BLI_binary_search.hh

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/* SPDX-FileCopyrightText: 2024 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#include <algorithm>
 
namespace blender::binary_search {
 
template<typename Iterator, typename Predicate>
static int64_t first_if(Iterator begin, Iterator end, Predicate &&predicate)
{
  return std::lower_bound(begin,
                          end,
                          nullptr,
                          [&](const auto &value, void * /*dummy*/) { return !predicate(value); }) -
         begin;
}
 
template<typename Iterator, typename Predicate>
static int64_t last_if(Iterator begin, Iterator end, Predicate &&predicate)
{
  return std::upper_bound(begin,
                          end,
                          nullptr,
                          [&](void * /*dummy*/, const auto &value) { return !predicate(value); }) -
         begin - 1;
}
 
template<typename Range, typename Predicate>
int64_t first_if(const Range &range, Predicate &&predicate)
{
  return first_if(range.begin(), range.end(), predicate);
}
 
template<typename Range, typename Predicate>
int64_t last_if(const Range &range, Predicate &&predicate)
{
  return last_if(range.begin(), range.end(), predicate);
}
 
}  // namespace blender::binary_search