Major Subsystem Rewrite (Reconciler Mk5) (#217)

server/src/snapshot/instance_snapshot.rs

@@ -0,0 +1,62 @@
+//! Defines the structure of an instance snapshot.
+
+use std::{
+    borrow::Cow,
+    collections::HashMap,
+};
+
+use rbx_dom_weak::{RbxTree, RbxId, RbxValue};
+
+/// A lightweight description of what an instance should look like. Attempts to
+/// be somewhat memory efficient by borrowing from its source data, indicated by
+/// the lifetime parameter, `'source`.
+///
+// Possible future improvements:
+// - Use refcounted/interned strings
+// - Replace use of RbxValue with a sum of RbxValue + borrowed value
+#[derive(Debug, Clone, PartialEq)]
+pub struct InstanceSnapshot<'source> {
+    pub snapshot_id: Option<RbxId>,
+
+    pub name: Cow<'source, str>,
+    pub class_name: Cow<'source, str>,
+    pub properties: HashMap<String, RbxValue>,
+    pub children: Vec<InstanceSnapshot<'source>>,
+
+    // TODO: Snapshot source, like a file or a project node?
+}
+
+impl<'source> InstanceSnapshot<'source> {
+    pub fn get_owned(&'source self) -> InstanceSnapshot<'static> {
+        let children: Vec<InstanceSnapshot<'static>> = self.children.iter()
+            .map(InstanceSnapshot::get_owned)
+            .collect();
+
+        InstanceSnapshot {
+            snapshot_id: None,
+            name: Cow::Owned(self.name.clone().into_owned()),
+            class_name: Cow::Owned(self.class_name.clone().into_owned()),
+            properties: self.properties.clone(),
+            children,
+        }
+    }
+
+    pub fn from_tree(tree: &RbxTree, id: RbxId) -> InstanceSnapshot<'static> {
+        let instance = tree.get_instance(id)
+            .expect("instance did not exist in tree");
+
+        let children = instance.get_children_ids()
+            .iter()
+            .cloned()
+            .map(|id| InstanceSnapshot::from_tree(tree, id))
+            .collect();
+
+        InstanceSnapshot {
+            snapshot_id: Some(id),
+            name: Cow::Owned(instance.name.clone()),
+            class_name: Cow::Owned(instance.class_name.clone()),
+            properties: instance.properties.clone(),
+            children,
+        }
+    }
+}