initial commit - enclose, joinstem, bysize

and tests

src/inflect.rs

@@ -0,0 +1,34 @@
+use std::collections::{ HashMap, HashSet };
+
+/// Encloses a string 's' in a non-capturing group.
+pub fn enclose(s: &str) -> String {
+    format!("(?:{})", s)
+}
+
+/// Joins the stem of each word in 'words' into a string for Regex.
+pub fn joinstem(cutpoint: Option<i32>, words: Option<Vec<&str>>) -> String {
+    let words = words.unwrap_or_else(|| Vec::new());
+    let stem = words
+        .iter()
+        .map(|w| {
+            if let Some(c) = cutpoint {
+                if c < 0 { &w[..w.len() - (-c as usize)] } else { &w[..c as usize] }
+            } else {
+                w
+            }
+        })
+        .collect::<Vec<&str>>()
+        .join("|");
+    enclose(&stem)
+}
+
+/// From a list of words, returns a HashMap of HashSets of words, keyed by word length.
+pub fn bysize(words: Vec<&str>) -> HashMap<usize, HashSet<String>> {
+    let mut res: HashMap<usize, HashSet<String>> = HashMap::new();
+    for word in words {
+        let len = word.len();
+        let entry = res.entry(len).or_insert_with(HashSet::new);
+        entry.insert(word.to_string());
+    }
+    res
+}