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use unicode_segmentation::UnicodeSegmentation;
#[derive(Debug, Clone)]
pub struct TabCfg {
replacement: String,
}
impl TabCfg {
pub fn new(width: usize) -> Self {
TabCfg {
replacement: " ".repeat(width),
}
}
pub fn width(&self) -> usize {
self.replacement.len()
}
pub fn replace(&self) -> bool {
!self.replacement.is_empty()
}
}
/// Expand tabs as spaces.
pub fn expand(line: &str, tab_cfg: &TabCfg) -> String {
if tab_cfg.replace() && line.as_bytes().iter().any(|c| *c == b'\t') {
itertools::join(line.split('\t'), &tab_cfg.replacement)
} else {
line.to_string()
}
}
/// Remove `prefix` chars from `line`, then call `tabs::expand()`.
pub fn remove_prefix_and_expand(prefix: usize, line: &str, tab_cfg: &TabCfg) -> String {
let line_bytes = line.as_bytes();
// The to-be-removed prefixes are almost always ascii +/- (or ++/ +/.. for merges) for
// which grapheme clusters are not required.
if line_bytes.len() >= prefix && line_bytes[..prefix].is_ascii() {
// Safety: slicing into the utf-8 line-str is ok, upto `prefix` only ascii was present.
expand(&line[prefix..], tab_cfg)
} else {
let cut_line = line.graphemes(true).skip(prefix).collect::<String>();
expand(&cut_line, tab_cfg)
}
}
#[cfg(test)]
pub mod tests {
use super::*;
#[test]
fn test_remove_prefix_and_expand() {
let line = "+-foo\tbar";
let result = remove_prefix_and_expand(2, line, &TabCfg::new(3));
assert_eq!(result, "foo bar");
let result = remove_prefix_and_expand(2, line, &TabCfg::new(0));
assert_eq!(result, "foo\tbar");
let utf8_prefix = "-│-foo\tbar";
let n = 3;
let result = remove_prefix_and_expand(n, utf8_prefix, &TabCfg::new(1));
assert_eq!(result, "foo bar");
// ensure non-ascii chars were removed:
assert!(utf8_prefix.len() - result.len() > n);
}
}
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