diff options
Diffstat (limited to 'include/gtest/internal/gtest-internal.h')
-rw-r--r-- | include/gtest/internal/gtest-internal.h | 38 |
1 files changed, 28 insertions, 10 deletions
diff --git a/include/gtest/internal/gtest-internal.h b/include/gtest/internal/gtest-internal.h index 947b162..cfa3885 100644 --- a/include/gtest/internal/gtest-internal.h +++ b/include/gtest/internal/gtest-internal.h @@ -896,21 +896,38 @@ struct IsAProtocolMessage ImplicitlyConvertible<const T*, const ::proto2::Message*>::value> { }; -// When the compiler sees expression IsContainerTest<C>(0), the first -// overload of IsContainerTest will be picked if C is an STL-style -// container class (since C::const_iterator* is a valid type and 0 can -// be converted to it), while the second overload will be picked -// otherwise (since C::const_iterator will be an invalid type in this -// case). Therefore, we can determine whether C is a container class -// by checking the type of IsContainerTest<C>(0). The value of the -// expression is insignificant. +// When the compiler sees expression IsContainerTest<C>(0), if C is an +// STL-style container class, the first overload of IsContainerTest +// will be viable (since both C::iterator* and C::const_iterator* are +// valid types and NULL can be implicitly converted to them). It will +// be picked over the second overload as 'int' is a perfect match for +// the type of argument 0. If C::iterator or C::const_iterator is not +// a valid type, the first overload is not viable, and the second +// overload will be picked. Therefore, we can determine whether C is +// a container class by checking the type of IsContainerTest<C>(0). +// The value of the expression is insignificant. +// +// Note that we look for both C::iterator and C::const_iterator. The +// reason is that C++ injects the name of a class as a member of the +// class itself (e.g. you can refer to class iterator as either +// 'iterator' or 'iterator::iterator'). If we look for C::iterator +// only, for example, we would mistakenly think that a class named +// iterator is an STL container. +// +// Also note that the simpler approach of overloading +// IsContainerTest(typename C::const_iterator*) and +// IsContainerTest(...) doesn't work with Visual Age C++ and Sun C++. typedef int IsContainer; template <class C> -IsContainer IsContainerTest(typename C::const_iterator*) { return 0; } +IsContainer IsContainerTest(int /* dummy */, + typename C::iterator* /* it */ = NULL, + typename C::const_iterator* /* const_it */ = NULL) { + return 0; +} typedef char IsNotContainer; template <class C> -IsNotContainer IsContainerTest(...) { return '\0'; } +IsNotContainer IsContainerTest(long /* dummy */) { return '\0'; } // EnableIf<condition>::type is void when 'Cond' is true, and // undefined when 'Cond' is false. To use SFINAE to make a function @@ -1009,6 +1026,7 @@ class NativeArray { public: // STL-style container typedefs. typedef Element value_type; + typedef Element* iterator; typedef const Element* const_iterator; // Constructs from a native array. |