nushell/crates/nu-protocol/src/did_you_mean.rs
Christopher Durham 0f600bc3f5
Improve case insensitivity consistency (#10884)
# Description

Add an extension trait `IgnoreCaseExt` to nu_utils which adds some case
insensitivity helpers, and use them throughout nu to improve the
handling of case insensitivity. Proper case folding is done via unicase,
which is already a dependency via mime_guess from nu-command.

In actuality a lot of code still does `to_lowercase`, because unicase
only provides immediate comparison and doesn't expose a `to_folded_case`
yet. And since we do a lot of `contains`/`starts_with`/`ends_with`, it's
not sufficient to just have `eq_ignore_case`. But if we get access in
the future, this makes us ready to use it with a change in one place.

Plus, it's clearer what the purpose is at the call site to call
`to_folded_case` instead of `to_lowercase` if it's exclusively for the
purpose of case insensitive comparison, even if it just does
`to_lowercase` still.

# User-Facing Changes

- Some commands that were supposed to be case insensitive remained only
insensitive to ASCII case (a-z), and now are case insensitive w.r.t.
non-ASCII characters as well.

# Tests + Formatting

- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>
2023-11-08 23:58:54 +01:00

88 lines
3.4 KiB
Rust

pub fn did_you_mean<'a, 'b, I, S>(possibilities: I, input: &'b str) -> Option<String>
where
I: IntoIterator<Item = &'a S>,
S: AsRef<str> + 'a + ?Sized,
{
let possibilities: Vec<&str> = possibilities.into_iter().map(|s| s.as_ref()).collect();
let suggestion =
crate::lev_distance::find_best_match_for_name_with_substrings(&possibilities, input, None)
.map(|s| s.to_string());
if let Some(suggestion) = &suggestion {
if suggestion.len() == 1 && !suggestion.eq_ignore_ascii_case(input) {
return None;
}
}
suggestion
}
#[cfg(test)]
mod tests {
use super::did_you_mean;
#[test]
fn did_you_mean_examples() {
let all_cases = [
(
vec!["a", "b"],
vec![
("a", Some("a"), ""),
("A", Some("a"), ""),
(
"c",
None,
"Not helpful to suggest an arbitrary choice when none are close",
),
("ccccccccccccccccccccccc", None, "Not helpful to suggest an arbitrary choice when none are close"),
],
),
(
vec!["OS", "PWD", "PWDPWDPWDPWD"],
vec![
("pwd", Some("PWD"), "Exact case insensitive match yields a match"),
("pwdpwdpwdpwd", Some("PWDPWDPWDPWD"), "Exact case insensitive match yields a match"),
("PWF", Some("PWD"), "One-letter typo yields a match"),
("pwf", None, "Case difference plus typo yields no match"),
("Xwdpwdpwdpwd", None, "Case difference plus typo yields no match"),
]
),
(
vec!["foo", "bar", "baz"],
vec![
("fox", Some("foo"), ""),
("FOO", Some("foo"), ""),
("FOX", None, ""),
(
"ccc",
None,
"Not helpful to suggest an arbitrary choice when none are close",
),
(
"zzz",
None,
"'baz' does share a character, but rustc rule is edit distance must be <= 1/3 of the length of the user input",
),
],
),
(
vec!["aaaaaa"],
vec![
("XXaaaa", Some("aaaaaa"), "Distance of 2 out of 6 chars: close enough to meet rustc's rule"),
("XXXaaa", None, "Distance of 3 out of 6 chars: not close enough to meet rustc's rule"),
("XaaaaX", Some("aaaaaa"), "Distance of 2 out of 6 chars: close enough to meet rustc's rule"),
("XXaaaaXX", None, "Distance of 4 out of 6 chars: not close enough to meet rustc's rule")
]
),
];
for (possibilities, cases) in all_cases {
for (input, expected_suggestion, discussion) in cases {
let suggestion = did_you_mean(&possibilities, input);
assert_eq!(
suggestion.as_deref(),
expected_suggestion,
"Expected the following reasoning to hold but it did not: '{discussion}'"
);
}
}
}
}