boost::mpl::vector(MSVC)源码分析

代码看起来很直接，没有前面宏定义那么复杂。但头文件的相互包括比较复杂。 如果仅仅是利用VS助手来寻找代码，出错的可能性非常之大。 对于模板元的调试非常的特殊。正确的代码是不能调试的，而是故意把它写错:比如， vector1只能存放一个元素，那么故意写成两个元素，超出了界限，编译器自然会报错。 这样可以知道编译器调用的是什么地方的代码了。否则调用的是什么地方的代码都不知道（花了大量的时间来寻找代码）。 有些模板仅仅是声明没有定义。这样只是起一个标记作用，用类型来标记。这个vector同那个vector是不同的。比如：vector_tag<1>和vector_tag<2>就是不同，他们代表不同的类型。它的差异仅仅用类型就可以做到。网上仅有一篇博客说是定义，这儿显然是不对。如果是定义可以生成对像，我试了aux::vector_tag不能生成对像。 // Copyright Aleksey Gurtovoy 2000-2004 // // Distributed under the Boost Software License, Version 1.0. // (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // // Preprocessed version of "boost/mpl/vector/vector10.hpp" header // -- DO NOT modify by hand! # define BOOST_MPL_AUX_NTTP_DECL(T, x) T x /**/ struct v_iter_tag;//仅仅是一个标志 struct integral_c_tag { BOOST_STATIC_CONSTANT(int, value = 0); }; template< int N> struct int_ { enum { value = N }; typedef int type; typedef int_ value_type; typedef integral_c_tag tag; typedef int_<value+1> next; typedef int_<value-1> prior; // enables uniform function call syntax for families of overloaded // functions that return objects of both arithmetic ('int', 'long', // 'double', etc.) and wrapped integral types (for an example, see // "mpl/example/power.cpp") operator int() const { return static_cast<int>(this->value); } }; namespace boost { namespace mpl { //起标记作用。同STL的代码这点来说很相似。 struct forward_iterator_tag : int_<0> { typedef forward_iterator_tag type; }; struct bidirectional_iterator_tag : int_<1> { typedef bidirectional_iterator_tag type; }; struct random_access_iterator_tag : int_<2> { typedef random_access_iterator_tag type; }; }} # define BOOST_MPL_AUX_COMMON_NAME_WKND(name) /**/ #define BOOST_MPL_AUX_NA_PARAM(param) param = na namespace boost { namespace mpl { BOOST_MPL_AUX_COMMON_NAME_WKND(next) BOOST_MPL_AUX_COMMON_NAME_WKND(prior) template< typename BOOST_MPL_AUX_NA_PARAM(T)// typename T = na > struct next { typedef typename T::next type; BOOST_MPL_AUX_LAMBDA_SUPPORT(1,next,(T)) }; template< typename BOOST_MPL_AUX_NA_PARAM(T) > struct prior { typedef typename T::prior type; BOOST_MPL_AUX_LAMBDA_SUPPORT(1,prior,(T)) }; BOOST_MPL_AUX_NA_SPEC(1, next) BOOST_MPL_AUX_NA_SPEC(1, prior) }} namespace boost { namespace mpl { //# define BOOST_MPL_AUX_NTTP_DECL(T, x) T x /**/ template< typename Vector ,long n_ > struct v_iter { typedef aux::v_iter_tag tag; //标记 typedef random_access_iterator_tag category;//迭代器类型 typedef typename v_at<Vector,n_>::type type;//这是在vector中特化的版本。 typedef Vector vector_; typedef mpl::long_<n_> pos; #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) enum { next_ = n_ + 1 , prior_ = n_ - 1 , pos_ = n_ }; typedef v_iter<Vector,next_> next; //实际上重新生成一个v_iter typedef v_iter<Vector,prior_> prior; #endif }; #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) template< typename Vector , BOOST_MPL_AUX_NTTP_DECL(long, n_)//long n_ > struct next< v_iter<Vector,n_> >//这儿来看，显然不主模版。因为这儿只有一个参数v_iter,是一个特化版本。 { typedef v_iter<Vector,(n_ + 1)> type;//重新生成一个v_iter }; template< typename Vector , BOOST_MPL_AUX_NTTP_DECL(long, n_) > struct prior< v_iter<Vector,n_> >//同上面一样。 { typedef v_iter<Vector,(n_ - 1)> type;//重新生成一个v_iter }; # define BOOST_MPL_AUX_NESTED_VALUE_WKND(T, C) / BOOST_MPL_AUX_VALUE_WKND(C)::value / /**/ # define BOOST_MPL_AUX_VALUE_WKND(C) C #endif }} #endif // BOOST_MPL_AUX_VECTOR_ITERATOR_HPP_INCLUDED namespace boost { namespace mpl { //特化版本，在其他地方声明 template< typename V > struct v_at< V,0 > { typedef typename V::item0 type;//V代表的是vector,item0就是第一个元素值。 }; template< typename T0 > struct vector1 { //这仅是一个标记，只对它进行了声明，没有对它进行定义。代表一个特定的类型。 typedef aux::vector_tag<1> tag; typedef vector1 type; typedef T0 item0;//vector1存放的元素T0 typedef void_ item1;// typedef T0 back; typedef v_iter< type,0 > begin; // typedef v_iter< type,1 > end; }; template<> struct push_front_impl< aux::vector_tag<0> > { template< typename Vector, typename T > struct apply { typedef vector1<//只有一个元素，重新生成一个vector1即可。 