Use a function template instead of struct template for Null

This commit is contained in:
Behdad Esfahbod 2010-04-21 00:32:47 -04:00
parent ffd321afd9
commit 9d3677899f
1 changed files with 10 additions and 14 deletions

View File

@ -61,27 +61,25 @@
/* Null objects */
/* Global nul-content Null pool. Enlarge as necessary. */
static const void *NullPool[32 / sizeof (void *)];
static const void *_NullPool[32 / sizeof (void *)];
/* Generic template for nul-content sizeof-sized Null objects. */
template <typename Type>
struct Null
{
ASSERT_STATIC (sizeof (Type) <= sizeof (NullPool));
static inline const Type &get () { return CONST_CAST (Type, *NullPool, 0); }
};
static inline const Type& Null () {
ASSERT_STATIC (sizeof (Type) <= sizeof (_NullPool));
return CONST_CAST (Type, *_NullPool, 0);
}
/* Specializaiton for arbitrary-content arbitrary-sized Null objects. */
#define DEFINE_NULL_DATA(Type, size, data) \
static const char _Null##Type[size] = data; \
static const char _Null##Type[size + 1] = data; \
template <> \
struct Null <Type> \
{ \
static inline const Type &get () { return CONST_CAST (Type, *_Null##Type, 0); } \
inline const Type& Null<Type> () { \
return CONST_CAST (Type, *_Null##Type, 0); \
}
/* Accessor macro. */
#define Null(Type) (Null<Type>::get())
#define Null(Type) Null<Type>()
/* get_for_data() is a static class method returning a reference to an
@ -398,9 +396,7 @@ struct Tag : ULONG
}
};
ASSERT_SIZE (Tag, 4);
#define _NULL_TAG_INIT {' ', ' ', ' ', ' '}
DEFINE_NULL_DATA (Tag, 4, _NULL_TAG_INIT);
#undef _NULL_TAG_INIT
DEFINE_NULL_DATA (Tag, 4, " ");
/* Glyph index number, same as uint16 (length = 16 bits) */
typedef USHORT GlyphID;