Changeset 104333 in webkit

Timestamp:

Jan 6, 2012 1:57:22 PM (12 years ago)

Author:

weinig@apple.com

Message:

Add a DecayArray type trait as a first step towards merging OwnPtr and OwnArrayPtr
​https://bugs.webkit.org/show_bug.cgi?id=75737

Reviewed by Anders Carlsson.

• wtf/TypeTraits.cpp:
• wtf/TypeTraits.h:

Added a DecayArray trait, that can convert T[] and T[3] -> T*. DecayArray
is composed of some helpers which are also exposed, Conditional<>, which
can provide one type or another based on a boolean predicate, IsArray<>
which can deduce array types, and RemoveExtent<>, which removes the extent
from an array type.

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• wtf/TypeTraits.cpp (modified) (1 diff)
• wtf/TypeTraits.h (modified) (4 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2012-01-06  Sam Weinig  <sam@webkit.org>
+
+        Add a DecayArray type trait as a first step towards merging OwnPtr and OwnArrayPtr
+        https://bugs.webkit.org/show_bug.cgi?id=75737
+
+        Reviewed by Anders Carlsson.
+
+        * wtf/TypeTraits.cpp:
+        * wtf/TypeTraits.h:
+        Added a DecayArray trait, that can convert T[] and T[3] -> T*. DecayArray
+        is composed of some helpers which are also exposed, Conditional<>, which
+        can provide one type or another based on a boolean predicate, IsArray<>
+        which can deduce array types, and RemoveExtent<>, which removes the extent
+        from an array type. 
+
 2012-01-06  Oliver Hunt  <oliver@apple.com>
 

trunk/Source/JavaScriptCore/wtf/TypeTraits.cpp

@@ -140 +140 @@
 COMPILE_ASSERT((IsSameType<int, RemoveReference<int&>::Type>::value), WTF_Test_RemoveReference_int_reference);
 
+
+typedef int IntArray[];
+typedef int IntArraySized[4];
+
+COMPILE_ASSERT((IsArray<IntArray>::value), WTF_Test_IsArray_int_array);
+COMPILE_ASSERT((IsArray<IntArraySized>::value), WTF_Test_IsArray_int_sized_array);
+
+COMPILE_ASSERT((IsSameType<int, RemoveExtent<IntArray>::Type>::value), WTF_Test_RemoveExtent_int_array);
+COMPILE_ASSERT((IsSameType<int, RemoveExtent<IntArraySized>::Type>::value), WTF_Test_RemoveReference_int_sized_array);
+
+COMPILE_ASSERT((IsSameType<int*, DecayArray<IntArray>::Type>::value), WTF_Test_DecayArray_int_array);
+COMPILE_ASSERT((IsSameType<int*, DecayArray<IntArraySized>::Type>::value), WTF_Test_DecayArray_int_sized_array);
+
+COMPILE_ASSERT((IsSameType<int*, DecayArray<IntArray&>::Type>::value), WTF_Test_DecayArray_int_array_reference);
+COMPILE_ASSERT((IsSameType<int*, DecayArray<IntArraySized&>::Type>::value), WTF_Test_DecayArray_int_sized_array_reference);
+
 } // namespace WTF

trunk/Source/JavaScriptCore/wtf/TypeTraits.h

@@ -36 +36 @@
     // The following are provided in this file:
     //
+    //   Conditional<Predicate, If, Then>::Type
+    //
     //   IsInteger<T>::value
     //   IsPod<T>::value, see the definition for a note about its limitations
     //   IsConvertibleToInteger<T>::value
+    //
+    //   IsArray<T>::value
     //
     //   IsSameType<T, U>::value
@@ -47 +51 @@
     //   RemoveVolatile<T>::Type
     //   RemoveConstVolatile<T>::Type
+    //   RemoveExtent<T>::Type
+    //
+    //   DecayArray<T>::Type
     //
     //   COMPILE_ASSERT's in TypeTraits.cpp illustrate their usage and what they do.
+
+    template <bool Predicate, class If, class Then> struct Conditional  { typedef If Type; };
+    template <class If, class Then> struct Conditional<false, If, Then> { typedef Then Type; };
 
     template<typename T> struct IsInteger           { static const bool value = false; };
@@ -105 +115 @@
     };
 
+
+    template <class T> struct IsArray {
+        static const bool value = false;
+    };
+
+    template <class T> struct IsArray<T[]> {
+        static const bool value = true;
+    };
+
+    template <class T, size_t N> struct IsArray<T[N]> {
+        static const bool value = true;
+    };
+
+
     template <typename T, typename U> struct IsSameType {
         static const bool value = false;
@@ -181 +205 @@
     template <typename T> struct RemoveReference<T&> {
         typedef T Type;
+    };
+
+    template <typename T> struct RemoveExtent {
+        typedef T Type;
+    };
+
+    template <typename T> struct RemoveExtent<T[]> {
+        typedef T Type;
+    };
+
+    template <typename T, size_t N> struct RemoveExtent<T[N]> {
+        typedef T Type;
+    };
+
+    template <class T> struct DecayArray {
+        typedef typename RemoveReference<T>::Type U;
+    public:
+        typedef typename Conditional<
+            IsArray<U>::value,
+            typename RemoveExtent<U>::Type*,
+            typename RemoveConstVolatile<U>::Type
+        >::Type Type;
     };