typst/macros/src/util.rs
2023-03-13 21:40:06 +01:00

91 lines
2.6 KiB
Rust

use heck::ToKebabCase;
use super::*;
/// Return an error at the given item.
macro_rules! bail {
(callsite, $fmt:literal $($tts:tt)*) => {
return Err(syn::Error::new(
proc_macro2::Span::call_site(),
format!(concat!("typst: ", $fmt) $($tts)*)
))
};
($item:expr, $fmt:literal $($tts:tt)*) => {
return Err(syn::Error::new_spanned(
&$item,
format!(concat!("typst: ", $fmt) $($tts)*)
))
};
}
/// Whether an attribute list has a specified attribute.
pub fn has_attr(attrs: &mut Vec<syn::Attribute>, target: &str) -> bool {
take_attr(attrs, target).is_some()
}
/// Whether an attribute list has a specified attribute.
pub fn parse_attr<T: Parse>(
attrs: &mut Vec<syn::Attribute>,
target: &str,
) -> Result<Option<Option<T>>> {
take_attr(attrs, target)
.map(|attr| (!attr.tokens.is_empty()).then(|| attr.parse_args()).transpose())
.transpose()
}
/// Whether an attribute list has a specified attribute.
pub fn take_attr(
attrs: &mut Vec<syn::Attribute>,
target: &str,
) -> Option<syn::Attribute> {
attrs
.iter()
.position(|attr| attr.path.is_ident(target))
.map(|i| attrs.remove(i))
}
/// Ensure that no unrecognized attributes remain.
pub fn validate_attrs(attrs: &[syn::Attribute]) -> Result<()> {
for attr in attrs {
if !attr.path.is_ident("doc") {
let ident = attr.path.get_ident().unwrap();
bail!(ident, "unrecognized attribute: {:?}", ident.to_string());
}
}
Ok(())
}
/// Convert an identifier to a kebab-case string.
pub fn kebab_case(name: &Ident) -> String {
name.to_string().to_kebab_case()
}
/// Extract documentation comments from an attribute list.
pub fn documentation(attrs: &[syn::Attribute]) -> String {
let mut doc = String::new();
// Parse doc comments.
for attr in attrs {
if let Ok(syn::Meta::NameValue(meta)) = attr.parse_meta() {
if meta.path.is_ident("doc") {
if let syn::Lit::Str(string) = &meta.lit {
let full = string.value();
let line = full.strip_prefix(' ').unwrap_or(&full);
doc.push_str(line);
doc.push('\n');
}
}
}
}
doc.trim().into()
}
/// Extract a line of metadata from documentation.
pub fn meta_line<'a>(lines: &mut Vec<&'a str>, key: &str) -> Result<&'a str> {
match lines.pop().and_then(|line| line.strip_prefix(&format!("{key}:"))) {
Some(value) => Ok(value.trim()),
None => bail!(callsite, "missing metadata key: {}", key),
}
}