// Flyweight pattern -- Real World example

using System;
using System.Collections;

namespace DoFactory.GangOfFour.Flyweight.RealWorld
{

// MainApp test application

class MainApp
{
static void Main()
{
// Build a document with text
string document = "AAZZBBZB";
char[] chars = document.ToCharArray();

CharacterFactory f = new CharacterFactory();

// extrinsic state
int pointSize = 10;

// For each character use a flyweight object
foreach (char c in chars)
{
pointSize++;
Character character = f.GetCharacter(c);
character.Display(pointSize);
}

// Wait for user
Console.Read();
}
}

// "FlyweightFactory"

class CharacterFactory
{
private Hashtable characters = new Hashtable();

public Character GetCharacter(char key)
{
// Uses "lazy initialization"
Character character = characters[key] as Character;
if (character == null)
{
switch (key)
{
case 'A': character = new CharacterA(); break;
case 'B': character = new CharacterB(); break;
//...
case 'Z': character = new CharacterZ(); break;
}
characters.Add(key, character);
}
return character;
}
}

// "Flyweight"

abstract class Character
{
protected char symbol;
protected int width;
protected int height;
protected int ascent;
protected int descent;
protected int pointSize;

public abstract void Display(int pointSize);
}

// "ConcreteFlyweight"

class CharacterA : Character
{
// Constructor
public CharacterA()
{
this.symbol = 'A';
this.height = 100;
this.width = 120;
this.ascent = 70;
this.descent = 0;
}

public override void Display(int pointSize)
{
this.pointSize = pointSize;
Console.WriteLine(this.symbol +
" (pointsize " + this.pointSize + ")");
}
}

// "ConcreteFlyweight"

class CharacterB : Character
{
// Constructor
public CharacterB()
{
this.symbol = 'B';
this.height = 100;
this.width = 140;
this.ascent = 72;
this.descent = 0;
}

public override void Display(int pointSize)
{
this.pointSize = pointSize;
Console.WriteLine(this.symbol +
" (pointsize " + this.pointSize + ")");
}

}

// ... C, D, E, etc.

// "ConcreteFlyweight"

class CharacterZ : Character
{
// Constructor
public CharacterZ()
{
this.symbol = 'Z';
this.height = 100;
this.width = 100;
this.ascent = 68;
this.descent = 0;
}

public override void Display(int pointSize)
{
this.pointSize = pointSize;
Console.WriteLine(this.symbol +
" (pointsize " + this.pointSize + ")");
}
}
}