Merge plugin back into main repository (#49)

server/src/plugin.rs

@@ -0,0 +1,82 @@
+use rbx::RbxInstance;
+use vfs::VfsItem;
+use core::Route;
+
+pub enum TransformFileResult {
+    Value(Option<RbxInstance>),
+    Pass,
+
+    // TODO: Error case
+}
+
+pub enum RbxChangeResult {
+    Write(Option<VfsItem>),
+    Pass,
+
+    // TODO: Error case
+}
+
+pub enum FileChangeResult {
+    MarkChanged(Option<Vec<Route>>),
+    Pass,
+}
+
+pub trait Plugin {
+    /// Invoked when a file is read from the filesystem and needs to be turned
+    /// into a Roblox instance.
+    fn transform_file(&self, plugins: &PluginChain, vfs_item: &VfsItem) -> TransformFileResult;
+
+    /// Invoked when a Roblox Instance change is reported by the Roblox Studio
+    /// plugin and needs to be turned into a file to save.
+    fn handle_rbx_change(&self, route: &Route, rbx_item: &RbxInstance) -> RbxChangeResult;
+
+    /// Invoked when a file changes on the filesystem. The result defines what
+    /// routes are marked as needing to be refreshed.
+    fn handle_file_change(&self, route: &Route) -> FileChangeResult;
+}
+
+/// A set of plugins that are composed in order.
+pub struct PluginChain {
+    plugins: Vec<Box<Plugin + Send + Sync>>,
+}
+
+impl PluginChain {
+    pub fn new(plugins: Vec<Box<Plugin + Send + Sync>>) -> PluginChain {
+        PluginChain {
+            plugins,
+        }
+    }
+
+    pub fn transform_file(&self, vfs_item: &VfsItem) -> Option<RbxInstance> {
+        for plugin in &self.plugins {
+            match plugin.transform_file(self, vfs_item) {
+                TransformFileResult::Value(rbx_item) => return rbx_item,
+                TransformFileResult::Pass => {},
+            }
+        }
+
+        None
+    }
+
+    pub fn handle_rbx_change(&self, route: &Route, rbx_item: &RbxInstance) -> Option<VfsItem> {
+        for plugin in &self.plugins {
+            match plugin.handle_rbx_change(route, rbx_item) {
+                RbxChangeResult::Write(vfs_item) => return vfs_item,
+                RbxChangeResult::Pass => {},
+            }
+        }
+
+        None
+    }
+
+    pub fn handle_file_change(&self, route: &Route) -> Option<Vec<Route>> {
+        for plugin in &self.plugins {
+            match plugin.handle_file_change(route) {
+                FileChangeResult::MarkChanged(changes) => return changes,
+                FileChangeResult::Pass => {},
+            }
+        }
+
+        None
+    }
+}