最近心血来潮想在C++里实现一些像在python里一样好用的小组件，主要是希望充分发挥C++11里for循环的威力。在完成了enumerate之后，在zip的完成上用了比较久的时间。
在这里记录下来自己对zip的简单实现。
主要就用了模板递归，结合了一些C++11的新特性完成的。
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| #pragma once
namespace twistoy {
template<typename first, typename... last>
class zip_iterator {
public:
using value_type = std::tuple<typename first::reference, typename last::reference...>;
using rebind = zip_iterator<first, last...>;
using sub_iterator = zip_iterator<last...>;
private:
first it_;
sub_iterator sub_it_;
public:
zip_iterator(first it, sub_iterator sub_it) : it_(it), sub_it_(sub_it) {}
rebind& operator++() {
++it_;
++sub_it_;
return *this;
}
value_type operator *() {
return std::tuple_cat(std::tuple<typename first::reference>(*it_), *sub_it_);
}
bool operator != (const rebind& others) const {
return (it_ != others.it_) && (sub_it_ != others.sub_it_);
}
};
template<typename first>
class zip_iterator<first> {
public:
using value_type = std::tuple<typename first::reference>;
using rebind = zip_iterator<first>;
private:
first it_;
public:
zip_iterator(first it) : it_(it) {}
value_type operator *() {
return value_type(*it_);
}
rebind& operator++() {
++it_;
return *this;
}
bool operator != (const rebind& others) const {
return it_ != others.it_;
}
};
template<typename first, typename... last>
class zip_impl : zip_impl<last...> {
public:
using iterator = zip_iterator<typename first::iterator, typename last::iterator...>;
private:
first& value_;
public:
zip_impl(first& value, last&... args) : value_(value), zip_impl<last...>(args...) {}
iterator begin() {
return iterator(value_.begin(), zip_impl<last...>::begin());
}
iterator end() {
return iterator(value_.end(), zip_impl<last...>::end());
}
};
template<typename first>
class zip_impl<first> {
public:
using iterator = zip_iterator<typename first::iterator>;
private:
first& value_;
public:
zip_impl(first& value) : value_(value) {}
iterator begin() {
return iterator(value_.begin());
}
iterator end() {
return iterator(value_.end());
}
};
template<typename... args_t>
zip_impl<typename std::decay<args_t>::type...> zip(args_t&... args) {
zip_impl<typename std::decay<args_t>::type...> tmp(args...);
return tmp;
}
}
|
Hawtian Wang
