# markup.rs
A blazing fast, type-safe template engine for Rust.
[](https://github.com/utkarshkukreti/markup.rs/actions/workflows/build.yml)
[](https://crates.io/crates/markup)
[](https://docs.rs/markup)
[](https://crates.io/crates/markup)
[](https://crates.io/crates/markup)
`markup.rs` is a template engine for Rust powered by procedural macros which
parses the template at compile time and generates optimal Rust code to render
the template at run time. The templates may embed Rust code which is type
checked by the Rust compiler enabling full type-safety.
## Features
* Fully type-safe with inline highlighted errors when using editor extensions like [rust-analyzer](https://github.com/rust-analyzer/rust-analyzer).
* Less error-prone and terse syntax inspired by [Haml](https://haml.info/), [Slim](http://slim-lang.com/), and [Pug](https://pugjs.org).
* Zero unsafe code.
* Zero runtime dependencies.
* ⚡ Blazing fast. The fastest in [this](https://github.com/djc/template-benchmarks-rs) benchmark among the ones which do not use unsafe code, the second fastest overall.
## Install
```toml
[dependencies]
markup = "0.15.0"
```
## Framework Integration
We have integration examples for the following web frameworks:
1. [Axum](examples/axum/src/main.rs)
2. [Rocket](examples/rocket/src/main.rs)
## Quick Example
```rust
markup::define! {
Home<'a>(title: &'a str) {
@markup::doctype()
html {
head {
title { @title }
style {
"body { background: #fafbfc; }"
"#main { padding: 2rem; }"
}
}
body {
@Header { title }
#main {
p {
"This domain is for use in illustrative examples in documents. You may \
use this domain in literature without prior coordination or asking for \
permission."
}
p {
a[href = "https://www.iana.org/domains/example"] {
"More information..."
}
}
}
@Footer { year: 2020 }
}
}
}
Header<'a>(title: &'a str) {
header {
h1 { @title }
}
}
Footer(year: u32) {
footer {
"(c) " @year
}
}
}
fn main() {
println!(
"{}",
Home {
title: "Example Domain"
}
)
}
```
### Output
```html
Example Domain
Example Domain
This domain is for use in illustrative examples in documents. You may use this domain in literature without prior coordination or asking for permission.
```
### Output (manually prettified)
```html
Example Domain
Example Domain
This domain is for use in illustrative examples in documents. You may
use this domain in literature without prior coordination or asking for
permission.
```
## Syntax Reference (WIP)
### markup::define! and markup::new!
There are two ways to define templates: `markup::define!` and `markup::new!`.
`markup::define!` defines a template with named arguments. These templates cannot access variables from outer scope. The templates can have generic parameters. Under the hood, `markup::define!` compiles to a Rust struct that implements `markup::Render` and `std::fmt::Display` traits.
Code
```rust
markup::define! {
Hello<'a>(name: &'a str) {
"Hello, " @name "!"
}
HelloGeneric(name: T) {
"Hello, " @name.to_string() "!"
}
}
// The template can now be printed directly or written to a stream:
println!("{}", Hello { name: "World" });
writeln!(&mut std::io::stdout(), "{}", HelloGeneric { name: "World 2" }).unwrap();
// The template can also be rendered to a String:
let string = Hello { name: "World 3" }.to_string();
println!("{}", string);
```
Output
```html
Hello, World!
Hello, World 2!
Hello, World 3!
```
`markup::new!` defines a template without any arguments. These can access variables from outer scope.
Code
```rust
let name = "World";
let template = markup::new! {
"Hello, " @name "!"
};
// The template can now be printed directly or written to a stream:
println!("{}", template);
writeln!(&mut std::io::stdout(), "{}", template).unwrap();
// The template can also be rendered to a String:
let string = template.to_string();
println!("{}", string);
```
### Expressions
Templates can have bare literal values, which are rendered as is. They can also have expressions (including function and macro calls) preceded by `@` sign. All strings are HTML-escaped unless they are wrapped in `markup::raw()`.
