syn-rsx

syn-powered parser for JSX-like TokenStreams, aka RSX. The parsed result is a nested Node structure, similar to the browser DOM, where node name and value are syn expressions to support building proc macros.

use std::convert::TryFrom;

use eyre::bail;
use quote::quote;
use syn_rsx::{parse2, Node, NodeAttribute, NodeElement, NodeText};

// Create HTML `TokenStream`.
let tokens = quote! { <hello world>"hi"</hello> };

// Parse the tokens into a tree of `Node`s.
let nodes = parse2(tokens)?;

// Extract some specific nodes from the tree.
let Node::Element(element) = &nodes[0] else { bail!("element") };
let Node::Attribute(attribute) = &element.attributes[0] else { bail!("attribute") };
let Node::Text(text) = &element.children[0] else { bail!("text") };

// Work with the nodes.
assert_eq!(element.name.to_string(), "hello");
assert_eq!(attribute.key.to_string(), "world");
assert_eq!(String::try_from(&text.value)?, "hi");

You might want to check out the html-to-string-macro example as well.

Features

Not opinionated

Every tag or attribute name is valid
```
<hello world />
```
Text nodes

Support for unquoted text is planned.
```
<div>"String literal"</div>
```

Node names separated by dash, colon or double colon

<tag-name some:attribute-key="value" />
<tag::name attribute::key="value" />

Node names with reserved keywords
```
<input type="submit" />
```

Doctypes, Comments and Fragments

<!DOCTYPE html>
<!-- "comment" -->
<></>

Braced blocks are parsed as arbitrary Rust code

<{ let block = "in node name position"; } />
<div>{ let block = "in node position"; }</div>
<div { let block = "in attribute position"; } />
<div key={ let block = "in attribute value position"; } />

Attribute values can be any valid syn expression without requiring braces
```
<div key=some::value() />
```

Helpful error reporting out of the box

error: open tag has no corresponding close tag and is not self-closing
--> examples/html-to-string-macro/tests/lib.rs:5:24
  |
5 |     html_to_string! { <div> };
  |                        ^^^

Possibility to get the span for a whole node

This can be used to improve error reporting, e.g.

error: Invalid element
--> examples/src/main.rs:14:13
   |
14 | /             <div>
15 | |                 "invalid node for some consumer specific reason"
16 | |             </div>
   | |__________________^

Customization

A ParserConfig to customize parsing behavior is available, so if you have slightly different requirements for parsing and it's not yet customizable feel free to open an issue or pull request to extend the configuration.

One highlight with regards to customization is the transform_block configuration, which takes a closure that receives raw block content as ParseStream and lets you optionally convert it to a TokenStream. That makes it possible to have custom syntax in blocks. More details in #9

wasix-org / syn-rsx

syn-rsx

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