(proof-new) More term context utilities. (#4912)

These utilities will be used for making some of the core proof utilities term-context-sensitve.

4 files changed, 292 insertions, 0 deletions

diff --git a/src/expr/term_context_node.cpp b/src/expr/term_context_node.cpp
new file mode 100644
index 000000000..519012ae8
--- /dev/null
+++ b/src/expr/term_context_node.cpp
@@ -0,0 +1,76 @@
+/*********************                                                        */
+/*! \file term_context_node.cpp
+ ** \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 Term context node utility.
+ **/
+
+#include "expr/term_context_node.h"
+
+#include "expr/term_context.h"
+
+namespace CVC4 {
+
+TCtxNode::TCtxNode(Node n, const TermContext* tctx)
+    : d_node(n), d_val(tctx->initialValue()), d_tctx(tctx)
+{
+}
+
+TCtxNode::TCtxNode(Node n, uint32_t val, const TermContext* tctx)
+    : d_node(n), d_val(val), d_tctx(tctx)
+{
+}
+
+size_t TCtxNode::getNumChildren() const { return d_node.getNumChildren(); }
+
+TCtxNode TCtxNode::getChild(size_t i) const
+{
+  Assert(i < d_node.getNumChildren());
+  // we are still computing the same term context, with the given child, where
+  // the hash has been updated based on the kind, node, current value and child
+  // index.
+  return TCtxNode(d_node[i], d_tctx->computeValue(d_node, d_val, i), d_tctx);
+}
+
+Node TCtxNode::getNode() const { return d_node; }
+
+uint32_t TCtxNode::getContextId() const { return d_val; }
+
+const TermContext* TCtxNode::getTermContext() const { return d_tctx; }
+
+Node TCtxNode::getNodeHash() const { return computeNodeHash(d_node, d_val); }
+
+Node TCtxNode::computeNodeHash(Node n, uint32_t val)
+{
+  NodeManager* nm = NodeManager::currentNM();
+  return nm->mkNode(kind::SEXPR, n, nm->mkConst(Rational(val)));
+}
+
+Node TCtxNode::decomposeNodeHash(Node h, uint32_t& val)
+{
+  if (h.getKind() != kind::SEXPR || h.getNumChildren() != 2)
+  {
+    Assert(false) << "TermContext::decomposeNodeHash: unexpected node " << h;
+    return Node::null();
+  }
+  Node ival = h[1];
+  if (!ival.isConst() || !ival.getType().isInteger()
+      || !ival.getConst<Rational>().getNumerator().fitsUnsignedInt())
+  {
+    Assert(false) << "TermContext::decomposeNodeHash: unexpected term context "
+                     "integer in hash "
+                  << h;
+    return Node::null();
+  }
+  val = ival.getConst<Rational>().getNumerator().toUnsignedInt();
+  return h[0];
+}
+
+}  // namespace CVC4
diff --git a/src/expr/term_context_node.h b/src/expr/term_context_node.h
new file mode 100644
index 000000000..028a590b1
--- /dev/null
+++ b/src/expr/term_context_node.h
@@ -0,0 +1,79 @@
+/*********************                                                        */
+/*! \file term_context.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 Term context node utility.
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef CVC4__EXPR__TERM_CONTEXT_NODE_H
+#define CVC4__EXPR__TERM_CONTEXT_NODE_H
+
+#include "expr/node.h"
+#include "expr/term_context.h"
+
+namespace CVC4 {
+
+class TCtxStack;
+
+/**
+ * A (term-context) sensitive term. This is a wrapper around a Node that
+ * additionally has a term context identifier, see getTermContext(). It depends
+ * on a pointer to a TermContext callback class (see term_context.h).
+ */
+class TCtxNode
+{
+  friend class TCtxStack;
+
+ public:
+  TCtxNode(Node n, const TermContext* tctx);
+  /** get number of children */
+  size_t getNumChildren() const;
+  /** get child at index i */
+  TCtxNode getChild(size_t i) const;
+  /** get node */
+  Node getNode() const;
+  /** get context */
+  uint32_t getContextId() const;
+  /** get term context */
+  const TermContext* getTermContext() const;
+  //---------------------- utility methods
+  /**
+   * Get node hash, which is a unique node representation of this TCtxNode.
+   * This method calls the method below on the data members of this class.
+   */
+  Node getNodeHash() const;
+  /**
+   * Get node hash, which is a unique node representation of the pair (n, val).
+   * In particular, this returns (SEXPR n (CONST_RATIONAL val)).
+   */
+  static Node computeNodeHash(Node n, uint32_t val);
+  /**
+   * Decompose node hash, which is an inverse of the above operation. In
+   * particular, given input h, this returns a node n and sets val to a value
