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d4b0bb186e
This patch introduces a bit of infrastructure -- namely, a minimal std::optional analogue called gdb::optional, and an RAII template class that works like make_cleanup_ui_out_tuple_begin_end or make_cleanup_ui_out_list_begin_end -- and then uses these in the Python code. This removes a number of cleanups and generally simplifies this code. std::optional is only available in C++17. Normally I would have had this code check __cplusplus, but my gcc apparently isn't new enough to find <optional>, even with -std=c++1z; so, because I could not test it, the patch does not do this. gdb/ChangeLog 2017-02-10 Tom Tromey <tom@tromey.com> * ui-out.h (ui_out_emit_type): New class. (ui_out_emit_tuple, ui_out_emit_list): New typedefs. * python/py-framefilter.c (py_print_single_arg): Use gdb::optional and ui_out_emit_tuple. (enumerate_locals): Likewise. (py_mi_print_variables, py_print_locals, py_print_args): Use ui_out_emit_list. (py_print_frame): Use gdb::optional, ui_out_emit_tuple, ui_out_emit_list. * common/gdb_optional.h: New file.
88 lines
2.1 KiB
C++
88 lines
2.1 KiB
C++
/* An optional object.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License 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 this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef GDB_OPTIONAL_H
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#define GDB_OPTIONAL_H
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namespace gdb
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{
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/* This class attempts to be a compatible subset of std::optional,
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which is slated to be available in C++17. This class optionally
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holds an object of some type -- by default it is constructed not
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holding an object, but later the object can be "emplaced". This is
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similar to using std::unique_ptr, but in-object allocation is
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guaranteed. */
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template<typename T>
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class optional
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{
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public:
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optional ()
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: m_instantiated (false)
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{
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}
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~optional ()
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{
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if (m_instantiated)
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destroy ();
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}
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/* These aren't deleted in std::optional, but it was simpler to
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delete them here, because currently the users of this class don't
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need them, and making them depend on the definition of T is
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somewhat complicated. */
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optional (const optional &other) = delete;
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optional<T> &operator= (const optional &other) = delete;
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template<typename... Args>
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void emplace (Args &&... args)
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{
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if (m_instantiated)
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destroy ();
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new (&m_item) T (std::forward<Args>(args)...);
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m_instantiated = true;
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}
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private:
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/* Destroy the object. */
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void destroy ()
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{
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gdb_assert (m_instantiated);
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m_instantiated = false;
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m_item.~T ();
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}
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/* The object. */
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union
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{
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struct { } m_dummy;
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T m_item;
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};
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/* True if the object was ever emplaced. */
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bool m_instantiated;
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};
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}
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#endif /* GDB_OPTIONAL_H */
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