(proof-new) Proof node updater (#4647)

Adds utility for updating proof nodes. The module for post-processing proof nodes in the SmtEngine for the sake of proof conversion to external formats will build on this utility.

Requires #4617.

1 files changed, 79 insertions, 0 deletions

diff --git a/src/expr/proof_node_updater.h b/src/expr/proof_node_updater.h
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+++ b/src/expr/proof_node_updater.h
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+/*********************                                                        */
+/*! \file proof_node_updater.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds
+ ** 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 utility for updating proof nodes
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef CVC4__EXPR__PROOF_NODE_UPDATER_H
+#define CVC4__EXPR__PROOF_NODE_UPDATER_H
+
+#include <map>
+#include <unordered_set>
+
+#include "expr/proof.h"
+#include "expr/proof_node.h"
+#include "expr/proof_node_manager.h"
+
+namespace CVC4 {
+
+/**
+ * A virtual callback class for updating ProofNode. An example use case of this
+ * class is to eliminate a proof rule by expansion.
+ */
+class ProofNodeUpdaterCallback
+{
+ public:
+  ProofNodeUpdaterCallback();
+  virtual ~ProofNodeUpdaterCallback();
+  /** Should proof pn be updated? */
+  virtual bool shouldUpdate(ProofNode* pn) = 0;
+  /**
+   * Update the proof rule application, store steps in cdp. Return true if
+   * the proof changed. It can be assumed that cdp contains proofs of each
+   * fact in children.
+   */
+  virtual bool update(PfRule id,
+                      const std::vector<Node>& children,
+                      const std::vector<Node>& args,
+                      CDProof* cdp) = 0;
+};
+
+/**
+ * A generic class for updating ProofNode. It is parameterized by a callback
+ * class. Its process method runs this callback on all subproofs of a provided
+ * ProofNode application that meet some criteria
+ * (ProofNodeUpdaterCallback::shouldUpdate)
+ * and overwrites them based on the update procedure of the callback
+ * (ProofNodeUpdaterCallback::update), which uses local CDProof objects that
+ * should be filled in the callback for each ProofNode to update.
+ */
+class ProofNodeUpdater
+{
+ public:
+  ProofNodeUpdater(ProofNodeManager* pnm, ProofNodeUpdaterCallback& cb);
+  /**
+   * Post-process, which performs the main post-processing technique described
+   * above.
+   */
+  void process(std::shared_ptr<ProofNode> pf);
+
+ private:
+  /** The proof node manager */
+  ProofNodeManager* d_pnm;
+  /** The callback */
+  ProofNodeUpdaterCallback& d_cb;
+};
+
+}  // namespace CVC4
+
+#endif