T > type; }; }; template<> struct pop_front_impl< aux::vector_tag<1> > { template< typename Vector > struct apply { typedef vector0< //对于vector1来说，pop出一个元素之后，就没有任何元素了。 > type; }; }; template<> struct push_back_impl< aux::vector_tag<0> > { template< typename Vector, typename T > struct apply { typedef vector1< //同样重新生成一个vector1，模板元是不能改变其元素值。 //要改变只得重新生成一个新的vector。 T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<1> > { template< typename Vector > struct apply { typedef vector0<//对于只有一个元素的vector,pop之后就没有任何元素了。 > type; }; }; template< typename V > struct v_at< V,1 > { typedef typename V::item1 type;//vector的第二个元素值，比较直接。 }; //下面的特化版本同上面的非常类似。而代码写得很清晰，而又直接。 template< typename T0, typename T1 > struct vector2 { typedef aux::vector_tag<2> tag; typedef vector2 type; typedef T0 item0; typedef T1 item1; typedef void_ item2; typedef T1 back; typedef v_iter< type,0 > begin; typedef v_iter< type,2 > end; }; template<> struct push_front_impl< aux::vector_tag<1> > { template< typename Vector, typename T > struct apply { typedef vector2< T , typename Vector::item0 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<2> > { template< typename Vector > struct apply { typedef vector1< typename Vector::item1 > type; }; }; template<> struct push_back_impl< aux::vector_tag<1> > { template< typename Vector, typename T > struct apply { typedef vector2< typename Vector::item0 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<2> > { template< typename Vector > struct apply { typedef vector1< typename Vector::item0 > type; }; }; template< typename V > struct v_at< V,2 > { typedef typename V::item2 type; }; template< typename T0, typename T1, typename T2 > struct vector3 { typedef aux::vector_tag<3> tag; typedef vector3 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef void_ item3; typedef T2 back; typedef v_iter< type,0 > begin; typedef v_iter< type,3 > end; }; template<> struct push_front_impl< aux::vector_tag<2> > { template< typename Vector, typename T > struct apply { typedef vector3< T , typename Vector::item0, typename Vector::item1 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<3> > { template< typename Vector > struct apply { typedef vector2< typename Vector::item1, typename Vector::item2 > type; }; }; template<> struct push_back_impl< aux::vector_tag<2> > { template< typename Vector, typename T > struct apply { typedef vector3< typename Vector::item0, typename Vector::item1 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<3> > { template< typename Vector > struct apply { typedef vector2< typename Vector::item0, typename Vector::item1 > type; }; }; template< typename V > struct v_at< V,3 > { typedef typename V::item3 type; }; template< typename T0, typename T1, typename T2, typename T3 > struct vector4 { typedef aux::vector_tag<4> tag; typedef vector4 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef T3 item3; typedef void_ item4; typedef T3 back; typedef v_iter< type,0 > begin; typedef v_iter< type,4 > end; }; template<> struct push_front_impl< aux::vector_tag<3> > { template< typename Vector, typename T > struct apply { typedef vector4< T , typename Vector::item0, typename Vector::item1 , typename Vector::item2 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<4> > { template< typename Vector > struct apply { typedef vector3< typename Vector::item1, typename Vector::item2 , typename Vector::item3 > type; }; }; template<> struct push_back_impl< aux::vector_tag<3> > { template< typename Vector, typename T > struct apply { typedef vector4< typename Vector::item0, typename Vector::item1 , typename Vector::item2 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<4> > { template< typename Vector > struct apply { typedef vector3< typename Vector::item0, typename Vector::item1 , typename Vector::item2 > type; }; }; template< typename V > struct v_at< V,4 > { typedef typename V::item4 type; }; template< typename T0, typename T1, typename T2, typename T3, typename T4 > struct vector5 { typedef aux::vector_tag<5> tag; typedef