path: root/src/expr/node.h

/*********************                                                        */
/** node.h
 ** Original author: mdeters
 ** Major contributors: dejan
 ** Minor contributors (to current version): taking
 ** This file is part of the CVC4 prototype.
 ** Copyright (c) 2009, 2010  The Analysis of Computer Systems Group (ACSys)
 ** Courant Institute of Mathematical Sciences
 ** New York University
 ** See the file COPYING in the top-level source directory for licensing
 ** information.
 **
 ** Reference-counted encapsulation of a pointer to node information.
 **/

#include "cvc4_private.h"

#include "expr/node_value.h"

#ifndef __CVC4__NODE_H
#define __CVC4__NODE_H

#include <vector>
#include <string>
#include <iostream>
#include <stdint.h>

#include "cvc4_config.h"
#include "expr/kind.h"
#include "expr/type.h"
#include "util/Assert.h"

#include "util/output.h"

namespace CVC4 {

class Type;
class NodeManager;

template <bool ref_count>
class NodeTemplate;

/**
 * The Node class encapsulates the NodeValue with reference counting.
 */
typedef NodeTemplate<true> Node;

/**
 * The TNode class encapsulates the NodeValue but doesn't count references.
 */
typedef NodeTemplate<false> TNode;

namespace expr {

class NodeValue;

  namespace attr {
    class AttributeManager;
  }/* CVC4::expr::attr namespace */

}/* CVC4::expr namespace */

/**
 * Encapsulation of an NodeValue pointer.  The reference count is
 * maintained in the NodeValue if ref_count is true.
 * @param ref_count if true reference are counted in the NodeValue
 */
template <bool ref_count>
class NodeTemplate {

  /**
   * The NodeValue has access to the private constructors, so that the
   * iterators can can create new nodes.
   */
  friend class expr::NodeValue;

  /** A convenient null-valued encapsulated pointer */
  static NodeTemplate s_null;

  /** The referenced NodeValue */
  expr::NodeValue* d_nv;

  /**
   * This constructor is reserved for use by the NodeTemplate package; one
   * must construct an NodeTemplate using one of the build mechanisms of the
   * NodeTemplate package.
   *
   * FIXME: there's a type-system escape here to cast away the const,
   * since the refcount needs to be updated.  But conceptually Nodes
   * don't change their arguments, and it's nice to have
   * const_iterators over them.
   *
   * This really does needs to be explicit to avoid hard to track errors with
   * Nodes implicitly wrapping NodeValues
   */
  explicit NodeTemplate(const expr::NodeValue*);

  friend class NodeTemplate<true>;
  friend class NodeTemplate<false>;
  friend class NodeManager;

  template <unsigned>
  friend class NodeBuilder;

  friend class ::CVC4::expr::attr::AttributeManager;

  /**
   * Assigns the expression value and does reference counting. No assumptions
   * are made on the expression, and should only be used if we know what we 
   * are doing.
   *
   * @param ev the expression value to assign
   */
  void assignNodeValue(expr::NodeValue* ev);

public:

  /** Default constructor, makes a null expression. */
  NodeTemplate() : d_nv(&expr::NodeValue::s_null) { }

  /**
   * Conversion between nodes that are reference-counted and those that are
   * not.
   * @param node the node to make copy of
   */
  NodeTemplate(const NodeTemplate<!ref_count>& node);

  /**
   * Copy constructor.  Note that GCC does NOT recognize an instantiation of
   * the above template as a copy constructor and problems ensue.  So we
   * provide an explicit one here.
   * @param node the node to make copy of
   */
  NodeTemplate(const NodeTemplate& node);

  /**
   * Assignment operator for nodes, copies the relevant information from node
   * to this node.
   * @param node the node to copy
   * @return reference to this node
   */
  NodeTemplate& operator=(const NodeTemplate& node);

  /**
   * Assignment operator for nodes, copies the relevant information from node
   * to this node.
   * @param node the node to copy
   * @return reference to this node
   */
  NodeTemplate& operator=(const NodeTemplate<!ref_count>& node);

  /**
   * Destructor. If ref_count is true it will decrement the reference count
   * and, if zero, collect the NodeValue.
   */
  ~NodeTemplate() throw(AssertionException);

  /**
   * Return the null node.
   * @return the null node
   */
  static NodeTemplate null() {
    return s_null;
  }

  /**
   * Returns true if this expression is a null expression.
   * @return true if null
   */
  bool isNull() const {
    return d_nv == &expr::NodeValue::s_null;
  }

