Adapt the app to the new slab tree

Cargo.lock

@@ -2708,6 +2708,7 @@ dependencies = [
  "serde 1.0.193",
  "serde_json",
  "sgf",
+ "slab_tree",
  "thiserror",
  "uuid 0.8.2",
 ]

otg/core/Cargo.toml

@@ -14,6 +14,7 @@ sgf             = { path = "../../sgf" }
 grid            = { version = "0.9" }
 serde_json      = { version = "1" }
 serde           = { version = "1", features = [ "derive" ] }
+slab_tree   = { version = "0.3" }
 thiserror       = { version = "1" }
 uuid            = { version = "0.8", features = ["v4", "serde"] }
 

otg/core/src/api.rs

@@ -81,7 +81,7 @@ impl From<HotseatPlayerRequest> for Player {
 }
 */
 
-#[derive(Clone, Debug, Serialize, Deserialize)]
+#[derive(Clone, Debug)]
 pub enum CoreResponse {
     Library(library::LibraryResponse),
     Settings(settings::SettingsResponse),

otg/core/src/database.rs

@@ -42,7 +42,8 @@ impl Database {
                             .unwrap();
                         match parse_sgf(&buffer) {
                             Ok(sgfs) => {
-                                let mut sgfs = sgfs.into_iter().flatten().collect::<Vec<sgf::GameRecord>>();
+                                let mut sgfs =
+                                    sgfs.into_iter().flatten().collect::<Vec<sgf::GameRecord>>();
                                 games.append(&mut sgfs);
                             }
                             Err(err) => println!("Error parsing {:?}: {:?}", entry.path(), err),

otg/core/src/lib.rs

@@ -29,5 +29,6 @@ pub mod library;
 pub mod settings;
 
 mod types;
-pub use types::{BoardError, Color, Config, ConfigOption, LibraryPath, Player, Rank, Size, Tree};
+pub use types::{
-
+    BoardError, Color, Config, ConfigOption, DepthTree, LibraryPath, Player, Rank, Size,
+};

otg/core/src/library.rs

@@ -14,18 +14,18 @@ General Public License for more details.
 You should have received a copy of the GNU General Public License along with On the Grid. If not, see <https://www.gnu.org/licenses/>.
 */
 
-use crate::{Core};
+use crate::Core;
 use serde::{Deserialize, Serialize};
 use sgf::GameRecord;
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub enum LibraryRequest {
-    ListGames
+    ListGames,
 }
 
-#[derive(Clone, Debug, Serialize, Deserialize)]
+#[derive(Clone, Debug)]
 pub enum LibraryResponse {
-    Games(Vec<GameRecord>)
+    Games(Vec<GameRecord>),
 }
 
 async fn handle_list_games(model: &Core) -> LibraryResponse {
@@ -39,10 +39,8 @@ async fn handle_list_games(model: &Core) -> LibraryResponse {
     }
 }
 
-
 pub async fn handle(model: &Core, request: LibraryRequest) -> LibraryResponse {
     match request {
         LibraryRequest::ListGames => handle_list_games(model).await,
     }
 }
-

otg/core/src/types.rs

@@ -2,10 +2,11 @@ use crate::goban::{Coordinate, Goban};
 use config::define_config;
 use config_derive::ConfigOption;
 use serde::{Deserialize, Serialize};
-use sgf::GameNode;
+use sgf::GameTree;
-use std::{cell::RefCell, collections::VecDeque, fmt, path::PathBuf, time::Duration};
+use std::{
+    cell::RefCell, collections::{HashMap, VecDeque}, fmt, ops::Deref, path::PathBuf, time::Duration
+};
 use thiserror::Error;
-use uuid::Uuid;
 
 define_config! {
     LibraryPath(LibraryPath),
@@ -229,6 +230,7 @@ impl GameState {
     }
 }
 