vector5 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef T3 item3; typedef T4 item4; typedef void_ item5; typedef T4 back; typedef v_iter< type,0 > begin; typedef v_iter< type,5 > end; }; template<> struct push_front_impl< aux::vector_tag<4> > { template< typename Vector, typename T > struct apply { typedef vector5< T , typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<5> > { template< typename Vector > struct apply { typedef vector4< typename Vector::item1, typename Vector::item2 , typename Vector::item3, typename Vector::item4 > type; }; }; template<> struct push_back_impl< aux::vector_tag<4> > { template< typename Vector, typename T > struct apply { typedef vector5< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<5> > { template< typename Vector > struct apply { typedef vector4< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 > type; }; }; template< typename V > struct v_at< V,5 > { typedef typename V::item5 type; }; template< typename T0, typename T1, typename T2, typename T3, typename T4 , typename T5 > struct vector6 { typedef aux::vector_tag<6> tag; typedef vector6 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef T3 item3; typedef T4 item4; typedef T5 item5; typedef void_ item6; typedef T5 back; typedef v_iter< type,0 > begin; typedef v_iter< type,6 > end; }; template<> struct push_front_impl< aux::vector_tag<5> > { template< typename Vector, typename T > struct apply { typedef vector6< T , typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<6> > { template< typename Vector > struct apply { typedef vector5< typename Vector::item1, typename Vector::item2 , typename Vector::item3, typename Vector::item4 , typename Vector::item5 > type; }; }; template<> struct push_back_impl< aux::vector_tag<5> > { template< typename Vector, typename T > struct apply { typedef vector6< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<6> > { template< typename Vector > struct apply { typedef vector5< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4 > type; }; }; template< typename V > struct v_at< V,6 > { typedef typename V::item6 type; }; template< typename T0, typename T1, typename T2, typename T3, typename T4 , typename T5, typename T6 > struct vector7 { typedef aux::vector_tag<7> tag; typedef vector7 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef T3 item3; typedef T4 item4; typedef T5 item5; typedef T6 item6; typedef void_ item7; typedef T6 back; typedef v_iter< type,0 > begin; typedef v_iter< type,7 > end; }; template<> struct push_front_impl< aux::vector_tag<6> > { template< typename Vector, typename T > struct apply { typedef vector7< T , typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<7> > { template< typename Vector > struct apply { typedef vector6< typename Vector::item1, typename Vector::item2 , typename Vector::item3, typename Vector::item4 , typename Vector::item5, typename Vector::item6 > type; }; }; template<> struct push_back_impl< aux::vector_tag<6> > { template< typename Vector, typename T > struct apply { typedef vector7< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<7> > { template< typename Vector > struct apply { typedef vector6< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 > type; }; }; template< typename V > struct v_at< V,7 > { typedef typename V::item7 type; }; template< typename T0, typename T1, typename T2, typename T3, typename T4 , typename T5, typename T6, typename T7 > struct vector8 { typedef aux::vector_tag<8> tag; typedef vector8 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef T3 item3; typedef T4 item4; typedef T5 item5; typedef T6 item6; typedef T7 item7; typedef void_ item8; typedef T7 back; typedef v_iter< type,0 > begin; typedef v_iter< type,8 > end; }; template<> struct push_front_impl< aux::vector_tag<7> > { template< typename Vector, typename T > struct apply { typedef vector8< T , typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<8> > { template< typename