add priority queue to instantiation

src/ast/CMakeLists.txt

@@ -15,6 +15,7 @@ z3_add_component(ast
     ast_util.cpp
     bv_decl_plugin.cpp
     char_decl_plugin.cpp
+    cost_evaluator.cpp
     datatype_decl_plugin.cpp
     decl_collector.cpp
     display_dimacs.cpp

src/ast/cost_evaluator.cpp

@@ -0,0 +1,100 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    cost_evaluator.cpp
+
+Abstract:
+
+    <abstract>
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-06-14.
+
+Revision History:
+
+--*/
+#include "ast/cost_evaluator.h"
+#include "util/warning.h"
+
+cost_evaluator::cost_evaluator(ast_manager & m):
+    m(m), 
+    m_util(m) {
+}
+
+float cost_evaluator::eval(expr * f) const {
+#define E(IDX) eval(to_app(f)->get_arg(IDX))
+    if (is_app(f)) {
+        family_id fid = to_app(f)->get_family_id();
+        if (fid == m.get_basic_family_id()) {
+            switch (to_app(f)->get_decl_kind()) {
+            case OP_TRUE:     return 1.0f;
+            case OP_FALSE:    return 0.0f;
+            case OP_NOT:      return E(0) == 0.0f ? 1.0f : 0.0f;
+            case OP_AND:  
+                for (expr* arg : *to_app(f))
+                    if (eval(arg) == 0.0f)
+                        return 0.0f;
+                return 1.0f;
+            case OP_OR:
+                for (expr* arg : *to_app(f))
+                    if (eval(arg) != 0.0f)
+                        return 1.0f;
+                return 0.0f;
+            case OP_ITE:      return E(0) != 0.0f ? E(1) : E(2);
+            case OP_EQ:       return E(0) == E(1) ? 1.0f : 0.0f;
+            case OP_XOR:      return E(0) != E(1) ? 1.0f : 0.0f;
+            case OP_IMPLIES:  
+                if (E(0) == 0.0f)
+                    return 1.0f;
+                return E(1) != 0.0f ? 1.0f : 0.0f;
+            default:
+                ;
+            }
+        }
+        else if (fid == m_util.get_family_id()) {
+            switch (to_app(f)->get_decl_kind()) {
+            case OP_NUM: {
+                rational r = to_app(f)->get_decl()->get_parameter(0).get_rational();
+                return static_cast<float>(numerator(r).get_int64())/static_cast<float>(denominator(r).get_int64());
+            } 
+            case OP_LE:       return E(0) <= E(1) ? 1.0f : 0.0f;
+            case OP_GE:       return E(0) >= E(1) ? 1.0f : 0.0f;
+            case OP_LT:       return E(0) <  E(1) ? 1.0f : 0.0f;
+            case OP_GT:       return E(0) >  E(1) ? 1.0f : 0.0f;
+            case OP_ADD:      return E(0) + E(1);
+            case OP_SUB:      return E(0) - E(1);
+            case OP_UMINUS:   return - E(0);
+            case OP_MUL:      return E(0) * E(1);
+            case OP_DIV: {     
+                float q = E(1);
+                if (q == 0.0f) {
+                    warning_msg("cost function division by zero");
+                    return 1.0f;
+                }
+                return E(0) / q;
+            }
+            default:
+                ;
+            }
+        }
+    }
+    else if (is_var(f)) {
+        unsigned idx = to_var(f)->get_idx();
+        if (idx < m_num_args)
+            return m_args[m_num_args - idx - 1];
+    }
+    warning_msg("cost function evaluation error");
+    return 1.0f;
+}
+
+float cost_evaluator::operator()(expr * f, unsigned num_args, float const * args) {
+    m_num_args = num_args;
+    m_args     = args;
+    return eval(f);
+}
+
+
+

src/ast/cost_evaluator.h

@@ -0,0 +1,41 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    cost_evaluator.h
+
+Abstract:
+
+    Simple evaluator for cost function
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-06-14.
+
+Revision History:
+
+--*/
+#pragma once
+
+#include "ast/ast.h"
+#include "ast/arith_decl_plugin.h"
+
+class cost_evaluator {
+    ast_manager &   m;
+    arith_util      m_util;
+    unsigned        m_num_args;
+    float const *   m_args;
+    float eval(expr * f) const;
+public:
+    cost_evaluator(ast_manager & m);
+    /**
+       I'm using the same standard used in quantifier instantiation.
+       (VAR 0) is stored in the last position of the array.
+       ...
+       (VAR (num_args - 1)) is stored in the first position of the array.
+    */
+    float operator()(expr * f, unsigned num_args, float const * args);
+};
+
+

src/ast/euf/euf_egraph.h

@@ -295,8 +295,6 @@ namespace euf {
         enode_vector const& nodes() const { return m_nodes; }
 
         ast_manager& get_manager() { return m; }
-        bool is_relevant(enode* n) const { return true; } // TODO
-        bool resource_limits_exceeded() const { return false; } // TODO
 
         void invariant();
         void copy_from(egraph const& src, std::function<void*(void*)>& copy_justification);