Add abstract-factory pattern example

cpp/patterns/abstract-factory/abstract-factory.hpp

@@ -0,0 +1,60 @@
+
+#ifndef FACTORY_HPP
+#define FACTORY_HPP
+
+#include <array>
+#include <string>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+#include "parts.hpp"
+
+class AbstractFactory {
+public:
+  AbstractFactory(std::string name_): name(std::move(name_)) {}
+  virtual ~AbstractFactory() = default;
+
+  Part* requestPart();
+  Part* requestPart(std::string partName, float price);
+  void showStock() const;
+  std::string getName() const { return name;}
+
+protected:
+  virtual Part* makePart() = 0;
+  virtual Part* makePart(std::string name, float price) = 0;
+
+private:
+  std::string name;
+  std::unordered_map<std::string, int> inventory;
+};
+
+
+/*****************************************************************************/
+// Gear Concrete Factory
+
+class GearFactory : public AbstractFactory {
+public:
+  explicit GearFactory(std::string name_="GearFactory") :
+      AbstractFactory(std::move(name_)) {}
+
+protected:
+  Part* makePart() override;
+  Part* makePart(std::string name, float price);
+};
+
+
+/*****************************************************************************/
+// Spring Concrete Factory
+
+class SpringFactory : public AbstractFactory {
+public:
+  explicit SpringFactory (std::string name_="SpringFactory"):
+      AbstractFactory(std::move(name_)) {}
+
+protected:
+  Part* makePart() override;
+  Part* makePart(std::string name, float price);
+};
+
+#endif // FACTORY_HPP