// The test harness will belong to the following package; the hash table
// implementation will belong to it as well.  In addition, the hash table
// implementation will specify package access for all data members in order 
// that the test harness may have access to them.
//
package Minor.P3.DS;

public class HashTable<T extends Hashable> {

    T[]         Table;        // stores data objects
    slotState[] Status;       // stores corresponding status values
    int         Size;         // dimension of Table
    int         Usage;        // # of data objects stored in Table
    FileWriter  Log;          // target of logged output
    boolean     loggingOn;    // write output iff this is true

    // Construct hash table with specified size.
    // Pre:
    //      Sz is a positive integer of the form 2^k.
    // Post:
    //      this.Table is an array of dimension Sz; all entries are null
    //      this.Status is an array of dimension Sz; all entries are EMPTY
    //      this.Usage == 0
    //      this.Log == null
    //      this.loggingOn == false
    //      
    public HashTable(int Sz) { . . . }

    
    // Attempt insertion of Elem. 
    // Pre:
    //      Elem is a proper object of type T
    // Post:
    //      If Elem already occurs in Table (according to equals()):
    //         this.Table is unchanged
    //         this.Usage is unchanged
    //      Otherwise:
    //         Elem is added to Table
    //         this.Usage is incremented
    //      If loggingOn == true:
    //         indices accessed during search are written to Log and
    //         success/failure message is written to Log
    // Return: reference to inserted object or null if insertion fails
    //
    public T Insert(T Elem) throws IOException { . . . }
    
    // Search Table for match to Elem (according to equals()).
    // Pre:
    //      Elem is a proper object of type T
    // Post:
    //      No member of the hash table object is changed.
    //      If loggingOn == true:
    //         indices accessed during search are written to Log and
    //         success/failure message is written to Log
    // Return reference to matching data object, or null if no match 
    //      is found.
    public T Find(T Elem) throws IOException { . . . }
    
    // Delete data object that matches Elem.
    // Pre:
    //      Elem is a proper object of type t
    // Post:
    //      If Elem does not occur in Table (according to equals()):
    //         this.Table is unchanged
    //         this.Usage is unchanged
    //      Otherwise:
    //         matching reference in Table is null
    //         this.Usage is decremented
    //      If loggingOn == true:
    //         indices accessed during search are written to Log and
    //         success/failure message is written to Log
    // Return reference to deleted object, or null if not found.
    public T Delete(T Elem) throws IOException { . . . }
    
    // Reset hash table to (almost) same state as when first constructed.
    // Post:
    //      this.Table is an array of dimension Sz; all entries are null
    //      this.Status is an array of dimension Sz; all entries are
    //           EMPTY
    //      this.Opt is unchanged
    //      this.Usage == 0
    //      this.Log  is unchanged
    //      this.loggingOn is unchanged
    // 
    public void Clear() { . . . }
    

    // Reset hash table's log output target.
    // Pre:
    //      Log is an open on a file, or is null
    // Post:
    //      If Log is null, no changes are made.
    //      Otherwise: this.Log == Log
    // Return true iff this.Log has been changed and is not null.
    //
    public boolean setLog(FileWriter Log) { . . . }
    
    // Turn internal logging on.
    // Post:
    //      If this.Log is not null, loggingOn == true
    //      Otherwise, loggingOn == false
    // Returns final value of loggingOn.
    //
    public boolean logOn() { . . . }
    
    // Turn internal logging off.
    // Post:
    //      loggingOn == false
    // Returns final value of loggingOn.
    //
    public boolean logOff() { . . . }
}