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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
*/
/// Given a list of keywords for a suggestion, returns a phrase that best
/// completes the user's query. This function uses two heuristics to pick the
/// best match:
///
/// 1. Find the first keyword in the list that has at least one more word than
/// the query, then trim the keyword up to the end of that word.
/// 2. If there isn't a keyword with more words, pick the keyword that forms the
/// longest suffix of the query. This might be the query itself.
pub fn full_keyword(query: &str, keywords: &[impl AsRef<str>]) -> String {
let query_words_len = query.split_whitespace().count();
let min_phrase_words_len = if query.ends_with(char::is_whitespace) {
// If the query ends with a space, find a keyword with at least one more
// word, so that the completed phrase can show a word after the space.
query_words_len + 1
} else {
query_words_len
};
keywords
.iter()
.map(AsRef::as_ref)
.filter(|phrase| phrase.starts_with(query))
.map(|phrase| phrase.split_whitespace().collect::<Vec<_>>())
.find(|phrase_words| phrase_words.len() > min_phrase_words_len)
.map(|phrase_words| phrase_words[..min_phrase_words_len].join(" "))
.unwrap_or_else(|| {
keywords
.iter()
.map(AsRef::as_ref)
.filter(|phrase| phrase.starts_with(query) && query.len() < phrase.len())
.max_by_key(|phrase| phrase.trim().len())
.unwrap_or(query)
.to_owned()
})
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn keywords_with_more_words() {
assert_eq!(
full_keyword(
"moz",
&[
"moz",
"mozi",
"mozil",
"mozill",
"mozilla",
"mozilla firefox"
]
),
"mozilla".to_owned(),
);
assert_eq!(
full_keyword(
"mozilla",
&[
"moz",
"mozi",
"mozil",
"mozill",
"mozilla",
"mozilla firefox"
]
),
"mozilla".to_owned(),
);
}
#[test]
fn keywords_with_longer_phrase() {
assert_eq!(
full_keyword("moz", &["moz", "mozi", "mozil", "mozill", "mozilla"]),
"mozilla".to_owned()
);
assert_eq!(
full_keyword(
"mozilla f",
&["moz", "mozi", "mozil", "mozill", "mozilla firefox"]
),
"mozilla firefox".to_owned()
);
}
#[test]
fn query_ends_with_space() {
assert_eq!(
full_keyword(
"mozilla ",
&["moz", "mozi", "mozil", "mozill", "mozilla firefox"]
),
"mozilla firefox".to_owned()
);
}
}