chromium/base/containers/contains.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_CONTAINERS_CONTAINS_H_
#define BASE_CONTAINERS_CONTAINS_H_

#include <ranges>
#include <type_traits>
#include <utility>

#include "base/ranges/algorithm.h"
// TODO(dcheng): Remove this after fixing any IWYU errors.
#include "base/ranges/ranges.h"

namespace base {

namespace internal {

// Small helper to detect whether a given type has a nested `key_type` typedef.
// Used below to catch misuses of the API for associative containers.
HasKeyType;

}  // namespace internal

// A general purpose utility to check whether `container` contains `value`. This
// will probe whether a `contains` or `find` member function on `container`
// exists, and fall back to a generic linear search over `container`.
template <typename Container, typename Value>
constexpr bool Contains(const Container& container, const Value& value) { … }

// Overload that allows to provide an additional projection invocable. This
// projection will be applied to every element in `container` before comparing
// it with `value`. This will always perform a linear search.
template <typename Container, typename Value, typename Proj>
constexpr bool Contains(const Container& container,
                        const Value& value,
                        Proj proj) { … }

}  // namespace base

#endif  // BASE_CONTAINERS_CONTAINS_H_