Piece.h

#ifndef PIECE_H
#define PIECE_H

#include <utility>

namespace Chess
{
  class Piece {

  public:
    // The destructor for Piece is declared virtual so derived classes can override it
    virtual ~Piece(){}

    // Returns information about the color of the piece.
    bool is_white() const { return white; }

    // Indicates whether the given start and end coordinates describe a move that
    // would be considered valid for this piece if there is no piece at the end
    // position (i.e. this is not a capture move)
    virtual bool legal_move_shape(std::pair<char, char> start,
                    std::pair<char, char> end) const = 0;

    // Indicates whether the given start and end coordinates describe a move that
    // would be considered valid for this piece if there is a piece at the end
    // position (i.e. this is a capture move)
    virtual bool legal_capture_shape(std::pair<char, char> start,
                     std::pair<char, char> end) const {
      return legal_move_shape(start, end);
    }

    // Returns a character representing the piece type. Should be upper-case
    // for white and lower-case for black. Characters are:
    //    King:    K/k
    //    Queen:    Q/q
    //    Bishop:    B/b
    //    Knight:    N/n
    //    Rook:    R/r
    //    Pawn:    P/p
    //    Mystery:  M/m
    virtual char to_ascii() const = 0;

  protected:
    // When a piece is created, its color must be provided as an argument
    Piece(bool is_white) : white(is_white){ }

  private:
    // A boolean value indicating whether the piece is white or black
    bool white;
  };
}
#endif // PIECE_H