separate out int-branch

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

src/math/lp/int_branch.h

@@ -0,0 +1,41 @@
+/*++
+Copyright (c) 2020 Microsoft Corporation
+
+Module Name:
+
+    int_branch.h
+
+Abstract:
+
+    Branch heuristic
+
+Author:
+    Nikolaj Bjorner (nbjorner)
+    Lev Nachmanson (levnach)
+
+Revision History:
+--*/
+#pragma once
+
+#include "math/lp/lia_move.h"
+
+namespace lp {
+    class int_solver;
+    class lar_solver;
+    class int_branch {
+        class int_solver& lia;
+        class lar_solver& lra;
+        lia_move create_branch_on_column(int j);
+        bool left_branch_is_more_narrow_than_right(unsigned j);
+        int find_inf_int_base_column();
+        int get_kth_inf_int(unsigned k) const;
+        int find_inf_int_nbasis_column() const;
+        int find_any_inf_int_column_basis_first();
+        int find_inf_int_boxed_base_column_with_smallest_range(unsigned & inf_int_count);
+
+    public:
+        int_branch(int_solver& lia);
+        ~int_branch() {}
+        lia_move operator()();
+    };
+}