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52 lines
1.5 KiB
C++
52 lines
1.5 KiB
C++
/* Template for deferring object creation until the object is needed.
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Copyright (C) 2024-2026 Free Software Foundation, Inc.
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Contributed by David Malcolm <dmalcolm@redhat.com>
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef GCC_LAZILY_CREATED_H
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#define GCC_LAZILY_CREATED_H
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/* A template for deferring object creation for a type T until the object
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is needed, to avoid potentially expensive creation of T unless it's
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actually needed (e.g. for directed graphs associated with a diagnostic,
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which are ignored by the default "text" sink). */
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template <typename T>
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class lazily_created
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{
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public:
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virtual ~lazily_created () {}
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const T &
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get_or_create () const
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{
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if (!m_object)
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m_object = create_object ();
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gcc_assert (m_object);
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return *m_object;
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}
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private:
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virtual std::unique_ptr<T>
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create_object () const = 0;
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mutable std::unique_ptr<T> m_object;
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};
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#endif /* ! GCC_LAZILY_CREATED_H */
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