Make visitor accept functions return results

source/base/inc/tactile/base/document/component_view.hpp

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "tactile/base/container/expected.hpp"
 #include "tactile/base/container/pair.hpp"
 #include "tactile/base/container/string.hpp"
 #include "tactile/base/int.hpp"
@@ -24,8 +25,12 @@ class IComponentView
    * Inspects the component.
    *
    * \param visitor The visitor to use.
+   *
+   * \return
+   * Nothing if successful; an error code otherwise.
    */
-  virtual void accept(IDocumentVisitor& visitor) const = 0;
+  [[nodiscard]]
+  virtual auto accept(IDocumentVisitor& visitor) const -> Result<void> = 0;
 
   /**
    * Returns the name of the component.
@@ -45,8 +50,7 @@ class IComponentView
    * An attribute key and value pair.
    */
   [[nodiscard]]
-  virtual auto get_attribute(usize index) const
-      -> Pair<const String&, const Attribute&> = 0;
+  virtual auto get_attribute(usize index) const -> Pair<const String&, const Attribute&> = 0;
 
   /**
    * Returns the number of attributes in the component.

source/base/inc/tactile/base/document/document.hpp

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "tactile/base/container/expected.hpp"
 #include "tactile/base/container/path.hpp"
 #include "tactile/base/numeric/vec.hpp"
 #include "tactile/base/prelude.hpp"
@@ -24,8 +25,12 @@ class IDocument
    * Inspects the document.
    *
    * \param visitor The visitor to use.
+   *
+   * \return
+   * Nothing if successful; an error code otherwise.
    */
-  virtual void accept(IDocumentVisitor& visitor) const = 0;
+  [[nodiscard]]
+  virtual auto accept(IDocumentVisitor& visitor) const -> Result<void> = 0;
 
   /**
    * Updates the state of the document.

source/base/inc/tactile/base/document/layer_view.hpp

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "tactile/base/container/expected.hpp"
 #include "tactile/base/container/maybe.hpp"
 #include "tactile/base/container/string.hpp"
 #include "tactile/base/id.hpp"
@@ -30,8 +31,12 @@ class ILayerView
    * Inspects the layer.
    *
    * \param visitor The visitor to use.
+   *
+   * \return
+   * Nothing if successful; an error code otherwise.
    */
-  virtual void accept(IDocumentVisitor& visitor) const = 0;
+  [[nodiscard]]
+  virtual auto accept(IDocumentVisitor& visitor) const -> Result<void> = 0;
 
   virtual void write_tile_bytes(ByteStream& byte_stream) const = 0;
 

source/base/inc/tactile/base/document/map_view.hpp

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "tactile/base/container/expected.hpp"
 #include "tactile/base/container/maybe.hpp"
 #include "tactile/base/id.hpp"
 #include "tactile/base/int.hpp"
@@ -28,8 +29,11 @@ class IMapView
    * Inspects the map.
    *
    * \param visitor The visitor to use.
+   *
+   * \return
+   * Nothing if successful; an error code otherwise.
    */
-  virtual void accept(IDocumentVisitor& visitor) const = 0;
+  virtual auto accept(IDocumentVisitor& visitor) const -> Result<void> = 0;
 
   /**
    * Returns the logical size of tiles in the map.

source/base/inc/tactile/base/document/object_view.hpp

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "tactile/base/container/expected.hpp"
 #include "tactile/base/container/string.hpp"
 #include "tactile/base/id.hpp"
 #include "tactile/base/layer/object_type.hpp"
@@ -27,8 +28,12 @@ class IObjectView
    * Inspects the object.
    *
    * \param visitor The visitor to use.
+   *
+   * \return
+   * Nothing if successful; an error code otherwise.
    */
-  virtual void accept(IDocumentVisitor& visitor) const = 0;
+  [[nodiscard]]
+  virtual auto accept(IDocumentVisitor& visitor) const -> Result<void> = 0;
 
