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/* A forward filtered iterator for GDB, the GNU debugger.
Copyright (C) 2018-2024 Free Software Foundation, Inc.
This file is part of GDB.
This program 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 of the License, or
(at your option) any later version.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef GDBSUPPORT_FILTERED_ITERATOR_H
#define GDBSUPPORT_FILTERED_ITERATOR_H
#include <type_traits>
/* A filtered iterator. This wraps BaseIterator and automatically
skips elements that FilterFunc filters out. Requires that
default-constructing a BaseIterator creates a valid one-past-end
iterator. */
template<typename BaseIterator, typename FilterFunc>
class filtered_iterator
{
public:
typedef filtered_iterator self_type;
typedef typename BaseIterator::value_type value_type;
typedef typename BaseIterator::reference reference;
typedef typename BaseIterator::pointer pointer;
typedef typename BaseIterator::iterator_category iterator_category;
typedef typename BaseIterator::difference_type difference_type;
/* Construct by forwarding all arguments to the underlying
iterator. */
template<typename... Args>
explicit filtered_iterator (Args &&...args)
: m_it (std::forward<Args> (args)...)
{ skip_filtered (); }
/* Create a one-past-end iterator. */
filtered_iterator () = default;
/* Need these as the variadic constructor would be a better match
otherwise. */
filtered_iterator (filtered_iterator &) = default;
filtered_iterator (const filtered_iterator &) = default;
filtered_iterator (filtered_iterator &&) = default;
filtered_iterator (const filtered_iterator &&other)
: filtered_iterator (static_cast<const filtered_iterator &> (other))
{}
typename std::invoke_result<decltype(&BaseIterator::operator*),
BaseIterator>::type
operator* () const
{ return *m_it; }
self_type &operator++ ()
{
++m_it;
skip_filtered ();
return *this;
}
bool operator== (const self_type &other) const
{ return m_it == other.m_it; }
bool operator!= (const self_type &other) const
{ return m_it != other.m_it; }
private:
void skip_filtered ()
{
for (; m_it != m_end; ++m_it)
if (m_filter (*m_it))
break;
}
private:
FilterFunc m_filter {};
BaseIterator m_it {};
BaseIterator m_end {};
};
#endif /* GDBSUPPORT_FILTERED_ITERATOR_H */
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