Vector > struct apply { typedef vector7< typename Vector::item1, typename Vector::item2 , typename Vector::item3, typename Vector::item4 , typename Vector::item5, typename Vector::item6 , typename Vector::item7 > type; }; }; template<> struct push_back_impl< aux::vector_tag<7> > { template< typename Vector, typename T > struct apply { typedef vector8< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<8> > { template< typename Vector > struct apply { typedef vector7< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6 > type; }; }; template< typename V > struct v_at< V,8 > { typedef typename V::item8 type; }; template< typename T0, typename T1, typename T2, typename T3, typename T4 , typename T5, typename T6, typename T7, typename T8 > struct vector9 { typedef aux::vector_tag<9> tag; typedef vector9 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef T3 item3; typedef T4 item4; typedef T5 item5; typedef T6 item6; typedef T7 item7; typedef T8 item8; typedef void_ item9; typedef T8 back; typedef v_iter< type,0 > begin; typedef v_iter< type,9 > end; }; template<> struct push_front_impl< aux::vector_tag<8> > { template< typename Vector, typename T > struct apply { typedef vector9< T , typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6, typename Vector::item7 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<9> > { template< typename Vector > struct apply { typedef vector8< typename Vector::item1, typename Vector::item2 , typename Vector::item3, typename Vector::item4 , typename Vector::item5, typename Vector::item6 , typename Vector::item7, typename Vector::item8 > type; }; }; template<> struct push_back_impl< aux::vector_tag<8> > { template< typename Vector, typename T > struct apply { typedef vector9< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6, typename Vector::item7 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<9> > { template< typename Vector > struct apply { typedef vector8< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6, typename Vector::item7 > type; }; }; template< typename V > struct v_at< V,9 > { typedef typename V::item9 type; }; template< typename T0, typename T1, typename T2, typename T3, typename T4 , typename T5, typename T6, typename T7, typename T8, typename T9 > struct vector10 { //vector_tag只有声明，没有定义。在这儿表示类型,不需要定义，只是一个标记。 typedef aux::vector_tag<10> tag; typedef vector10 type; typedef T0 item0; typedef T1 item1; typedef T2 item2; typedef T3 item3; typedef T4 item4; typedef T5 item5; typedef T6 item6; typedef T7 item7; typedef T8 item8; typedef T9 item9; typedef void_ item10; typedef T9 back; typedef v_iter< type,0 > begin; typedef v_iter< type,10 > end; }; template<> struct push_front_impl< aux::vector_tag<9> > { template< typename Vector, typename T > struct apply { typedef vector10< T , typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6, typename Vector::item7 , typename Vector::item8 > type; }; }; template<> struct pop_front_impl< aux::vector_tag<10> > { template< typename Vector > struct apply { typedef vector9< typename Vector::item1, typename Vector::item2 , typename Vector::item3, typename Vector::item4 , typename Vector::item5, typename Vector::item6 , typename Vector::item7, typename Vector::item8 , typename Vector::item9 > type; }; }; template<> struct push_back_impl< aux::vector_tag<9> > { template< typename Vector, typename T > struct apply { typedef vector10< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6, typename Vector::item7 , typename Vector::item8 , T > type; }; }; template<> struct pop_back_impl< aux::vector_tag<10> > { template< typename Vector > struct apply { typedef vector9< typename Vector::item0, typename Vector::item1 , typename Vector::item2, typename Vector::item3 , typename Vector::item4, typename Vector::item5 , typename Vector::item6, typename Vector::item7 , typename Vector::item8 > type; }; }; template< typename V > struct v_at< V,10 > { typedef typename V::item10 type; }; }}