| //===- llvm/Support/type_traits.h - Simplfied type traits -------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file provides a template class that determines if a type is a class or |
| // not. The basic mechanism, based on using the pointer to member function of |
| // a zero argument to a function was "boosted" from the boost type_traits |
| // library. See http://www.boost.org/ for all the gory details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_SUPPORT_TYPE_TRAITS_H |
| #define LLVM_SUPPORT_TYPE_TRAITS_H |
| |
| // This is actually the conforming implementation which works with abstract |
| // classes. However, enough compilers have trouble with it that most will use |
| // the one in boost/type_traits/object_traits.hpp. This implementation actually |
| // works with VC7.0, but other interactions seem to fail when we use it. |
| |
| namespace llvm { |
| |
| namespace dont_use |
| { |
| // These two functions should never be used. They are helpers to |
| // the is_class template below. They cannot be located inside |
| // is_class because doing so causes at least GCC to think that |
| // the value of the "value" enumerator is not constant. Placing |
| // them out here (for some strange reason) allows the sizeof |
| // operator against them to magically be constant. This is |
| // important to make the is_class<T>::value idiom zero cost. it |
| // evaluates to a constant 1 or 0 depending on whether the |
| // parameter T is a class or not (respectively). |
| template<typename T> char is_class_helper(void(T::*)(void)); |
| template<typename T> double is_class_helper(...); |
| } |
| |
| template <typename T> |
| struct is_class |
| { |
| // is_class<> metafunction due to Paul Mensonides (leavings@attbi.com). For |
| // more details: |
| // http://groups.google.com/groups?hl=en&selm=000001c1cc83%24e154d5e0%247772e50c%40c161550a&rnum=1 |
| public: |
| enum { value = sizeof(char) == sizeof(dont_use::is_class_helper<T>(0)) }; |
| }; |
| |
| } |
| |
| #endif |