Recursive box seems to work

immer/experimental/immer-archive/box/archive.hpp

@@ -19,6 +19,11 @@ struct archive_save
 
     immer::map<const void*, container_id> ids;
 
+    friend bool operator==(const archive_save& left, const archive_save& right)
+    {
+        return left.boxes == right.boxes;
+    }
+
     template <class Archive>
     void save(Archive& ar) const
     {

immer/experimental/immer-archive/champ/archive.hpp

@@ -26,6 +26,17 @@ struct inner_node_save
     bitmap_t datamap;
     bool collisions{false};
 
+    auto tie() const
+    {
+        return std::tie(values, children, nodemap, datamap, collisions);
+    }
+
+    friend bool operator==(const inner_node_save& left,
+                           const inner_node_save& right)
+    {
+        return left.tie() == right.tie();
+    }
+
     template <class Archive>
     void save(Archive& ar) const
     {
@@ -79,6 +90,11 @@ struct nodes_save
     immer::map<node_id, inner_node_save<T, B>> inners;
 
     immer::map<const void*, node_id> node_ptr_to_id;
+
+    friend bool operator==(const nodes_save& left, const nodes_save& right)
+    {
+        return left.inners == right.inners;
+    }
 };
 
 template <typename T,
@@ -141,6 +157,12 @@ struct container_archive_save
     // happen.
     immer::vector<Container> containers;
 
+    friend bool operator==(const container_archive_save& left,
+                           const container_archive_save& right)
+    {
+        return left.nodes == right.nodes;
+    }
+
     template <class Archive>
     void save(Archive& ar) const
     {

immer/experimental/immer-archive/common/archive.hpp

@@ -19,6 +19,13 @@ struct values_save
 {
     const T* begin = nullptr;
     const T* end   = nullptr;
+
+    auto tie() const { return std::tie(begin, end); }
+
+    friend bool operator==(const values_save& left, const values_save& right)
+    {
+        return left.tie() == right.tie();
+    }
 };
 
 template <class T>

immer/experimental/immer-archive/json/json_with_archive.hpp

@@ -57,6 +57,12 @@ struct archives_save
         }
         return storage[hana::type_c<T>];
     }
+
+    friend bool operator==(const archives_save& left,
+                           const archives_save& right)
+    {
+        return left.storage == right.storage;
+    }
 };
 
 template <class Container>
@@ -175,21 +181,31 @@ auto to_json_with_archive(const T& serializable)
 {
     auto archives =
         detail::generate_archives_save(get_archives_types(serializable));
+    using Archives = std::decay_t<decltype(archives)>;
+
+    const auto save_archive = [&archives] {
+        auto os2 = std::ostringstream{};
+        auto ar2 =
+            immer_archive::json_immer_output_archive<Archives>{archives, os2};
+        ar2(archives);
+        archives = ar2.get_output_archives();
+    };
+
     auto os = std::ostringstream{};
+
     {
-        auto ar =
-            immer_archive::json_immer_output_archive<decltype(archives)>{os};
+        auto ar = immer_archive::json_immer_output_archive<Archives>{os};
         ar(serializable);
         archives = ar.get_output_archives();
 
-        {
-            auto os2 = std::ostringstream{};
-            auto ar2 =
-                immer_archive::json_immer_output_archive<decltype(archives)>{
-                    archives, os2};
-            ar2(archives);
-            ar2.finalize();
-            archives = ar2.get_output_archives();
+        auto prev = archives;
+        while (true) {
+            // Keep saving archives until everything is saved.
+            save_archive();
+            if (prev == archives) {
+                break;
+            }
+            prev = archives;
         }
 
         ar.get_output_archives() = archives;

immer/experimental/immer-archive/rbts/archive.hpp

@@ -70,6 +70,13 @@ struct archive_save
     immer::vector<immer::flex_vector<T, MemoryPolicy, B, BL>>
         saved_flex_vectors;
 
+    auto tie() const { return std::tie(leaves, inners, vectors); }
+
+    friend bool operator==(const archive_save& left, const archive_save& right)
+    {
+        return left.tie() == right.tie();
+    }
+
     template <class Archive>
     void save(Archive& ar) const
     {

immer/experimental/immer-archive/rbts/load.hpp

@@ -167,7 +167,7 @@ class loader
             throw invalid_children_count{id};
         }
 
-        auto leaf = node_ptr{node_t::make_leaf_n(n),
+        auto leaf = node_ptr{n ? node_t::make_leaf_n(n) : rbtree::empty_tail(),
                              [n](auto* ptr) { node_t::delete_leaf(ptr, n); }};
         immer::detail::uninitialized_copy(
             node_info->data.begin(), node_info->data.end(), leaf.get()->leaf());

test/experimental/immer-archive/test_special_archive.cpp

@@ -661,16 +661,22 @@ TEST_CASE("Test recursive type, saving the box triggers saving the box of the "
         .children = {immer::box<recursive_type>{v1},
                      immer::box<recursive_type>{v3}},
     };
+    const auto v5 = recursive_type{
+        .data = 567,
+        .children =
+            {
+                immer::box<recursive_type>{v4},
+            },
+    };
 
-    const auto [json_str, archives] = immer_archive::to_json_with_archive(v4);
+    const auto [json_str, archives] = immer_archive::to_json_with_archive(v5);
     // REQUIRE(json_str == "");
 
     {
-        auto full_load =
+        const auto full_load =
             immer_archive::from_json_with_archive<recursive_type>(json_str);
-        REQUIRE(full_load == v4);
-        // XXX This must pass:
-        // REQUIRE(immer_archive::to_json_with_archive(full_load).first ==
-        //         json_str);
+        REQUIRE(full_load == v5);
+        REQUIRE(immer_archive::to_json_with_archive(full_load).first ==
+                json_str);
     }
 }