  /**
   * Structural comparison operator for expressions.
   * @param node the node to compare to
   * @return true if expressions are equal, false otherwise
   */
  template <bool ref_count_1>
  bool operator==(const NodeTemplate<ref_count_1>& node) const {
    return d_nv == node.d_nv;
  }

  /**
   * Structural comparison operator for expressions.
   * @param node the node to compare to
   * @return false if expressions are equal, true otherwise
   */
  template <bool ref_count_1>
  bool operator!=(const NodeTemplate<ref_count_1>& node) const {
    return d_nv != node.d_nv;
  }

  /**
   * We compare by expression ids so, keeping things deterministic and having
   * that subexpressions have to be smaller than the enclosing expressions.
   * @param node the node to compare to
   * @return true if this expression is smaller
   */
  template <bool ref_count_1>
  inline bool operator<(const NodeTemplate<ref_count_1>& node) const {
    return d_nv->d_id < node.d_nv->d_id;
  }

  /**
   * Returns the i-th child of this node.
   * @param i the index of the child
   * @return the node representing the i-th child
   */
  NodeTemplate operator[](int i) const {
    Assert(i >= 0 && unsigned(i) < d_nv->d_nchildren);
    return NodeTemplate(d_nv->d_children[i]);
  }

  /**
   * Returns true if this node is atomic (has no more Boolean structure)
   * @return true if atomic
   */
  bool isAtomic() const;

  /**
   * Returns the hash value of this node.
   * @return the hash value
   */
  size_t hash() const {
    return d_nv->getId();
  }

  /**
   * Returns the unique id of this node
   * @return the ud
   */
  uint64_t getId() const {
    return d_nv->getId();
  }

  /**
   * Returns a node representing the operator of this expression.
   * If this is an APPLY, then the operator will be a functional term.
   * Otherwise, it will be a node with kind BUILTIN
   */
  NodeTemplate<true> getOperator() const;

  /** Returns true if the node has an operator (i.e., it's not a variable or a constant). */
  bool hasOperator() const;

  /**
   * Returns the type of this node.
   * @return the type
   */
  const Type* getType() const;

  /**
   * Returns the kind of this node.
   * @return the kind
   */
  inline Kind getKind() const {
    return Kind(d_nv->d_kind);
  }

  /**
   * Returns the number of children this node has.
   * @return the number of children
   */
  inline size_t getNumChildren() const;

  /**
   * Returns the value of the given attribute that this has been attached.
   * @param attKind the kind of the attribute
   * @return the value of the attribute
   */
  template <class AttrKind>
  inline typename AttrKind::value_type getAttribute(const AttrKind& attKind) const;

  // Note that there are two, distinct hasAttribute() declarations for
  // a reason (rather than using a pointer-valued argument with a
  // default value): they permit more optimized code in the underlying
  // hasAttribute() implementations.

  /**
   * Returns true if this node has been associated an attribute of given kind.
   * Additionaly, if a pointer to the value_kind is give, and the attribute
   * value has been set for this node, it will be returned.
   * @param attKind the kind of the attribute
   * @return true if this node has the requested attribute
   */
  template <class AttrKind>
  inline bool hasAttribute(const AttrKind& attKind) const;

  /**
   * Returns true if this node has been associated an attribute of given kind.
   * Additionaly, if a pointer to the value_kind is give, and the attribute
   * value has been set for this node, it will be returned.
   * @param attKind the kind of the attribute
   * @param value where to store the value if it exists
   * @return true if this node has the requested attribute
   */
  template <class AttrKind>
  inline bool hasAttribute(const AttrKind& attKind,
                           typename AttrKind::value_type& value) const;

  /**
   * Sets the given attribute of this node to the given value.
   * @param attKind the kind of the atribute
   * @param value the value to set the attribute to
   */
  template <class AttrKind>
  inline void setAttribute(const AttrKind& attKind,
                           const typename AttrKind::value_type& value);

  /** Iterator allowing for scanning through the children. */
  typedef typename expr::NodeValue::iterator<ref_count> iterator;
  /** Constant iterator allowing for scanning through the children. */
  typedef typename expr::NodeValue::iterator<ref_count> const_iterator;

  /**
   * Returns the iterator pointing to the first child.
   * @return the iterator
   */
  inline iterator begin() {
    return d_nv->begin<ref_count>();
  }

  /**
   * Returns the iterator pointing to the end of the children (one beyond the
   * last one.
   * @return the end of the children iterator.
   */
  inline iterator end() {
    return d_nv->end<ref_count>();
  }

  /**
   * Returns the const_iterator pointing to the first child.
   * @return the const_iterator
   */
  inline const_iterator begin() const {
    return d_nv->begin<ref_count>();
  }

