Semantic matcher

Extends matcher with rewrites based on semantics of arithmetic operations

Like matcher, but uses arithmetic and logic rewrites to try to
get a semantic match.

src/muz/spacer/spacer_sem_matcher.h

@@ -0,0 +1,69 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation and Arie Gurfinkel
+
+Module Name:
+
+    sem_matcher.h
+
+Abstract:
+
+   Semantic matcher
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-02-02.
+    Arie Gurfinkel
+
+Revision History:
+
+--*/
+#ifndef SPACER_SEM_MATCHER_H_
+#define SPACER_SEM_MATCHER_H_
+
+#include "ast/substitution/substitution.h"
+#include "ast/arith_decl_plugin.h"
+#include "util/hashtable.h"
+
+namespace spacer {
+/**
+   \brief Functor for matching expressions.
+*/
+class sem_matcher {
+    typedef std::pair<expr *, expr *> expr_pair;
+    typedef pair_hash<obj_ptr_hash<expr>, obj_ptr_hash<expr> > expr_pair_hash;
+    typedef hashtable<expr_pair, expr_pair_hash, default_eq<expr_pair> > cache;
+
+    ast_manager &m;
+    arith_util m_arith;
+    expr_ref_vector m_pinned;
+    substitution *        m_subst;
+    svector<expr_pair>    m_todo;
+
+    void reset();
+
+    bool match_var(var *v, expr *e);
+public:
+    sem_matcher(ast_manager &man);
+
+    /**
+       \brief Return true if e2 is an instance of e1.
+       In case of success (result is true), it will store the substitution that makes e1 equals to e2 into s.
+       Sets pos to true if the match is positive and to false if it is negative (i.e., e1 equals !e2)
+
+       For example:
+       1) e1 = f(g(x), x), e2 = f(g(h(a)), h(a))
+       The result is true, and s will contain x -> h(a)
+
+       2) e1 = f(a, x)     e2 = f(x, a)
+       The result is false.
+
+       3) e1 = f(x, x)     e2 = f(y, a)
+       The result is false
+
+       4) e1 = f(x, y)     e2 = f(h(z), a)
+       The result is true, and s contains x->h(z) and y->a
+    */
+    bool operator()(expr * e1, expr * e2, substitution & s, bool &pos);
+};
+}
+#endif /* SPACER_SEM_MATCHER_H_ */