reduce(f, e);
     std::cout << "result of reduce " << f << " by " << e << " is " << r_fe << "\n" ;
     VERIFY(r_fe == f);
-    }
+}
 
-    static void test3() {
+static void test3() {
     std::cout << "\ntest3\n";
     pdd_manager m(4);
     pdd a = m.mk_var(0);
@@ -81,9 +82,9 @@ namespace dd {
     }
     e = e * b;
     std::cout << e << "\n";
-    }
+}
 
-    static void test_reset() {
+static void test_reset() {
     std::cout << "\ntest reset\n";
     pdd_manager m(4);
         pdd a = m.mk_var(0);