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|
//! Utilities for manipulating C/C++ comments.
use std::iter;
/// The type of a comment.
#[derive(Debug, PartialEq, Eq)]
enum Kind {
/// A `///` comment, or something of the like.
/// All lines in a comment should start with the same symbol.
SingleLines,
/// A `/**` comment, where each other line can start with `*` and the
/// entire block ends with `*/`.
MultiLine,
}
/// Preprocesses a C/C++ comment so that it is a valid Rust comment.
pub fn preprocess(comment: &str, indent: usize) -> String {
match self::kind(&comment) {
Some(Kind::SingleLines) => preprocess_single_lines(comment, indent),
Some(Kind::MultiLine) => preprocess_multi_line(comment, indent),
None => comment.to_owned(),
}
}
/// Gets the kind of the doc comment, if it is one.
fn kind(comment: &str) -> Option<Kind> {
if comment.starts_with("/*") {
Some(Kind::MultiLine)
} else if comment.starts_with("//") {
Some(Kind::SingleLines)
} else {
None
}
}
fn make_indent(indent: usize) -> String {
const RUST_INDENTATION: usize = 4;
iter::repeat(' ').take(indent * RUST_INDENTATION).collect()
}
/// Preprocesses multiple single line comments.
///
/// Handles lines starting with both `//` and `///`.
fn preprocess_single_lines(comment: &str, indent: usize) -> String {
debug_assert!(comment.starts_with("//"), "comment is not single line");
let indent = make_indent(indent);
let mut is_first = true;
let lines: Vec<_> = comment
.lines()
.map(|l| l.trim().trim_start_matches('/'))
.map(|l| {
let indent = if is_first { "" } else { &*indent };
is_first = false;
format!("{}///{}", indent, l)
})
.collect();
lines.join("\n")
}
fn preprocess_multi_line(comment: &str, indent: usize) -> String {
let comment = comment
.trim_start_matches('/')
.trim_end_matches('/')
.trim_end_matches('*');
let indent = make_indent(indent);
// Strip any potential `*` characters preceding each line.
let mut is_first = true;
let mut lines: Vec<_> = comment
.lines()
.map(|line| line.trim().trim_start_matches('*').trim_start_matches('!'))
.skip_while(|line| line.trim().is_empty()) // Skip the first empty lines.
.map(|line| {
let indent = if is_first { "" } else { &*indent };
is_first = false;
format!("{}///{}", indent, line)
})
.collect();
// Remove the trailing line corresponding to the `*/`.
if lines
.last()
.map_or(false, |l| l.trim().is_empty() || l.trim() == "///")
{
lines.pop();
}
lines.join("\n")
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn picks_up_single_and_multi_line_doc_comments() {
assert_eq!(kind("/// hello"), Some(Kind::SingleLines));
assert_eq!(kind("/** world */"), Some(Kind::MultiLine));
}
#[test]
fn processes_single_lines_correctly() {
assert_eq!(preprocess("/// hello", 0), "/// hello");
assert_eq!(preprocess("// hello", 0), "/// hello");
assert_eq!(preprocess("// hello", 0), "/// hello");
}
#[test]
fn processes_multi_lines_correctly() {
assert_eq!(
preprocess("/** hello \n * world \n * foo \n */", 0),
"/// hello\n/// world\n/// foo"
);
assert_eq!(
preprocess("/**\nhello\n*world\n*foo\n*/", 0),
"///hello\n///world\n///foo"
);
}
}
|
