moving remaining qsat functionality over

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/ast/rewriter/label_rewriter.cpp

@@ -0,0 +1,53 @@
+/*++
+Copyright (c) 2015 Microsoft Corporation
+
+Module Name:
+
+    label_rewriter.cpp
+
+Abstract:
+
+    Basic rewriting rules for removing labels.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2015-19-10
+
+Notes:
+
+--*/
+
+#include"rewriter.h"
+#include"rewriter_def.h"
+#include"label_rewriter.h"
+
+
+label_rewriter::label_rewriter(ast_manager & m) : 
+    m_label_fid(m.get_label_family_id()),
+    m_rwr(m, false, *this) {}
+
+label_rewriter::~label_rewriter() {}
+
+br_status label_rewriter::reduce_app(
+    func_decl * f, unsigned num, expr * const * args, expr_ref & result, 
+    proof_ref & result_pr) {
+    if (is_decl_of(f, m_label_fid, OP_LABEL)) {
+        SASSERT(num == 1);
+        result = args[0];
+        return BR_DONE;
+    }
+    return BR_FAILED;
+}
+
+void label_rewriter::remove_labels(expr_ref& fml, proof_ref& pr) {
+    ast_manager& m = fml.get_manager();
+    expr_ref tmp(m);
+    m_rwr(fml, tmp);
+    if (pr && fml != tmp) {        
+        pr = m.mk_modus_ponens(pr, m.mk_rewrite(fml, tmp));
+    }
+    fml = tmp;
+}
+
+
+//template class rewriter_tpl<label_rewriter>;

src/ast/rewriter/label_rewriter.h

@@ -0,0 +1,41 @@
+/*++
+Copyright (c) 2015 Microsoft Corporation
+
+Module Name:
+
+    label_rewriter.h
+
+Abstract:
+
+    Basic rewriting rules for labels.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2015-19-10
+
+Notes:
+
+--*/
+#ifndef LABEL_REWRITER_H_
+#define LABEL_REWRITER_H_
+
+#include"ast.h"
+#include"rewriter_types.h"
+
+
+class label_rewriter : public default_rewriter_cfg {
+    family_id m_label_fid;
+    rewriter_tpl<label_rewriter> m_rwr;
+public:    
+    label_rewriter(ast_manager & m);
+    ~label_rewriter();
+
+    br_status reduce_app(func_decl * f, unsigned num, expr * const * args, expr_ref & result, 
+                         proof_ref & result_pr);
+
+    
+    void remove_labels(expr_ref& fml, proof_ref& pr);
+    
+};
+
+#endif