Asset Catalogs: add catalog filter for the asset browser

Given an "active catalog" (i.e. the one selected in the UI), construct
an `AssetCatalogFilter` instance. This filter can determine whether an
asset should be shown or not. It returns `true` when The asset's catalog
ID is:

- the active catalog,
- an alias of the active catalog (so different UUID that maps to the
  same path),
- a sub-catalog of the active catalog.

Not yet hooked up to the UI.

source/blender/blenkernel/BKE_asset_catalog.hh

@@ -26,6 +26,7 @@
 
 #include "BLI_function_ref.hh"
 #include "BLI_map.hh"
+#include "BLI_set.hh"
 #include "BLI_string_ref.hh"
 #include "BLI_uuid.h"
 #include "BLI_vector.hh"
@@ -48,6 +49,7 @@ using CatalogFilePath = std::string;
 class AssetCatalog;
 class AssetCatalogDefinitionFile;
 class AssetCatalogTree;
+class AssetCatalogFilter;
 
 /* Manages the asset catalogs of a single asset library (i.e. of catalogs defined in a single
  * directory hierarchy). */
@@ -100,6 +102,14 @@ class AssetCatalogService {
    * efficient call as it's just a linear search over the catalogs. */
   AssetCatalog *find_catalog_by_path(const AssetCatalogPath &path) const;
 
+  /**
+   * Create a filter object that can be used to determine whether an asset belongs to the given
+   * catalog, or any of the catalogs in the sub-tree rooted at the given catalog.
+   *
+   * \see #AssetCatalogFilter
+   */
+  AssetCatalogFilter create_catalog_filter(CatalogID active_catalog_id) const;
+
   /** Create a catalog with some sensible auto-generated catalog ID.
    * The catalog will be saved to the default catalog file.*/
   AssetCatalog *create_catalog(const AssetCatalogPath &catalog_path);
@@ -331,4 +341,20 @@ struct AssetCatalogPathCmp {
  * Being a set, duplicates are removed. The catalog's simple name is ignored in this. */
 using AssetCatalogOrderedSet = std::set<const AssetCatalog *, AssetCatalogPathCmp>;
 
+/**
+ * Filter that can determine whether an asset should be visible or not, based on its catalog ID.
+ *
+ * \see AssetCatalogService::create_filter()
+ */
+class AssetCatalogFilter {
+ public:
+  bool contains(CatalogID asset_catalog_id) const;
+
+ protected:
+  friend AssetCatalogService;
+  const Set<CatalogID> matching_catalog_ids;
+
+  explicit AssetCatalogFilter(Set<CatalogID> &&matching_catalog_ids);
+};
+
 }  // namespace blender::bke

source/blender/blenkernel/intern/asset_catalog.cc

@@ -85,6 +85,33 @@ AssetCatalog *AssetCatalogService::find_catalog_by_path(const AssetCatalogPath &
   return nullptr;
 }
 
+AssetCatalogFilter AssetCatalogService::create_catalog_filter(
+    const CatalogID active_catalog_id) const
+{
+  Set<CatalogID> matching_catalog_ids;
+  matching_catalog_ids.add(active_catalog_id);
+
+  const AssetCatalog *active_catalog = find_catalog(active_catalog_id);
+  if (!active_catalog) {
+    /* If the UUID is unknown (i.e. not mapped to an actual Catalog), it is impossible to determine
+     * its children. The filter can still work on the given UUID. */
+    return AssetCatalogFilter(std::move(matching_catalog_ids));
+  }
+
+  /* This cannot just iterate over tree items to get all the required data, because tree items only
+   * represent single UUIDs. It could be used to get the main UUIDs of the children, though, and
+   * then only do an exact match on the path (instead of the more complex `is_contained_in()`
+   * call). Without an extra indexed-by-path acceleration structure, this is still going to require
+   * a linear search, though. */
+  for (const auto &catalog_uptr : this->catalogs_.values()) {
+    if (catalog_uptr->path.is_contained_in(active_catalog->path)) {
+      matching_catalog_ids.add(catalog_uptr->catalog_id);
+    }
+  }
+
+  return AssetCatalogFilter(std::move(matching_catalog_ids));
+}
+
 void AssetCatalogService::delete_catalog(CatalogID catalog_id)
 {
   std::unique_ptr<AssetCatalog> *catalog_uptr_ptr = this->catalogs_.lookup_ptr(catalog_id);
@@ -754,4 +781,14 @@ std::string AssetCatalog::sensible_simple_name_for_path(const AssetCatalogPath &
   return "..." + name.substr(name.length() - 60);
 }
 
