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|
use unscanny::Scanner;
use super::*;
/// Expand the `#[func]` macro.
pub fn func(item: syn::Item) -> Result<TokenStream> {
let docs = match &item {
syn::Item::Struct(item) => documentation(&item.attrs),
syn::Item::Enum(item) => documentation(&item.attrs),
syn::Item::Fn(item) => documentation(&item.attrs),
_ => String::new(),
};
let first = docs.lines().next().unwrap();
let display = first.strip_prefix("# ").unwrap();
let display = display.trim();
let mut docs = docs[first.len()..].to_string();
let (params, returns) = params(&mut docs)?;
let category = section(&mut docs, "Category", 2).expect("missing category");
let docs = docs.trim();
let info = quote! {
::typst::model::FuncInfo {
name,
display: #display,
category: #category,
docs: #docs,
params: ::std::vec![#(#params),*],
returns: ::std::vec![#(#returns),*]
}
};
if let syn::Item::Fn(item) = &item {
let vis = &item.vis;
let ident = &item.sig.ident;
let s = ident.to_string();
let mut chars = s.trim_end_matches('_').chars();
let ty = quote::format_ident!(
"{}{}Func",
chars.next().unwrap().to_ascii_uppercase(),
chars.as_str()
);
let full = if item.sig.inputs.len() == 1 {
quote! { |_, args| #ident(args) }
} else {
quote! { #ident }
};
Ok(quote! {
#item
#[doc(hidden)]
#vis enum #ty {}
impl::typst::model::FuncType for #ty {
fn create_func(name: &'static str) -> ::typst::model::Func {
::typst::model::Func::from_fn(#full, #info)
}
}
})
} else {
let (ident, generics) = match &item {
syn::Item::Struct(s) => (&s.ident, &s.generics),
syn::Item::Enum(s) => (&s.ident, &s.generics),
_ => bail!(item, "only structs, enums, and functions are supported"),
};
let (params, args, clause) = generics.split_for_impl();
Ok(quote! {
#item
impl #params ::typst::model::FuncType for #ident #args #clause {
fn create_func(name: &'static str) -> ::typst::model::Func {
::typst::model::Func::from_node::<Self>(#info)
}
}
})
}
}
/// Extract a section.
pub fn section(docs: &mut String, title: &str, level: usize) -> Option<String> {
let hashtags = "#".repeat(level);
let needle = format!("\n{hashtags} {title}\n");
let start = docs.find(&needle)?;
let rest = &docs[start..];
let len = rest[1..]
.find("\n# ")
.or_else(|| rest[1..].find("\n## "))
.or_else(|| rest[1..].find("\n### "))
.map(|x| 1 + x)
.unwrap_or(rest.len());
let end = start + len;
let section = docs[start + needle.len()..end].trim().to_owned();
docs.replace_range(start..end, "");
Some(section)
}
/// Parse the parameter section.
fn params(docs: &mut String) -> Result<(Vec<TokenStream>, Vec<String>)> {
let Some(section) = section(docs, "Parameters", 2) else {
return Ok((vec![], vec![]));
};
let mut s = Scanner::new(§ion);
let mut infos = vec![];
let mut returns = vec![];
while s.eat_if('-') {
let mut named = false;
let mut positional = false;
let mut required = false;
let mut variadic = false;
let mut settable = false;
s.eat_whitespace();
let name = s.eat_until(':');
s.expect(": ");
if name == "returns" {
returns = s
.eat_until('\n')
.split(" or ")
.map(str::trim)
.map(Into::into)
.collect();
s.eat_whitespace();
continue;
}
s.expect('`');
let ty: syn::Type = syn::parse_str(s.eat_until('`'))?;
s.expect('`');
s.eat_whitespace();
s.expect('(');
for part in s.eat_until(')').split(',').map(str::trim).filter(|s| !s.is_empty()) {
match part {
"named" => named = true,
"positional" => positional = true,
"required" => required = true,
"variadic" => variadic = true,
"settable" => settable = true,
_ => bail!(callsite, "unknown parameter flag {:?}", part),
}
}
if (!named && !positional) || (variadic && !positional) || (required && variadic)
{
bail!(callsite, "invalid combination of parameter flags");
}
s.expect(')');
let docs = dedent(s.eat_until("\n-").trim());
let docs = docs.trim();
infos.push(quote! {
::typst::model::ParamInfo {
name: #name,
docs: #docs,
cast: <#ty as ::typst::model::Cast<
::typst::syntax::Spanned<::typst::model::Value>
>>::describe(),
named: #named,
positional: #positional,
required: #required,
variadic: #variadic,
settable: #settable,
}
});
s.eat_whitespace();
}
Ok((infos, returns))
}
|
