Spacer engine for HORN logic

The algorithms implemented in the engine are described in the following papers

Anvesh Komuravelli, Nikolaj Bjørner, Arie Gurfinkel, Kenneth L. McMillan:
Compositional Verification of Procedural Programs using Horn Clauses over Integers and Arrays. FMCAD 2015: 89-96

Nikolaj Bjørner, Arie Gurfinkel:
Property Directed Polyhedral Abstraction. VMCAI 2015: 263-281

Anvesh Komuravelli, Arie Gurfinkel, Sagar Chaki:
SMT-Based Model Checking for Recursive Programs. CAV 2014: 17-34

src/muz/spacer/spacer_mev_array.h

@@ -0,0 +1,52 @@
+/*++
+Copyright (c) 2011 Microsoft Corporation
+
+Module Name:
+
+    spacer_mev_array.h
+
+Abstract:
+
+    Utilities to evaluate arrays in the model.
+
+Author:
+   based on model_evaluator in muz/pdr/pdr_util.h
+
+Revision History:
+
+--*/
+#ifndef _SPACER_MEV_ARRAY_H_
+#define _SPACER_MEV_ARRAY_H_
+
+#include"ast.h"
+#include"rewriter_types.h"
+#include"params.h"
+#include "array_decl_plugin.h"
+
+/**
+ * based on model_evaluator in muz/pdr/pdr_util.h
+ */
+class model_evaluator_array_util {
+    ast_manager&    m;
+    array_util      m_array;
+
+    void eval_exprs(model& mdl, expr_ref_vector& es);
+
+    bool extract_array_func_interp(model& mdl, expr* a, vector<expr_ref_vector>& stores, expr_ref& else_case);
+
+public:
+
+    model_evaluator_array_util (ast_manager& m):
+        m (m),
+        m_array (m)
+    {}
+
+    /**
+     * best effort evaluator of extensional array equality.
+     */
+    void eval_array_eq(model& mdl, app* e, expr* arg1, expr* arg2, expr_ref& res);
+
+    void eval(model& mdl, expr* e, expr_ref& r, bool model_completion = true);
+};
+
+#endif