adding drat

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

src/sat/sat_drat.cpp

@@ -0,0 +1,67 @@
+/*++
+Copyright (c) 2014 Microsoft Corporation
+
+Module Name:
+
+    sat_drat.cpp
+
+Abstract:
+   
+    Produce DRAT proofs.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2017-2-3
+
+Notes:
+
+--*/
+#include "sat_solver.h"
+#include "sat_drat.h"
+
+
+namespace sat {
+    drat::drat(solver& s):
+        s(s),
+        m_out(0)
+    {
+        if (s.m_config.m_drat) {
+            m_out = alloc(std::ofstream, "proof.drat");
+        }
+    }
+
+    drat::~drat() {
+        dealloc(m_out);
+    }
+    void drat::add_empty() {
+        (*m_out) << "0\n";
+    }
+    void drat::add_literal(literal l) {
+        (*m_out) << l << " 0\n";
+    }
+    void drat::add_binary(literal l1, literal l2) {
+        (*m_out) << l1 << " " << l2 << " 0\n";
+    }
+    void drat::add_ternary(literal l1, literal l2, literal l3) {
+        (*m_out) << l1 << " " << l2 << " " << l3 << " 0\n";
+    }
+    void drat::add_clause(clause& c) {
+        unsigned sz = c.size();
+        for (unsigned i = 0; i < sz; ++i) {
+            (*m_out) << c[i] << " ";
+        }
+        (*m_out) << "0\n";
+    }
+    void drat::del_literal(literal l) {
+        (*m_out) << "d ";
+        add_literal(l);
+    }
+    void drat::del_binary(literal l1, literal l2) {
+        (*m_out) << "d ";
+        add_binary(l1, l2);
+    }
+    void drat::del_clause(clause& c) {
+        (*m_out) << "d ";
+        add_clause(c);
+    }
+}