100 lines
2.8 KiB
Rust
100 lines
2.8 KiB
Rust
//! Utilities for manipulating C/C++ comments.
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/// The type of a comment.
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#[derive(Debug, PartialEq, Eq)]
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enum Kind {
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/// A `///` comment, or something of the like.
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/// All lines in a comment should start with the same symbol.
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SingleLines,
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/// A `/**` comment, where each other line can start with `*` and the
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/// entire block ends with `*/`.
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MultiLine,
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}
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/// Preprocesses a C/C++ comment so that it is a valid Rust comment.
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pub(crate) fn preprocess(comment: &str) -> String {
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match self::kind(comment) {
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Some(Kind::SingleLines) => preprocess_single_lines(comment),
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Some(Kind::MultiLine) => preprocess_multi_line(comment),
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None => comment.to_owned(),
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}
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}
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/// Gets the kind of the doc comment, if it is one.
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fn kind(comment: &str) -> Option<Kind> {
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if comment.starts_with("/*") {
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Some(Kind::MultiLine)
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} else if comment.starts_with("//") {
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Some(Kind::SingleLines)
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} else {
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None
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}
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}
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/// Preprocesses multiple single line comments.
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///
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/// Handles lines starting with both `//` and `///`.
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fn preprocess_single_lines(comment: &str) -> String {
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debug_assert!(comment.starts_with("//"), "comment is not single line");
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let lines: Vec<_> = comment
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.lines()
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.map(|l| l.trim().trim_start_matches('/'))
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.collect();
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lines.join("\n")
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}
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fn preprocess_multi_line(comment: &str) -> String {
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let comment = comment
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.trim_start_matches('/')
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.trim_end_matches('/')
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.trim_end_matches('*');
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// Strip any potential `*` characters preceding each line.
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let mut lines: Vec<_> = comment
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.lines()
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.map(|line| line.trim().trim_start_matches('*').trim_start_matches('!'))
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.skip_while(|line| line.trim().is_empty()) // Skip the first empty lines.
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.collect();
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// Remove the trailing line corresponding to the `*/`.
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if lines.last().map_or(false, |l| l.trim().is_empty()) {
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lines.pop();
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}
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lines.join("\n")
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn picks_up_single_and_multi_line_doc_comments() {
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assert_eq!(kind("/// hello"), Some(Kind::SingleLines));
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assert_eq!(kind("/** world */"), Some(Kind::MultiLine));
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}
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#[test]
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fn processes_single_lines_correctly() {
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assert_eq!(preprocess("///"), "");
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assert_eq!(preprocess("/// hello"), " hello");
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assert_eq!(preprocess("// hello"), " hello");
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assert_eq!(preprocess("// hello"), " hello");
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}
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#[test]
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fn processes_multi_lines_correctly() {
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assert_eq!(preprocess("/**/"), "");
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assert_eq!(
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preprocess("/** hello \n * world \n * foo \n */"),
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" hello\n world\n foo"
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);
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assert_eq!(
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preprocess("/**\nhello\n*world\n*foo\n*/"),
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"hello\nworld\nfoo"
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);
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}
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}
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