Asset Catalogs: loading a catalog definition file

Initial, limited implementation of loading a single asset catalog
definition file. These files are structured as follows:

  CATALOG_ID virtual/path/of/catalog
  SUBCATALOG_ID virtual/path/of/catalog/child
  SOMETHING_ELSE some/unrelated/hierarchy

These virtual paths will be used to show the catalog in a tree
structure; the tree structure itself is not part of this commit. Each
asset will have one catalog ID that determines where in that tree the
asset shows up.

Currently only a single catalog definition file can be read; merging
data from multiple such files, and writing them out again after changes
are made, is for future commits.

This commit only contains the code to load a single file, and unittests
to check that this actually works. No UI, no user-facing functionality
yet.

1 files changed, 97 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_asset_catalog.hh b/source/blender/blenkernel/BKE_asset_catalog.hh
new file mode 100644
index 00000000000..82449bcdbcc
--- /dev/null
+++ b/source/blender/blenkernel/BKE_asset_catalog.hh
@@ -0,0 +1,97 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup bke
+ */
+
+#pragma once
+
+#ifndef __cplusplus
+#  error This is a C++ header. The C interface is yet to be implemented/designed.
+#endif
+
+#include "BLI_map.hh"
+#include "BLI_set.hh"
+#include "BLI_string_ref.hh"
+#include "BLI_vector_set.hh"
+
+#include <filesystem>
+#include <memory>
+#include <string>
+
+namespace blender::bke {
+
+using CatalogID = std::string;
+using CatalogPath = std::string;
+using CatalogPathReference = StringRef;
+using CatalogPathComponent = std::string;
+using CatalogFilePath = std::filesystem::path;
+
+class AssetCatalog;
+class AssetCatalogDefinitionFile;
+class AssetCatalogTreeNode;
+
+/* Manages the asset catalogs of a single asset library (i.e. of catalogs defined in a single
+ * directory hierarchy). */
+class AssetCatalogService {
+  const char path_separator = '/';
+
+  /* TODO(@sybren): determine which properties should be private / get accessors. */
+
+  // These pointers are owned by this AssetCatalogService.
+  Map<CatalogID, std::unique_ptr<AssetCatalog>> catalogs;
+  std::unique_ptr<AssetCatalogDefinitionFile> catalog_definition_file;
+
+ public:
+  AssetCatalogService();
+
+  // Return nullptr if not found.
+  AssetCatalog *find_catalog(const CatalogID &catalog_id);
+
+  void load_from_disk(const CatalogFilePath &asset_library_root);
+
+ protected:
+  void load_directory_recursive(const CatalogFilePath &directory_path);
+  void load_single_file(const CatalogFilePath &catalog_definition_file_path);
+
+  std::unique_ptr<AssetCatalogDefinitionFile> parse_catalog_file(
+      const CatalogFilePath &catalog_definition_file_path);
+
+  std::unique_ptr<AssetCatalog> parse_catalog_line(
+      StringRef line, const AssetCatalogDefinitionFile *catalog_definition_file);
+};
+
+class AssetCatalogDefinitionFile {
+  /* TODO(@sybren): determine which properties should be private / get accessors. */
+ public:
+  CatalogFilePath file_path;
+  Map<CatalogID, AssetCatalog *> catalogs;
+
+  AssetCatalogDefinitionFile();
+};
+
+class AssetCatalog {
+  /* TODO(@sybren): determine which properties should be private / get accessors. */
+ public:
+  AssetCatalog();
+  AssetCatalog(const CatalogID &catalog_id, const CatalogPath &name);
+
+  CatalogID catalog_id;
+  CatalogPath path;
+};
+
+}  // namespace blender::bke