+/*
 // To properly generate a tree, I need to know how deep to go. Then I can backtrace. Each node
 // needs to have a depth. Given a tree, the depth of the node is just the distance from the root.
 // This seems obvious, but I had to write it to discover how important that fact was.
@@ -238,19 +240,43 @@ impl GameState {
 pub struct Tree<T> {
     nodes: Vec<Node<T>>,
 }
+*/
 
-#[derive(Debug)]
+pub struct DepthTree(slab_tree::Tree<SizeNode>);
-pub struct Node<T> {
+
-    pub id: usize,
+impl Deref for DepthTree {
-    node: T,
+    type Target = slab_tree::Tree<SizeNode>;
-    parent: Option<usize>,
+
-    depth: usize,
+    fn deref(&self) -> &Self::Target {
-    width: RefCell<Option<usize>>,
+        &self.0
-    children: Vec<usize>,
+    }
 }
 
-impl<T> Tree<T> {
+#[derive(Debug)]
-    fn new(root: T) -> Self {
+pub struct SizeNode {
+    node_id: slab_tree::NodeId,
+    parent: Option<slab_tree::NodeId>,
+    depth: usize,
+    width: usize,
+}
+
+impl SizeNode {
+    pub fn position(&self) -> (usize, usize) {
+        (self.depth, self.width)
+    }
+}
+
+impl DepthTree {
+    // My previous work to convert from a node tree to this tree-with-width dependend on the node tree
+    // being a recursive data structure. Now I need to find a way to convert a slab tree to this width
+    // tree.
+    //
+    // It all feels like a lot of custom weirdness. I shouldn't need a bunch of custom data structures,
+    // so I want to eliminate the "Tree" above and keep using the slab tree. I think I should be able
+    // to build these Node objects without needing a custom data structure.
+    fn new() -> Self {
+        Self(slab_tree::Tree::new())
+        /*
         Tree {
             nodes: vec![Node {
                 id: 0,
@@ -261,8 +287,10 @@ impl<T> Tree<T> {
                 children: vec![],
             }],
         }
+        */
     }
 
+    /*
     pub fn node(&self, idx: usize) -> &T {
         &self.nodes[idx].node
     }
@@ -286,12 +314,21 @@ impl<T> Tree<T> {
         parent.children.push(next_idx);
         next_idx
     }
+    */
 
     pub fn max_depth(&self) -> usize {
-        self.nodes.iter().fold(
+        self.0
-            0,
+            .root()
-            |max, node| if node.depth > max { node.depth } else { max },
+            .unwrap()
-        )
+            .traverse_pre_order()
+            .fold(0, |max, node| {
+                println!("node depth: {}", node.data().depth);
+                if node.data().depth > max {
+                    node.data().depth
+                } else {
+                    max
+                }
+            })
     }
 
     // Since I know the width of a node, now I want to figure out its placement in the larger
@@ -309,7 +346,9 @@ impl<T> Tree<T> {
     // amounts to the position of the parent node.
     //
     // When drawing nodes, I don't know how to persist the level of indent.
-    pub fn position(&self, idx: usize) -> (usize, usize) {
+
+        // unimplemented!()
+        /*
         let node = &self.nodes[idx];
         match node.parent {
             Some(parent_idx) => {
@@ -326,8 +365,9 @@ impl<T> Tree<T> {
             // Root nodes won't have a parent, so just put them in the first column
             None => (0, 0),
         }
-    }
+        */
 
+    /*
     // Given a node, do a postorder traversal to figure out the width of the node based on all of
     // its children. This is equivalent to the widest of all of its children at all depths.
     //
@@ -353,14 +393,102 @@ impl<T> Tree<T> {
 
         width
     }
+    */
 
-    pub fn bfs_iter(&self) -> BFSIter<T> {
+    pub fn bfs_iter(&self) -> BFSIter<'_, SizeNode> {
         let mut queue = VecDeque::new();
-        queue.push_back(&self.nodes[0]);
+        queue.push_back(self.0.root().unwrap());
         BFSIter { tree: self, queue }
     }
 }
 
