1 #ifndef MSP_CORE_VARIANT_H_
2 #define MSP_CORE_VARIANT_H_
11 class type_mismatch: public std::runtime_error
14 type_mismatch(const std::type_info &, const std::type_info &);
23 virtual ~StoreBase() { }
25 virtual const std::type_info &type_id() const = 0;
26 virtual StoreBase *clone() const = 0;
27 virtual bool type_equals(const StoreBase &) const = 0;
28 virtual bool value_equals(const StoreBase &) const = 0;
32 struct Store: public StoreBase
36 Store(const T &d): data(d) { }
38 const std::type_info &type_id() const override { return typeid(T); }
39 StoreBase *clone() const override { return new Store<T>(data); }
40 bool type_equals(const StoreBase &s) const override { return dynamic_cast<const Store<T> *>(&s); }
41 bool value_equals(const StoreBase &s) const override { return _value_equals<T>(s); }
44 typename std::enable_if<IsEqualityComparable<U>::value, bool>::type _value_equals(const StoreBase &s) const
45 { const Store<T> *t = dynamic_cast<const Store<T> *>(&s); return (t && t->data==data); }
48 typename std::enable_if<!IsEqualityComparable<U>::value, bool>::type _value_equals(const StoreBase &) const
52 StoreBase *store = nullptr;
57 Variant(const T &v): store(new Store<typename std::remove_cv<T>::type>(v)) { }
58 Variant(const Variant &v): store(v.store ? v.store->clone() : nullptr) { }
59 ~Variant() { delete store; }
62 Variant &operator=(const T &v)
65 store = new Store<typename std::remove_cv<T>::type>(v);
69 Variant &operator=(const Variant &v)
75 store = (v.store ? v.store->clone() : nullptr);
81 Store<typename std::remove_cv<T>::type> *get_typed_store() const
83 typedef typename std::remove_cv<T>::type NCT;
84 Store<NCT> *s = dynamic_cast<Store<NCT> *>(store);
86 throw type_mismatch(typeid(T), (store ? store->type_id() : typeid(void)));
94 return get_typed_store<T>()->data;
98 const T &value() const
100 return get_typed_store<T>()->data;
104 bool check_type() const
106 return dynamic_cast<Store<typename std::remove_cv<T>::type> *>(store);
109 bool check_same_type(const Variant &v) const
110 { return store && v.store && store->type_equals(*v.store); }
112 bool operator==(const Variant &v) const
113 { return store && v.store && store->value_equals(*v.store); }
115 bool operator!=(const Variant &v) const
116 { return !(operator==(v)); }
120 { return value<T>(); }