(proof-new) Proof step buffer utilities (#4533)

This class is used for delaying proof node creation until it is necessary.

diff --git a/src/expr/CMakeLists.txt b/src/expr/CMakeLists.txt
index 413041213e763dad4a299d2af7a0353566b33897..3d41b7a720f7dd0ac0f53b386da480cb421eb3c2 100644 (file)
--- a/src/expr/CMakeLists.txt
+++ b/src/expr/CMakeLists.txt
@@ -51,6 +51,8 @@ libcvc4_add_sources(
   proof_rule.h
   proof_skolem_cache.cpp
   proof_skolem_cache.h
+  proof_step_buffer.cpp
+  proof_step_buffer.h
   symbol_table.cpp
   symbol_table.h
   term_canonize.cpp

diff --git a/src/expr/proof_step_buffer.cpp b/src/expr/proof_step_buffer.cpp
new file mode 100644 (file)
index 0000000..800efa2
--- /dev/null
+++ b/src/expr/proof_step_buffer.cpp
@@ -0,0 +1,109 @@
+/*********************                                                        */
+/*! \file proof_step_buffer.cpp
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2019 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 proof step and proof step buffer utilities.
+ **/
+
+#include "expr/proof_step_buffer.h"
+
+using namespace CVC4::kind;
+
+namespace CVC4 {
+
+ProofStep::ProofStep() : d_rule(PfRule::UNKNOWN) {}
+ProofStep::ProofStep(PfRule r,
+                     const std::vector<Node>& children,
+                     const std::vector<Node>& args)
+    : d_rule(r), d_children(children), d_args(args)
+{
+}
+std::ostream& operator<<(std::ostream& out, ProofStep step)
+{
+  out << "(step " << step.d_rule;
+  for (const Node& c : step.d_children)
+  {
+    out << " " << c;
+  }
+  if (!step.d_args.empty())
+  {
+    out << " :args";
+    for (const Node& a : step.d_args)
+    {
+      out << " " << a;
+    }
+  }
+  out << ")";
+  return out;
+}
+
+ProofStepBuffer::ProofStepBuffer(ProofChecker* pc) : d_checker(pc) {}
+
+Node ProofStepBuffer::tryStep(PfRule id,
+                              const std::vector<Node>& children,
+                              const std::vector<Node>& args,
+                              Node expected)
+{
+  if (d_checker == nullptr)
+  {
+    Assert(false) << "ProofStepBuffer::ProofStepBuffer: no proof checker.";
+    return Node::null();
+  }
+  Node res =
+      d_checker->checkDebug(id, children, args, expected, "pf-step-buffer");
+  if (!res.isNull())
+  {
+    // add proof step
+    d_steps.push_back(
+        std::pair<Node, ProofStep>(res, ProofStep(id, children, args)));
+  }
+  return res;
+}
+
+void ProofStepBuffer::addStep(PfRule id,
+                              const std::vector<Node>& children,
+                              const std::vector<Node>& args,
+                              Node expected)
+{
+  d_steps.push_back(
+      std::pair<Node, ProofStep>(expected, ProofStep(id, children, args)));
+}
+
+void ProofStepBuffer::addSteps(ProofStepBuffer& psb)
+{
+  const std::vector<std::pair<Node, ProofStep>>& steps = psb.getSteps();
+  for (const std::pair<Node, ProofStep>& step : steps)
+  {
+    addStep(step.second.d_rule,
+            step.second.d_children,
+            step.second.d_args,
+            step.first);
+  }
+}
+
+void ProofStepBuffer::popStep()
+{
+  Assert(!d_steps.empty());
+  if (!d_steps.empty())
+  {
+    d_steps.pop_back();
+  }
+}
+
+size_t ProofStepBuffer::getNumSteps() const { return d_steps.size(); }
+
+const std::vector<std::pair<Node, ProofStep>>& ProofStepBuffer::getSteps() const
+{
+  return d_steps;
+}
+
+void ProofStepBuffer::clear() { d_steps.clear(); }
+
+}  // namespace CVC4

diff --git a/src/expr/proof_step_buffer.h b/src/expr/proof_step_buffer.h
new file mode 100644 (file)
index 0000000..005aee3
--- /dev/null
+++ b/src/expr/proof_step_buffer.h
@@ -0,0 +1,96 @@
+/*********************                                                        */
+/*! \file proof_step_buffer.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **   Andrew Reynolds
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2019 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 Proof step and proof step buffer utilities.
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef CVC4__EXPR__PROOF_STEP_BUFFER_H
+#define CVC4__EXPR__PROOF_STEP_BUFFER_H
+
+#include <vector>
+
+#include "expr/node.h"
+#include "expr/proof_checker.h"
+#include "expr/proof_rule.h"
+
+namespace CVC4 {
+
+/**
+ * Information for constructing a step in a CDProof. Notice that the conclusion
+ * of the proof step is intentionally not included in this data structure.
+ * Instead, it is intended that conclusions may be associated with proof steps
+ * based on e.g. the result of proof checking.
+ */
+class ProofStep
+{
+ public:
+  ProofStep();
+  ProofStep(PfRule r,
+            const std::vector<Node>& children,
+            const std::vector<Node>& args);
+  /** The proof rule */
+  PfRule d_rule;
+  /** The proof children */
+  std::vector<Node> d_children;
+  /** The proof arguments */
+  std::vector<Node> d_args;
+};
+std::ostream& operator<<(std::ostream& out, ProofStep step);
+
+/**
+ * Class used to speculatively try and buffer a set of proof steps before
+ * sending them to a proof object.
+ */
+class ProofStepBuffer
+{
+ public:
+  ProofStepBuffer(ProofChecker* pc = nullptr);
+  ~ProofStepBuffer() {}
+  /**
+   * Returns the conclusion of the proof step, as determined by the proof
+   * checker of the given proof. If this is non-null, then the given step
+   * is added to the buffer maintained by this class.
+   *
+   * If expected is non-null, then this method returns null if the result of
+   * checking is not equal to expected.
+   */
+  Node tryStep(PfRule id,
+               const std::vector<Node>& children,
+               const std::vector<Node>& args,
+               Node expected = Node::null());
+  /** Same as above, without checking */
+  void addStep(PfRule id,
+               const std::vector<Node>& children,
+               const std::vector<Node>& args,
+               Node expected);
+  /** Multi-step version */
+  void addSteps(ProofStepBuffer& psb);
+  /** pop step */
+  void popStep();
+  /** Get num steps */
+  size_t getNumSteps() const;
+  /** Get steps */
+  const std::vector<std::pair<Node, ProofStep>>& getSteps() const;
+  /** Clear */
+  void clear();
+
+ private:
+  /** The proof checker*/
+  ProofChecker* d_checker;
+  /** the queued proof steps */
+  std::vector<std::pair<Node, ProofStep>> d_steps;
+};
+
+}  // namespace CVC4
+
+#endif /* CVC4__EXPR__PROOF_STEP_BUFFER_H */