feat(tvix/store): implement iteration over Directory nodes

This provides a `Directory.nodes()` function, returning an iterator over
all three node types in an ordered fashion.

Change-Id: Ib98696c03a9db8b6c613d6e2bf5587c1ae35133f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7955
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

tvix/store/src/tests/directory_nodes_iterator.rs

@@ -0,0 +1,82 @@
+use crate::proto::node::Node;
+use crate::proto::Directory;
+use crate::proto::DirectoryNode;
+use crate::proto::FileNode;
+use crate::proto::SymlinkNode;
+
+#[test]
+fn iterator() -> anyhow::Result<()> {
+    let d = Directory {
+        directories: vec![
+            DirectoryNode {
+                name: "c".to_string(),
+                ..DirectoryNode::default()
+            },
+            DirectoryNode {
+                name: "d".to_string(),
+                ..DirectoryNode::default()
+            },
+            DirectoryNode {
+                name: "h".to_string(),
+                ..DirectoryNode::default()
+            },
+            DirectoryNode {
+                name: "l".to_string(),
+                ..DirectoryNode::default()
+            },
+        ],
+        files: vec![
+            FileNode {
+                name: "b".to_string(),
+                ..FileNode::default()
+            },
+            FileNode {
+                name: "e".to_string(),
+                ..FileNode::default()
+            },
+            FileNode {
+                name: "g".to_string(),
+                ..FileNode::default()
+            },
+            FileNode {
+                name: "j".to_string(),
+                ..FileNode::default()
+            },
+        ],
+        symlinks: vec![
+            SymlinkNode {
+                name: "a".to_string(),
+                ..SymlinkNode::default()
+            },
+            SymlinkNode {
+                name: "f".to_string(),
+                ..SymlinkNode::default()
+            },
+            SymlinkNode {
+                name: "i".to_string(),
+                ..SymlinkNode::default()
+            },
+            SymlinkNode {
+                name: "k".to_string(),
+                ..SymlinkNode::default()
+            },
+        ],
+    };
+
+    let mut node_names: Vec<String> = vec![];
+
+    for node in d.nodes() {
+        match node {
+            Node::Directory(n) => node_names.push(n.name),
+            Node::File(n) => node_names.push(n.name),
+            Node::Symlink(n) => node_names.push(n.name),
+        };
+    }
+
+    assert_eq!(
+        vec!["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"],
+        node_names
+    );
+
+    Ok(())
+}

tvix/store/src/tests/mod.rs

@@ -1,4 +1,5 @@
 mod directory;
+mod directory_nodes_iterator;
 mod directory_service;
 mod path_info_service;
 mod pathinfo;