  /**
   * Returns the const_iterator pointing to the end of the children (one
   * beyond the last one.
   * @return the end of the children const_iterator.
   */
  inline const_iterator end() const {
    return d_nv->end<ref_count>();
  }

  /**
   * Converts this node into a string representation.
   * @return the string representation of this node.
   */
  inline std::string toString() const {
    return d_nv->toString();
  }

  /**
   * Converst this node into a string representation and sends it to the
   * given stream
   * @param out the sream to serialise this node to
   */
  inline void toStream(std::ostream& out) const {
    d_nv->toStream(out);
  }

  /**
   * Very basic pretty printer for Node.
   * @param o output stream to print to.
   * @param indent number of spaces to indent the formula by.
   */
  void printAst(std::ostream & o, int indent = 0) const;

  NodeTemplate<true> eqNode(const NodeTemplate& right) const;

  NodeTemplate<true> notNode() const;
  NodeTemplate<true> andNode(const NodeTemplate& right) const;
  NodeTemplate<true> orNode(const NodeTemplate& right) const;
  NodeTemplate<true> iteNode(const NodeTemplate& thenpart,
                             const NodeTemplate& elsepart) const;
  NodeTemplate<true> iffNode(const NodeTemplate& right) const;
  NodeTemplate<true> impNode(const NodeTemplate& right) const;
  NodeTemplate<true> xorNode(const NodeTemplate& right) const;

private:

  /**
   * Indents the given stream a given amount of spaces.
   * @param out the stream to indent
   * @param indent the numer of spaces
   */
  static void indent(std::ostream& out, int indent) {
    for(int i = 0; i < indent; i++) {
      out << ' ';
    }
  }

};/* class NodeTemplate */

/**
 * Serializes a given node to the given stream.
 * @param out the output stream to use
 * @param node the node to output to the stream
 * @return the changed stream.
 */
inline std::ostream& operator<<(std::ostream& out, const Node& node) {
  node.toStream(out);
  return out;
}

}/* CVC4 namespace */

#include <ext/hash_map>

#include "expr/attribute.h"
#include "expr/node_manager.h"

namespace CVC4 {

// for hash_maps, hash_sets..
struct NodeHashFcn {
  size_t operator()(const CVC4::Node& node) const {
    return (size_t) node.hash();
  }
};

template <bool ref_count>
inline size_t NodeTemplate<ref_count>::getNumChildren() const {
  return d_nv->d_nchildren;
}

template <bool ref_count>
template <class AttrKind>
inline typename AttrKind::value_type NodeTemplate<ref_count>::
getAttribute(const AttrKind&) const {
  Assert( NodeManager::currentNM() != NULL,
          "There is no current CVC4::NodeManager associated to this thread.\n"
          "Perhaps a public-facing function is missing a NodeManagerScope ?" );
  return NodeManager::currentNM()->getAttribute(*this, AttrKind());
}

template <bool ref_count>
template <class AttrKind>
inline bool NodeTemplate<ref_count>::
hasAttribute(const AttrKind&) const {
  Assert( NodeManager::currentNM() != NULL,
          "There is no current CVC4::NodeManager associated to this thread.\n"
          "Perhaps a public-facing function is missing a NodeManagerScope ?" );
  return NodeManager::currentNM()->hasAttribute(*this, AttrKind());
}

template <bool ref_count>
template <class AttrKind>
inline bool NodeTemplate<ref_count>::hasAttribute(const AttrKind&,
                                                  typename AttrKind::value_type& ret) const {
  Assert( NodeManager::currentNM() != NULL,
          "There is no current CVC4::NodeManager associated to this thread.\n"
          "Perhaps a public-facing function is missing a NodeManagerScope ?" );
  return NodeManager::currentNM()->hasAttribute(*this, AttrKind(), ret);
}

template <bool ref_count>
template <class AttrKind>
inline void NodeTemplate<ref_count>::
setAttribute(const AttrKind&, const typename AttrKind::value_type& value) {
  Assert( NodeManager::currentNM() != NULL,
          "There is no current CVC4::NodeManager associated to this thread.\n"
          "Perhaps a public-facing function is missing a NodeManagerScope ?" );
  NodeManager::currentNM()->setAttribute(*this, AttrKind(), value);
}

template <bool ref_count>
NodeTemplate<ref_count> NodeTemplate<ref_count>::s_null(&expr::NodeValue::s_null);

