操作系统:ubuntu10.04
STL源码版本:2.91
前言:
要看一个项目的源码,首先要选中切入点。
那么在sgi stl 标准库中,其切入点是什么呢?
答案是:stl_config.h 文件。
不同的编译器对C++语言的支持程度不尽相同。为了具备广泛移植能力,SGI STL 定义了一个环境组态文件
。
其中声明了许多宏定义,在预编译的时候,通过这些宏定义来编译出对于平台的程序。
1,stl_config.h在linux平台下的实现:
1.1)为了知道linux平台下sgi stl 的宏定义有那些是被定义了的,有个简单,直接的方法,直接输出其宏名字。
测试代码如下:
运行结果:
1.2)通过以上的测试,可以得到在linux平台下,stl_config.h 的实现定义如下:
为了缩小篇幅,把相关的版权信息的屏蔽了。
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#ifndef __STL_CONFIG_H
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# define __STL_CONFIG_H
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# ifdef __GNUC__
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# include <_G_config.h>
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# define __STL_CLASS_PARTIAL_SPECIALIZATION
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# define __STL_FUNCTION_TMPL_PARTIAL_ORDER
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# define __STL_EXPLICIT_FUNCTION_TMPL_ARGS
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# define __STL_MEMBER_TEMPLATES
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# define __STL_PTHREADS
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# define __STL_USE_EXCEPTIONS
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# endif
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# define __STL_NULL_TMPL_ARGS
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# define __STL_TEMPLATE_NULL
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# define __STD
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# define __STL_BEGIN_NAMESPACE
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# define __STL_END_NAMESPACE
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# undef __STL_USE_NAMESPACE_FOR_RELOPS
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# define __STL_BEGIN_RELOPS_NAMESPACE
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# define __STL_END_RELOPS_NAMESPACE
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# define __STD_RELOPS
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# define __STL_TRY
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# define __STL_CATCH_ALL if (false)
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# define __STL_RETHROW
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# define __STL_NOTHROW
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# define __STL_UNWIND(action)
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# define __stl_assert(expr)
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#endif /* __STL_CONFIG_H */
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// Local Variables:
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// mode:C++
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// End:
2,对stl_config.h中的宏的详解:
2.1)__STL_STATIC_TEMPLATE_MEMBER_BUG
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#include <iostream>
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using namespace std;
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template <typename T>
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class testclass
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{
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public:
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static int _data;
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};
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template<> int testclass<int>::_data = 1;
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template<> int testclass<char>::_data = 2;
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int main()
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{
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cout<<testclass<int>::_data<<" "<<&testclass<int>::_data<<endl;
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cout<<testclass<char>::_data<<" "<<&testclass<char>::_data<<endl;
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testclass<int> obji1, obji2;
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testclass<char> objc1, objc2;
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cout<<obji1._data<<" "<<&obji1._data<<endl;
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cout<<obji2._data<<" "<<&obji2._data<<endl;
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cout<<objc1._data<<" "<<&objc1._data<<endl;
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cout<<objc2._data<<" "<<&objc2._data<<endl;
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obji1._data = 3;
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objc2._data = 4;
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cout<<obji1._data<<" "<<&obji1._data<<endl;
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cout<<obji2._data<<" "<<&obji2._data<<endl;
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cout<<objc1._data<<" "<<&objc1._data<<endl;
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cout<<objc2._data<<" "<<&objc2._data<<endl;
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return 1;
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}
2.2)__STL_CLASS_PARTIAL_SPECIALIZATION
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#include <iostream>
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using namespace std;
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template <class I, class O>
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struct testClass
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{
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testClass()
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{
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cout<<"I, O"<<endl;
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}
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};
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template <class T>
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struct testClass<T*, T*>
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{
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testClass()
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{
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cout<<"T*,T*"<<endl;
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}
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};
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template <class T>
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struct testClass<const T*, T*>
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{
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testClass()
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{
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cout<<"const T*, T*"<<endl;
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}
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};
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int main()
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{
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testClass<int, char> obj1;
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testClass<int*, int*> obj2;
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testClass<const int*, int*> obj3;
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return 1;
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}
2.3)__STL_FUNCTION_TMPL_PARTIAL_ORDER
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2.4)__STL_EXPLICIT_FUNCTION_TMPL_ARGS
整个 SGI STL 内都没有用到此一常数定义
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2.5)__STL_MEMBER_TEMPLATES
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#include <iostream>
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using namespace std;
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class alloc
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{
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};
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template <class T, class Alloc = alloc>
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class vector
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{
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public:
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typedef T value_type;
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typedef value_type* iterator;
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template <class I>
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void insert(iterator position, I first, I last)
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{
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cout<<"insert()"<<endl;
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}
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};
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int main()
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{
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int ia[5] = {0,1,2,3,4};
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cout<<*ia<<endl;
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cout<<*(ia+4)<<endl;
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vector<int> x;
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vector<int>::iterator ite = NULL;
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x.insert(ite, ia, ia+4);
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return 1;
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}
2.6)__STL_LIMITED_DEFAULT_TEMPLATES
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//测试template 参数可否根据前一个template参数而设定默认值
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#include <iostream>
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#include <cstddef>
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using namespace std;
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class alloc
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{
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};
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template <class T, class Alloc = alloc, size_t BufSiz = 0>
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class deque
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{
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public:
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deque()
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{
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cout<<"deque"<<endl;
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}
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};
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template <class T, class Sequence = deque<T> >
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class stack
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{
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public:
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stack()
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{
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cout<<"stack"<<endl;
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}
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private:
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Sequence c;
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};
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int main()
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{
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stack<int> x;
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}
2.7)__STL_NON_TYPE_TMPL_PARAM_BUG
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//测试class template 可否拥有non-type template参数
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#include <iostream>
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#include <cstddef>
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using namespace std;
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class alloc
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{
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};
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inline size_t __deque_buf_size(size_t n, size_t sz)
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{
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return n != 0 ? n : (sz < 512 ? size_t(512/sz) : size_t(1));
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}
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template <class T, class Ref, class Ptr, size_t BufSiz>
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struct __deque_iterator
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{
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typedef __deque_iterator<T, T&, T*, BufSiz> iterator;
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typedef __deque_iterator<T, const T&, const T*, BufSiz> const_iterator;
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static size_t buffer_size()
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{
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return __deque_buf_size(BufSiz, sizeof(T));
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}
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};
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template <class T, class Alloc = alloc, size_t BufSiz = 0>
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class deque
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{
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public:
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typedef __deque_iterator<T, T&, T*, BufSiz> iterator;
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};
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int main()
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{
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cout<<deque<int>::iterator::buffer_size()<<endl;
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cout<<deque<int,alloc,64>::iterator::buffer_size()<<endl;
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return 1;
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}
参考文献:
1,《STL源码剖析》
2,http://blog.csdn.net/segen_jaa/article/details/7930349
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