3 files changed, 149 insertions, 0 deletions
diff --git a/src/expr/CMakeLists.txt b/src/expr/CMakeLists.txt
index aed7a866c..3e3b569af 100644
--- a/src/expr/CMakeLists.txt
+++ b/src/expr/CMakeLists.txt
@@ -7,6 +7,8 @@ libcvc4_add_sources(
   attribute.cpp
   attribute_internals.h
   attribute_unique_id.h
+  buffered_proof_generator.cpp
+  buffered_proof_generator.h
   emptyset.cpp
   emptyset.h
   expr_iomanip.cpp
diff --git a/src/expr/buffered_proof_generator.cpp b/src/expr/buffered_proof_generator.cpp
new file mode 100644
index 000000000..aa0fe19bd
--- /dev/null
+++ b/src/expr/buffered_proof_generator.cpp
@@ -0,0 +1,82 @@
+/*********************                                                        */
+/*! \file buffered_proof_generator.cpp
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds, Haniel Barbosa
+ ** 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 a proof generator for buffered proof steps
+ **/
+
+#include "expr/buffered_proof_generator.h"
+
+#include "expr/proof.h"
+
+namespace CVC4 {
+
+BufferedProofGenerator::BufferedProofGenerator(context::Context* c,
+                                               ProofNodeManager* pnm)
+    : ProofGenerator(), d_facts(c), d_pnm(pnm)
+{
+}
+
+bool BufferedProofGenerator::addStep(Node fact,
+                                     ProofStep ps,
+                                     CDPOverwrite opolicy)
+{
+  // check duplicates if we are not always overwriting
+  if (opolicy != CDPOverwrite::ALWAYS)
+  {
+    if (d_facts.find(fact) != d_facts.end())
+    {
+      // duplicate
+      return false;
+    }
+    Node symFact = CDProof::getSymmFact(fact);
+    if (!symFact.isNull())
+    {
+      if (d_facts.find(symFact) != d_facts.end())
+      {
+        // duplicate due to symmetry
+        return false;
+      }
+    }
+  }
+  // note that this replaces the value fact is mapped to if there is already one
+  d_facts.insert(fact, std::make_shared<ProofStep>(ps));
+  return true;
+}
+
+std::shared_ptr<ProofNode> BufferedProofGenerator::getProofFor(Node fact)
+{
+  Trace("pfee-fact-gen") << "BufferedProofGenerator::getProofFor: " << fact
+                         << std::endl;
+  NodeProofStepMap::iterator it = d_facts.find(fact);
+  if (it == d_facts.end())
+  {
+    Node symFact = CDProof::getSymmFact(fact);
+    if (symFact.isNull())
+    {
+      Trace("pfee-fact-gen") << "...cannot find step" << std::endl;
+      Assert(false);
+      return nullptr;
+    }
+    it = d_facts.find(symFact);
+    if (it == d_facts.end())
+    {
+      Assert(false);
+      Trace("pfee-fact-gen") << "...cannot find step (no sym)" << std::endl;
+      return nullptr;
+    }
+  }
+  Trace("pfee-fact-gen") << "...return via step " << *(*it).second << std::endl;
+  CDProof cdp(d_pnm);
+  cdp.addStep(fact, *(*it).second);
+  return cdp.getProofFor(fact);
+}
+
+}  // namespace CVC4
diff --git a/src/expr/buffered_proof_generator.h b/src/expr/buffered_proof_generator.h
new file mode 100644
index 000000000..987bd2465
--- /dev/null
+++ b/src/expr/buffered_proof_generator.h
@@ -0,0 +1,65 @@
+/*********************                                                        */
+/*! \file buffered_proof_generator.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds, Haniel Barbosa
+ ** 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 A proof generator for buffered proof steps
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef CVC4__EXPR__BUFFERED_PROOF_GENERATOR_H
+#define CVC4__EXPR__BUFFERED_PROOF_GENERATOR_H
+
+#include <map>
+#include <vector>
+
+#include "context/cdhashmap.h"
+#include "context/cdhashset.h"
+#include "expr/proof_generator.h"
+#include "expr/proof_node_manager.h"
+#include "expr/proof_step_buffer.h"
+
+namespace CVC4 {
+
+/**
+ * The proof generator for buffered steps. This class is a context-dependent
+ * mapping from formulas to proof steps. It does not generate ProofNodes until it
+ * is asked to provide a proof for a given fact.
+ */
+class BufferedProofGenerator : public ProofGenerator
+{
+  typedef context::CDHashMap<Node, std::shared_ptr<ProofStep>, NodeHashFunction>
+      NodeProofStepMap;
+
+ public:
+  BufferedProofGenerator(context::Context* c, ProofNodeManager* pnm);
+  ~BufferedProofGenerator() {}
+  /** add step
+   * Unless the overwrite policy is ALWAYS it does not replace previously
+   * registered steps (modulo (dis)equality symmetry).
+   */
+  bool addStep(Node fact,
+               ProofStep ps,
+               CDPOverwrite opolicy = CDPOverwrite::NEVER);
+  /** Get proof for. It is robust to (dis)equality symmetry. */
+  std::shared_ptr<ProofNode> getProofFor(Node f) override;
+  /** identify */
+  std::string identify() const override { return "BufferedProofGenerator"; }
+
+ private:
+  /** maps expected to ProofStep */
+  NodeProofStepMap d_facts;
+  /** the proof node manager */
+  ProofNodeManager* d_pnm;
+};
+
+}  // namespace CVC4
+
+#endif /* CVC4__EXPR__BUFFERED_PROOF_GENERATOR_H */