////FIXME: This function is a major hack! Should be changed ASAP
////TODO: Should use positive definition, i.e. what kinds are atomic.
template <bool ref_count>
bool NodeTemplate<ref_count>::isAtomic() const {
  using namespace kind;
  switch(getKind()) {
  case NOT:
  case XOR:
  case ITE:
  case IFF:
  case IMPLIES:
  case OR:
  case AND:
    return false;
  default:
    return true;
  }
}

// FIXME: escape from type system convenient but is there a better
// way?  Nodes conceptually don't change their expr values but of
// course they do modify the refcount.  But it's nice to be able to
// support node_iterators over const NodeValue*.  So.... hm.
template <bool ref_count>
NodeTemplate<ref_count>::NodeTemplate(const expr::NodeValue* ev) :
  d_nv(const_cast<expr::NodeValue*> (ev)) {
  Assert(d_nv != NULL, "Expecting a non-NULL expression value!");
  if(ref_count) {
    d_nv->inc();
  }
}

// the code for these two "conversion/copy constructors" is identical, but
// apparently we need both.  see comment in the class.
template <bool ref_count>
NodeTemplate<ref_count>::NodeTemplate(const NodeTemplate<!ref_count>& e) {
  Assert(e.d_nv != NULL, "Expecting a non-NULL expression value!");
  d_nv = e.d_nv;
  if(ref_count) {
    d_nv->inc();
  }
}

template <bool ref_count>
NodeTemplate<ref_count>::NodeTemplate(const NodeTemplate& e) {
  Assert(e.d_nv != NULL, "Expecting a non-NULL expression value!");
  d_nv = e.d_nv;
  if(ref_count) {
    d_nv->inc();
  }
}

template <bool ref_count>
NodeTemplate<ref_count>::~NodeTemplate() throw(AssertionException) {
  Assert(d_nv != NULL, "Expecting a non-NULL expression value!");
  if(ref_count) {
    d_nv->dec();
  }
  Assert(ref_count || d_nv->d_rc > 0,
         "Temporary node pointing to an expired node");
}

template <bool ref_count>
void NodeTemplate<ref_count>::assignNodeValue(expr::NodeValue* ev) {
  d_nv = ev;
  if(ref_count) {
    d_nv->inc();
  }
}

template <bool ref_count>
NodeTemplate<ref_count>& NodeTemplate<ref_count>::
operator=(const NodeTemplate& e) {
  Assert(d_nv != NULL, "Expecting a non-NULL expression value!");
  Assert(e.d_nv != NULL, "Expecting a non-NULL expression value on RHS!");
  if(EXPECT_TRUE( d_nv != e.d_nv )) {
    if(ref_count) {
      d_nv->dec();
    }
    d_nv = e.d_nv;
    if(ref_count) {
      d_nv->inc();
    }
  }
  return *this;
}

template <bool ref_count>
NodeTemplate<ref_count>& NodeTemplate<ref_count>::
operator=(const NodeTemplate<!ref_count>& e) {
  Assert(d_nv != NULL, "Expecting a non-NULL expression value!");
  Assert(e.d_nv != NULL, "Expecting a non-NULL expression value on RHS!");
  if(EXPECT_TRUE( d_nv != e.d_nv )) {
    if(ref_count) {
      d_nv->dec();
    }
    d_nv = e.d_nv;
    if(ref_count) {
      d_nv->inc();
    }
  }
  return *this;
}

template <bool ref_count>
NodeTemplate<true>
NodeTemplate<ref_count>::eqNode(const NodeTemplate<ref_count>& right) const {
  return NodeManager::currentNM()->mkNode(kind::EQUAL, *this, right);
}

template <bool ref_count>
NodeTemplate<true> NodeTemplate<ref_count>::notNode() const {
  return NodeManager::currentNM()->mkNode(kind::NOT, *this);
}

template <bool ref_count>
NodeTemplate<true>
NodeTemplate<ref_count>::andNode(const NodeTemplate<ref_count>& right) const {
  return NodeManager::currentNM()->mkNode(kind::AND, *this, right);
}

template <bool ref_count>
NodeTemplate<true>
NodeTemplate<ref_count>::orNode(const NodeTemplate<ref_count>& right) const {
  return NodeManager::currentNM()->mkNode(kind::OR, *this, right);
}

template <bool ref_count>
NodeTemplate<true>
NodeTemplate<ref_count>::iteNode(const NodeTemplate<ref_count>& thenpart,
                                 const NodeTemplate<ref_count>& elsepart) const {
  return NodeManager::currentNM()->mkNode(kind::ITE, *this, thenpart, elsepart);
}

