rustdoc/
markdown.rs

1//! Standalone markdown rendering.
2//!
3//! For the (much more common) case of rendering markdown in doc-comments, see
4//! [crate::html::markdown].
5//!
6//! This is used when [rendering a markdown file to an html file][docs], without processing
7//! rust source code.
8//!
9//! [docs]: https://doc.rust-lang.org/stable/rustdoc/#using-standalone-markdown-files
10
11use std::fmt::{self, Write as _};
12use std::fs::{File, create_dir_all, read_to_string};
13use std::io::prelude::*;
14use std::path::Path;
15
16use rustc_span::edition::Edition;
17
18use crate::config::RenderOptions;
19use crate::html::escape::Escape;
20use crate::html::markdown;
21use crate::html::markdown::{ErrorCodes, HeadingOffset, IdMap, Markdown, MarkdownWithToc};
22
23/// Separate any lines at the start of the file that begin with `# ` or `%`.
24fn extract_leading_metadata(s: &str) -> (Vec<&str>, &str) {
25    let mut metadata = Vec::new();
26    let mut count = 0;
27
28    for line in s.lines() {
29        if line.starts_with("# ") || line.starts_with('%') {
30            // trim the whitespace after the symbol
31            metadata.push(line[1..].trim_start());
32            count += line.len() + 1;
33        } else {
34            return (metadata, &s[count..]);
35        }
36    }
37
38    // if we're here, then all lines were metadata `# ` or `%` lines.
39    (metadata, "")
40}
41
42/// Render `input` (e.g., "foo.md") into an HTML file in `output`
43/// (e.g., output = "bar" => "bar/foo.html").
44///
45/// Requires session globals to be available, for symbol interning.
46pub(crate) fn render_and_write<P: AsRef<Path>>(
47    input: P,
48    options: RenderOptions,
49    edition: Edition,
50) -> Result<(), String> {
51    if let Err(e) = create_dir_all(&options.output) {
52        return Err(format!("{output}: {e}", output = options.output.display()));
53    }
54
55    let input = input.as_ref();
56    let mut output = options.output;
57    output.push(input.file_name().unwrap());
58    output.set_extension("html");
59
60    let mut css = String::new();
61    for name in &options.markdown_css {
62        write!(css, r#"<link rel="stylesheet" href="{name}">"#)
63            .expect("Writing to a String can't fail");
64    }
65
66    let input_str =
67        read_to_string(input).map_err(|err| format!("{input}: {err}", input = input.display()))?;
68    let playground_url = options.markdown_playground_url.or(options.playground_url);
69    let playground = playground_url.map(|url| markdown::Playground { crate_name: None, url });
70
71    let mut out =
72        File::create(&output).map_err(|e| format!("{output}: {e}", output = output.display()))?;
73
74    let (metadata, text) = extract_leading_metadata(&input_str);
75    if metadata.is_empty() {
76        return Err("invalid markdown file: no initial lines starting with `# ` or `%`".to_owned());
77    }
78    let title = metadata[0];
79
80    let error_codes = ErrorCodes::from(options.unstable_features.is_nightly_build());
81    let text = fmt::from_fn(|f| {
82        if !options.markdown_no_toc {
83            MarkdownWithToc {
84                content: text,
85                links: &[],
86                ids: &mut IdMap::new(),
87                error_codes,
88                edition,
89                playground: &playground,
90            }
91            .write_into(f)
92        } else {
93            Markdown {
94                content: text,
95                links: &[],
96                ids: &mut IdMap::new(),
97                error_codes,
98                edition,
99                playground: &playground,
100                heading_offset: HeadingOffset::H1,
101            }
102            .write_into(f)
103        }
104    });
105
106    let res = write!(
107        &mut out,
108        r#"<!DOCTYPE html>
109<html lang="en">
110<head>
111    <meta charset="utf-8">
112    <meta name="viewport" content="width=device-width, initial-scale=1.0">
113    <meta name="generator" content="rustdoc">
114    <title>{title}</title>
115
116    {css}
117    {in_header}
118</head>
119<body class="rustdoc">
120    <!--[if lte IE 8]>
121    <div class="warning">
122        This old browser is unsupported and will most likely display funky
123        things.
124    </div>
125    <![endif]-->
126
127    {before_content}
128    <h1 class="title">{title}</h1>
129    {text}
130    {after_content}
131</body>
132</html>"#,
133        title = Escape(title),
134        in_header = options.external_html.in_header,
135        before_content = options.external_html.before_content,
136        after_content = options.external_html.after_content,
137    );
138
139    res.map_err(|e| format!("cannot write to `{output}`: {e}", output = output.display()))
140}
rustdoc/markdown.rs

rustdoc/
markdown.rs
