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/* Template for deferring object creation until the object is needed.
Copyright (C) 2024-2025 Free Software Foundation, Inc.
Contributed by David Malcolm <dmalcolm@redhat.com>
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#ifndef GCC_LAZILY_CREATED_H
#define GCC_LAZILY_CREATED_H
/* A template for deferring object creation for a type T until the object
is needed, to avoid potentially expensive creation of T unless it's
actually needed (e.g. for directed graphs associated with a diagnostic,
which are ignored by the default "text" sink). */
template <typename T>
class lazily_created
{
public:
virtual ~lazily_created () {}
const T &
get_or_create () const
{
if (!m_object)
m_object = create_object ();
gcc_assert (m_object);
return *m_object;
}
private:
virtual std::unique_ptr<T>
create_object () const = 0;
mutable std::unique_ptr<T> m_object;
};
#endif /* ! GCC_LAZILY_CREATED_H */
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