+   * such that computeNodeHash(n, val) returns h.
+   */
+  static Node decomposeNodeHash(Node h, uint32_t& val);
+  //---------------------- end utility methods
+ private:
+  /** private constructor */
+  TCtxNode(Node n, uint32_t val, const TermContext* tctx);
+  /** The node */
+  Node d_node;
+  /** The term context identifier */
+  uint32_t d_val;
+  /** The term context */
+  const TermContext* d_tctx;
+};
+
+}  // namespace CVC4
+
+#endif /* CVC4__EXPR__TERM_CONVERSION_PROOF_GENERATOR_H */
diff --git a/src/expr/term_context_stack.cpp b/src/expr/term_context_stack.cpp
new file mode 100644
index 000000000..4c2e32033
--- /dev/null
+++ b/src/expr/term_context_stack.cpp
@@ -0,0 +1,69 @@
+/*********************                                                        */
+/*! \file term_context_stack.cpp
+ ** \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 Term context stack
+ **/
+
+#include "expr/term_context_stack.h"
+
+namespace CVC4 {
+
+TCtxStack::TCtxStack(const TermContext* tctx) : d_tctx(tctx) {}
+
+void TCtxStack::pushInitial(Node t)
+{
+  Assert(d_stack.empty());
+  d_stack.push_back(std::pair<Node, uint32_t>(t, d_tctx->initialValue()));
+}
+
+void TCtxStack::pushChildren(Node t, uint32_t tval)
+{
+  for (size_t i = 0, nchild = t.getNumChildren(); i < nchild; i++)
+  {
+    pushChild(t, tval, i);
+  }
+}
+
+void TCtxStack::pushChild(Node t, uint32_t tval, size_t index)
+{
+  Assert(index < t.getNumChildren());
+  Trace("tctx-debug") << "TCtxStack::pushChild: computing " << t << "[" << index
+                      << "] / " << tval << std::endl;
+  uint32_t tcval = d_tctx->computeValue(t, tval, index);
+  Trace("tctx-debug") << "TCtxStack::pushChild: returned " << t << "[" << index
+                      << "] / " << tval << " ---> " << tcval << std::endl;
+  d_stack.push_back(std::pair<Node, uint32_t>(t[index], tcval));
+}
+
+void TCtxStack::push(Node t, uint32_t tval)
+{
+  d_stack.push_back(std::pair<Node, uint32_t>(t, tval));
+}
+
+void TCtxStack::pop() { d_stack.pop_back(); }
+
+void TCtxStack::clear() { d_stack.clear(); }
+size_t TCtxStack::size() const { return d_stack.size(); }
+
+bool TCtxStack::empty() const { return d_stack.empty(); }
+
+std::pair<Node, uint32_t> TCtxStack::getCurrent() const
+{
+  return d_stack.back();
+}
+
+TCtxNode TCtxStack::getCurrentNode() const
+{
+  std::pair<Node, uint32_t> curr = TCtxStack::getCurrent();
+  return TCtxNode(curr.first, curr.second, d_tctx);
+}
+
+}  // namespace CVC4
diff --git a/src/expr/term_context_stack.h b/src/expr/term_context_stack.h
new file mode 100644
index 000000000..9aeea04c2
--- /dev/null
+++ b/src/expr/term_context_stack.h
@@ -0,0 +1,68 @@
+/*********************                                                        */
+/*! \file term_context_stack.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 Term context
+ **/
+
+#include "cvc4_private.h"
+
+#ifndef CVC4__EXPR__TERM_CONTEXT_STACK_H
+#define CVC4__EXPR__TERM_CONTEXT_STACK_H
+
+#include "expr/term_context_node.h"
+
+namespace CVC4 {
+
+/**
+ * A stack for term-context-sensitive terms. Its main advantage is that
+ * it does not rely on explicit construction of TCtxNode for efficiency.
+ */
+class TCtxStack
+{
+ public:
+  TCtxStack(const TermContext* tctx);
+  virtual ~TCtxStack() {}
+  /** Push t to the stack */
+  void pushInitial(Node t);
+  /**
+   * Push all children of t to the stack, where tval is the term context hash
+   * of t. */
+  void pushChildren(Node t, uint32_t tval);
+  /**
+   * Push the child of t with the given index to the stack, where tval is
+   * the term context hash of t.
+   */
+  void pushChild(Node t, uint32_t tval, size_t index);
+  /** Push t to the stack with term context hash tval. */
+  void push(Node t, uint32_t tval);
+  /** Pop a term from the context */
+  void pop();
+  /** Clear the stack */
+  void clear();
+  /** Return the size of the stack */
+  size_t size() const;
+  /** Return true if the stack is empty */
+  bool empty() const;
+  /** Get the current stack element */
+  std::pair<Node, uint32_t> getCurrent() const;
+  /** Get the current stack element, node version */
+  TCtxNode getCurrentNode() const;
+
+ private:
+  /** The stack */
+  std::vector<std::pair<Node, uint32_t>> d_stack;
+  /** The term context */
+  const TermContext* d_tctx;
+};
+
+}  // namespace CVC4
+
+#endif /* CVC4__EXPR__TERM_CONTEXT_STACK_H */