Z3 sources

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

lib/unifier.h

@@ -0,0 +1,70 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    unifier.h
+
+Abstract:
+
+    Quasi-linear unification.
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-01-28.
+
+Revision History:
+
+--*/
+#ifndef _UNIFIER_H_
+#define _UNIFIER_H_
+
+#include"ast.h"
+#include"substitution.h"
+
+/**
+   \brief Functor for unifying expressions.
+   It implements a quasi-linear unification algorithm.
+
+   It has support for two different variable banks: left and right.
+   That is, variable i in left bank is considered different from
+   variable i in the right bank.  This feature allows us to avoid
+   unnecessary variable renaming.
+*/
+class unifier {
+    typedef std::pair<expr_offset, expr_offset> entry;
+    
+    ast_manager &                m_manager;
+    substitution *               m_subst;
+    
+    svector<entry>               m_todo;
+    expr_offset_map<expr_offset> m_find;
+    expr_offset_map<unsigned>    m_size;
+
+    bool                         m_last_call_succeeded;
+
+    expr_offset find(expr_offset n);
+    void save_var(expr_offset const & p, expr_offset const & t);
+    void union1(expr_offset const & n1, expr_offset const & n2);
+    void union2(expr_offset n1, expr_offset n2);
+    void reset(unsigned num_offsets);
+
+    bool unify_core(expr_offset p1, expr_offset p2);
+    
+public:
+    unifier(ast_manager & m):m_manager(m), m_last_call_succeeded(false) {}
+
+    /**
+       \brief Unify the given expressions. Return true if succeeded,
+       and store the result in the given substitution.
+       
+       If use_offsets is true, then the variables in the given expressions are assumed to be 
+       in different banks.
+    */
+    bool operator()(unsigned num_exprs, expr ** es, substitution & s, bool use_offsets = true);
+
+    bool operator()(expr * e1, expr * e2, substitution & s, bool use_offsets = true);
+};
+
+#endif /* _UNIFIER_H_ */
+