   /**
    * Returns a view of the parent object layer, if any.

source/base/inc/tactile/base/document/tile_view.hpp

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "tactile/base/container/expected.hpp"
 #include "tactile/base/container/pair.hpp"
 #include "tactile/base/id.hpp"
 #include "tactile/base/prelude.hpp"
@@ -25,8 +26,12 @@ class ITileView
    * Inspects the tile.
    *
    * \param visitor The visitor to use.
+   *
+   * \return
+   * Nothing if successful; an error code otherwise.
    */
-  virtual void accept(IDocumentVisitor& visitor) const = 0;
+  [[nodiscard]]
+  virtual auto accept(IDocumentVisitor& visitor) const -> Result<void> = 0;
 
   /**
    * Returns the tileset that hosts the tile.
@@ -73,8 +78,7 @@ class ITileView
    * A tile index and frame duration pair.
    */
   [[nodiscard]]
-  virtual auto get_animation_frame(usize index) const
-      -> Pair<TileIndex, Milliseconds> = 0;
+  virtual auto get_animation_frame(usize index) const -> Pair<TileIndex, Milliseconds> = 0;
 
   /**
    * Returns a view of the associated metadata.

source/base/inc/tactile/base/document/tileset_view.hpp

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "tactile/base/container/expected.hpp"
 #include "tactile/base/container/path.hpp"
 #include "tactile/base/container/string.hpp"
 #include "tactile/base/id.hpp"
@@ -26,8 +27,12 @@ class ITilesetView
    * Inspects the tileset.
    *
    * \param visitor The visitor to use.
+   *
+   * \return
+   * Nothing if successful; an error code otherwise.
    */
-  virtual void accept(IDocumentVisitor& visitor) const = 0;
+  [[nodiscard]]
+  virtual auto accept(IDocumentVisitor& visitor) const -> Result<void> = 0;
 
   /**
    * Returns the first global tile identifier associated with the tileset.

source/base/test_util/inc/tactile/base/test_util/document_view_mocks.hpp

@@ -57,12 +57,13 @@ class ObjectViewMock : public IObjectView
   {
     ON_CALL(*this, accept).WillByDefault([this](IDocumentVisitor& visitor) {
       visitor.visit(*this).value();
+      return kOK;
     });
 
     ON_CALL(*this, get_meta).WillByDefault(testing::ReturnRef(mMeta));
   }
 
-  MOCK_METHOD(void, accept, (IDocumentVisitor&), (const, override));
+  MOCK_METHOD(Result<void>, accept, (IDocumentVisitor&), (const, override));
 
   MOCK_METHOD(const ILayerView*, get_parent_layer, (), (const, override));
 
@@ -100,7 +101,7 @@ class TileViewMock : public ITileView
     ON_CALL(*this, get_meta).WillByDefault(testing::ReturnRef(mMeta));
   }
 
-  MOCK_METHOD(void, accept, (IDocumentVisitor&), (const, override));
+  MOCK_METHOD(Result<void>, accept, (IDocumentVisitor&), (const, override));
 
   MOCK_METHOD(const ITilesetView&, get_parent_tileset, (), (const, override));
 
@@ -135,7 +136,7 @@ class TilesetViewMock : public ITilesetView
     ON_CALL(*this, get_meta).WillByDefault(testing::ReturnRef(mMeta));
   }
 
-  MOCK_METHOD(void, accept, (IDocumentVisitor&), (const, override));
+  MOCK_METHOD(Result<void>, accept, (IDocumentVisitor&), (const, override));
 
   MOCK_METHOD(TileID, get_first_tile_id, (), (const, override));
 
@@ -173,7 +174,7 @@ class LayerViewMock : public ILayerView
     ON_CALL(*this, get_meta).WillByDefault(testing::ReturnRef(mMeta));
   }
 
-  MOCK_METHOD(void, accept, (IDocumentVisitor&), (const, override));
+  MOCK_METHOD(Result<void>, accept, (IDocumentVisitor&), (const, override));
 
