15 releases

0.1.14	Feb 15, 2024
0.1.13	Feb 15, 2024
0.1.11	Oct 1, 2023
0.1.9	Sep 20, 2023

#2127 in Procedural macros

Used in 3 crates (via rscx)

MIT license

25KB
433 lines

RSCx - Rust Server Components

RSCx is a server-side HTML rendering engine library with a neat developer experience and great performance.

Features:

all components are async functions
JSX-like syntax called RSX parsed with rstml
contexts, to easily pass values down the components tree (example)
inspired by Maud and Leptos

⚠️ Warning: not production-ready yet. It lacks important features such as HTML escaping!

Usage

All the examples can be found in rscx/examples/.

use rscx::{component, html, props, CollectFragment};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let app = app().await;
    println!("{}", app);
    Ok(())
}

// simple function returning a String
// it will call the Items() function
async fn app() -> String {
    let s = "ul { color: red; }";
    html! {
        <!DOCTYPE html>
        <html>
            <head>
                <style>{s}</style>
            </head>
            <body>
                // call a component with no props
                <Section />

                // call a component with props and children
                <Section title="Hello">
                    <Items />
                </Section>
            </body>
        </html>
    }
}

#[component]
/// mark functions with #[component] to use them as components inside html! macro
fn Section(
    // you can use `builder` attributes to specify a default value (makes this prop optional)
    #[builder(default = "Default title".into(), setter(into))] title: String,
    #[builder(default)] children: String,
) -> String {
    html! {
        <div>
            <h1>{ title }</h1>
            { children }
        </div>
    }
}

#[component]
async fn Items() -> String {
    let data = load_data_async().await;
    html! {
        <ul>
            {
                data
                    .into_iter()
                    .map(|item| html! { <li>{ item }</li> })
                    .collect_fragment() // helper method to collect a list of components into a String
            }
        </ul>
    }
}

/// async functions can be easily used in the body of a component, as every component is an async
/// function
async fn load_data_async() -> Vec<String> {
    vec!["a".to_string(), "b".to_string(), "c".to_string()]
}

Benchmarks

RSCx is fast.

Disclaimer: RSCx is for servers, as the name suggests. Therefore the following comparisons with Leptos are unfair. This library contains only a fraction of Leptos' features.

Disclaimer 2: The benchmarks are pretty basics and should not influence your decision on whether to use or not this library. Focus on the DX. They are included as I kept running them to make sure I didn't fall too much behind alternatives.

The time in the middle of the three is the average.

Run the benchmarks locally

cd bench
# cargo install criterion
cargo criterion

Benchmark 1: single element, lots of HTML attributes

many_attrs/maud_many_attrs
                        time:   [205.89 ns 208.35 ns 211.53 ns]
many_attrs/horrorshow_many_attrs
                        time:   [37.221 µs 37.304 µs 37.401 µs]
many_attrs/html_node_many_attrs
                        time:   [67.726 µs 67.830 µs 67.939 µs]
many_attrs/leptos_many_attrs
                        time:   [923.31 ns 928.46 ns 935.04 ns]
many_attrs/rscx_many_attrs
                        time:   [207.96 ns 212.82 ns 219.28 ns]

RSCx and Maud pretty much are the same as their macros output is effectively a static string with the result.

Benchmark 2: little element with props and child

small_fragment/maud_small_fragment
                        time:   [107.60 ns 107.71 ns 107.81 ns]
small_fragment/horrorshow_small_fragment
                        time:   [405.98 ns 406.08 ns 406.21 ns]
small_fragment/leptos_small_fragment
                        time:   [1.7641 µs 1.7652 µs 1.7662 µs]
small_fragment/rscx_small_fragment
                        time:   [101.79 ns 101.87 ns 101.97 ns]

RSCx offers a better DX than Maud, as the syntax is nicer and values such as i32 can be passed as props/attributes, while in Maud every attribute must be a static string.

Benchmark 3: dynamic attributes (read for variable)

many_dyn_attrs/horrorshow_many_dyn_attrs
                        time:   [50.445 µs 50.702 µs 50.977 µs]
many_dyn_attrs/leptos_many_dyn_attrs
                        time:   [100.13 µs 100.52 µs 101.00 µs]
many_dyn_attrs/rscx_many_dyn_attrs
                        time:   [33.953 µs 33.990 µs 34.037 µs]

Benchmark 4: async component rendering a list of 100 items

async_list/maud_async_list
                        time:   [2.3114 µs 2.3241 µs 2.3377 µs]
async_list/leptos_async_list
                        time:   [55.149 µs 55.228 µs 55.315 µs]
async_list/rscx_async_list
                        time:   [5.4809 µs 5.4987 µs 5.5151 µs]

I'll reiterate the disclaimer: Leptos is not specifically made for SSR. Going through its reactivity system (using async resources) adds overhead.

Dependencies

~1–1.5MB
~30K SLoC