20170326STL08_STL_SGI_config.h

config.h：

1：sgi是一个公司的简称，有一个操作系统是SGI unix？，商业化的，很难接触到。

2：前端部分是版权声明，说明了可以做什么，不可做什么。

3：下面一大段注释是解释了整个文档做的事。下面代码基本就没有注释了（这是一个比较老的习惯）。

4：SGISTL里面会来检测这与编译器相关的宏是否被定义，从而得出编译器是否支持这些特性，根据这些情况来控制代码，确保跨平台不出错。

// Flags:// * __STL_NO_BOOL: defined if the compiler doesn't have bool as a builtin//编译器没有内部定义原生bool的时候就会定义宏   __STL_NO_BOOL//看编译器是否有定义bool（原生bool）//   type.// * __STL_HAS_WCHAR_T: defined if the compier has wchar_t as a builtin type.//_WCHAR_T_IS_KEYWORD 宏，看编译器内部是否有定义wchar_t，没有的时候就会定义这个宏//判断这些是否有定义有两种方式：1，看编译器是否有定义这些宏。2，通过编译器的版本直接判断// * __STL_NO_DRAND48: defined if the compiler doesn't have the drand48 //   function.//求随机数的。非C标准里面的函数，Linux下面会有//一下的就是判断是否支持某些特性// * __STL_STATIC_TEMPLATE_MEMBER_BUG: defined if the compiler can't handle//   static members of template classes.//是否支持在模板类里面定义一个静态成员，不支持就定义这个宏//模板类里面如果定义静态成员，对编译器来说是个非常复杂的事情。// * __STL_STATIC_CONST_INIT_BUG: defined if the compiler can't handle a//   constant-initializer in the declaration of a static const data member//   of integer type.  (See section 9.4.2, paragraph 4, of the C++ standard.)//static const 的这样的静态常量的定义。是否可以在类里面正常初始化/*class Demo{public:int a_ = 0;//是个非常危险的写法，不应该这样写，不能再类中初始化static int b_;//不可初始化static const int c_ = 10;//仅仅是int类型可以在类里面初始化static const double d_;//不可初始化};int Demo::b_ = 10;double Demo::d_ = 2.5;*/// * __STL_CLASS_PARTIAL_SPECIALIZATION: defined if the compiler supports//   partial specialization of template classes.//是否支持模板类的局部特化，基本每个编译器都会支持。// * __STL_PARTIAL_SPECIALIZATION_SYNTAX: defined if the compiler //   supports partial specialization syntax for full specialization of//   class templates.  (Even if it doesn't actually support partial //   specialization itself.)//是否支持类模板的部分排序，偏序实例化。在有重载和特化的情况下就会有偏序。/*//偏序实例化：和推导相关template<typename T>void Foo(T t){}template<typename T>void Foo(T *t)//重载（所有指针类型）{}template<typename T>//这些写法在很多比较老的编译器下是不被支持的。void Foo(const T *t){}template<>void Foo(int *t)//这个特化应该是属于(T *t)，是对他的特化，{}*/// * __STL_FUNCTION_TMPL_PARTIAL_ORDER: defined if the compiler supports//   partial ordering of function templates.  (a.k.a partial specialization//   of function templates.)//是否支持函数模板的部分排序，偏序实例化// * __STL_MEMBER_TEMPLATES: defined if the compiler supports template//   member functions of classes.//类模板里面支持模板函数,大部分编译器都支持/*template<typename T>class {public:template<typename X>void Foo(T t){}protected:};*/// * __STL_MEMBER_TEMPLATE_CLASSES: defined if the compiler supports //   nested classes that are member templates of other classes.//是否支持一个模板类支持内嵌类为一个模板类。一般编译器都支持，甚至模板类都支持内部模板类//内嵌类就是内部类。/*class Demo{public:template<typename T>class Demo1{T data_;public:Demo1(T t) :data_(t){}};Demo1<int> data_;protected:Demo(int data) :data_(data){}};*/// * __STL_TEMPLATE_FRIENDS: defined if the compiler supports templatized//   friend declarations.//一个模板类是否可以为其他类的友元//一般的都支持，否则流运算符（<<>>）就无法重载了。// * __STL_EXPLICIT_FUNCTION_TMPL_ARGS: defined if the compiler //   supports calling a function template by providing its template//   arguments explicitly.//是否支持函数对模板参数的推导// * __STL_LIMITED_DEFAULT_TEMPLATES: defined if the compiler is unable//   to handle default template parameters that depend on previous template//   parameters.//是否支持下面这种（前一个参数为后一个参数的默认值）/*//几乎都支持template<typename T, typename CON = std::vector<T> >class Demo{};*/// * __STL_NON_TYPE_TMPL_PARAM_BUG: defined if the compiler has trouble with//   function template argument deduction for non-type template parameters.//是否支持模板接收一个non type的一个参数，如下/*//基本都只支持的template<int size>class Demo{public:};*/// * __SGI_STL_NO_ARROW_OPERATOR: defined if the compiler is unable//   to support the -> operator for iterators.//是否支持迭代器里面重载->运算符，不支持则定义这个宏。// * __STL_DEFAULT_CONSTRUCTOR_BUG: defined if T() does not work properly//   when T is a builtin type.//不支持T()，定义这个宏，eg：printf("%d",int(10));，就是临时对象//是否支持默认类型 int->int()，char->char()。// * __STL_USE_EXCEPTIONS: defined if the compiler (in the current compilation//   mode) supports exceptions.//是否支持异常// * __STL_USE_NAMESPACES: defined if the compiler has the necessary//   support for namespaces.//是否支持命名空间// * __STL_NO_EXCEPTION_HEADER: defined if the compiler does not have a//   standard-conforming header <exception>.