【C++ Primer 第六章】 1. 定义模板

类模板

题目描述：实现StrBlob的模板版本。

 /*    Blob.h    */
 #include<iostream>
 #include<vector>
 #include<initializer_list>
 #include<memory>
 using namespace std;

 template <typename T> class Blob {
 public:
     typedef typename vector<T>::size_type size_type;
     Blob();
     Blob(initializer_list<T> il);

     size_type size() const { return data->size(); }
     bool empty() const { return data->empty(); }
     void push_back(const T &t) { data->push_back(t); }
     void push_back(T &&t) { data->push_back(std::move(t)); }

     T& back();
     T& front();
     T& operator[](size_type i);
 private:
     shared_ptr<vector<T>> data;
     void check(size_type i, const T &msg);
 };

 template <typename T>
 Blob<T>::Blob(): data(make_shared<vector<T>()) {}

 template <typename T>
 Blob<T>::Blob(initializer_list<T> il): data(make_shared<vector<T>>(il)) {}

 template <typename T>
 void Blob<T>::check(size_type i, const T& msg)
 {
     if (i >= data->size())
         throw out_of_range(msg);
 }

 template <typename T>
 T& Blob<T>::back()
 {
     check(, "back on empty Blob");
     return data->back();
 }

 template <typename T>
 T& Blob<T>::front()
 {
     check(, "front on empty Blob");
     return data->front();
 }

 template <typename T>
 T& Blob<T>::operator[](size_type i)
 {
     check(i, "subscript out of range");
     return (*data)[];
 }