Recursive traversal of types to generate required pools

alex-sparus · alex-sparus · commit 3fc43af9e524 · 2024-05-24T15:04:05.000+02:00
diff --git a/immer/extra/persist/common/type_traverse.hpp b/immer/extra/persist/common/type_traverse.hpp
@@ -0,0 +1,152 @@
+#pragma once
+
+#include <immer/flex_vector.hpp>
+#include <immer/map.hpp>
+#include <immer/set.hpp>
+#include <immer/table.hpp>
+#include <immer/vector.hpp>
+
+#include <boost/hana.hpp>
+
+namespace immer::persist::util {
+
+namespace detail {
+
+namespace hana = boost::hana;
+
+template <class T, class = void>
+struct get_inner_types_t
+{
+    static auto apply()
+    {
+        return hana::make_tuple(
+            hana::make_pair(hana::type_c<T>, BOOST_HANA_STRING("")));
+    }
+};
+
+template <class T>
+struct get_inner_types_t<T, std::enable_if_t<hana::Struct<T>::value>>
+{
+    static auto apply()
+    {
+        auto value = T{};
+        return hana::transform(hana::keys(value), [&](auto key) {
+            const auto& member = hana::at_key(value, key);
+            return hana::make_pair(hana::typeid_(member), key);
+        });
+    }
+};
+
+template <typename T,
+          typename MemoryPolicy,
+          immer::detail::rbts::bits_t B,
+          immer::detail::rbts::bits_t BL>
+struct get_inner_types_t<immer::vector<T, MemoryPolicy, B, BL>>
+    : get_inner_types_t<T>
+{};
+
+template <typename T,
+          typename MemoryPolicy,
+          immer::detail::rbts::bits_t B,
+          immer::detail::rbts::bits_t BL>
+struct get_inner_types_t<immer::flex_vector<T, MemoryPolicy, B, BL>>
+    : get_inner_types_t<T>
+{};
+
+template <typename T, typename MemoryPolicy>
+struct get_inner_types_t<immer::box<T, MemoryPolicy>> : get_inner_types_t<T>
+{};
+
+template <typename T,
+          typename Hash,
+          typename Equal,
+          typename MemoryPolicy,
+          immer::detail::hamts::bits_t B>
+struct get_inner_types_t<immer::set<T, Hash, Equal, MemoryPolicy, B>>
+    : get_inner_types_t<T>
+{};
+
+template <typename K,
+          typename T,
+          typename Hash,
+          typename Equal,
+          typename MemoryPolicy,
+          immer::detail::hamts::bits_t B>
+struct get_inner_types_t<immer::map<K, T, Hash, Equal, MemoryPolicy, B>>
+{
+    static auto apply()
+    {
+        return hana::concat(get_inner_types_t<K>::apply(),
+                            get_inner_types_t<T>::apply());
+    }
+};
+
+template <typename T,
+          typename KeyFn,
+          typename Hash,
+          typename Equal,
+          typename MemoryPolicy,
+          immer::detail::hamts::bits_t B>
+struct get_inner_types_t<immer::table<T, KeyFn, Hash, Equal, MemoryPolicy, B>>
+    : get_inner_types_t<T>
+{};
+
+constexpr auto insert_conditionally = [](auto map, auto pair) {
+    namespace hana = hana;
+    using contains_t =
+        decltype(hana::is_just(hana::find(map, hana::first(pair))));
+    if constexpr (contains_t::value) {
+        const auto empty_string = BOOST_HANA_STRING("");
+        using is_empty_t        = decltype(hana::second(pair) == empty_string);
+        if constexpr (is_empty_t::value) {
+            // Do not replace with empty string
+            return map;
+        } else {
+            return hana::insert(map, pair);
+        }
+    } else {
+        return hana::insert(map, pair);
+    }
+};
+
+} // namespace detail
+
+/**
+ * Generate a map (type, member_name) for all members of a given type,
+ * recursively.
+ */
+inline auto get_inner_types(const auto& type)
+{
+    namespace hana = boost::hana;
+
+    constexpr auto get_for_one_type = [](auto type) {
+        using T = typename decltype(type)::type;
+        return detail::get_inner_types_t<T>::apply();
+    };
+
+    constexpr auto get_for_many = [get_for_one_type](const auto& map) {
+        auto new_pairs = hana::to_tuple(map) | [get_for_one_type](auto pair) {
+            return get_for_one_type(hana::first(pair));
+        };
+
+        return hana::fold_left(
+            hana::to_map(new_pairs), map, detail::insert_conditionally);
+    };
+
+    constexpr auto can_expand = [get_for_many](const auto& set) {
+        return set != get_for_many(set);
+    };
+
+    auto expanded = hana::while_(
+        can_expand, hana::to_map(get_for_one_type(type)), get_for_many);
+
+    // Throw away types we don't know names for
+    const auto empty_string = BOOST_HANA_STRING("");
+    auto result =
+        hana::filter(hana::to_tuple(expanded), [empty_string](auto pair) {
+            return hana::second(pair) != empty_string;
+        });
+    return hana::to_map(result);
+}
+
+} // namespace immer::persist::util
diff --git a/immer/extra/persist/json/json_with_pool_auto.hpp b/immer/extra/persist/json/json_with_pool_auto.hpp
@@ -9,6 +9,8 @@
 #include <immer/extra/persist/champ/traits.hpp>
 #include <immer/extra/persist/rbts/traits.hpp>
 
