127 lines
3.6 KiB
Rust
127 lines
3.6 KiB
Rust
//! The preprocessing we apply to doc comments.
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//!
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//! #[derive(Parser)] works in terms of "paragraphs". Paragraph is a sequence of
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//! non-empty adjacent lines, delimited by sequences of blank (whitespace only) lines.
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use std::iter;
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pub fn extract_doc_comment(attrs: &[syn::Attribute]) -> Vec<String> {
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// multiline comments (`/** ... */`) may have LFs (`\n`) in them,
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// we need to split so we could handle the lines correctly
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//
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// we also need to remove leading and trailing blank lines
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let mut lines: Vec<_> = attrs
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.iter()
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.filter(|attr| attr.path().is_ident("doc"))
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.filter_map(|attr| {
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// non #[doc = "..."] attributes are not our concern
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// we leave them for rustc to handle
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match &attr.meta {
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syn::Meta::NameValue(syn::MetaNameValue {
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value:
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syn::Expr::Lit(syn::ExprLit {
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lit: syn::Lit::Str(s),
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..
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}),
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..
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}) => Some(s.value()),
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_ => None,
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}
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})
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.skip_while(|s| is_blank(s))
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.flat_map(|s| {
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let lines = s
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.split('\n')
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.map(|s| {
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// remove one leading space no matter what
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let s = s.strip_prefix(' ').unwrap_or(s);
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s.to_owned()
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})
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.collect::<Vec<_>>();
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lines
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})
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.collect();
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while let Some(true) = lines.last().map(|s| is_blank(s)) {
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lines.pop();
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}
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lines
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}
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pub fn format_doc_comment(
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lines: &[String],
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preprocess: bool,
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force_long: bool,
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) -> (Option<String>, Option<String>) {
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if let Some(first_blank) = lines.iter().position(|s| is_blank(s)) {
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let (short, long) = if preprocess {
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let paragraphs = split_paragraphs(lines);
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let short = paragraphs[0].clone();
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let long = paragraphs.join("\n\n");
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(remove_period(short), long)
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} else {
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let short = lines[..first_blank].join("\n");
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let long = lines.join("\n");
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(short, long)
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};
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(Some(short), Some(long))
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} else {
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let (short, long) = if preprocess {
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let short = merge_lines(lines);
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let long = force_long.then(|| short.clone());
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let short = remove_period(short);
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(short, long)
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} else {
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let short = lines.join("\n");
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let long = force_long.then(|| short.clone());
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(short, long)
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};
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(Some(short), long)
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}
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}
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fn split_paragraphs(lines: &[String]) -> Vec<String> {
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let mut last_line = 0;
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iter::from_fn(|| {
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let slice = &lines[last_line..];
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let start = slice.iter().position(|s| !is_blank(s)).unwrap_or(0);
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let slice = &slice[start..];
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let len = slice
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.iter()
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.position(|s| is_blank(s))
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.unwrap_or(slice.len());
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last_line += start + len;
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if len != 0 {
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Some(merge_lines(&slice[..len]))
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} else {
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None
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}
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})
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.collect()
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}
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fn remove_period(mut s: String) -> String {
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if s.ends_with('.') && !s.ends_with("..") {
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s.pop();
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}
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s
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}
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fn is_blank(s: &str) -> bool {
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s.trim().is_empty()
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}
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fn merge_lines(lines: impl IntoIterator<Item = impl AsRef<str>>) -> String {
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lines
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.into_iter()
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.map(|s| s.as_ref().trim().to_owned())
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.collect::<Vec<_>>()
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.join(" ")
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}
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