Change run function to reduce boilerplate

README.md

@@ -38,15 +38,16 @@ but you can bring your own state management tools or build your own framework us
 
 ### Hello World
 ```rust
-fn main() {
-    let mut cx = Context::default();
-    let root = Element::new()
+fn app(cx: &mut Context) -> NodeKey {
+    Element::new()
         .align_items(AlignItems::Center)
         .justify_content(JustifyContent::Center)
         .child(cx.insert("Hello World!"))
-        .build(&mut cx);
+        .build(cx)
+}
 
-    viewbuilder::run(tree, root)
+fn main() {
+    viewbuilder::run(app)
 }
 ```
 

examples/counter.rs

@@ -17,32 +17,33 @@ fn button(
         .build(cx)
 }
 
-fn main() {
-    let mut cx = Context::default();
-
+fn app(cx: &mut Context) -> NodeKey {
     let inc_count = Rc::new(AtomicI64::new(0));
     let dec_count = inc_count.clone();
 
     let text = cx.insert("0");
-    let root = Element::new()
+
+    Element::new()
         .flex_direction(FlexDirection::Column)
-        .child(Element::new().child(text).build(&mut cx))
+        .child(Element::new().child(text).build(cx))
         .child(
             Element::new()
                 .flex_direction(FlexDirection::Row)
-                .child(button(&mut cx, "More!", move |cx| {
+                .child(button(cx, "More!", move |cx| {
                     inc_count.fetch_add(1, Ordering::SeqCst);
                     cx.node(text)
                         .set_text(inc_count.load(Ordering::SeqCst).to_string())
                 }))
-                .child(button(&mut cx, "Less!", move |cx| {
+                .child(button(cx, "Less!", move |cx| {
                     dec_count.fetch_sub(1, Ordering::SeqCst);
                     cx.node(text)
                         .set_text(dec_count.load(Ordering::SeqCst).to_string())
                 }))
-                .build(&mut cx),
+                .build(cx),
         )
-        .build(&mut cx);
+        .build(cx)
+}
 
-    viewbuilder::run(cx, root)
+fn main() {
+    viewbuilder::run(app)
 }

examples/hello.rs

@@ -1,13 +1,14 @@
 use taffy::style::{AlignItems, JustifyContent};
-use viewbuilder::{Context, Element};
+use viewbuilder::{Context, Element, NodeKey};
 
-fn main() {
-    let mut tree = Context::default();
-    let root = Element::new()
+fn app(cx: &mut Context) -> NodeKey {
+    Element::new()
         .align_items(AlignItems::Center)
         .justify_content(JustifyContent::Center)
-        .child(tree.insert("Hello World!"))
-        .build(&mut tree);
+        .child(cx.insert("Hello World!"))
+        .build(cx)
+}
 
-    viewbuilder::run(tree, root)
+fn main() {
+    viewbuilder::run(app)
 }

src/lib.rs

@@ -6,7 +6,6 @@
 //! It supports layout, drawing, and accessability.
 
 pub mod node;
-
 pub use node::Node;
 
 pub mod tree;
@@ -32,7 +31,11 @@ slotmap::new_key_type! {
 ///
 /// This will create a new window and render the tree,
 /// propagating events and re-rendering as they occuring.
-pub fn run(tree: Context, root: NodeKey) {
+pub fn run(f: impl FnOnce(&mut Context) -> NodeKey) {
     let renderer = Renderer::new();
-    renderer.run(tree, root)
+
+    let mut cx = Context::default();
+    let root = f(&mut cx);
+
+    renderer.run(cx, root)
 }

src/node.rs

@@ -28,21 +28,22 @@ pub enum NodeData {
     Text(Cow<'static, str>),
 }
 
+/// Node of a tree.
 pub struct Node {
     /// Data type of the node.
-    pub data: NodeData,
+    pub(crate) data: NodeData,
 
     /// Parent node id.
-    pub parent: Option<NodeKey>,
+    pub(crate)  parent: Option<NodeKey>,
 
     /// Child node ids.
-    pub children: Option<Vec<NodeKey>>,
+    pub(crate)  children: Option<Vec<NodeKey>>,
 
     /// Layout key for the taffy node.
-    pub layout_key: Option<DefaultKey>,
+    pub(crate)  layout_key: Option<DefaultKey>,
 
     /// Absolute layout of the node, relative to the window.
-    pub layout: Option<Layout>,
+    pub(crate)  layout: Option<Layout>,
 }
 
 impl Node {