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use proc_macro::TokenStream;
use quote::quote;
use syn::{
parse::{discouraged::Speculative, ParseBuffer},
Expr, ExprLit, Result, Token,
};
use syn_rsx::{parse_with_config, Node, NodeType, ParserConfig};
fn walk_nodes(nodes: Vec<Node>, nodes_context: Option<NodeType>) -> (String, Vec<Expr>) {
let mut out = String::new();
let mut values = vec![];
for node in nodes {
match node.node_type {
NodeType::Element => {
let name = node.name_as_string().expect("unexpected missing node name");
out.push_str(&format!("<{}", name));
let (html_string, attribute_values) =
walk_nodes(node.attributes, Some(NodeType::Attribute));
out.push_str(&html_string);
values.extend(attribute_values);
out.push('>');
match name.as_str() {
"area" | "base" | "br" | "col" | "embed" | "hr" | "img" | "input" | "link"
| "meta" | "param" | "source" | "track" | "wbr" => continue,
_ => (),
}
let (html_string, children_values) =
walk_nodes(node.children, Some(NodeType::Element));
out.push_str(&html_string);
values.extend(children_values);
out.push_str(&format!("</{}>", name));
}
NodeType::Attribute => {
out.push_str(&format!(
" {}",
node.name_as_string().expect("unexpected missing node name")
));
if node.value.is_some() {
out.push_str(r#"="{}""#);
values.push(node.value.expect("unexpected missing node value"));
}
}
NodeType::Text | NodeType::Block => {
if let Some(nodes_context) = &nodes_context {
if nodes_context == &NodeType::Attribute {
out.push(' ');
}
}
out.push_str("{}");
values.push(node.value.expect("unexpected missing node value"));
}
NodeType::Fragment => {
let (html_string, children_values) =
walk_nodes(node.children, Some(NodeType::Fragment));
out.push_str(&html_string);
values.extend(children_values);
}
NodeType::Comment => {
out.push_str("<!-- {} -->");
values.push(node.value.expect("unexpected missing node value"));
}
NodeType::Doctype => {
let value = node
.value_as_string()
.expect("unexpected missing node value");
out.push_str(&format!("<!DOCTYPE {}>", value));
}
}
}
(out, values)
}
#[proc_macro]
pub fn html(tokens: TokenStream) -> TokenStream {
match parse_with_config(
tokens,
ParserConfig::new().transform_block(|input| {
let fork = input.fork();
if let Ok(text) = parse_escape_syntax(&fork) {
input.advance_to(&fork);
if !input.is_empty() {
return Err(input.error("escape syntax should end after the last %"));
}
Ok(Some(quote! { yate::html_escape::encode_text(#text) }))
} else {
Ok(None)
}
}),
) {
Ok(nodes) => {
let (html_string, values) = walk_nodes(nodes, None);
quote! { format!(#html_string, #(#values),*) }
}
Err(error) => error.to_compile_error(),
}
.into()
}
fn parse_escape_syntax(input: &ParseBuffer) -> Result<ExprLit> {
input.parse::<Token![%]>()?;
input.parse::<Token![=]>()?;
let text = input.parse::<ExprLit>()?;
input.parse::<Token![%]>()?;
Ok(text)
}