mithril_doc_derive/
doc.rs

1//! The preprocessing we apply to doc comments.
2//!
3//! #[derive(Parser)] works in terms of "paragraphs". Paragraph is a sequence of
4//! non-empty adjacent lines, delimited by sequences of blank (whitespace only) lines.
5
6// From https://github1s.com/clap-rs/clap/tree/master clap_derive/src/utils
7// This file was copied without modification.
8// It's an utilities file and not all function may be used in our project.
9// This is why we allow dead code.
10#![allow(dead_code)]
11
12use std::iter;
13
14pub fn extract_doc_comment(attrs: &[syn::Attribute]) -> Vec<String> {
15    // multiline comments (`/** ... */`) may have LFs (`\n`) in them,
16    // we need to split so we could handle the lines correctly
17    //
18    // we also need to remove leading and trailing blank lines
19    let mut lines: Vec<_> = attrs
20        .iter()
21        .filter(|attr| attr.path().is_ident("doc"))
22        .filter_map(|attr| {
23            // non #[doc = "..."] attributes are not our concern
24            // we leave them for rustc to handle
25            match &attr.meta {
26                syn::Meta::NameValue(syn::MetaNameValue {
27                    value:
28                        syn::Expr::Lit(syn::ExprLit {
29                            lit: syn::Lit::Str(s),
30                            ..
31                        }),
32                    ..
33                }) => Some(s.value()),
34                _ => None,
35            }
36        })
37        .skip_while(|s| is_blank(s))
38        .flat_map(|s| {
39            s.split('\n')
40                .map(|s| {
41                    // remove one leading space no matter what
42                    let s = s.strip_prefix(' ').unwrap_or(s);
43                    s.to_owned()
44                })
45                .collect::<Vec<_>>()
46        })
47        .collect();
48
49    while let Some(true) = lines.last().map(|s| is_blank(s)) {
50        lines.pop();
51    }
52
53    lines
54}
55
56pub fn format_doc_comment(
57    lines: &[String],
58    preprocess: bool,
59    force_long: bool,
60) -> (Option<String>, Option<String>) {
61    if let Some(first_blank) = lines.iter().position(|s| is_blank(s)) {
62        let (short, long) = if preprocess {
63            let paragraphs = split_paragraphs(lines);
64            let short = paragraphs[0].clone();
65            let long = paragraphs.join("\n\n");
66            (remove_period(short), long)
67        } else {
68            let short = lines[..first_blank].join("\n");
69            let long = lines.join("\n");
70            (short, long)
71        };
72
73        (Some(short), Some(long))
74    } else {
75        let (short, long) = if preprocess {
76            let short = merge_lines(lines);
77            let long = force_long.then(|| short.clone());
78            let short = remove_period(short);
79            (short, long)
80        } else {
81            let short = lines.join("\n");
82            let long = force_long.then(|| short.clone());
83            (short, long)
84        };
85
86        (Some(short), long)
87    }
88}
89
90fn split_paragraphs(lines: &[String]) -> Vec<String> {
91    let mut last_line = 0;
92    iter::from_fn(|| {
93        let slice = &lines[last_line..];
94        let start = slice.iter().position(|s| !is_blank(s)).unwrap_or(0);
95
96        let slice = &slice[start..];
97        let len = slice.iter().position(|s| is_blank(s)).unwrap_or(slice.len());
98
99        last_line += start + len;
100
101        if len != 0 {
102            Some(merge_lines(&slice[..len]))
103        } else {
104            None
105        }
106    })
107    .collect()
108}
109
110fn remove_period(mut s: String) -> String {
111    if s.ends_with('.') && !s.ends_with("..") {
112        s.pop();
113    }
114    s
115}
116
117fn is_blank(s: &str) -> bool {
118    s.trim().is_empty()
119}
120
121fn merge_lines(lines: impl IntoIterator<Item = impl AsRef<str>>) -> String {
122    lines
123        .into_iter()
124        .map(|s| s.as_ref().trim().to_owned())
125        .collect::<Vec<_>>()
126        .join(" ")
127}
mithril_doc_derive/doc.rs

mithril_doc_derive/
doc.rs
