Lecture 08.md

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ТУТ КАКОЕ ТО ГОВНО, СОРИ

Еще о вариадиках

void f(int, int, int);
bind(f, 1, 2, 3)(); 			 //f(1, 2, 3)
bind(f, 4, _1, 5)(6); 			 //f(4, 6, 5)
bind(f, _3, _2, _1)(7, 8, 9);    //f(9, 8, 7)
bind(f, _2, _2, _3)(10, 11, 12); //f(11, 11, 12)
bind(f, -1, bind(g, _2, 42), 43)(44, 45); //f(44, g(45, 42), 43)

Идея
Пусть f принимает n аргументов, bindвызываем с k аргументами

f(g1(a1, a2, ..., ak), ..., gn(a1, a2, ..., ak));
bind(f, 1, 2, 3)(4, 5, 6) назовем bind(f, b1, b2, b3)(a1, a2, a3);
template <typename F, typename ... Bs>
bind_f <F, Bs ...> bind(F f, Bs ... bs) {
return bind_f<F, BS ..>(move(f), move(bs) ...);
}
template <typename T>
struct G {
G(T value) : value(move(value)){}
<span class="token keyword">template</span> <span class="token operator">&lt;</span><span class="token keyword">typename</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> As<span class="token operator">&gt;</span>
T <span class="token function">opetator</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">(</span>As <span class="token keyword">const</span><span class="token operator">&amp;</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> as<span class="token punctuation">)</span> <span class="token punctuation">{</span>
	<span class="token keyword">return</span> value<span class="token punctuation">;</span>
<span class="token punctuation">}</span>

private:
T value;
}
template <size_t N>
struct G<placeholder<N>> {
template <typename A, typename... As>
auto operator()(A const& a0, As const& ... as) {
return G<N - 1>()(As);
}
}
template <>
struct G<placeholder<0>> {
template <typename A, typename... As>
A operator()(A const& a, As const& ... as) {
return a;
}
}
template<size_t ... Indices>
struct index_tuple {};
template<size_t N, size_t ... Indices>
struct make_index_tuple {
typedef make_index_tuple<N - 1, N - 1, Indices ...>::type type;
}
template <size_t ... Indices>
struct make_index_tuple<0> {
typedef index_tuple<Indeces ...> type;
}
template <typename F, typename ... Bs>
struct bind_f {
bind_f(F f, Bs ... bs) : f(move(f)), gs(move(bs)...) {}
auto call(index_tuple<Indices...>, As const& ... as) {
return f(get<Indices>(gs)(as ...)...);
}
<span class="token keyword">auto</span> <span class="token keyword">operator</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">(</span>As <span class="token keyword">const</span><span class="token operator">&amp;</span> as<span class="token punctuation">)</span> <span class="token punctuation">{</span>
	<span class="token keyword">return</span> <span class="token function">call</span><span class="token punctuation">(</span>make_index_tuple<span class="token operator">&lt;</span><span class="token keyword">sizeof</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">(</span>Bs<span class="token punctuation">)</span><span class="token operator">&gt;</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> as<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

private:
F f;
tuple<G<BS>...> gs;
}

TODO