dioxus/packages/core/src/properties.rs
2022-11-19 17:07:29 -08:00

75 lines
2.8 KiB
Rust

use crate::innerlude::*;
/// Every "Props" used for a component must implement the `Properties` trait. This trait gives some hints to Dioxus
/// on how to memoize the props and some additional optimizations that can be made. We strongly encourage using the
/// derive macro to implement the `Properties` trait automatically as guarantee that your memoization strategy is safe.
///
/// If your props are 'static, then Dioxus will require that they also be PartialEq for the derived memoize strategy. However,
/// if your props borrow data, then the memoization strategy will simply default to "false" and the PartialEq will be ignored.
/// This tends to be useful when props borrow something that simply cannot be compared (IE a reference to a closure);
///
/// By default, the memoization strategy is very conservative, but can be tuned to be more aggressive manually. However,
/// this is only safe if the props are 'static - otherwise you might borrow references after-free.
///
/// We strongly suggest that any changes to memoization be done at the "PartialEq" level for 'static props. Additionally,
/// we advise the use of smart pointers in cases where memoization is important.
///
/// ## Example
///
/// For props that are 'static:
/// ```rust, ignore
/// #[derive(Props, PartialEq)]
/// struct MyProps {
/// data: String
/// }
/// ```
///
/// For props that borrow:
///
/// ```rust, ignore
/// #[derive(Props)]
/// struct MyProps<'a >{
/// data: &'a str
/// }
/// ```
pub trait Properties: Sized {
/// The type of the builder for this component.
/// Used to create "in-progress" versions of the props.
type Builder;
/// An indication if these props are can be memoized automatically.
const IS_STATIC: bool;
/// Create a builder for this component.
fn builder() -> Self::Builder;
/// Memoization can only happen if the props are valid for the 'static lifetime
///
/// # Safety
/// The user must know if their props are static, but if they make a mistake, UB happens
/// Therefore it's unsafe to memoize.
unsafe fn memoize(&self, other: &Self) -> bool;
}
impl Properties for () {
type Builder = EmptyBuilder;
const IS_STATIC: bool = true;
fn builder() -> Self::Builder {
EmptyBuilder {}
}
unsafe fn memoize(&self, _other: &Self) -> bool {
true
}
}
// We allow components to use the () generic parameter if they have no props. This impl enables the "build" method
// that the macros use to anonymously complete prop construction.
pub struct EmptyBuilder;
impl EmptyBuilder {
pub fn build(self) {}
}
/// This utility function launches the builder method so rsx! and html! macros can use the typed-builder pattern
/// to initialize a component's props.
pub fn fc_to_builder<'a, A, T: Properties + 'a>(_: fn(Scope<'a, T>) -> A) -> T::Builder {
T::builder()
}