ladybird/AK/Find.h
Lenny Maiorani 4333a9a8d6 AK: Find a value in any container offering iterators
Problem:
- `find` is implemented inside of each container. This coupling
  requires that each container needs to individually provide `find`.

Solution:
- Decouple the `find` functionality from the container. This allows
  provides a `find` algorithm which can work with all
  containers. Containers can still provide their own `find` in the
  case where it can be optimized.
- This also allows for searching sub-ranges of a container rather than
  the entire container as some of the container-specific member
  functions enforced.

Note:
- @davidstone's talk from 2015 C++Now conference entitled "Functions
  Want to be Free" encourages this style:
  (https://www.youtube.com/watch?v=_lVlC0xzXDc), but it does come at
  the cost of composability.
- A logical follow-on to this is to provide a mechanism to use a
  short-hand function which automatically searches the entire
  container. This could automatically use the container-provided
  version if available so that functions which provide their own
  optimized version get the benefit.
2021-01-11 19:45:05 +01:00

57 lines
2.1 KiB
C++

/*
* Copyright (c) 2021, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/Traits.h>
#include <AK/Types.h>
namespace AK {
template<typename TIterator, typename TUnaryPredicate>
constexpr TIterator find_if(TIterator first, TIterator last, TUnaryPredicate&& pred)
{
for (; first != last; ++first) {
if (pred(*first)) {
return first;
}
}
return last;
}
template<typename TIterator, typename T>
constexpr TIterator find(TIterator first, TIterator last, const T& value)
{
return find_if(first, last, [&](const auto& v) { return Traits<T>::equals(value, v); });
}
template<typename TIterator, typename T>
constexpr size_t find_index(TIterator first, TIterator last, const T& value)
{
return find_if(first, last, [&](const auto& v) { return Traits<T>::equals(value, v); }).index();
}
}