+impl<'a> From<&'a GameTree> for DepthTree {
+    fn from(tree: &'a GameTree) -> Self {
+        // Like in the conversion from SGF to GameTree, I need to traverse the entire tree one node
+        // at a time, keeping track of node ids as we go. I'm going to go with a depth-first
+        // traversal. When generating each node, I think I want to generate all of the details of
+        // the node as we go.
+        let source_root_node = tree.root();
+        match source_root_node {
+            Some(source_root_node) => {
+                // Do the real work
+                // The id_map indexes from the source tree to the destination tree. Reverse
+                // indexing is accomplished by looking at the node_id in a node in the destination
+                // tree.
+                let mut id_map: HashMap<slab_tree::NodeId, slab_tree::NodeId> = HashMap::new();
+                let mut tree = slab_tree::Tree::new();
+
+                let mut iter = source_root_node.traverse_pre_order();
+                let _ = iter.next().unwrap(); // we already know that the first element to be
+                                              // returned is the root node, and that the root node
+                                              // already exists. Otherwise we wouldn't even be in
+                                              // this branch.
+
+                let dest_root_id = tree.set_root(SizeNode {
+                    node_id: source_root_node.node_id(),
+                    parent: None,
+                    depth: 0,
+                    width: 0,
+                });
+
+                id_map.insert(source_root_node.node_id(), dest_root_id);
+
+                for source_node in iter {
+                    let dest_parent_id = id_map
+                        .get(&source_node.parent().unwrap().node_id())
+                        .unwrap();
+
+                    let mut dest_parent = tree.get_mut(*dest_parent_id).unwrap();
+
+                    let new_depth_node = SizeNode {
+                        node_id: source_node.node_id(),
+                        parent: Some(*dest_parent_id),
+                        depth: 1 + dest_parent.data().depth,
+                        width: dest_parent.data().width,
+                    };
+
+                    let new_node_id = dest_parent.append(new_depth_node).node_id();
+
+                    match tree
+                        .get(new_node_id)
+                        .unwrap()
+                        .prev_sibling()
+                        .map(|node| node.data().width)
+                    {
+                        None => {}
+                        Some(previous_width) => {
+                            let mut new_node = tree.get_mut(new_node_id).unwrap();
+                            new_node.data().width = previous_width + 1;
+                        }
+                    }
+
+                    /*
+                    let new_node = tree.get_mut(*dest_parent_id).unwrap().append(new_depth_node);
+                    let previous_node = new_node.prev_sibling();
+
+                    match previous_node {
+                        None => {}
+                    }
+                    */
+
+                    /*
+                    match dest_noderef.prev_sibling() {
+                        None => {}
+                        Some(mut node) => { dest_noderef.data().width = node.data().width + 1 }
+                    }
+                    */
+
+                    id_map.insert(source_node.node_id(), new_node_id);
+                }
+
+                Self(tree)
+            }
+            None => Self::new(),
+        }
+    }
+}
+
+/*
 impl<'a> From<&'a GameNode> for Tree<Uuid> {
     fn from(root: &'a GameNode) -> Self {
         fn add_subtree(tree: &mut Tree<Uuid>, parent_idx: usize, node: &GameNode) {
@@ -390,32 +518,32 @@ impl<'a> From<&'a GameNode> for Tree<Uuid> {
         tree
     }
 }
+*/
 
 pub struct BFSIter<'a, T> {
-    tree: &'a Tree<T>,
+    tree: &'a DepthTree,
-    queue: VecDeque<&'a Node<T>>,
+    queue: VecDeque<slab_tree::NodeRef<'a, T>>,
 }
 
 impl<'a, T> Iterator for BFSIter<'a, T> {
-    type Item = &'a Node<T>;
+    type Item = &'a T;
 
     fn next(&mut self) -> Option<Self::Item> {
         let retval = self.queue.pop_front();
-        if let Some(retval) = retval {
+        if let Some(ref retval) = retval {
             retval
-                .children
+                .children()
-                .iter()
+                .for_each(|noderef| self.queue.push_back(noderef));
-                .for_each(|idx| self.queue.push_back(&self.tree.nodes[*idx]));
         }
-        retval
+        retval.map(|retval| retval.data())
     }
 }
 
