/******************************************************************************
  Lab #10 -- Interface file for type "Sequence" (chained implementation)
******************************************************************************/

#ifndef SEQUENCE_
#define SEQUENCE_

#include <cstdlib>
#include <new>

typedef double EType;

/*-----------------------------------------------------------------------------
   Type "Sequence" represents an unordered sequence of N items (in positions 0
   to N-1), where each item is of type "EType".  Duplicate items are allowed.

   Type "EType" must support "operator=()" and "operator==()".
-----------------------------------------------------------------------------*/

class Sequence
{
  public:

    // Initialize the sequence
    //
    Sequence();

    // De-initialize the sequence
    //
    ~Sequence();

    // Re-initialize the sequence
    //
    void reset();

    // Return status information
    //
    unsigned length() const { return Num; }
    bool is_empty() const { return Num == 0; }

    // Return the position of a specified item (unless it is not present)
    //
    unsigned find( const EType& X ) const;

    // Retrieve an item from position I (unless I is not valid)
    //
    bool retrieve( EType& X, unsigned I ) const;

    // Remove an item from position I (unless I is not valid)
    //
    bool remove( EType& X, unsigned I );

    // Insert an item at position I (unless I is not valid)
    //
    bool insert( const EType& X, unsigned I );

  private:

    struct Node
    {
      EType Item;
      Node * Next;
    };

    unsigned Num;    // Number of items in the sequence
    Node * Head;     // Pointer to node at head of sequence

    // Disabled operations
    //
    Sequence( const Sequence& RHS ) { exit( 1 ); }
    Sequence& operator=( const Sequence& RHS ) { exit( 1 ); }
};

#endif