Add new infrastructure for preprocessing passes (#1053)

This commit adds new infrastructure for preprocessing passes. It is preparation only, it does not change how the current preprocessing passes work (this will be done in future commits).

1 files changed, 126 insertions, 0 deletions

diff --git a/src/preprocessing/preprocessing_pass.h b/src/preprocessing/preprocessing_pass.h
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+/*********************                                                        */
+/*! \file preprocessing_pass.h
+ ** \verbatim
+ ** Top contributors (to current version):
+ **  Justin Xu
+ ** This file is part of the CVC4 project.
+ ** Copyright (c) 2009-2017 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 The preprocessing pass super class
+ **
+ ** Implementation of the preprocessing pass super class. Preprocessing passes
+ ** that inherit from this class, need to pass their name to the constructor to
+ ** register the pass appropriately. The core of a preprocessing pass lives
+ ** in applyInternal(), which operates on a list of assertions and is called
+ ** from apply() in the super class. The apply() method automatically takes
+ ** care of the following:
+ **
+ ** - Dumping assertions before and after the pass
+ ** - Initializing the timer
+ ** - Tracing and chatting
+ **
+ ** Optionally, preprocessing passes can overwrite the initInteral() method to
+ ** do work that only needs to be done once.
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef __CVC4__PREPROCESSING__PREPROCESSING_PASS_H
+#define __CVC4__PREPROCESSING__PREPROCESSING_PASS_H
+
+#include <string>
+#include <vector>
+
+#include "expr/node.h"
+#include "preprocessing/preprocessing_pass_context.h"
+#include "smt/smt_engine_scope.h"
+
+namespace CVC4 {
+namespace preprocessing {
+
+/* Assertion Pipeline stores a list of assertions modified by preprocessing
+ * passes. */
+class AssertionPipeline {
+  std::vector<Node> d_nodes;
+
+ public:
+  size_t size() const { return d_nodes.size(); }
+
+  void resize(size_t n) { d_nodes.resize(n); }
+  void clear() { d_nodes.clear(); }
+
+  Node& operator[](size_t i) { return d_nodes[i]; }
+  const Node& operator[](size_t i) const { return d_nodes[i]; }
+  void push_back(Node n) { d_nodes.push_back(n); }
+
+  std::vector<Node>& ref() { return d_nodes; }
+  const std::vector<Node>& ref() const { return d_nodes; }
+
+  std::vector<Node>::const_iterator begin() const { return d_nodes.cbegin(); }
+  std::vector<Node>::const_iterator end() const { return d_nodes.cend(); }
+
+  /*
+   * Replaces assertion i with node n and records the dependency between the
+   * original assertion and its replacement.
+   */
+  void replace(size_t i, Node n);
+
+  /*
+   * Replaces assertion i with node n and records that this replacement depends
+   * on assertion i and the nodes listed in addnDeps. The dependency
+   * information is used for unsat cores and proofs.
+   */
+  void replace(size_t i, Node n, const std::vector<Node>& addnDeps);
+
+  /*
+   * Replaces an assertion with a vector of assertions and records the
+   * dependencies.
+   */
+  void replace(size_t i, const std::vector<Node>& ns);
+}; /* class AssertionPipeline */
+
+/**
+ * Preprocessing passes return a result which indicates whether a conflict has
+ * been detected during preprocessing.
+ */
+enum PreprocessingPassResult { CONFLICT, NO_CONFLICT };
+
+class PreprocessingPass {
+ public:
+  /* Preprocesses a list of assertions assertionsToPreprocess */
+  PreprocessingPassResult apply(AssertionPipeline* assertionsToPreprocess);
+
+  PreprocessingPass(PreprocessingPassContext* preprocContext,
+                    const std::string& name);
+  virtual ~PreprocessingPass();
+
+ protected:
+  /*
+   * Method for dumping assertions within a pass. Also called before and after
+   * applying the pass.
+   */
+  void dumpAssertions(const char* key, const AssertionPipeline& assertionList);
+
+  /*
+   * Abstract method that each pass implements to do the actual preprocessing.
+   */
+  virtual PreprocessingPassResult applyInternal(
+      AssertionPipeline* assertionsToPreprocess) = 0;
+
+  /* Context for Preprocessing Passes that initializes necessary variables */
+  PreprocessingPassContext* d_preprocContext;
+
+ private:
+  /* Name of pass */
+  std::string d_name;
+  /* Timer for registering the preprocessing time of this pass */
+  TimerStat d_timer;
+};
+
+}  // namespace preprocessing
+}  // namespace CVC4
+
+#endif /* __CVC4__PREPROCESSING__PREPROCESSING_PASS_H */