+#include <immer/extra/persist/common/type_traverse.hpp>
+
 namespace immer::persist {
 
 template <class T>
@@ -114,54 +116,20 @@ constexpr auto wrap_for_loading = exclude_internal_pool_types(
     make_conditional_func(is_persistable, to_persistable_loader));
 
 /**
- * Generate a hana map of persistable members for a given type T.
- * Where key is a type (persistable immer container) and value is a name for
- * that pool (using the member name from the given struct). Example:
+ * Generate a hana map of persistable members for the given type, recursively.
+ * Example:
  * [(type_c<immer::map<K, V>>, "tracks")]
  */
-template <class T>
-auto get_auto_pools_types(const T& value)
+auto get_pools_for_type(auto type)
 {
-    namespace hana = boost::hana;
-    static_assert(hana::Struct<T>::value,
-                  "get_auto_pools_types works only with types that "
-                  "implement hana::Struct concept");
-
-    constexpr auto is_persistable_key = [](auto key) {
-        return is_persistable(hana::at_key(T{}, key));
-    };
-
-    // A list of pairs like (hana::type_c<Container>, "member_name")
-    auto pairs = hana::transform(
-        hana::filter(hana::keys(value), is_persistable_key), [&](auto key) {
-            const auto& member = hana::at_key(value, key);
-            return hana::make_pair(hana::typeid_(member), key);
+    namespace hana     = boost::hana;
+    auto all_types_map = util::get_inner_types(type);
+    auto persistable =
+        hana::filter(hana::to_tuple(all_types_map), [&](auto pair) {
+            using T = typename decltype(+hana::first(pair))::type;
+            return is_persistable(T{});
         });
-
-    return hana::unpack(pairs, hana::make_map);
-}
-
-/**
- * Generate a hana map of persistable members for the given types and apply
- * manual overrides for names.
- * manual_overrides is a map of manual overrides.
- */
-auto get_pools_for_types(auto types,
-                         auto manual_overrides = boost::hana::make_map())
-{
-    namespace hana = boost::hana;
-    // Automatically generate names and pools
-    const auto names =
-        hana::fold_left(hana::transform(types,
-                                        [](auto t) {
-                                            using T =
-                                                typename decltype(t)::type;
-                                            return get_auto_pools_types(T{});
-                                        }),
-                        hana::make_map(),
-                        hana::union_);
-    // Apply the overrides
-    return hana::union_(names, manual_overrides);
+    return hana::to_map(persistable);
 }
 