   MOCK_METHOD(void, write_tile_bytes, (ByteStream&), (const, override));
 
@@ -242,7 +243,7 @@ class MapViewMock : public IMapView
     ON_CALL(*this, get_meta).WillByDefault(testing::ReturnRef(mMeta));
   }
 
-  MOCK_METHOD(void, accept, (IDocumentVisitor&), (const, override));
+  MOCK_METHOD(Result<void>, accept, (IDocumentVisitor&), (const, override));
 
   MOCK_METHOD(Int2, get_tile_size, (), (const, override));
 

source/core/inc/tactile/core/document/layer_view_impl.hpp

@@ -30,7 +30,8 @@ class LayerViewImpl final : public ILayerView
                 const ILayerView* parent_layer,
                 EntityID layer_id);
 
-  void accept(IDocumentVisitor& visitor) const override;
+  [[nodiscard]]
+  auto accept(IDocumentVisitor& visitor) const -> Result<void> override;
 
   void write_tile_bytes(ByteStream& byte_stream) const override;
 

source/core/inc/tactile/core/document/map_document.hpp

@@ -50,7 +50,8 @@ class MapDocument final : public IDocument
 
   ~MapDocument() noexcept override;
 
-  void accept(IDocumentVisitor& visitor) const override;
+  [[nodiscard]]
+  auto accept(IDocumentVisitor& visitor) const -> Result<void> override;
 
   void update() override;
 

source/core/inc/tactile/core/document/map_view_impl.hpp

@@ -26,7 +26,8 @@ class MapViewImpl final : public IMapView
    */
   MapViewImpl(const MapDocument* document);
 
-  void accept(IDocumentVisitor& visitor) const override;
+  [[nodiscard]]
+  auto accept(IDocumentVisitor& visitor) const -> Result<void> override;
 
   [[nodiscard]]
   auto get_tile_size() const -> Int2 override;

source/core/inc/tactile/core/document/object_view_impl.hpp

@@ -39,7 +39,8 @@ class ObjectViewImpl final : public IObjectView
                  const ITileView* parent_tile,
                  EntityID object_id);
 
-  void accept(IDocumentVisitor& visitor) const override;
+  [[nodiscard]]
+  auto accept(IDocumentVisitor& visitor) const -> Result<void> override;
 
   [[nodiscard]]
   auto get_parent_layer() const -> const ILayerView* override;

source/core/inc/tactile/core/document/tile_view_impl.hpp

@@ -31,7 +31,8 @@ class TileViewImpl final : public ITileView
                const ITilesetView* tileset_view,
                EntityID tile_id);
 
-  void accept(IDocumentVisitor& visitor) const override;
+  [[nodiscard]]
+  auto accept(IDocumentVisitor& visitor) const -> Result<void> override;
 
   [[nodiscard]]
   auto get_parent_tileset() const -> const ITilesetView& override;

source/core/inc/tactile/core/document/tileset_view_impl.hpp

@@ -25,7 +25,8 @@ class TilesetViewImpl final : public ITilesetView
    */
   TilesetViewImpl(const MapDocument* document, EntityID tileset_id);
 
-  void accept(IDocumentVisitor& visitor) const override;
+  [[nodiscard]]
+  auto accept(IDocumentVisitor& visitor) const -> Result<void> override;
 
   [[nodiscard]]
   auto get_first_tile_id() const -> TileID override;

source/core/src/tactile/core/document/layer_view_impl.cpp

@@ -27,28 +27,37 @@ LayerViewImpl::LayerViewImpl(const MapDocument* document,
     mMeta {document, mLayerId}
 {}
 
-void LayerViewImpl::accept(IDocumentVisitor& visitor) const
+auto LayerViewImpl::accept(IDocumentVisitor& visitor) const -> Result<void>
 {
   const auto& registry = mDocument->get_registry();
 
