AK: Add ConstPeekType to Traits

Also, the PeekType of smart pointers is now T* instead of const T*.

Note: This commit doesn't compile, it breaks HashMap::get() for some
types. Fixed in the next commit.

AK/NonnullOwnPtr.h

@@ -158,7 +158,8 @@ make(Args&&... args)
 
 template<typename T>
 struct Traits<NonnullOwnPtr<T>> : public GenericTraits<NonnullOwnPtr<T>> {
- using PeekType = const T*;
+ using PeekType = T*;
+ using ConstPeekType = const T*;
  static unsigned hash(const NonnullOwnPtr<T>& p) { return int_hash((u32)p.ptr()); }
  static bool equals(const NonnullOwnPtr<T>& a, const NonnullOwnPtr<T>& b) { return a.ptr() == b.ptr(); }
 };

AK/OwnPtr.h

@@ -193,7 +193,8 @@ inline void swap(OwnPtr<T>& a, OwnPtr<U>& b)
 
 template<typename T>
 struct Traits<OwnPtr<T>> : public GenericTraits<OwnPtr<T>> {
- using PeekType = const T*;
+ using PeekType = T*;
+ using ConstPeekType = const T*;
  static unsigned hash(const OwnPtr<T>& p) { return ptr_hash(p.ptr()); }
  static bool equals(const OwnPtr<T>& a, const OwnPtr<T>& b) { return a.ptr() == b.ptr(); }
 };

AK/RefPtr.h

@@ -451,7 +451,8 @@ struct Formatter<RefPtr<T>> : Formatter<const T*> {
 
 template<typename T>
 struct Traits<RefPtr<T>> : public GenericTraits<RefPtr<T>> {
- using PeekType = const T*;
+ using PeekType = T*;
+ using ConstPeekType = const T*;
  static unsigned hash(const RefPtr<T>& p) { return ptr_hash(p.ptr()); }
  static bool equals(const RefPtr<T>& a, const RefPtr<T>& b) { return a.ptr() == b.ptr(); }
 };

AK/Traits.h

@@ -14,6 +14,7 @@ namespace AK {
 template<typename T>
 struct GenericTraits {
  using PeekType = T;
+ using ConstPeekType = T;
  static constexpr bool is_trivial() { return false; }
  static constexpr bool equals(const T& a, const T& b) { return a == b; }
 };