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-rw-r--r--cutl/shared-ptr/base.cxx63
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+// file : cutl/shared-ptr/base.cxx
+// author : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : Copyright (c) 2009 Code Synthesis Tools CC
+// license : MIT; see accompanying LICENSE file
+
+#include <cutl/shared-ptr/base.hxx>
+
+using std::size_t;
+
+//
+//
+cutl::share shared = cutl::share (1);
+cutl::share exclusive = cutl::share (2);
+
+//
+//
+namespace cutl
+{
+ char const* not_shared::
+ what () const throw ()
+ {
+ return "object is not shared";
+ }
+}
+
+//
+//
+void*
+operator new (size_t n, cutl::share s) throw (std::bad_alloc)
+{
+ if (s == shared)
+ {
+ // Here we need to make sure we don't break the alignment of the
+ // returned block. For that we need to know the maximum alignment
+ // of this platform. Twice the pointer size is a good guess for
+ // most platforms.
+ //
+ size_t* p = static_cast<size_t*> (operator new (n + 2 * sizeof (size_t)));
+ *p++ = 1; // Initial count.
+ *p++ = 0xDEADBEEF; // Signature.
+ return p;
+ }
+ else
+ return operator new (n);
+
+}
+
+void
+operator delete (void* p, cutl::share s) throw ()
+{
+ // This version of operator delete is only called when the c-tor
+ // fails. In this case there is no object and we can just free the
+ // memory.
+ //
+ if (s == shared)
+ {
+ size_t* sp = static_cast<size_t*> (p);
+ sp -= 2;
+ operator delete (sp);
+ }
+ else
+ operator delete (p);
+}