-  visitor.visit(*this);
+  if (const auto layer_result = visitor.visit(*this); !layer_result.has_value()) {
+    return propagate_unexpected(layer_result);
+  }
 
   if (is_group_layer(registry, mLayerId)) {
     const auto& group_layer = registry.get<CGroupLayer>(mLayerId);
 
     for (const auto sublayer_id : group_layer.layers) {
       const LayerViewImpl sublayer_view {mDocument, this, sublayer_id};
-      sublayer_view.accept(visitor);
+      if (const auto sublayer_result = sublayer_view.accept(visitor);
+          !sublayer_result.has_value()) {
+        return propagate_unexpected(sublayer_result);
+      }
     }
   }
   else if (is_object_layer(registry, mLayerId)) {
     const auto& object_layer = registry.get<CObjectLayer>(mLayerId);
 
     for (const auto object_id : object_layer.objects) {
       const ObjectViewImpl object_view {mDocument, this, object_id};
-      object_view.accept(visitor);
+      if (const auto object_result = object_view.accept(visitor); !object_result.has_value()) {
+        return propagate_unexpected(object_result);
+      }
     }
   }
+
+  return kOK;
 }
 
 void LayerViewImpl::write_tile_bytes(ByteStream& byte_stream) const

source/core/src/tactile/core/document/map_document.cpp

@@ -87,10 +87,10 @@ TACTILE_DEFINE_MOVE(MapDocument);
 
 MapDocument::~MapDocument() noexcept = default;
 
-void MapDocument::accept(IDocumentVisitor& visitor) const
+auto MapDocument::accept(IDocumentVisitor& visitor) const -> Result<void>
 {
   const MapViewImpl map_view {this};
-  map_view.accept(visitor);
+  return map_view.accept(visitor);
 }
 
 void MapDocument::update()

source/core/src/tactile/core/document/map_view_impl.cpp

@@ -19,26 +19,35 @@ MapViewImpl::MapViewImpl(const MapDocument* document)
     mMeta {mDocument, mDocument->get_registry().get<CDocumentInfo>().root}
 {}
 
-void MapViewImpl::accept(IDocumentVisitor& visitor) const
+auto MapViewImpl::accept(IDocumentVisitor& visitor) const -> Result<void>
 {
   const auto& registry = mDocument->get_registry();
 
   const auto& map = _get_map();
   const auto& root_layer = registry.get<CGroupLayer>(map.root_layer);
 
-  visitor.visit(*this);
+  if (const auto map_result = visitor.visit(*this); !map_result.has_value()) {
+    return propagate_unexpected(map_result);
+  }
 
   for (const auto tileset_id : map.attached_tilesets) {
     const TilesetViewImpl tileset_view {mDocument, tileset_id};
-    tileset_view.accept(visitor);
+    if (const auto tileset_result = tileset_view.accept(visitor);
+        !tileset_result.has_value()) {
+      return propagate_unexpected(tileset_result);
+    }
   }
 
   for (const auto layer_id : root_layer.layers) {
     const LayerViewImpl layer_view {mDocument, nullptr, layer_id};
-    layer_view.accept(visitor);
+    if (const auto layer_result = layer_view.accept(visitor); !layer_result.has_value()) {
+      return propagate_unexpected(layer_result);
+    }
   }
 
   // TODO iterate component definitions
+
+  return kOK;
 }
 
 auto MapViewImpl::get_tile_size() const -> Int2

source/core/src/tactile/core/document/object_view_impl.cpp

@@ -30,9 +30,9 @@ ObjectViewImpl::ObjectViewImpl(const IDocument* document,
     mMeta {document, object_id}
 {}
 
-void ObjectViewImpl::accept(IDocumentVisitor& visitor) const
+auto ObjectViewImpl::accept(IDocumentVisitor& visitor) const -> Result<void>
 {
-  visitor.visit(*this);
+  return visitor.visit(*this);
 }
 
 auto ObjectViewImpl::get_parent_layer() const -> const ILayerView*