template <bool ref_count>
NodeTemplate<true>
NodeTemplate<ref_count>::iffNode(const NodeTemplate<ref_count>& right) const {
  return NodeManager::currentNM()->mkNode(kind::IFF, *this, right);
}

template <bool ref_count>
NodeTemplate<true>
NodeTemplate<ref_count>::impNode(const NodeTemplate<ref_count>& right) const {
  return NodeManager::currentNM()->mkNode(kind::IMPLIES, *this, right);
}

template <bool ref_count>
NodeTemplate<true>
NodeTemplate<ref_count>::xorNode(const NodeTemplate<ref_count>& right) const {
  return NodeManager::currentNM()->mkNode(kind::XOR, *this, right);
}

template <bool ref_count>
void NodeTemplate<ref_count>::printAst(std::ostream& out, int ind) const {
  indent(out, ind);
  out << '(';
  out << getKind();
  if(getKind() == kind::VARIABLE) {
    out << ' ' << getId();

  } else if(getNumChildren() >= 1) {
    for(const_iterator child = begin(); child != end(); ++child) {
      out << std::endl;
      NodeTemplate((*child)).printAst(out, ind + 1);
    }
    out << std::endl;
    indent(out, ind);
  }
  out << ')';
}

/**
 * Returns a node representing the operator of this expression.
 * If this is an APPLY, then the operator will be a functional term.
 * Otherwise, it will be a node with kind BUILTIN
 */
template <bool ref_count>
NodeTemplate<true> NodeTemplate<ref_count>::getOperator() const {
  switch(Kind k = getKind()) {
  case kind::APPLY:
    /* The operator is the first child. */
    return NodeTemplate<true>(d_nv->d_children[0]);

  case kind::EQUAL:
  case kind::ITE:
  case kind::TUPLE:
  case kind::NOT:
  case kind::AND:
  case kind::IFF:
  case kind::IMPLIES:
  case kind::OR:
  case kind::XOR:
  case kind::PLUS: {
    /* Returns a BUILTIN node. */
    /* TODO: construct a singleton at load-time? */
    /* TODO: maybe keep a table like the TheoryOfTable ? */
    NodeTemplate<true> n = NodeManager::currentNM()->mkNode(k);
    return NodeManager::currentNM()->mkNode(kind::BUILTIN, n);
  }

  case kind::FALSE:
  case kind::TRUE:
  case kind::SKOLEM:
  case kind::VARIABLE:
    IllegalArgument(*this, "getOperator() called on kind with no operator");

  default:
    Unhandled(getKind());
  }
}

/**
 * Returns true if the node has an operator (i.e., it's not a variable
 * or a constant).
 */
template <bool ref_count>
bool NodeTemplate<ref_count>::hasOperator() const {
  switch(getKind()) {
  case kind::APPLY:
  case kind::EQUAL:
  case kind::ITE:
  case kind::TUPLE:
  case kind::FALSE:
  case kind::TRUE:
  case kind::NOT:
  case kind::AND:
  case kind::IFF:
  case kind::IMPLIES:
  case kind::OR:
  case kind::XOR:
  case kind::PLUS:
    return true;

  case kind::SKOLEM:
  case kind::VARIABLE:
    return false;

  default:
    Unhandled(getKind());
  }
}

template <bool ref_count>
const Type* NodeTemplate<ref_count>::getType() const {
  Assert( NodeManager::currentNM() != NULL,
          "There is no current CVC4::NodeManager associated to this thread.\n"
          "Perhaps a public-facing function is missing a NodeManagerScope ?" );
  return NodeManager::currentNM()->getType(*this);
}

#ifdef CVC4_DEBUG
/**
 * Pretty printer for use within gdb.  This is not intended to be used
 * outside of gdb.  This writes to the Warning() stream and immediately
 * flushes the stream.
 *
 * Note that this function cannot be a template, since the compiler
 * won't instantiate it.  Even if we explicitly instantiate.  (Odd?)
 * So we implement twice.  We mark as __attribute__((used)) so that
 * GCC emits code for it even though static analysis indicates it's
 * never called.
 *
 * Tim's Note: I moved this into the node.h file because this allows gdb
 * to find the symbol, and use it, which is the first standard this code needs
 * to meet. A cleaner solution is welcomed.
 */
static void __attribute__((used)) debugPrintNode(const NodeTemplate<true>& n) {
  n.printAst(Warning(), 0);
  Warning().flush();
}

static void __attribute__((used)) debugPrintTNode(const NodeTemplate<false>& n) {
  n.printAst(Warning(), 0);
  Warning().flush();
}
#endif /* CVC4_DEBUG */

}/* CVC4 namespace */

#endif /* __CVC4__NODE_H */