Revert "Add enable_shared_from_sibling."

This reverts commit 652d6ef.

include/bitcoin/network/async/enable_shared_from_base.hpp

@@ -25,18 +25,8 @@
 namespace libbitcoin {
 namespace network {
 
-// "The constructors of std::shared_ptr detect the presence of an unambiguous
-// and accessible (i.e. public inheritance is mandatory)
-// enable_shared_from_this base and assign the newly created std::shared_ptr
-// to weak-this if not already owned by a live std::shared_ptr.
-// Constructing a std::shared_ptr for an object that is already managed by
-// another std::shared_ptr will not consult weak-this and is undefined behavior.
-// It is permitted to call shared_from_this only on a previously shared object,
-// i.e. on an object managed by std::shared_ptr<T>. Otherwise,
-// std::bad_weak_ptr is thrown(by the shared_ptr constructor).."
-// en.cppreference.com/w/cpp/memory/enable_shared_from_this
-
-/// Base instance must be downcastable to Derived.
+/// Thread safe, base class.
+/// Empty base optimization using CRTP.
 /// Because enable_shared_from_this does not support inheritance.
 template <class Base>
 class enable_shared_from_base
@@ -52,53 +42,6 @@ class enable_shared_from_base
     std::shared_ptr<Derived> shared_from_base() NOEXCEPT;
 };
 
-/// Sibling instance must be castable to Derived:Base.
-/// Because enable_shared_from_this/base do not support multiple inheritance.
-/// Avoids diamond inheritance ambiguity by requiring a primary inheritance
-/// linear path (sibling) from which classes in an independent path (Base)
-/// may obtain a shared pointer within their own path (Derived).
-template <class Base, class Sibling>
-class enable_shared_from_sibling
-{
-public:
-    DELETE_COPY_MOVE(enable_shared_from_sibling);
-
-    enable_shared_from_sibling() NOEXCEPT;
-
-    /// Must be a polymorphic type (to use dynamic_cast).
-    virtual ~enable_shared_from_sibling() NOEXCEPT;
-
-    /// Simplifies capture of the shared pointer for a nop handler.
-    void nop() volatile NOEXCEPT;
-
-protected:
-    /// Sibling (not Derived:Base) implements enable_shared_from...
-    /// Use in Derived to create shared instance of Derived from its Sibling.
-    /// Undefined behavior if cast from Sibling* to Derived* not well formed.
-    template <class Derived, bc::if_base_of<Base, Derived> = true>
-    std::shared_ptr<Derived> shared_from_sibling() NOEXCEPT;
-};
-
-// class foo__ : enabled_shared_from_base<foo__>
-// class foo_ : foo__
-// class foo: foo_
-// auto fooptr = foo.shared_from_this()
-// auto foo_ptr = foo.shared_from_base<foo_>()
-// auto foo__ptr = foo.shared_from_base<foo__>()
-//
-// class bar__ : enabled_shared_from_sibling<bar__, foo>
-// class bar_ : bar__
-// class bar : bar_
-// bar__/bar_/bar must be joined with foo.
-//
-// class foobar : public foo, public bar
-// auto barptr = foobar.shared_from_sibling<bar>()
-// auto bar_ptr = foobar.shared_from_sibling<bar_>()
-// auto bar__ptr = foobar.shared_from_sibling<bar__>()
-// auto fooptr = foobar.shared_from_base<foo>()
-// auto foo_ptr = foobar.shared_from_base<foo_>()
-// auto foo__ptr = foobar.shared_from_base<foo__>()
-
 } // namespace network
 } // namespace libbitcoin
 

include/bitcoin/network/impl/async/enable_shared_from_base.ipp

@@ -24,13 +24,9 @@
 
 namespace libbitcoin {
 namespace network {
-
-// enable_shared_from_base : enable_shared_from_this
-// ----------------------------------------------------------------------------
 
 template <class Base>
-void enable_shared_from_base<Base>::
-nop() volatile NOEXCEPT
+void enable_shared_from_base<Base>::nop() volatile NOEXCEPT
 {
 }
 
@@ -39,44 +35,8 @@ template <class Derived, bc::if_base_of<Base, Derived>>
 std::shared_ptr<Derived> enable_shared_from_base<Base>::
 shared_from_base() NOEXCEPT
 {
-    BC_PUSH_WARNING(NO_THROW_IN_NOEXCEPT)
+    // Instance must be downcastable to Derived.
     return std::static_pointer_cast<Derived>(this->shared_from_this());
-    BC_POP_WARNING()
-}
-
-// enable_shared_from_sibling
-// ----------------------------------------------------------------------------
-
-template <class Base, class Sibling>
-enable_shared_from_sibling<Base, Sibling>::
-enable_shared_from_sibling() NOEXCEPT
-{
-}
-
-template <class Base, class Sibling>
-enable_shared_from_sibling<Base, Sibling>::
-~enable_shared_from_sibling() NOEXCEPT
-{
-}
-
-template <class Base, class Sibling>
-void enable_shared_from_sibling<Base, Sibling>::
-nop() volatile NOEXCEPT
-{
-}
-
-template <class Base, class Sibling>
-template <class Derived, bc::if_base_of<Base, Derived>>
-std::shared_ptr<Derived> enable_shared_from_sibling<Base, Sibling>::
-shared_from_sibling() NOEXCEPT
-{
-    BC_PUSH_WARNING(NO_THROW_IN_NOEXCEPT)
-    // Obtain shared pointer to object from Sibling class inheritance path.
-    const auto sibling = dynamic_cast<Sibling*>(this)->shared_from_this();
-    BC_POP_WARNING()
-
-    // Cast pointer back to Derived (from Base) class it was created from.
-    return std::dynamic_pointer_cast<Derived>(sibling);
 }
 
 } // namespace network