//是否有exception头文件，没有就定义这个宏// * __STL_NO_BAD_ALLOC: defined if the compiler does not have a <new>//   header, or if <new> does not contain a bad_alloc class.  If a bad_alloc//   class exists, it is assumed to be in namespace std.//是否有<new>头文件，或者<new>里面没有bad_alloc类，就定义这个宏。（必须在std命名空间里面）// * __STL_SGI_THREADS: defined if this is being compiled for an SGI IRIX//   system in multithreaded mode, using native SGI threads instead of //   pthreads.//线程相关// * __STL_WIN32THREADS: defined if this is being compiled on a WIN32//   compiler in multithreaded mode.// * __STL_PTHREADS: defined if we should use portable pthreads//   synchronization.// * __STL_UITHREADS: defined if we should use UI / solaris / UnixWare threads//   synchronization.  UIthreads are similar to pthreads, but are based //   on an earlier version of the Posix threads standard.//以上都是线程相关的// * __STL_LONG_LONG if the compiler has long long and unsigned long long//   types.  (They're not in the C++ standard, but they are expected to be //   included in the forthcoming C9X standard.)//是否有long long 和 unsigned long long// * __STL_THREADS is defined if thread safety is needed.//是否线程安全// * __STL_VOLATILE is defined to be "volatile" if threads are being//   used, and the empty string otherwise.//线程相关// * __STL_USE_CONCEPT_CHECKS enables some extra compile-time error//   checking to make sure that user-defined template arguments satisfy//   all of the appropriate requirements.  This may result in more//   comprehensible error messages.  It incurs no runtime overhead.  This //   feature requires member templates and partial specialization.//编译器选项：开了会进行错误检查……// * __STL_NO_USING_CLAUSE_IN_CLASS: The compiler does not handle "using"//   clauses inside of class definitions.//类定义中不能用using。不支持的话肯定是非主流编译器// * __STL_NO_FRIEND_TEMPLATE_CLASS: The compiler does not handle friend//   declaractions where the friend is a template class.//不支持模板类成为其他的友元// * __STL_NO_FUNCTION_PTR_IN_CLASS_TEMPLATE: The compiler does not//   support the use of a function pointer type as the argument//   for a template.//不支持函数指针成为一个类模板参数//template<typename T>,T不能为函数指针// * __STL_MEMBER_TEMPLATE_KEYWORD: standard C++ requires the template//   keyword in a few new places (14.2.4).  This flag is set for//   compilers that support (and require) this usage.// User-settable macros that control compilation://用户自定义的// * __STL_USE_SGI_ALLOCATORS: if defined, then the STL will use older//   SGI-style allocators, instead of standard-conforming allocators,//   even if the compiler supports all of the language features needed//   for standard-conforming allocators.//被定义的话，会用老版本的sgi的alloc。// * __STL_NO_NAMESPACES: if defined, don't put the library in namespace//   std, even if the compiler supports namespaces.//将生成的library不加到namespace std中。// * __STL_NO_RELOPS_NAMESPACE: if defined, don't put the relational//   operator templates (>, <=. >=, !=) in namespace std::rel_ops, even//   if the compiler supports namespaces and partial ordering of//   function templates.// * __STL_ASSERTIONS: if defined, then enable runtime checking through the//   __stl_assert macro.// * _PTHREADS: if defined, use Posix threads for multithreading support.// * _UITHREADS:if defined, use SCO/Solaris/UI threads for multithreading //   support// * _NOTHREADS: if defined, don't use any multithreading support.  // * _STL_NO_CONCEPT_CHECKS: if defined, disables the error checking that//   we get from __STL_USE_CONCEPT_CHECKS.// * __STL_USE_NEW_IOSTREAMS: if defined, then the STL will use new,//   standard-conforming iostreams (e.g. the <iosfwd> header).  If not//   defined, the STL will use old cfront-style iostreams (e.g. the//   <iostream.h> header).// Other macros defined by this file:// * bool, true, and false, if __STL_NO_BOOL is defined.// * typename, as a null macro if it's not already a keyword.// * explicit, as a null macro if it's not already a keyword.// * namespace-related macros (__STD, __STL_BEGIN_NAMESPACE, etc.)// * exception-related macros (__STL_TRY, __STL_UNWIND, etc.)// * __stl_assert, either as a test or as a null macro, depending on//   whether or not __STL_ASSERTIONS is defined.