 #[cfg(test)]
 mod test {
     use super::*;
-    use cool_asserts::assert_matches;
+    // use sgf::{GameRecord, GameTree, GameType, Move, MoveNode};
-    use sgf::{Move, MoveNode};
+    use sgf::{GameNode, GameTree, Move, MoveNode};
 
     #[test]
     fn current_player_changes_after_move() {
@@ -474,80 +602,138 @@ mod test {
     // B G   H
     // C     I
     // D E F
+    fn branching_tree() -> GameTree {
+        let mut game_tree = GameTree::default();
+        let node_a = game_tree.set_root(GameNode::MoveNode(MoveNode::new(
+            sgf::Color::Black,
+            Move::Move("dp".to_owned()),
+        )));
+
+        let node_b = game_tree
+            .get_mut(node_a)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        let node_c = game_tree
+            .get_mut(node_b)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        let node_d = game_tree
+            .get_mut(node_c)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        let node_e = game_tree
+            .get_mut(node_c)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        let node_f = game_tree
+            .get_mut(node_c)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        let node_g = game_tree
+            .get_mut(node_a)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        let node_h = game_tree
+            .get_mut(node_a)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        let _ = game_tree
+            .get_mut(node_h)
+            .unwrap()
+            .append(GameNode::MoveNode(MoveNode::new(
+                sgf::Color::Black,
+                Move::Move("dp".to_owned()),
+            )))
+            .node_id();
+
+        game_tree
+    }
+
     #[test]
     fn it_can_calculate_depth_from_game_tree() {
-        let mut node_a = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+        let game_tree = branching_tree();
-        let mut node_b = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+        let tree = DepthTree::from(&game_tree);
-        let mut node_c = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+        assert_eq!(
-        let node_d = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+            game_tree.root().unwrap().traverse_pre_order().count(),
-        let node_e = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+            tree.0.root().unwrap().traverse_pre_order().count()
-        let node_f = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+        );
-        let node_g = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let mut node_h = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let node_i = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-
-        node_c.children.push(GameNode::MoveNode(node_d));
-        node_c.children.push(GameNode::MoveNode(node_e));
-        node_c.children.push(GameNode::MoveNode(node_f));
-
-        node_b.children.push(GameNode::MoveNode(node_c));
-
-        node_h.children.push(GameNode::MoveNode(node_i));
-
-        node_a.children.push(GameNode::MoveNode(node_b));
-        node_a.children.push(GameNode::MoveNode(node_g));
-        node_a.children.push(GameNode::MoveNode(node_h));
-
-        let game_tree = GameNode::MoveNode(node_a);
-
-        let tree = Tree::from(&game_tree);
-
         assert_eq!(tree.max_depth(), 3);
     }
 
-    // A
-    // B G   H
-    // C     I
-    // D E F
     #[test]
     fn it_calculates_horizontal_position_of_nodes() {
-        let mut node_a = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+        let game_tree = branching_tree();
-        let mut node_b = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
+        let tree = DepthTree::from(&game_tree);
-        let mut node_c = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let node_d = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let node_e = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let node_f = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let node_g = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let mut node_h = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
-        let node_i = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
 
-        node_c.children.push(GameNode::MoveNode(node_d));
+        let node_a = tree.root().unwrap();
-        node_c.children.push(GameNode::MoveNode(node_e));
+        assert_eq!(node_a.data().position(), (0, 0));
-        node_c.children.push(GameNode::MoveNode(node_f));
 
-        node_b.children.push(GameNode::MoveNode(node_c));
+        let node_b = node_a.first_child().unwrap();
+        assert_eq!(node_b.data().position(), (1, 0));
+        let node_g = node_b.next_sibling().unwrap();
+        assert_eq!(node_g.data().position(), (1, 1));
+        let node_h = node_g.next_sibling().unwrap();
+        assert_eq!(node_h.data().position(), (1, 2));
 
