using System;
using System.Collections.Generic;
namespace DoFactory.GangOfFour.Composite.RealWorld
{
/// <summary>
/// MainApp startup class for Real-World
/// Composite Design Pattern.
/// </summary>
class MainApp
{
/// <summary>
/// Entry point into console application.
/// </summary>
static void Main()
{
// Create a tree structure
CompositeElement root =
new CompositeElement("Picture");
root.Add(new PrimitiveElement("Red Line"));
root.Add(new PrimitiveElement("Blue Circle"));
root.Add(new PrimitiveElement("Green Box"));
// Create a branch
CompositeElement comp =
new CompositeElement("Two Circles");
comp.Add(new PrimitiveElement("Black Circle"));
comp.Add(new PrimitiveElement("White Circle"));
root.Add(comp);
// Add and remove a PrimitiveElement
PrimitiveElement pe =
new PrimitiveElement("Yellow Line");
root.Add(pe);
root.Remove(pe);
// Recursively display nodes
root.Display(1);
// Wait for user
Console.ReadKey();
}
}
/// <summary>
/// The 'Component' Treenode
/// </summary>
abstract class DrawingElement
{
protected string _name;
// Constructor
public DrawingElement(string name)
{
this._name = name;
}
public abstract void Add(DrawingElement d);
public abstract void Remove(DrawingElement d);
public abstract void Display(int indent);
}
/// <summary>
/// The 'Leaf' class
/// </summary>
class PrimitiveElement : DrawingElement
{
// Constructor
public PrimitiveElement(string name)
: base(name)
{
}
public override void Add(DrawingElement c)
{
Console.WriteLine(
"Cannot add to a PrimitiveElement");
}
public override void Remove(DrawingElement c)
{
Console.WriteLine(
"Cannot remove from a PrimitiveElement");
}
public override void Display(int indent)
{
Console.WriteLine(
new String('-', indent) + " " + _name);
}
}
/// <summary>
/// The 'Composite' class
/// </summary>
class CompositeElement : DrawingElement
{
private List<DrawingElement> elements =
new List<DrawingElement>();
// Constructor
public CompositeElement(string name)
: base(name)
{
}
public override void Add(DrawingElement d)
{
elements.Add(d);
}
public override void Remove(DrawingElement d)
{
elements.Remove(d);
}
public override void Display(int indent)
{
Console.WriteLine(new String('-', indent) +
"+ " + _name);
// Display each child element on this node
foreach (DrawingElement d in elements)
{
d.Display(indent + 2);
}
}
}
}