dioxus-mirror/packages/core/src/any_props.rs

use std::marker::PhantomData;

use futures_util::Future;

use crate::{
    factory::ReturnType,
    scopes::{Scope, ScopeState},
    Element,
};

pub trait AnyProps<'a> {
    fn as_ptr(&self) -> *const ();
    fn render(&'a self, bump: &'a ScopeState) -> Element<'a>;
    unsafe fn memoize(&self, other: &dyn AnyProps) -> bool;
}

pub(crate) struct VComponentProps<'a, P, A, F = Element<'a>>
where
    F: ReturnType<'a, A>,
{
    pub render_fn: fn(Scope<'a, P>) -> F,
    pub memo: unsafe fn(&P, &P) -> bool,
    pub props: *const P,
    pub _marker: PhantomData<A>,
}

impl<'a> VComponentProps<'a, (), ()> {
    pub fn new_empty(render_fn: fn(Scope) -> Element) -> Self {
        Self {
            render_fn,
            memo: <() as PartialEq>::eq,
            props: std::ptr::null_mut(),
            _marker: PhantomData,
        }
    }
}

impl<'a, P, A, F: ReturnType<'a, A>> VComponentProps<'a, P, A, F> {
    pub(crate) fn new(
        render_fn: fn(Scope<'a, P>) -> F,
        memo: unsafe fn(&P, &P) -> bool,
        props: *const P,
    ) -> Self {
        Self {
            render_fn,
            memo,
            props,
            _marker: PhantomData,
        }
    }
}

impl<'a, P, A, F: ReturnType<'a, A>> AnyProps<'a> for VComponentProps<'a, P, A, F> {
    fn as_ptr(&self) -> *const () {
        &self.props as *const _ as *const ()
    }

    // Safety:
    // this will downcast the other ptr as our swallowed type!
    // you *must* make this check *before* calling this method
    // if your functions are not the same, then you will downcast a pointer into a different type (UB)
    unsafe fn memoize(&self, other: &dyn AnyProps) -> bool {
        let real_other: &P = &*(other.as_ptr() as *const _ as *const P);
        let real_us: &P = &*(self.as_ptr() as *const _ as *const P);
        (self.memo)(real_us, real_other)
    }

    fn render<'b>(&'b self, scope: &'b ScopeState) -> Element<'b> {
        // Make sure the scope ptr is not null
        // self.props.state.set(scope);

        let scope = Scope {
            props: unsafe { &*self.props },
            scope,
        };

        // Call the render function directly
        // todo: implement async
        // let res = match self.render_fn {
        //     ComponentFn::Sync(f) => {
        //         let f = unsafe { std::mem::transmute(f) };
        //         f(scope)
        //     }
        //     ComponentFn::Async(_) => todo!(),
        // };

        todo!()
    }
}