 template <typename T,
@@ -265,7 +233,7 @@ auto get_auto_pool(const T& serializable,
 constexpr auto reload_pool_auto = [](auto wrap) {
     return [wrap](std::istream& is, auto pools, bool ignore_pool_exceptions) {
         using Pools                  = std::decay_t<decltype(pools)>;
-        auto restore                 = util::istream_snapshot{is};
+        auto restore                 = immer::util::istream_snapshot{is};
         pools.ignore_pool_exceptions = ignore_pool_exceptions;
         auto previous =
             json_immer_input_archive<cereal::JSONInputArchive, Pools>{
diff --git a/test/extra/persist/test_circular_dependency_conversion.cpp b/test/extra/persist/test_circular_dependency_conversion.cpp
@@ -234,9 +234,8 @@ TEST_CASE("Test exception while circular converting")
         };
     }();
 
-    const auto names = immer::persist::get_pools_for_types(
-        hana::tuple_t<model::value_one, model::value_two, model::two_boxed>,
-        hana::make_map());
+    const auto names =
+        immer::persist::get_pools_for_type(hana::type_c<model::value_one>);
     const auto [json_str, model_pool] =
         immer::persist::to_json_with_auto_pool(value, names);
     // REQUIRE(json_str == "");
@@ -398,9 +397,8 @@ TEST_CASE("Test circular dependency pools", "[conversion]")
         };
     }();
 
-    const auto names = immer::persist::get_pools_for_types(
-        hana::tuple_t<model::value_one, model::value_two, model::two_boxed>,
-        hana::make_map());
+    const auto names =
+        immer::persist::get_pools_for_type(hana::type_c<model::value_one>);
     const auto model_pools = immer::persist::get_auto_pool(value, names);
 
     /**
@@ -508,9 +506,8 @@ TEST_CASE("Test circular dependency pools", "[conversion]")
     (void) format_load_pools;
     // show_type<decltype(format_load_pools)> qwe;
 
-    const auto format_names = immer::persist::get_pools_for_types(
-        hana::tuple_t<format::value_one, format::value_two, format::two_boxed>,
-        hana::make_map());
+    const auto format_names =
+        immer::persist::get_pools_for_type(hana::type_c<format::value_one>);
 
     SECTION("vector")
     {
diff --git a/test/extra/persist/test_conversion.cpp b/test/extra/persist/test_conversion.cpp
@@ -2,6 +2,8 @@
 
 #include <immer/extra/persist/json/json_with_pool_auto.hpp>
 
+#include <immer/extra/persist/common/type_traverse.hpp>
+
 #include "utils.hpp"
 
 #define DEFINE_OPERATIONS(name)                                                \
@@ -141,10 +143,10 @@ class Z;
 TEST_CASE("Convert between two hierarchies via JSON compatibility",
           "[conversion]")
 {
-    const auto model_names = immer::persist::get_pools_for_types(
-        hana::tuple_t<model::history, model::arrangement>, hana::make_map());
-    const auto format_names = immer::persist::get_pools_for_types(
-        hana::tuple_t<format::history, format::arrangement>, hana::make_map());
+    const auto model_names =
+        immer::persist::get_pools_for_type(hana::type_c<model::history>);
+    const auto format_names =
+        immer::persist::get_pools_for_type(hana::type_c<format::history>);
     (void) format_names;
 
     const auto value = model::make_example_history();
@@ -202,8 +204,8 @@ struct two_vectors
 
 TEST_CASE("Not every type is converted", "[conversion]")
 {
-    const auto names = immer::persist::get_pools_for_types(
-        hana::tuple_t<two_vectors>, hana::make_map());
+    const auto names =
+        immer::persist::get_pools_for_type(hana::type_c<two_vectors>);
     const auto [json_str, pools] =
         immer::persist::to_json_with_auto_pool(two_vectors{}, names);
 
diff --git a/test/extra/persist/test_special_pool_auto.cpp b/test/extra/persist/test_special_pool_auto.cpp
