/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
 *  Main authors:
 *     Guido Tack <tack@gecode.org>
 *
 *  Copyright:
 *     Guido Tack, 2006
 *
 *  Last modified:
 *     $Date: 2010-08-12 21:38:27 +1000 (Thu, 12 Aug 2010) $ by $Author: zayenz $
 *     $Revision: 11349 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#ifndef GECODE_GIST_NODE_HH
#define GECODE_GIST_NODE_HH

#include <gecode/kernel.hh>

namespace Gecode { namespace Gist {

  class VisualNode;

  /// Node allocator
  template<class T>
  class NodeAllocatorBase {
  private:
    /// Size of each block of nodes
    static const int NodeBlockSize = 1<<14;
    /// Blocks of nodes
    class Block {
    public:
      /// The actual nodes
      T b[NodeBlockSize];
      /// The index of the best known previous solution for each node
      int best[NodeBlockSize];
    };
    /// Array of blocks
    Block** b;
    /// Size of the array
    int n;
    /// Current block number
    int cur_b;
    /// Current node number in current block
    int cur_t;
    /// Allocate new block, potentially reallocate block array
    void allocate(void);
    /// Flag whether search uses branch-and-bound
    bool _bab;
  public:
    /// Constructor
    NodeAllocatorBase(bool bab);
    /// Destructor
    ~NodeAllocatorBase(void);
    /// Allocate new node with parent \a p
    int allocate(int p);
    /// Allocate new root node for space \a root
    int allocate(Space* root);
    /// Return node for index \a i
    T* operator [](int i) const;
    /// Return index of best node before \a i
    T* best(int i) const;
    /// Set index of best node before \a i to \a b
    void setBest(int i, int b);
    /// Return branch-and-bound flag
    bool bab(void) const;
  };

  /// \brief Base class for nodes of the search tree
  class Node {
  private:
    /// Tags that are used to encode the number of children
    enum {
      UNDET, //< Number of children not determined
      LEAF,  //< Leaf node
      TWO_CHILDREN, //< Node with at most two children
      MORE_CHILDREN //< Node with more than two children
    };

    /// The children, or in case there are at most two, the first child
    void* childrenOrFirstChild;

    /** The number of children, in case it is greater than 2, or the first
     *  child (if negative)
     */
    int noOfChildren;

    /// The parent of this node, or NULL for the root
    int parent;

    /// Read the tag of childrenOrFirstChild
    unsigned int getTag(void) const;
    /// Set the tag of childrenOrFirstChild
    void setTag(unsigned int tag);
    /// Return childrenOrFirstChild without tag
    void* getPtr(void) const;
    /// Return childrenOrFirstChild as integer
    int getFirstChild(void) const;

  protected:
    /// Return whether this node is undetermined
    bool isUndetermined(void) const;

    /// Return index of child no \a n
    int getChild(int n) const;
  public:
    typedef NodeAllocatorBase<VisualNode> NodeAllocator;

    /// Construct node with parent \a p
    Node(int p, bool failed = false);

    /// Return the parent
    int getParent(void) const;
    /// Return the parent
    VisualNode* getParent(const NodeAllocator& na) const;
    /// Return child no \a n
    VisualNode* getChild(const NodeAllocator& na, int n) const;

    /// Return index of this node
    int getIndex(const NodeAllocator& na) const;

    /// Check if this node is the root of a tree
    bool isRoot(void) const;

    /// Set the number of children to \a n and initialize children
    void setNumberOfChildren(unsigned int n, NodeAllocator& na);

    /// Return the number of children
    unsigned int getNumberOfChildren(void) const;
    
  };

}}

#endif

// STATISTICS: gist-any