[FEATURE] Make search work with dynamic mode configuration.

Enables the dynamic mode configuration within the search algorithm by transforming it
into a static configuration.

include/seqan3/search/algorithm/detail/search.hpp

@@ -12,7 +12,10 @@
 
 #pragma once
 
+#include <variant>
+
 #include <seqan3/core/type_traits/pre.hpp>
+#include <seqan3/core/type_traits/function.hpp>
 #include <seqan3/search/algorithm/detail/search_scheme_algorithm.hpp>
 #include <seqan3/search/algorithm/detail/search_traits.hpp>
 #include <seqan3/search/algorithm/detail/search_trivial.hpp>
@@ -112,7 +115,7 @@ inline auto search_single(index_t const & index, query_t & query, configuration_
         if (!internal_hits.empty())
         {
             internal_hits.clear(); // TODO: don't clear when using Optimum Search Schemes with lower error bounds
-            uint8_t const s = get<search_cfg::mode>(cfg).value;
+            uint8_t const s = get<internal_search_mode>(cfg).value;
             max_error2.total += s - 1;
             detail::search_algo<false>(index, query, max_error2, internal_delegate);
         }
@@ -178,6 +181,9 @@ inline auto search_single(index_t const & index, query_t & query, configuration_
  * specified in `cfg` also has a strong exception guarantee; basic exception guarantee otherwise.
  */
 template <typename index_t, typename queries_t, typename configuration_t>
+//!\cond
+    requires configuration_t::template exists<internal_search_mode>()
+//!\endcond
 inline auto search_all(index_t const & index, queries_t && queries, configuration_t const & cfg)
 {
     using cfg_t = remove_cvref_t<configuration_t>;
@@ -210,6 +216,32 @@ inline auto search_all(index_t const & index, queries_t && queries, configuratio
     }
 }
 
+//!\overload
+template <typename index_t, typename queries_t, typename configuration_t>
+//!\cond
+    requires !configuration_t::template exists<internal_search_mode>()
+//!\endcond
+inline auto search_all(index_t const & index, queries_t && queries, configuration_t const & cfg)
+{
+    using seqan3::get;
+    auto mode_config = get<search_cfg::mode>(cfg);
+
+    if constexpr (decltype(mode_config)::has_dynamic_state)
+    {
+        return std::visit(multi_invocable
+        {
+            [&] (search_mode_all_best) { return search_all(index, queries, cfg | internal_search_mode{search_cfg::all_best}); },
+            [&] (search_mode_best) { return search_all(index, queries, cfg | internal_search_mode{search_cfg::best}); },
+            [&] (search_cfg::strata const & strata) { return search_all(index, queries, cfg | internal_search_mode{strata}); },
+            [&] (auto) { return search_all(index, queries, cfg | internal_search_mode{search_cfg::all}); }
+        }, mode_config.search_modes());
+    }
+    else
+    {
+        return search_all(index, std::forward<queries_t>(queries), cfg | internal_search_mode{mode_config.value});
+    }
+}
+
 //!\}
 
 } // namespace seqan3::detail

include/seqan3/search/algorithm/detail/search_traits.hpp

@@ -40,21 +40,24 @@ struct search_traits
 
     //!\brief A flag indicating whether search should find all hits.
     static constexpr bool search_all_hits =
-        search_configuration_t::template exists<search_cfg::mode<detail::search_mode_all>>();
+        search_configuration_t::template exists<search_cfg::mode<detail::search_mode_all>>() |
+        search_configuration_t::template exists<detail::internal_search_mode<detail::search_mode_all>>();
     //!\brief A flag indicating whether search should find best hits.
     static constexpr bool search_best_hits =
-        search_configuration_t::template exists<search_cfg::mode<detail::search_mode_best>>();
+        search_configuration_t::template exists<search_cfg::mode<detail::search_mode_best>>() |
+        search_configuration_t::template exists<detail::internal_search_mode<detail::search_mode_best>>();
     //!\brief A flag indicating whether search should find all best hits.
     static constexpr bool search_all_best_hits =
-        search_configuration_t::template exists<search_cfg::mode<detail::search_mode_all_best>>();
+        search_configuration_t::template exists<search_cfg::mode<detail::search_mode_all_best>>() |
+        search_configuration_t::template exists<detail::internal_search_mode<detail::search_mode_all_best>>();
     //!\brief A flag indicating whether search should find strata hits.
     static constexpr bool search_strata_hits =
-        search_configuration_t::template exists<search_cfg::mode<search_cfg::strata>>();
+        search_configuration_t::template exists<search_cfg::mode<search_cfg::strata>>() |
+        search_configuration_t::template exists<detail::internal_search_mode<search_cfg::strata>>();
     //!\brief A flag indicating whether mode configuration was set in the search configuration.
-    static constexpr bool has_mode_configuration = search_all_hits |
-                                                   search_best_hits |
-                                                   search_all_best_hits |
-                                                   search_strata_hits;
+    static constexpr bool has_mode_configuration =
+        search_configuration_t::template exists<search_cfg::mode>() |
+        search_configuration_t::template exists<detail::internal_search_mode>();
 
