program System_Collections_CollectionBase;
{$APPTYPE CONSOLE}
{$AUTOBOX ON}

uses System.Collections;

type
  Int16Collection = class(CollectionBase)
  public
    function get_Item(index: Integer): Int16;
    procedure set_Item(index: Integer; const Value: Int16);

    function Add(value: Int16): Integer;
    function IndexOf(value: Int16): Integer;
    procedure Insert(index: Integer; value: Int16);
    procedure Remove(value: Int16);
    function Contains(value: Int16): Boolean;

    property Item[index: Integer]: Int16
             read get_Item
             write set_Item;
             default;
  strict protected
    procedure OnInsert(index: Integer;
                       value: System.Object); override;
    procedure OnRemove(index: Integer;
                       value: System.Object); override;
    procedure OnSet(index: Integer;
                    oldValue: System.Object;
                    newValue: System.Object); override;
    procedure OnValidate(value: System.Object); override;
  end;

  SamplesCollectionBase = class
  public
    class procedure Main;
  private
    class procedure PrintIndexAndValues
                    (myCol: Int16Collection);
  end;


{ SamplesCollectionBase }

class procedure SamplesCollectionBase.Main;
var
  i: Integer;
  myI16: Int16Collection;
begin
  // Creates and initializes a new CollectionBase
  myI16 := Int16Collection.Create;
  myI16.Add(Int16(1));
  myI16.Add(Int16(2));
  myI16.Add(Int16(3));
  myI16.Add(Int16(5));
  myI16.Add(Int16(7));

  // Displays the contents of the 
  //collection using the enumerator
  Console.WriteLine('Initial contents of the collection:');
  PrintIndexAndValues(myI16);

  // Searches the collection with Contains and IndexOf
  Console.WriteLine('Contains 3: {0}', 
                    myI16.Contains(3));
  Console.WriteLine('2 is at index {0}.', 
                    myI16.IndexOf(2));
  Console.WriteLine;

  // Inserts an element into the collection at index 3
  myI16.Insert(3, (Int16(13)));
  Console.WriteLine('Contents of the collection 
                     after inserting at index 3:');
  PrintIndexAndValues(myI16);

  // Gets and sets an element using the index.
  myI16[4] := 123;
  Console.WriteLine('Contents of the collection after 
                     setting the element at index 4 to 123:');
  PrintIndexAndValues(myI16);

  // Removes an element from the collection
  myI16.Remove((Int16(2)));

  // Displays the contents of 
  //the collection using the index.
  Console.WriteLine('Contents of the collection 
                     after removing the element 2:');
  i := 0;
  while (i < myI16.Count) do
  begin
    Console.WriteLine('[{0}]:   {1}', i, myI16[i]);
    i := i + 1;
  end;
end;

class procedure SamplesCollectionBase.PrintIndexAndValues
                (myCol: Int16Collection);
var
  myEnumerator: System.Collections.IEnumerator;
  i: Integer;
begin
  i := 0;
  myEnumerator := myCol.GetEnumerator;
  while myEnumerator.MoveNext do
  begin
    Console.WriteLine('[{0}]:   {1}',
                      i,
                      myEnumerator.Current);
    i:=i+1;
  end;
  Console.WriteLine;
end;

{ Int16Collection }

function Int16Collection.Add(value: Int16): Integer;
begin
  Result := List.Add(value);
end;

function Int16Collection.Contains(value: Int16): Boolean;
begin
  // If value is not of type Int16, this will return false.
  Result := List.Contains(value);
end;

function Int16Collection.get_Item(index: Integer): Int16;
begin
  Result := (Int16(List[index]));
end;

function Int16Collection.IndexOf(value: Int16): Integer;
begin
  Result := List.IndexOf(value);
end;

procedure Int16Collection.Insert
           (index: Integer; value: Int16);
begin
  List.Insert(index, value);
end;

procedure Int16Collection.OnInsert
          (index: Integer; value: System.Object);
begin
  if (value.GetType <>  System.Type.GetType('System.Int16')) 
  then
    raise ArgumentException.Create
            ('value must be of type Int16.', 
             'value');
end;

procedure Int16Collection.OnRemove
          (index: Integer; value: System.Object);
begin
 if (value.GetType <> System.Type.GetType('System.Int16')) 
 then
    raise ArgumentException.Create
               ('value must be of type Int16.', 
                'value');
end;

procedure Int16Collection.OnSet
          (index: Integer; oldValue, newValue: System.Object);
begin
  if (newValue.GetType <> System.Type.GetType('System.Int16')) 
  then
    raise ArgumentException.Create
              ('newValue must be of type Int16.', 
               'newValue');
end;

procedure Int16Collection.OnValidate
          (value: System.Object);
begin
  if (value.GetType <> System.Type.GetType('System.Int16')) 
  then
    raise ArgumentException.Create
           ('value must be of type Int16.');
end;

procedure Int16Collection.Remove(value: Int16);
begin
  List.Remove(value);
end;

procedure Int16Collection.set_Item
          (index: Integer; const Value: Int16);
begin
  List[index] := value;
end;

//test program
begin
  SamplesCollectionBase.Main;
end.