Create memo view

README.md

@@ -1,6 +1,6 @@
 <div align="center">
  <h1>Concoct</h1>
- 
+
  <a href="https://crates.io/crates/concoct">
  <img src="https://img.shields.io/crates/v/concoct?style=flat-square"
  alt="Crates.io version" />
@@ -23,10 +23,9 @@
 
 Concoct is a framework for user-interfaces in Rust.
 
-This crate provides a diffing-engine and state management system for any backend.
+This crate provides a virtual DOM and state management system for any backend.
 Concoct uses static typing to describe your UI at compile-time to create an efficient
-tree without allocations. Updates to state re-render your application top-down,
-starting at the state's parent component.
+tree without allocations.
 
 ```rust
 #[derive(Default)]

crates/concoct/src/lib.rs

@@ -1,3 +1,26 @@
+//! Concoct is a framework for user-interfaces in Rust.
+//!
+//! This crate provides a virtual DOM and state management system for any backend.
+//! Concoct uses static typing to describe your UI at compile-time to create an efficient
+//! tree without allocations.
+//!
+//! ```ignore
+//! #[derive(Default)]
+//! struct Counter {
+//! count: i32,
+//! }
+//!
+//! impl View<Counter> for Counter {
+//! fn body(&mut self, _cx: &Scope<Counter>) -> impl View<Counter> {
+//! (
+//! format!("High five count: {}", self.count),
+//! html::button("Up high!").on_click(|state: &mut Self, _event| state.count += 1),
+//! html::button("Down low!").on_click(|state: &mut Self, _event| state.count -= 1),
+//! )
+//! }
+//! }
+//! ```
+
 use rustc_hash::FxHashMap;
 use slotmap::{DefaultKey, SlotMap};
 use std::{
@@ -29,7 +52,7 @@ impl<T, A> Handle<T, A> {
 }
 
 pub struct Scope<T, A = ()> {
- pub key: DefaultKey,
+ key: DefaultKey,
  node: Node,
  update: Rc<dyn Fn(Rc<dyn Fn(&mut T) -> Option<ActionResult<A>>>)>,
  is_empty: Cell<bool>,

crates/concoct/src/view/adapt.rs

@@ -1,6 +1,7 @@
-use crate::{build_inner, ActionResult, Scope, View};
+use crate::{build_inner, rebuild_inner, ActionResult, Scope, View};
 use std::{cell::RefCell, marker::PhantomData, rc::Rc};
 
+/// Adapt a view's state to a different one.
 pub fn adapt<T1, A1, F, V, T2, A2>(f: F, view: V) -> Adapt<T1, A1, F, V, T2, A2>
 where
  T1: 'static,
@@ -18,6 +19,7 @@ where
  }
 }
 
+/// View for the [`adapt`] function.
 pub struct Adapt<T1, A1, F, V, T2, A2> {
  f: Rc<RefCell<F>>,
  view: V,
@@ -49,6 +51,11 @@ where
  nodes: cx.nodes.clone(),
  contexts: cx.contexts.clone(),
  };
- build_inner(&mut self.view, &child_cx);
+
+ if cx.node.inner.borrow().children.is_empty() {
+ build_inner(&mut self.view, &child_cx);
+ } else {
+ rebuild_inner(&mut self.view, &child_cx);
+ }
  }
 }

crates/concoct/src/view/memo.rs

@@ -0,0 +1,41 @@
+use crate::{build_inner, hook::use_ref, rebuild_inner, Scope, View};
+use rustc_hash::FxHasher;
+use std::hash::{Hash, Hasher};
+
+/// Memoize a view, only running it when dependencies have change.
+pub fn memo<V>(dependencies: impl Hash, view: V) -> Memo<V> {
+ let mut hasher = FxHasher::default();
+ dependencies.hash(&mut hasher);
+ let hash = hasher.finish();
+
+ Memo { hash, view }
+}
+
+/// View for the [`memo`] function.
+pub struct Memo<V> {
+ hash: u64,
+ view: V,
+}
+
+impl<T, A, V> View<T, A> for Memo<V>
+where
+ V: View<T, A>,
+{
+ fn body(&mut self, cx: &Scope<T, A>) -> impl View<T, A> {
+ let mut is_init = false;
+ let last_hash = use_ref(cx, || {
+ is_init = true;
+ self.hash
+ });
+
+ if is_init || self.hash != *last_hash {
+ *last_hash = self.hash;
+
+ if cx.node.inner.borrow().children.is_empty() {
+ build_inner(&mut self.view, &cx);
+ } else {
+ rebuild_inner(&mut self.view, &cx);
+ }
+ }
+ }
+}

crates/concoct/src/view/mod.rs

@@ -4,7 +4,12 @@ use std::{cell::Cell, rc::Rc};
 mod adapt;
 pub use self::adapt::{adapt, Adapt};
 
+mod memo;
+pub use self::memo::{memo, Memo};
+
+/// Viewable component.
 pub trait View<T, A = ()> {
+ /// View this component, returning its body.
  fn body(&mut self, cx: &Scope<T, A>) -> impl View<T, A>;
 }