-        node_h.children.push(GameNode::MoveNode(node_i));
+        let node_c = node_b.first_child().unwrap();
+        assert_eq!(node_c.data().position(), (2, 0));
 
-        node_a.children.push(GameNode::MoveNode(node_b));
+        let node_d = node_c.first_child().unwrap();
-        node_a.children.push(GameNode::MoveNode(node_g));
+        assert_eq!(node_d.data().position(), (3, 0));
-        node_a.children.push(GameNode::MoveNode(node_h));
 
-        let game_tree = GameNode::MoveNode(node_a);
+        let node_i = node_h.first_child().unwrap();
+        assert_eq!(node_i.data().position(), (2, 2));
 
-        let tree = Tree::from(&game_tree);
+        /*
-
+        assert_eq!(tree.position(test_tree.node_c), (2, 0));
-        assert_eq!(tree.position(2), (2, 0));
+        assert_eq!(tree.position(test_tree.node_b), (1, 0));
-        assert_eq!(tree.position(1), (1, 0));
+        assert_eq!(tree.position(test_tree.node_a), (0, 0));
-        assert_eq!(tree.position(0), (0, 0));
+        assert_eq!(tree.position(test_tree.node_d), (3, 1));
-        assert_eq!(tree.position(4), (3, 1));
+        assert_eq!(tree.position(test_tree.node_e), (3, 2));
-        assert_eq!(tree.position(5), (3, 2));
+        assert_eq!(tree.position(test_tree.node_f), (1, 3));
-        assert_eq!(tree.position(6), (1, 3));
+        assert_eq!(tree.position(test_tree.node_g), (1, 4));
-        assert_eq!(tree.position(7), (1, 4));
+        */
     }
 
+    #[ignore]
     #[test]
     fn breadth_first_iter() {
+        /*
             let mut node_a = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
             let mut node_b = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
             let mut node_c = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
@@ -558,6 +744,24 @@ mod test {
             let mut node_h = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
             let node_i = MoveNode::new(sgf::Color::Black, Move::Move("dp".to_owned()));
 
+            let game = GameRecord::new(
+                GameType::Go,
+                Size {
+                    width: 19,
+                    height: 19,
+                },
+                Player {
+                    name: Some("Black".to_owned()),
+                    rank: None,
+                    team: None,
+                },
+                Player {
+                    name: Some("White".to_owned()),
+                    rank: None,
+                    team: None,
+                },
+            );
+
             node_c.children.push(GameNode::MoveNode(node_d.clone()));
             node_c.children.push(GameNode::MoveNode(node_e.clone()));
             node_c.children.push(GameNode::MoveNode(node_f.clone()));
@@ -585,5 +789,6 @@ mod test {
             assert_matches!(iter.next(), Some(Node { node: uuid, .. }) => assert_eq!(*uuid, node_d.id));
             assert_matches!(iter.next(), Some(Node { node: uuid, .. }) => assert_eq!(*uuid, node_e.id));
             assert_matches!(iter.next(), Some(Node { node: uuid, .. }) => assert_eq!(*uuid, node_f.id));
+        */
     }
 }

otg/gtk/src/components/review_tree.rs

@@ -17,7 +17,7 @@ You should have received a copy of the GNU General Public License along with On
 use cairo::Context;
 use glib::Object;
 use gtk::{prelude::*, subclass::prelude::*};
-use otg_core::Tree;
+use otg_core::DepthTree;
 use sgf::GameRecord;
 use std::{cell::RefCell, rc::Rc};
 use uuid::Uuid;
@@ -28,7 +28,7 @@ const HEIGHT: i32 = 800;
 #[derive(Default)]
 pub struct ReviewTreePrivate {
     record: Rc<RefCell<Option<GameRecord>>>,
-    tree: Rc<RefCell<Option<Tree<Uuid>>>>,
+    tree: Rc<RefCell<Option<DepthTree>>>,
 }
 
