Added builder example source code.

examples/creational/builder.cpp

@@ -0,0 +1,114 @@
+#include <iostream>
+#include <memory>
+
+class BurgerBuilder;
+
+class Burger
+{
+  public:
+    typedef std::shared_ptr<Burger> ptr_t;
+    Burger(BurgerBuilder* builder);
+    void getDescription(void);
+
+  private:
+    int patties_;
+    bool cheese_;
+    bool pepperoni_;
+    bool lettuce_;
+    bool tomato_;
+};
+
+class BurgerBuilder
+{
+  public:
+    BurgerBuilder(int patties)
+        : patties(patties), cheese(false), pepperoni(false), lettuce(false),
+          tomato(false)
+    {
+    }
+
+    BurgerBuilder& addCheese(void)
+    {
+      cheese = true;
+      return (*this);
+    }
+
+    BurgerBuilder& addPepperoni(void)
+    {
+      pepperoni = true;
+      return (*this);
+    }
+
+    BurgerBuilder& addLettuce(void)
+    {
+      lettuce = true;
+      return (*this);
+    }
+
+    BurgerBuilder& addTomato(void)
+    {
+      tomato = true;
+      return (*this);
+    }
+
+    Burger::ptr_t build(void)
+    {
+      Burger::ptr_t burger(new Burger(this));
+      return burger;
+    }
+
+    int patties;
+    bool cheese;
+    bool pepperoni;
+    bool lettuce;
+    bool tomato;
+};
+
+Burger::Burger(BurgerBuilder* builder)
+    : patties_(builder->patties), cheese_(builder->cheese),
+      pepperoni_(builder->pepperoni), lettuce_(builder->lettuce),
+      tomato_(builder->tomato)
+{
+}
+
+void Burger::getDescription(void)
+{
+  std::cout << patties_ << " patties";
+  if (cheese_) {
+    std::cout << ", cheese";
+  }
+  if (pepperoni_) {
+    std::cout << ", pepperoni";
+  }
+  if (lettuce_){
+    std::cout << ", lettuce";
+  }
+  if (tomato_) {
+    std::cout << ", tomato";
+  }
+  std::cout << std::endl;
+}
+
+int main()
+{
+  // One double patty burger with no dairy.
+  Burger::ptr_t burger = BurgerBuilder(2).
+      addPepperoni().
+      addLettuce().
+      addTomato().
+      build();
+  // Output: 2 patties, pepperoni, lettuce, tomato
+  burger->getDescription();
+
+  // One triple patty buger with everything.
+  Burger::ptr_t burger2 = BurgerBuilder(3).
+      addPepperoni().
+      addCheese().
+      addLettuce().
+      addTomato().
+      build();
+  // Output: 3 patties, cheese, pepperoni, lettuce, tomato
+  burger2->getDescription();
+
+  return 0;
+}