【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(0, "back on empty Blob");
    return data->back();
}

template <typename T>
T& Blob<T>::front()
{
    check(0, "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)[];
}