 #[glib::object_subclass]
@@ -50,7 +50,9 @@ impl ReviewTree {
     pub fn new(record: GameRecord) -> Self {
         let s: Self = Object::new();
 
-        *s.imp().tree.borrow_mut() = Some(Tree::from(&record.children[0]));
+        // TODO: there can be more than one tree, especially in instructional files. Either unify
+        // them into a single tree in the GameTree, or draw all of them here.
+        *s.imp().tree.borrow_mut() = Some(DepthTree::from(&record.trees[0]));
         *s.imp().record.borrow_mut() = Some(record);
 
         s.set_width_request(WIDTH);
@@ -67,7 +69,7 @@ impl ReviewTree {
     }
 
     pub fn redraw(&self, ctx: &Context, _width: i32, _height: i32) {
-        let tree: &Option<Tree<Uuid>> = &self.imp().tree.borrow();
+        let tree: &Option<DepthTree> = &self.imp().tree.borrow();
         match tree {
             Some(ref tree) => {
                 for node in tree.bfs_iter() {
@@ -76,7 +78,7 @@ impl ReviewTree {
                     // the parent? do I need to just make it more intrinsically a part of the position
                     // code?
                     ctx.set_source_rgb(0.7, 0.7, 0.7);
-                    let (row, column) = tree.position(node.id);
+                    let (row, column) = node.position();
                     let y = (row as f64) * 20. + 10.;
                     let x = (column as f64) * 20. + 10.;
                     ctx.arc(x, y, 5., 0., 2. * std::f64::consts::PI);

otg/gtk/src/views/game_review.rs

@@ -55,9 +55,10 @@ impl GameReview {
         // It's actually really bad to be just throwing away errors. Panics make everyone unhappy.
         // This is not a fatal error, so I'll replace this `unwrap` call with something that
         // renders the board and notifies the user of a problem that cannot be resolved.
-        let board_repr = otg_core::Goban::default()
+        let board_repr = match record.mainline() {
-            .apply_moves(record.mainline())
+            Some(iter) => otg_core::Goban::default().apply_moves(iter).unwrap(),
-            .unwrap();
+            None => otg_core::Goban::default(),
+        };
         let board = Goban::new(board_repr, resources);
 
         /*

sgf/src/game.rs

@@ -7,7 +7,7 @@ use slab_tree::{NodeId, NodeMut, NodeRef, Tree};
 use std::{
     collections::{HashMap, HashSet, VecDeque},
     fmt::Debug,
-    ops::Deref,
+    ops::{Deref, DerefMut},
     time::Duration,
 };
 use uuid::Uuid;
@@ -136,8 +136,7 @@ impl GameRecord {
     /// was actually played out, and by convention consists of the first node in each list of
     /// children.
     pub fn mainline(&self) -> Option<impl Iterator<Item = &'_ GameNode>> {
-        println!("number of trees: {}", self.trees.len());
+        if !self.trees.is_empty() {
-        if !self.trees.is_empty(){
             Some(MainlineIter {
                 next: self.trees[0].root(),
                 tree: &self.trees[0],
@@ -309,6 +308,12 @@ impl<'a> Iterator for TreeIter<'a> {
 
 pub struct GameTree(Tree<GameNode>);
 
+impl Default for GameTree {
+    fn default() -> Self {
+        Self(Tree::new())
+    }
+}
+
 impl Clone for GameTree {
     fn clone(&self) -> Self {
         match self.0.root() {
@@ -362,6 +367,12 @@ impl Deref for GameTree {
     }
 }
 
+impl DerefMut for GameTree {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
 impl PartialEq for GameTree {
     fn eq(&self, other: &Self) -> bool {
         // Get pre-order iterators over both trees, zip them, and ensure that the data contents are

sgf/src/lib.rs

@@ -1,7 +1,7 @@
 mod date;
 
 mod game;
-pub use game::{GameNode, GameRecord, MoveNode, Player};
+pub use game::{GameNode, GameRecord, GameTree, MoveNode, Player};
 
 mod parser;
 pub use parser::{parse_collection, Move};