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use syn::{Attribute, Expr, Lit, Meta};
const DOC_ATTRIBUTE_TYPE: &str = "doc";
/// CommentAttributes holds Vec of parsed doc comments
#[cfg_attr(feature = "debug", derive(Debug))]
pub(crate) struct CommentAttributes(pub(crate) Vec<String>);
impl CommentAttributes {
/// Creates new [`CommentAttributes`] instance from [`Attribute`] slice filtering out all
/// other attributes which are not `doc` comments
pub(crate) fn from_attributes(attributes: &[Attribute]) -> Self {
let mut docs = attributes
.iter()
.filter_map(|attr| {
if !matches!(attr.path().get_ident(), Some(ident) if ident == DOC_ATTRIBUTE_TYPE) {
return None;
}
// ignore `#[doc(hidden)]` and similar tags.
if let Meta::NameValue(name_value) = &attr.meta {
if let Expr::Lit(ref doc_comment) = name_value.value {
if let Lit::Str(ref doc) = doc_comment.lit {
let mut doc = doc.value();
// NB. Only trim trailing whitespaces. Leading whitespaces are handled
// below.
doc.truncate(doc.trim_end().len());
return Some(doc);
}
}
}
None
})
.collect::<Vec<_>>();
// Calculate the minimum indentation of all non-empty lines and strip them.
// This can get rid of typical single space after doc comment start `///`, but not messing
// up indentation of markdown list or code.
let min_indent = docs
.iter()
.filter(|s| !s.is_empty())
// Only recognize ASCII space, not unicode multi-bytes ones.
// `str::trim_ascii_start` requires 1.80 which is greater than our MSRV yet.
.map(|s| s.len() - s.trim_start_matches(' ').len())
.min()
.unwrap_or(0);
for line in &mut docs {
if !line.is_empty() {
line.drain(..min_indent);
}
}
Self(docs)
}
pub(crate) fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Returns found `doc comments` as formatted `String` joining them all with `\n` _(new line)_.
pub(crate) fn as_formatted_string(&self) -> String {
self.0.join("\n")
}
}