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#![allow(clippy::inline_always)]
// -----------------------------------------------------------------------------
impl<K: Ord> crate::simple::search_index::SearchIndex<K> {
/// Scans the entire search index for the closest matching keyword using
/// the the specified string similarity metric from the
/// [strsim](https://crates.io/crates/strsim) crate.
///
/// When the user's search string contains a keyword that returns no
/// matches, this method can be used to find the best match to be used as a
/// substitution.
///
/// All keywords in the search index will potentially be examined.
///
/// # Input
///
/// * `user_keyword` ยท This keyword is used to search the search index.
///
/// For example, if the user provided the misspelled word `nthing`, this
/// could potentially return `nothing` as an alternative keyword if it
/// was present in the index.
///
/// # Output
///
/// This method returns the single best matching alternative keyword.
///
/// If no reasonable alternative keywords were found, a `None` will be
/// returned.
///
/// # Notes
///
/// * This method differs from `strsim_substitute` in that this is a
/// generic method. This method will be monomorphized for each `strsim`
/// string similarity metric (`DamerauLevenshtein`, `Jaro`, `Osa`, etc.)
///
/// `strsim_substitute` will call these monomorphized methods
/// using dynamic-dispatch, based on the search index's string similarity
/// metric settings.
#[must_use]
#[inline(always)]
pub fn strsim_substitute_metric<'s, M>(
&'s self,
user_keyword: &str,
index_range: &str,
) -> Option<&'s str>
where M: crate::simple::internal::fuzzers::strsim::Metric {
// Scan the search index for the highest scoring keyword:
self.b_tree_map
// Get matching keywords starting with (partial) keyword string:
.range(kstring::KString::from_ref(index_range)..)
// We did not specify an end bound for our `range` function (see
// above.) `range` will return _every_ keyword greater than the
// supplied keyword. The below `take_while` will effectively break
// iteration when we reach a keyword that does not start with our
// supplied (partial) keyword.
.take_while(|(index_keyword, _keys)|
index_keyword.starts_with::<&str>(index_range.as_ref())
)
// For each keyword in the search index, calculate its similarity
// to the user's keyword. Map the `(keyword, keys)` tuple into
// a `(keyword, score)` tuple:
.map(|(index_keyword, _keys)| {
(index_keyword, M::similarity(index_keyword, user_keyword))
}) // map
// Find the `(keyword, score)` tuple with the highest score:
.max_by(|(_a_keyword, a_score), (_b_keyword, b_score)|
a_score.total_cmp(b_score)
) // max_by
// Return the `keyword` portion of the `(keyword, score)` tuple
// to the caller:
.map(|(keyword, _score)| keyword.as_str())
} // fn
} // impl