search_configurator.hpp

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// -----------------------------------------------------------------------------------------------------
// Copyright (c) 2006-2020, Knut Reinert & Freie Universität Berlin
// Copyright (c) 2016-2020, Knut Reinert & MPI für molekulare Genetik
// This file may be used, modified and/or redistributed under the terms of the 3-clause BSD-License
// shipped with this file and also available at: https://github.com/seqan/seqan3/blob/master/LICENSE.md
// -----------------------------------------------------------------------------------------------------
 
#pragma once
 
#include <seqan3/core/type_list/type_list.hpp>
#include <seqan3/core/type_traits/function.hpp>
#include <seqan3/core/type_traits/lazy.hpp>
#include <seqan3/core/type_traits/template_inspection.hpp>
#include <seqan3/search/configuration/hit.hpp>
#include <seqan3/search/configuration/max_error.hpp>
#include <seqan3/search/configuration/output.hpp>
#include <seqan3/search/configuration/result_type.hpp>
#include <seqan3/search/detail/policy_max_error.hpp>
#include <seqan3/search/detail/policy_search_result_builder.hpp>
#include <seqan3/search/detail/search_scheme_algorithm.hpp>
#include <seqan3/search/detail/unidirectional_search_algorithm.hpp>
#include <seqan3/search/search_result.hpp>
 
namespace seqan3::detail
{
 
class search_configurator
{
private:
    template <typename search_configuration_t, typename index_t, typename query_index_t>
    struct select_search_result
    {
    private:
        using index_cursor_type = typename index_t::cursor_type;
        using index_size_type = typename index_t::size_type;
        using traits_type = search_traits<search_configuration_t>;
 
        using query_id_t = std::conditional_t<traits_type::output_query_id, size_t, empty_type>;
        using index_cursor_t = std::conditional_t<traits_type::output_index_cursor, index_cursor_type, empty_type>;
        using reference_id_t = std::conditional_t<traits_type::output_reference_id, index_size_type, empty_type>;
        using reference_begin_position_t = std::conditional_t<traits_type::output_reference_begin_position,
                                                              index_size_type,
                                                              empty_type>;
 
    public:
        using type = search_result<query_id_t, index_cursor_t, reference_id_t, reference_begin_position_t>;
    };
 
    template <typename configuration_t, typename index_t, typename ...policies_t>
    struct select_search_algorithm
    {
        using type =
            lazy_conditional_t<bi_fm_index_specialisation<index_t>,
                               lazy<search_scheme_algorithm, configuration_t, index_t, policies_t...>,
                               lazy<unidirectional_search_algorithm, configuration_t, index_t, policies_t...>>;
    };
 
public:
    template <typename configuration_t>
    static auto add_default_hit_configuration(configuration_t const & cfg)
    {
        if constexpr (!detail::search_traits<configuration_t>::has_hit_configuration)
            return cfg | search_cfg::hit_all{};
        else
            return cfg;
    }
 
    template <typename configuration_t>
    static auto add_default_output_configuration(configuration_t const & cfg)
    {
        if constexpr (!seqan3::detail::search_traits<configuration_t>::has_output_configuration)
            return cfg |
                   search_cfg::output_query_id{} |
                   search_cfg::output_reference_id{} |
                   search_cfg::output_reference_begin_position{};
        else
            return cfg;
    }
 
    template <typename configuration_t>
    static auto add_defaults(configuration_t const & cfg)
    {
        static_assert(detail::is_type_specialisation_of_v<configuration_t, configuration>,
                      "cfg must be a specialisation of seqan3::configuration.");
 
        auto cfg1 = add_default_hit_configuration(cfg);
        auto cfg2 = add_default_output_configuration(cfg1);
 
        return cfg2;
    }
 
    template <typename query_t, typename configuration_t, typename index_t>
    static auto configure_algorithm(configuration_t const & cfg, index_t const & index)
    {
        using query_index_t = std::tuple_element_t<0, query_t>;
        using search_result_t = typename select_search_result<configuration_t, index_t, query_index_t>::type;
        using callback_t = std::function<void(search_result_t)>;
        using type_erased_algorithm_t = std::function<void(query_t, callback_t)>;
 
        auto complete_config = cfg | search_cfg::detail::result_type<search_result_t>{};
        return std::pair{configure_hit_strategy<type_erased_algorithm_t>(complete_config, index), complete_config};
    }
 
    template <typename algorithm_t, typename configuration_t, typename index_t>
    static algorithm_t configure_hit_strategy(configuration_t const &, index_t const &);
 
    template <typename algorithm_t, typename configuration_t, typename index_t>
    static algorithm_t select_and_return_algorithm(configuration_t const & config, index_t const & index)
    {
        using selected_algorithm_t =
            typename select_search_algorithm<configuration_t,
                                             index_t,
                                             policy_max_error,
                                             policy_search_result_builder<configuration_t>>::type;
 
        return selected_algorithm_t{config, index};
    }
};
 
template <typename algorithm_t, typename configuration_t, typename index_t>
algorithm_t search_configurator::configure_hit_strategy(configuration_t const & cfg, index_t const & index)
{
    // Delegate to the next config with the modified configuration.
    auto next_config_step = [&] (auto new_cfg) -> algorithm_t
    {
        return select_and_return_algorithm<algorithm_t>(new_cfg, index);
    };
 
    // Check if dynamic config present, otherwise continue.
    if constexpr (configuration_t::template exists<search_cfg::hit>())
    {
        auto hit_variant = get<search_cfg::hit>(cfg).hit_variant;
 
        if (std::holds_alternative<empty_type>(hit_variant))
            throw std::invalid_argument{"The dynamic hit strategy was not initialised! "
                                        "Please refer to the configuration documentation of the search algorithm for "
                                        "more details."};
 
        // Remove dynamic config first.
        auto cfg_without_hit = cfg.template remove<search_cfg::hit>();
 
        // Apply the correct static configuration element.
        return std::visit(multi_invocable
        {
            [&] (search_cfg::hit_all_best) { return next_config_step(cfg_without_hit | search_cfg::hit_all_best{}); },
            [&] (search_cfg::hit_single_best) { return next_config_step(cfg_without_hit | search_cfg::hit_single_best{}); },
            [&] (search_cfg::hit_strata const & strata) { return next_config_step(cfg_without_hit | strata); },
            [&] (auto) { return next_config_step(cfg_without_hit | search_cfg::hit_all{}); }
        }, hit_variant);
    }
    else // Already statically configured.
    {
        static_assert(detail::search_traits<configuration_t>::has_hit_configuration,
                      "The hit strategy for the search algorithm was not configured. "
                      "Please refer to the configuration documentation of the search algorithm for more details.");
 
        return next_config_step(cfg);
    }
}
 
} // namespace seqan3::detail