     //!\brief A flag indicating whether search should return the index cursor.
     static constexpr bool search_return_index_cursor =

include/seqan3/search/algorithm/search.hpp

@@ -167,7 +167,7 @@ namespace seqan3
  *
  * \include test/snippet/search/algorithm/search.cpp
  */
-template <fm_index_specialisation index_t, typename queries_t, typename configuration_t = decltype(search_cfg::default_configuration)>
+template <typename queries_t, fm_index_specialisation index_t, typename configuration_t = decltype(search_cfg::default_configuration)>
 inline auto search(queries_t && queries,
                    index_t const & index,
                    configuration_t const & cfg = search_cfg::default_configuration)

include/seqan3/search/configuration/mode.hpp

@@ -34,7 +34,6 @@ struct search_mode_all_best {};
 //!\brief Type for the "best" value for the configuration element "mode".
 //!\ingroup search_configuration
 struct search_mode_best {};
-
 } // namespace seqan3::detail
 
 namespace seqan3::search_cfg
@@ -61,9 +60,21 @@ struct strata : detail::strong_type<uint8_t, strata, detail::strong_type_skill::
     using detail::strong_type<uint8_t, strata, detail::strong_type_skill::convert>::strong_type;
 };
 
+//!\brief A helper variable template to check if the given mode type is a valid search mode.
+//!\ingroup search_configuration
+//!\hideinitializer
+template <typename search_mode_t>
+inline constexpr bool is_valid_search_mode_v = std::same_as<search_mode_t, detail::search_mode_all> ||
+                                               std::same_as<search_mode_t, detail::search_mode_all_best> ||
+                                               std::same_as<search_mode_t, detail::search_mode_best> ||
+                                               std::same_as<search_mode_t, strata>;
+
 /*!\brief Configuration element to determine the search mode.
  * \ingroup search_configuration
  *
+ * \tparam search_mode_t The type of the search mode to use; seqan3::search_cfg::is_valid_mode_type must evaluate to
+ *                       `true` or must be of type seqan3::dynamic_state.
+ *
  * \details
  *
  * This configuration element can be used to determine which hits are supported.
@@ -92,11 +103,7 @@ struct strata : detail::strong_type<uint8_t, strata, detail::strong_type_skill::
  */
 template <typename search_mode_t>
 //!\cond
-    requires std::same_as<search_mode_t, detail::search_mode_all> ||
-             std::same_as<search_mode_t, detail::search_mode_all_best> ||
-             std::same_as<search_mode_t, detail::search_mode_best> ||
-             std::same_as<search_mode_t, strata> ||
-             std::same_as<search_mode_t, dynamic_state>
+    requires is_valid_search_mode_v<search_mode_t> || std::same_as<search_mode_t, dynamic_state>
 //!\endcond
 class mode : public pipeable_config_element<mode<search_mode_t>, search_mode_t>
 {
@@ -121,6 +128,8 @@ class mode : public pipeable_config_element<mode<search_mode_t>, search_mode_t>
     ~mode() = default; //!< Defaulted.
 
     /*!\brief Construction of a fixed search mode with the given mode option.
+     *
+     * \tparam new_search_mode_t The type of the search mode to set.
      *
      * \param[in] new_search_mode The instance of the search mode option to use.
      *
@@ -131,30 +140,25 @@ class mode : public pipeable_config_element<mode<search_mode_t>, search_mode_t>
      */
     template <typename new_search_mode_t>
     //!\cond
-        requires !std::same_as<new_search_mode_t, mode> &&
-                 (std::same_as<new_search_mode_t, detail::search_mode_all> ||
-                  std::same_as<new_search_mode_t, detail::search_mode_all_best> ||
-                  std::same_as<new_search_mode_t, detail::search_mode_best> ||
-                  std::same_as<new_search_mode_t, strata>)
+        requires !std::same_as<new_search_mode_t, mode> && is_valid_search_mode_v<new_search_mode_t>
     //!\endcond
     explicit constexpr mode(new_search_mode_t new_search_mode) : base_t{std::move(new_search_mode)}
     {}
 
