Allow any type to be used as Children (take 2)

[futursolo]

Description

Partially supersedes #3042.
(There are some additional optimisation in the original PR, so I want to preserve the PR draft instead of closing it)

This pull request makes the following changes:

1. Allowing any type to be passed as children as long as IntoPropValue<T> for children with type T.
   E.g.: One can now use render props as children:

   html! {
       <Comp>
           {|p: RenderProps| html!{<>{"Hello, "}{p.name}</>}}
       </Comp>
   }

2. Added a ToHtml trait. Previously std::fmt::Display was the blanket implementation when a variable is referenced like {item}, this only allows {item} to be converted to VText. Renderable allows a variable to be converted to a VNode, which gives user greater control.

3. Users can now choose between Children, ChildrenWithProps(ChildrenRenderer<VChild<T>>)
   and Html for html-like Children. As Htmls created by html! is Rc'd, it is faster to use Html when you don't need specific features from Children and ChildrenWithProps.

4. When a component has only 1 child, it does not pass through an iterator and Vec.

5. VTag now holds VNode as its children type. This optimises for single child VTag by avoiding an allocation of single child VList.

This new implementation not only allows more types to be used as children, but also reduces code size and is faster.

Checklist

• I have reviewed my own code
• I have added tests

[github-actions]

Visit the preview URL for this PR (updated for commit b00667d):

https://yew-rs--pr3289-any-children-wrt96p3l.web.app

_{(expires Sat, 17 Jun 2023 13:05:16 GMT)}

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[github-actions]

Size Comparison

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	104.027	103.119	-0.908	-0.873%
boids	177.417	176.696	-0.721	-0.406%
communication_child_to_parent	96.902	95.781	-1.121	-1.157%
communication_grandchild_with_grandparent	109.604	109.838	+0.234	+0.214%
communication_grandparent_to_grandchild	105.703	106.322	+0.619	+0.586%
communication_parent_to_child	94.017	93.111	-0.905	-0.963%
contexts	110.692	111.853	+1.160	+1.048%
counter	90.253	89.611	-0.642	-0.711%
counter_functional	90.729	90.390	-0.339	-0.373%
dyn_create_destroy_apps	93.112	92.761	-0.352	-0.378%
file_upload	104.446	103.765	-0.682	-0.653%
function_memory_game	176.521	175.130	-1.392	-0.788%
function_router	349.635	346.331	-3.304	-0.945%
function_todomvc	164.782	163.723	-1.060	-0.643%
futures	227.538	227.683	+0.145	+0.064%
game_of_life	113.052	112.207	-0.845	-0.747%
immutable	190.416	188.901	-1.515	-0.795%
inner_html	86.809	86.389	-0.420	-0.484%
js_callback	114.744	113.857	-0.887	-0.773%
keyed_list	204.797	202.085	-2.712	-1.324%
mount_point	89.933	89.578	-0.354	-0.394%
nested_list	115.313	114.465	-0.849	-0.736%
node_refs	97.721	96.632	-1.089	-1.114%
password_strength	1589.795	1589.260	-0.535	-0.034%
portals	99.127	99.100	-0.027	-0.028%
router	315.734	312.195	-3.539	-1.121%
simple_ssr	146.230	145.125	-1.105	-0.756%
ssr_router	387.476	383.702	-3.773	-0.974%
suspense	112.170	111.172	-0.998	-0.890%
timer	93.050	92.241	-0.809	-0.869%
timer_functional	101.822	100.916	-0.906	-0.890%
todomvc	144.887	143.967	-0.920	-0.635%
two_apps	90.892	90.258	-0.634	-0.697%
web_worker_fib	155.599	154.972	-0.627	-0.403%
webgl	89.323	88.846	-0.478	-0.535%

⚠️ The following examples have changed their size significantly:

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
communication_child_to_parent	96.902	95.781	-1.121	-1.157%
contexts	110.692	111.853	+1.160	+1.048%
keyed_list	204.797	202.085	-2.712	-1.324%
node_refs	97.721	96.632	-1.089	-1.114%
router	315.734	312.195	-3.539	-1.121%

[github-actions]

Benchmark - SSR

Yew Master

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	319.245	320.168	319.531	0.317
Hello World	10	657.955	661.203	658.924	1.265
Function Router	10	2212.318	2218.537	2215.432	2.171
Concurrent Task	10	1007.491	1008.923	1008.270	0.469
Many Providers	10	1699.065	1721.156	1710.257	7.489

Pull Request

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	338.784	339.989	339.486	0.346
Hello World	10	648.297	668.178	656.372	6.341
Function Router	10	2093.251	2113.675	2101.398	6.992
Concurrent Task	10	1007.108	1008.171	1007.568	0.345
Many Providers	10	1449.720	1468.142	1456.331	5.535

[ranile]

Thanks for taking the time to implement it!

[ranile]

Wouldn't VNode be also fine for this? {vnode} should work fine

[ranile]

Looks good to me!

One question though: I don't see any error messages in tests that say "ToHtml is not implemented". Is that supposed to be like that because of From conversions? Or are failing tests missing, in which case we should add them?

[futursolo]

Looks good to me!

One question though: I don't see any error messages in tests that say "ToHtml is not implemented". Is that supposed to be like that because of From conversions? Or are failing tests missing, in which case we should add them?

I would think this as expected.
This is due to ToHtml is never directly required. The conversion goes through IntoPropValue<VNode> and then in turn require ToHtml via a blanket implementation.