+AssetCatalogFilter::AssetCatalogFilter(Set<CatalogID> &&matching_catalog_ids)
+    : matching_catalog_ids(std::move(matching_catalog_ids))
+{
+}
+
+bool AssetCatalogFilter::contains(const CatalogID asset_catalog_id) const
+{
+  return matching_catalog_ids.contains(asset_catalog_id);
+}
+
 }  // namespace blender::bke

source/blender/blenkernel/intern/asset_catalog_test.cc

@@ -906,4 +906,60 @@ TEST_F(AssetCatalogTest, create_missing_catalogs_after_loading)
   EXPECT_EQ(1, loaded_service.count_catalogs_with_path("character/Ružena"));
 }
 
+TEST_F(AssetCatalogTest, create_catalog_filter)
+{
+  AssetCatalogService service(asset_library_root_);
+  service.load_from_disk();
+
+  /* Alias for the same catalog as the main one. */
+  AssetCatalog *alias_ruzena = service.create_catalog("character/Ružena/poselib");
+  /* Alias for a sub-catalog. */
+  AssetCatalog *alias_ruzena_hand = service.create_catalog("character/Ružena/poselib/hand");
+
+  AssetCatalogFilter filter = service.create_catalog_filter(UUID_POSES_RUZENA);
+
+  /* Positive test for loaded-from-disk catalogs. */
+  EXPECT_TRUE(filter.contains(UUID_POSES_RUZENA))
+      << "Main catalog should be included in the filter.";
+  EXPECT_TRUE(filter.contains(UUID_POSES_RUZENA_HAND))
+      << "Sub-catalog should be included in the filter.";
+  EXPECT_TRUE(filter.contains(UUID_POSES_RUZENA_FACE))
+      << "Sub-catalog should be included in the filter.";
+
+  /* Positive test for newly-created catalogs. */
+  EXPECT_TRUE(filter.contains(alias_ruzena->catalog_id))
+      << "Alias of main catalog should be included in the filter.";
+  EXPECT_TRUE(filter.contains(alias_ruzena_hand->catalog_id))
+      << "Alias of sub-catalog should be included in the filter.";
+
+  /* Negative test for unrelated catalogs. */
+  EXPECT_FALSE(filter.contains(BLI_uuid_nil())) << "Nil catalog should not be included.";
+  EXPECT_FALSE(filter.contains(UUID_ID_WITHOUT_PATH));
+  EXPECT_FALSE(filter.contains(UUID_POSES_ELLIE));
+  EXPECT_FALSE(filter.contains(UUID_POSES_ELLIE_WHITESPACE));
+  EXPECT_FALSE(filter.contains(UUID_POSES_ELLIE_TRAILING_SLASH));
+  EXPECT_FALSE(filter.contains(UUID_WITHOUT_SIMPLENAME));
+}
+
+TEST_F(AssetCatalogTest, create_catalog_filter_for_unknown_uuid)
+{
+  AssetCatalogService service;
+  const bUUID unknown_uuid = BLI_uuid_generate_random();
+
+  AssetCatalogFilter filter = service.create_catalog_filter(unknown_uuid);
+  EXPECT_TRUE(filter.contains(unknown_uuid));
+
+  EXPECT_FALSE(filter.contains(BLI_uuid_nil())) << "Nil catalog should not be included.";
+  EXPECT_FALSE(filter.contains(UUID_POSES_ELLIE));
+}
+
+TEST_F(AssetCatalogTest, create_catalog_filter_for_unassigned_assets)
+{
+  AssetCatalogService service;
+
+  AssetCatalogFilter filter = service.create_catalog_filter(BLI_uuid_nil());
+  EXPECT_TRUE(filter.contains(BLI_uuid_nil()));
+  EXPECT_FALSE(filter.contains(UUID_POSES_ELLIE));
+}
+
 }  // namespace blender::bke::tests