Revert r122114 (CallbackVH observing use-list changes) because it caused severe slowd...

[oota-llvm.git] / include / llvm / Support / type_traits.h

diff --git a/include/llvm/Support/type_traits.h b/include/llvm/Support/type_traits.h
index 5000a8b859b8c188d00cf62f4fd03cf7ba97bf01..515295bdd66feb7e4471710ee403acac78506d9c 100644 (file)
--- a/include/llvm/Support/type_traits.h
+++ b/include/llvm/Support/type_traits.h
@@ -17,13 +17,15 @@
 #ifndef LLVM_SUPPORT_TYPE_TRAITS_H
 #define LLVM_SUPPORT_TYPE_TRAITS_H
 
+#include <utility>
+
 // 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
@@ -35,7 +37,7 @@ namespace dont_use
     // 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> char is_class_helper(void(T::*)());
     template<typename T> double is_class_helper(...);
 }
 
@@ -48,6 +50,76 @@ struct is_class
  public:
     enum { value = sizeof(char) == sizeof(dont_use::is_class_helper<T>(0)) };
 };
+  
+  
+/// isPodLike - This is a type trait that is used to determine whether a given
+/// type can be copied around with memcpy instead of running ctors etc.
+template <typename T>
+struct isPodLike {
+  // If we don't know anything else, we can (at least) assume that all non-class
+  // types are PODs.
+  static const bool value = !is_class<T>::value;
+};
+
+// std::pair's are pod-like if their elements are.
+template<typename T, typename U>
+struct isPodLike<std::pair<T, U> > {
+  static const bool value = isPodLike<T>::value & isPodLike<U>::value;
+};
+  
+
+/// \brief Metafunction that determines whether the two given types are 
+/// equivalent.
+template<typename T, typename U>
+struct is_same {
+  static const bool value = false;
+};
+
+template<typename T>
+struct is_same<T, T> {
+  static const bool value = true;
+};
+  
+// enable_if_c - Enable/disable a template based on a metafunction
+template<bool Cond, typename T = void>
+struct enable_if_c {
+  typedef T type;
+};
+
+template<typename T> struct enable_if_c<false, T> { };
+  
+// enable_if - Enable/disable a template based on a metafunction
+template<typename Cond, typename T = void>
+struct enable_if : public enable_if_c<Cond::value, T> { };
+
+namespace dont_use {
+  template<typename Base> char base_of_helper(const volatile Base*);
+  template<typename Base> double base_of_helper(...);
+}
+
+/// is_base_of - Metafunction to determine whether one type is a base class of
+/// (or identical to) another type.
+template<typename Base, typename Derived>
+struct is_base_of {
+  static const bool value 
+    = is_class<Base>::value && is_class<Derived>::value &&
+      sizeof(char) == sizeof(dont_use::base_of_helper<Base>((Derived*)0));
+};
+
+// remove_pointer - Metafunction to turn Foo* into Foo.  Defined in
+// C++0x [meta.trans.ptr].
+template <typename T> struct remove_pointer { typedef T type; };
+template <typename T> struct remove_pointer<T*> { typedef T type; };
+template <typename T> struct remove_pointer<T*const> { typedef T type; };
+template <typename T> struct remove_pointer<T*volatile> { typedef T type; };
+template <typename T> struct remove_pointer<T*const volatile> {
+    typedef T type; };
+
+template <bool, typename T, typename F>
+struct conditional { typedef T type; };
+
+template <typename T, typename F>
+struct conditional<false, T, F> { typedef F type; };
 
 }