utility/container/concept.hpp

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// SPDX-FileCopyrightText: 2006-2025 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2025 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <concepts>
#include <initializer_list>
#include <iterator>
#include <type_traits>
 
#include <seqan3/core/platform.hpp>
 
#if SEQAN3_WORKAROUND_GCC_NO_CXX11_ABI
#    include <string>
 
namespace seqan3::detail
{
 
template <typename basic_string_t>
struct is_basic_string : std::false_type
{};
 
template <typename value_t, typename traits_t, typename allocator_t>
struct is_basic_string<std::basic_string<value_t, traits_t, allocator_t>> : std::true_type
{};
 
template <typename basic_string_t>
constexpr bool is_basic_string_v = is_basic_string<basic_string_t>::value;
 
} // namespace seqan3::detail
#endif // SEQAN3_WORKAROUND_GCC_NO_CXX11_ABI
 
namespace seqan3
{
 
template <typename type>
concept container = requires (type val, type val2, type const cval, typename type::iterator it) {
    // member types
    typename type::value_type;
    typename type::reference;
    typename type::const_reference;
    /*
    typename type::iterator;
    requires std::forward_iterator<typename type::iterator>;
    // NOTE check whether iterator is const convertible
    {it} -> std::same_as<typename type::const_iterator>;
 
    typename type::const_iterator;
    requires std::forward_iterator<typename type::const_iterator>;
 
    typename type::difference_type;
    typename type::size_type;
    requires std::is_same_v<
        typename type::difference_type,
        typename std::iterator_traits<typename type::iterator>::difference_type
    >;
    requires std::is_same_v<
        typename std::iterator_traits<typename type::iterator>::difference_type,
        typename std::iterator_traits<typename type::const_iterator>::difference_type
    >;
*/
    // methods and operator
    { type{} } -> std::same_as<type>;       // default constructor
    { type{type{}} } -> std::same_as<type>; // copy/move constructor
    { val = val2 } -> std::same_as<type &>; // assignment
    { (&val)->~type() };                    // destructor
 
    { val.begin() } -> std::same_as<typename type::iterator>;
    { val.end() } -> std::same_as<typename type::iterator>;
    { cval.begin() } -> std::same_as<typename type::const_iterator>;
    { cval.end() } -> std::same_as<typename type::const_iterator>;
    { val.cbegin() } -> std::same_as<typename type::const_iterator>;
    { val.cend() } -> std::same_as<typename type::const_iterator>;
 
    requires !std::equality_comparable<typename type::value_type> || std::equality_comparable<type>;
 
    { val.swap(val2) } -> std::same_as<void>;
    { swap(val, val2) } -> std::same_as<void>;
    { std::swap(val, val2) } -> std::same_as<void>;
 
    { val.size() } -> std::same_as<typename type::size_type>;
    { val.max_size() } -> std::same_as<typename type::size_type>;
    { val.empty() } -> std::same_as<bool>;
};
 
template <typename type>
concept sequence_container = requires (type val, type val2, type const cval) {
    requires container<type>;
 
    // construction
    { type(typename type::size_type{}, typename type::value_type{}) };
    { type{val2.begin(), val2.end()} }; // NOTE that this could be any input iterator:
    { type{std::initializer_list<typename type::value_type>{}} };
    { val = std::initializer_list<typename type::value_type>{} } -> std::same_as<type &>;
 
    // assignment NOTE return type is type & for std::string and void for other stl containers:
    { val.assign(val2.begin(), val2.end()) };
    { val.assign(std::initializer_list<typename type::value_type>{}) };
    { val.assign(typename type::size_type{}, typename type::value_type{}) };
 
    // modify container
    // TODO: how do you model this?
    // {val.emplace(typename type::const_iterator{}, ?)} -> std::same_as<typename type::iterator>;
#if SEQAN3_WORKAROUND_GCC_NO_CXX11_ABI
    { val.insert(val.begin(), val2.front()) } -> std::same_as<typename type::iterator>;
    { val.insert(val.begin(), typename type::value_type{}) } -> std::same_as<typename type::iterator>;
 
    // std::string is missing the const_iterator versions for insert in pre-C++11 ABI
    requires detail::is_basic_string_v<type>
                 || requires (type val, type val2)
#else  // ^^^ workaround / no workaround vvv
    requires requires (type val, type val2)
#endif // SEQAN3_WORKAROUND_GCC_NO_CXX11_ABI
    {
        { val.insert(val.cbegin(), val2.front()) } -> std::same_as<typename type::iterator>;
        { val.insert(val.cbegin(), typename type::value_type{}) } -> std::same_as<typename type::iterator>;
        {
            val.insert(val.cbegin(), typename type::size_type{}, typename type::value_type{})
        } -> std::same_as<typename type::iterator>;
        { val.insert(val.cbegin(), val2.begin(), val2.end()) } -> std::same_as<typename type::iterator>;
        {
            val.insert(val.cbegin(), std::initializer_list<typename type::value_type>{})
        } -> std::same_as<typename type::iterator>;
    };
 
#if SEQAN3_WORKAROUND_GCC_NO_CXX11_ABI
    // std::string is missing the const_iterator versions for erase in pre-C++11 ABI
    requires detail::is_basic_string_v<type>
                 || requires (type val)
#else  // ^^^ workaround / no workaround vvv
    requires requires (type val)
#endif // SEQAN3_WORKAROUND_GCC_NO_CXX11_ABI
    {
        { val.erase(val.cbegin()) } -> std::same_as<typename type::iterator>;
        { val.erase(val.cbegin(), val.cend()) } -> std::same_as<typename type::iterator>;
    };
 
    { val.push_back(val.front()) } -> std::same_as<void>;
    { val.push_back(typename type::value_type{}) } -> std::same_as<void>;
    { val.pop_back() } -> std::same_as<void>;
    { val.clear() } -> std::same_as<void>;
 
    // access container
    { val.front() } -> std::same_as<typename type::reference>;
    { cval.front() } -> std::same_as<typename type::const_reference>;
    { val.back() } -> std::same_as<typename type::reference>;
    { cval.back() } -> std::same_as<typename type::const_reference>;
};
 
template <typename type>
concept random_access_container = requires (type val) {
    requires sequence_container<type>;
 
    // access container
    { val[0] } -> std::same_as<typename type::reference>;
    { val.at(0) } -> std::same_as<typename type::reference>;
 
    // modify container
    { val.resize(0) } -> std::same_as<void>;
    { val.resize(0, typename type::value_type{}) } -> std::same_as<void>;
};
 
template <typename type>
concept reservible_container = requires (type val) {
    requires random_access_container<type>;
 
    { val.capacity() } -> std::same_as<typename type::size_type>;
    { val.reserve(0) } -> std::same_as<void>;
    { val.shrink_to_fit() } -> std::same_as<void>;
};
 
} // namespace seqan3