Implement bags rewriter (#5132)

This PR implements rewrite rules for bags. This PR focuses on rewrite rules for non constant nodes.
Rewriting nodes with constant children is delegated to bags::NormalForm class (future PR).

1 files changed, 76 insertions, 0 deletions

diff --git a/src/theory/bags/rewrites.cpp b/src/theory/bags/rewrites.cpp
new file mode 100644
index 000000000..758f8a6e6
--- /dev/null
+++ b/src/theory/bags/rewrites.cpp
@@ -0,0 +1,76 @@
+/*********************                                                        */
+/*! \file rewrites.cpp
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Mudathir Mohamed
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2020 by the authors listed in the file AUTHORS
+ ** in the top-level source directory and their institutional affiliations.
+ ** All rights reserved.  See the file COPYING in the top-level source
+ ** directory for licensing information.\endverbatim
+ **
+ ** \brief Implementation of inference information utility.
+ **/
+
+#include "theory/bags/rewrites.h"
+
+#include <iostream>
+
+namespace CVC4 {
+namespace theory {
+namespace bags {
+
+const char* toString(Rewrite r)
+{
+  switch (r)
+  {
+    case Rewrite::NONE: return "NONE";
+    case Rewrite::CARD_DISJOINT: return "CARD_DISJOINT";
+    case Rewrite::CARD_MK_BAG: return "CARD_MK_BAG";
+    case Rewrite::CHOOSE_MK_BAG: return "CHOOSE_MK_BAG";
+    case Rewrite::CONSTANT_EVALUATION: return "CONSTANT_EVALUATION";
+    case Rewrite::COUNT_EMPTY: return "COUNT_EMPTY";
+    case Rewrite::COUNT_MK_BAG: return "COUNT_MK_BAG";
+    case Rewrite::IDENTICAL_NODES: return "IDENTICAL_NODES";
+    case Rewrite::INTERSECTION_EMPTY_LEFT: return "INTERSECTION_EMPTY_LEFT";
+    case Rewrite::INTERSECTION_EMPTY_RIGHT: return "INTERSECTION_EMPTY_RIGHT";
+    case Rewrite::INTERSECTION_SAME: return "INTERSECTION_SAME";
+    case Rewrite::INTERSECTION_SHARED_LEFT: return "INTERSECTION_SHARED_LEFT";
+    case Rewrite::INTERSECTION_SHARED_RIGHT: return "INTERSECTION_SHARED_RIGHT";
+    case Rewrite::IS_SINGLETON_MK_BAG: return "IS_SINGLETON_MK_BAG";
+    case Rewrite::MK_BAG_COUNT_NEGATIVE: return "MK_BAG_COUNT_NEGATIVE";
+    case Rewrite::REMOVE_FROM_UNION: return "REMOVE_FROM_UNION";
+    case Rewrite::REMOVE_MIN: return "REMOVE_MIN";
+    case Rewrite::REMOVE_RETURN_LEFT: return "REMOVE_RETURN_LEFT";
+    case Rewrite::REMOVE_SAME: return "REMOVE_SAME";
+    case Rewrite::SUB_BAG: return "SUB_BAG";
+    case Rewrite::SUBTRACT_DISJOINT_SHARED_LEFT:
+      return "SUBTRACT_DISJOINT_SHARED_LEFT";
+    case Rewrite::SUBTRACT_DISJOINT_SHARED_RIGHT:
+      return "SUBTRACT_DISJOINT_SHARED_RIGHT";
+    case Rewrite::SUBTRACT_FROM_UNION: return "SUBTRACT_FROM_UNION";
+    case Rewrite::SUBTRACT_MIN: return "SUBTRACT_MIN";
+    case Rewrite::SUBTRACT_RETURN_LEFT: return "SUBTRACT_RETURN_LEFT";
+    case Rewrite::SUBTRACT_SAME: return "SUBTRACT_SAME";
+    case Rewrite::UNION_DISJOINT_EMPTY_LEFT: return "UNION_DISJOINT_EMPTY_LEFT";
+    case Rewrite::UNION_DISJOINT_EMPTY_RIGHT:
+      return "UNION_DISJOINT_EMPTY_RIGHT";
+    case Rewrite::UNION_DISJOINT_MAX_MIN: return "UNION_DISJOINT_MAX_MIN";
+    case Rewrite::UNION_MAX_EMPTY: return "UNION_MAX_EMPTY";
+    case Rewrite::UNION_MAX_SAME_OR_EMPTY: return "UNION_MAX_SAME_OR_EMPTY";
+    case Rewrite::UNION_MAX_UNION_LEFT: return "UNION_MAX_UNION_LEFT";
+    case Rewrite::UNION_MAX_UNION_RIGHT: return "UNION_MAX_UNION_RIGHT";
+
+    default: return "?";
+  }
+}
+
+std::ostream& operator<<(std::ostream& out, Rewrite r)
+{
+  out << toString(r);
+  return out;
+}
+
+}  // namespace bags
+}  // namespace theory
+}  // namespace CVC4