MoveIterator.h

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// cwchessboard -- A C++ chessboard tool set
//
//! @file MoveIterator.h This file contains the declaration of class MoveIterator.
//
// Copyright (C) 2008 - 2010, by
// 
// Carlo Wood, Run on IRC <carlo@alinoe.com>
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// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#ifndef MOVEITERATOR_H
#define MOVEITERATOR_H

#ifndef USE_PCH
#include <iterator>
#endif

#include "Move.h"
#include "BitBoard.h"
#include "Piece.h"

#define CWCHESSBOARD_LIKELY(condition) __builtin_expect(condition, true)

namespace cwchess {

class ChessPosition;

/** @brief Non-mutable iterator over all moves of a given chess piece.
* 
 * This iterator generates the Move objects while advancing to the next
 * move, storing the result in a member variable. The lifetime of the reference
 * or pointer to the Move is therefore equal to the lifetime of the iterator:
 * calling the increment or decrement operators overwrites the previous move.
* 
 * Usage example:
* 
 * \code
 * for (MoveIterator move_iter = chess_position.move_begin(index); move_iter != chess_position.move_end(); ++move_iter)
 * {
 *   Move const& move(*move_iter);
 *   // Use 'move'.
 * }
 * \endcode
* /
class MoveIterator : public std::iterator<std::bidirectional_iterator_tag, Move> {
  protected:
    ChessPosition const* M_chess_position;      //!< The underlaying chess position.
    BitBoard M_targets;                         //!< The targets that this piece can move to.
    Move M_current_move;                        //!< The actual move that is returned when dereferenced.

  public:
  /** @name Constructors* /
  //@{

    // Default Constructible.
    /** @brief Construct a one-past-the-end MoveIterator.
    * 
     * @sa ChessPosition::move_end()
    * /
    MoveIterator(void) : M_current_move(index_end, index_end, nothing) { }

    // Assignable.
    //! @brief Copy-Constructor.
    MoveIterator(MoveIterator const& iter) :
        M_chess_position(iter.M_chess_position), M_targets(iter.M_targets), M_current_move(iter.M_current_move) { }

    /** @brief Construct a fully initialized MoveIterator.
    * 
     * @param chess_position : The ChessPosition that we're generating moves for.
     * @param index : The index of the piece that we're generating moves for.
    * 
     * @sa ChessPosition::move_begin(Index const&)
    * /
    MoveIterator(ChessPosition const* chess_position, Index const& index);

  //@}

  /** @name Assignment operator* /
  //@{

    //! @brief Assignment operator.
    MoveIterator& operator=(MoveIterator const& iter)
        { M_chess_position = iter.M_chess_position; M_targets = iter.M_targets; M_current_move = iter.M_current_move; return* this; }

  //@}

  /** @name Comparision operators* /
  //@{

    // Equality Comparable.
    bool operator==(MoveIterator const& iter) const { return M_current_move == iter.M_current_move; }
    bool operator!=(MoveIterator const& iter) const { return M_current_move != iter.M_current_move; }

  //@}

  /** @name Accessors* /
  //@{

    // Dereferencable.
    Move const& operator*() const { return M_current_move; }
    Move const* operator->(void) const { return& M_current_move; }

  //@}

  /** @name Increment and decrement operators* /
  //@{

    // Bi-directional iterator.
    MoveIterator& operator++()
        {
          if (CWCHESSBOARD_LIKELY(!M_current_move.is_promotion()) || next_promotion())
          {
            Index current_index(M_current_move.to());
            current_index.next_bit_in(M_targets());
            M_current_move.set_to(current_index);
          }
          return* this;
        }

    MoveIterator operator++(int) { MoveIterator result(*this); operator++(); return result; }

    MoveIterator& operator--()
        {
          if (CWCHESSBOARD_LIKELY(!M_current_move.is_promotion()) || prev_promotion())
          {
            Index current_index(M_current_move.to());
            current_index.prev_bit_in(M_targets());
            M_current_move.set_to(current_index);
          }
          return* this;
        }

    MoveIterator operator--(int) { MoveIterator result(*this); operator--(); return result; }

  //@}

  public_notdocumented:
    // Indexing.
    uint32_t index(void) const { return M_current_move.to()(); } 

  private:
    bool next_promotion(void);
    bool prev_promotion(void);

    Index get_first_bitindex(void) const { Index result(index_pre_begin); result.next_bit_in(M_targets()); return result; }

    Type initial_type(Index const& index) const;
};

} // namespace cwchess

#endif  // MOVEITERATOR_H