     /*!\brief Assigns a new mode option to the search mode.
+     *
+     * \tparam new_search_mode_t The type of the search mode to set.
      *
      * \param[in] new_search_mode The instance of the search mode option to use.
      *
      * \details
      *
-     * Note this assignment operator is only available if the search mode was default constructed.
+     * Note this assignment operator is only available if the search mode was default constructed, i.e. `search_mode_t`
+     * is deduced as seqan3::dynamic_state.
      */
     template <typename new_search_mode_t>
     //!\cond
-        requires !std::same_as<new_search_mode_t, mode> &&
-                 (std::same_as<new_search_mode_t, detail::search_mode_all> ||
-                  std::same_as<new_search_mode_t, detail::search_mode_all_best> ||
-                  std::same_as<new_search_mode_t, detail::search_mode_best> ||
-                  std::same_as<new_search_mode_t, strata>)
+        requires !std::same_as<new_search_mode_t, mode> && is_valid_search_mode_v<new_search_mode_t>
     //!\endcond
     constexpr mode & operator=(new_search_mode_t new_search_mode)
     {
@@ -166,6 +170,9 @@ class mode : public pipeable_config_element<mode<search_mode_t>, search_mode_t>
     }
     //!\}
 
+    //!\brief Evaluates to `true` if the search mode can be configured at runtime, otherwise `false`.
+    static constexpr bool has_dynamic_state = std::same_as<search_mode_t, dynamic_state>;
+
     //!\privatesection
     //!\brief Internal id to check for consistent configuration settings.
     static constexpr detail::search_config_id id{detail::search_config_id::mode};
@@ -179,9 +186,6 @@ class mode : public pipeable_config_element<mode<search_mode_t>, search_mode_t>
         return search_mode_variant;
     }
 
-    //!\brief Evaluates to `true` if the search mode can be configured at runtime, otherwise `false`.
-    static constexpr bool has_dynamic_state = std::same_as<search_mode_t, dynamic_state>;
-
 private:
     //!\brief Stores the dynamically selected search mode option.
     search_modes_t search_mode_variant{};
@@ -205,9 +209,8 @@ namespace seqan3::detail
 /*!\brief An internal representation of the associated seqan3::search_cfg::mode.
  * \ingroup search_configuration
  *
- * \tparam search_mode_t The type of the search mode option; must be one of seqan3::detail::search_mode_all,
- *                       seqan3::detail::search_mode_best, seqan3::detail::search_mode_all_best, or
- *                       seqan3::detail::search_mode_strata.
+ * \tparam search_mode_t The type of the search mode option; seqan3::search_cfg::is_valid_search_mode_v must evaluate to
+ *                       `true`;
  *
  * \details
  *
@@ -220,10 +223,7 @@ namespace seqan3::detail
  */
 template <typename search_mode_t>
 //!\cond
-    requires std::same_as<search_mode_t, search_mode_all> ||
-             std::same_as<search_mode_t, search_mode_all_best> ||
-             std::same_as<search_mode_t, search_mode_best> ||
-             std::same_as<search_mode_t, search_cfg::strata>
+    requires search_cfg::is_valid_search_mode_v<search_mode_t>
 //!\endcond
 struct internal_search_mode : public pipeable_config_element<internal_search_mode<search_mode_t>, search_mode_t>
 {

test/snippet/search/configuration_modes_dynamic.cpp

@@ -4,10 +4,10 @@ int main()
 {
     seqan3::search_cfg::mode my_mode{}; // Enables the dynamic configuration, defaults to seqan3::search_cfg::all.
 
-    my_mode = seqan3::search_cfg::best; // Now the best mode is selected.
-
-    my_mode = seqan3::search_cfg::strata{2}; // Now the strata mode is selected.
-
+    if (true)
+        my_mode = seqan3::search_cfg::best; // The best mode is selected.
+    else
+        my_mode = seqan3::search_cfg::strata{2}; // The strata mode is selected.
 
     // Combine the dynamically configured mode with other search configurations.
     seqan3::configuration const cfg = my_mode |

test/unit/search/search_configuration_test.cpp

@@ -7,7 +7,7 @@
 
 #include <type_traits>
 
-#include <seqan3/search/algorithm/all.hpp>
+#include <seqan3/search/configuration/all.hpp>
 
 #include <gtest/gtest.h>
 
@@ -57,7 +57,7 @@ TYPED_TEST(search_configuration_test, configuration_exists)
 // See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93034
 TYPED_TEST(search_configuration_test, configuration_exists_constexpr)
 {
-    constexpr configuration cfg{TypeParam{}};
+    constexpr seqan3::configuration cfg{TypeParam{}};
     constexpr bool cfg_exists = decltype(cfg)::template exists<TypeParam>();
     EXPECT_TRUE(cfg_exists);
 }