1 files changed, 147 insertions, 0 deletions
diff --git a/clap/src/suggestions.rs b/clap/src/suggestions.rs
new file mode 100644
index 0000000..06071d2
--- /dev/null
+++ b/clap/src/suggestions.rs
@@ -0,0 +1,147 @@
+use app::App;
+// Third Party
+#[cfg(feature = "suggestions")]
+use strsim;
+
+// Internal
+use fmt::Format;
+
+/// Produces a string from a given list of possible values which is similar to
+/// the passed in value `v` with a certain confidence.
+/// Thus in a list of possible values like ["foo", "bar"], the value "fop" will yield
+/// `Some("foo")`, whereas "blark" would yield `None`.
+#[cfg(feature = "suggestions")]
+#[cfg_attr(feature = "lints", allow(needless_lifetimes))]
+pub fn did_you_mean<'a, T: ?Sized, I>(v: &str, possible_values: I) -> Option<&'a str>
+where
+    T: AsRef<str> + 'a,
+    I: IntoIterator<Item = &'a T>,
+{
+    let mut candidate: Option<(f64, &str)> = None;
+    for pv in possible_values {
+        let confidence = strsim::jaro_winkler(v, pv.as_ref());
+        if confidence > 0.8 && (candidate.is_none() || (candidate.as_ref().unwrap().0 < confidence))
+        {
+            candidate = Some((confidence, pv.as_ref()));
+        }
+    }
+    match candidate {
+        None => None,
+        Some((_, candidate)) => Some(candidate),
+    }
+}
+
+#[cfg(not(feature = "suggestions"))]
+pub fn did_you_mean<'a, T: ?Sized, I>(_: &str, _: I) -> Option<&'a str>
+where
+    T: AsRef<str> + 'a,
+    I: IntoIterator<Item = &'a T>,
+{
+    None
+}
+
+/// Returns a suffix that can be empty, or is the standard 'did you mean' phrase
+#[cfg_attr(feature = "lints", allow(needless_lifetimes))]
+pub fn did_you_mean_flag_suffix<'z, T, I>(
+    arg: &str,
+    args_rest: &'z [&str],
+    longs: I,
+    subcommands: &'z [App],
+) -> (String, Option<&'z str>)
+where
+    T: AsRef<str> + 'z,
+    I: IntoIterator<Item = &'z T>,
+{
+    if let Some(candidate) = did_you_mean(arg, longs) {
+        let suffix = format!(
+            "\n\tDid you mean {}{}?",
+            Format::Good("--"),
+            Format::Good(candidate)
+            );
+        return (suffix, Some(candidate));
+    }
+
+    subcommands
+        .into_iter()
+        .filter_map(|subcommand| {
+            let opts = subcommand
+                .p
+                .flags
+                .iter()
+                .filter_map(|f| f.s.long)
+                .chain(subcommand.p.opts.iter().filter_map(|o| o.s.long));
+
+            let candidate = match did_you_mean(arg, opts) {
+                Some(candidate) => candidate,
+                None => return None
+            };
+            let score = match args_rest.iter().position(|x| *x == subcommand.get_name()) {
+                Some(score) => score,
+                None => return None
+            };
+
+            let suffix = format!(
+                "\n\tDid you mean to put '{}{}' after the subcommand '{}'?",
+                Format::Good("--"),
+                Format::Good(candidate),
+                Format::Good(subcommand.get_name())
+            );
+
+            Some((score, (suffix, Some(candidate))))
+        })
+        .min_by_key(|&(score, _)| score)
+        .map(|(_, suggestion)| suggestion)
+        .unwrap_or_else(|| (String::new(), None))
+}
+
+/// Returns a suffix that can be empty, or is the standard 'did you mean' phrase
+pub fn did_you_mean_value_suffix<'z, T, I>(arg: &str, values: I) -> (String, Option<&'z str>)
+where
+    T: AsRef<str> + 'z,
+    I: IntoIterator<Item = &'z T>,
+{
+    match did_you_mean(arg, values) {
+        Some(candidate) => {
+            let suffix = format!("\n\tDid you mean '{}'?", Format::Good(candidate));
+            (suffix, Some(candidate))
+        }
+        None => (String::new(), None),
+    }
+}
+
+#[cfg(all(test, features = "suggestions"))]
+mod test {
+    use super::*;
+
+    #[test]
+    fn possible_values_match() {
+        let p_vals = ["test", "possible", "values"];
+        assert_eq!(did_you_mean("tst", p_vals.iter()), Some("test"));
+    }
+
+    #[test]
+    fn possible_values_nomatch() {
+        let p_vals = ["test", "possible", "values"];
+        assert!(did_you_mean("hahaahahah", p_vals.iter()).is_none());
+    }
+
+    #[test]
+    fn suffix_long() {
+        let p_vals = ["test", "possible", "values"];
+        let suffix = "\n\tDid you mean \'--test\'?";
+        assert_eq!(
+            did_you_mean_flag_suffix("tst", p_vals.iter(), []),
+            (suffix, Some("test"))
+        );
+    }
+
+    #[test]
+    fn suffix_enum() {
+        let p_vals = ["test", "possible", "values"];
+        let suffix = "\n\tDid you mean \'test\'?";
+        assert_eq!(
+            did_you_mean_value_suffix("tst", p_vals.iter()),
+            (suffix, Some("test"))
+        );
+    }
+}