Code
```rust
markup::define! {
Expressions(a: i32, b: i32) {
1 " + " 2 " = " @{1 + 2} '\n'
@a " - " @b " = " @{a - b} '\n'
@format!("{} * {} = {}", a, b, a * b) '\n'
@a " ^ 4 = " @a.pow(4) '\n'
// All output is escaped by default.
"<>\n"
// Escaping can be disabled using `markup::raw()`.
@markup::raw("")
}
}
println!("{}", Expressions { a: 5, b: 3 });
```
### Elements
Elements are defined using a CSS selector-like syntax. Elements can contain other nested elements in braces or be followed by a semicolon for self-closing elements.
Code
```rust
markup::define! {
Elements(name: &'static str) {
// Just a div.
div {}
'\n'
// Three nested elements.
main {
aside {
h3 { "Sidebar" }
}
}
'\n'
// Self-closing input element.
input;
'\n'
// Element with a name containing dashes.
$"my-custom-element" {}
'\n'
// Element with a dynamic name.
${name} {}
}
}
println!("{}", Elements { name: "span" });
```
Output
```html
```
### Attributes
Attributes are defined after the element name. `id` and `class` attributes can be defined using CSS selector-like syntax using `#` and `.`. Classes may be specified multiple times using this shorthand syntax. Other attributes are specified in square brackets.
Code
```rust
markup::define! {
Attributes(id: u32, category: String, data: std::collections::BTreeMap) {
// A div with an id and two classes.
// Note: Starting with Rust 2021, there must be a space between the
// element name and `#` due to reserved syntax (https://doc.rust-lang.org/edition-guide/rust-2021/reserving-syntax.html).
div #foo.bar.baz {}
'\n'
// A div with a dynamically computed id and one static and one dynamic class.
div #{format!("post-{}", id)}.post.{format!("category-{}", category)} {}
'\n'
// Boolean attributes are only rendered if true. Specifying no value is the same as `true`.
input[checked = true];
'\n'
input[checked = false];
'\n'
input[checked];
'\n'
// `Option` attributes are rendered only if they're `Some`.
input[type = Some("text"), minlength = None::];
'\n'
// Attribute names can also be expressions wrapped in braces.
div[{format!("{}{}", "data-", "post-id")} = id] {}
'\n'
// Multiple attributes can be added dynamically using the `..` syntax.
div[..data.iter().map(|(k, v)| (("data-", k), v))] {}
}
}
println!("{}", Attributes {
id: 123,
category: String::from("tutorial"),
data: [
(String::from("foo"), String::from("bar")),
(String::from("baz"), String::from("quux"))
].iter().cloned().collect(),
});
```
Output
```html
```
### @if and @if let
`@if` and `@if let` works similar to Rust.
Code
```rust
markup::define! {
If(x: u32, y: Option) {
@if *x == 1 {
"x = 1\n"
} else if *x == 2 {
"x = 2\n"
} else {
"x is neither 1 nor 2\n"
}
@if let Some(y) = y {
"y = " @y "\n"
} else {
"y is None\n"
}
}
}
println!("{}", If { x: 2, y: Some(2) });
println!("{}", If { x: 3, y: None });
```
Output
```html
x = 2
y = 2
x is neither 1 nor 2
y is None
```
### @match
`@match` works similar to Rust, but the branches must be wrapped in braces.
Code
```rust
markup::define! {
Match(x: Option) {
@match x {
Some(1) | Some(2) => {
"x is 1 or 2"
}
Some(x) if *x == 3 => {
"x is 3"
}
None => {
"x is None"
}
_ => {
"x is something else"
}
}
}
}
println!("{}", Match { x: None });
println!("{}", Match { x: Some(2) });
println!("{}", Match { x: Some(4) });
```
Output
```html
x is None
x is 1 or 2
x is something else
```
### Statements
Templates can have statements preceded by `@` sign. The most useful such
statement is `@let` to compute a value for later reuse. `@fn` can be used to
define a function. Also supported are `@struct`, `@mod`, `@impl`, `@const`,
`@static` and more.