Add code to disambiguate pronouns dynamically.

This commit improves the display code so that the
smallest unambiguous abbreviation is calculated
based on the contents of pronouns.tab.

src/pronouns/pages.clj

@@ -90,16 +90,14 @@
       (take 5 inputs)
       (u/table-lookup inputs pronouns-table))))
 
-;; we could choose to display the entire row for the label.
-;; currently the first two entries are enough to disambiguate the
-;; pronouns -- will that always be true?
-(defn make-link [row]
-  (let [link (str "/" (s/join "/" row))
-        label (str (first row) "/" (first (rest row)))]
+(defn make-link [pair]
+  (let [link (str "/" (s/join "/" (second pair)))
+        label (str (s/join "/" (first pair)))]
     [:li [:a {:href link} label]]))
 
 (defn front [pronouns-table]
-  (let [links (map make-link (sort pronouns-table))
+  (let [abbreviations (u/abbreviate (sort pronouns-table))
+        links (map make-link abbreviations)
         title "Pronoun Island"]
     (html
      [:html

src/pronouns/util.clj

@@ -14,3 +14,32 @@
 (defn tabfile-lookup
   [query-key tabfile]
   (table-lookup query-key (slurp-tabfile tabfile)))
+
+; given a row and its lexically-closest neighbors,
+; determine the smallest abbreviation which is still
+; distinct.
+(defn disambiguate
+  [prev row next]
+  (loop [n 1]
+    (let [row-n (take n row)]
+      (cond
+        (>= n 5) row
+        (= row-n (take n prev)) (recur (+ n 1))
+        (= row-n (take n next)) (recur (+ n 1))
+        :else row-n))))
+
+; given a list of pronoun rows, return a list of
+; pairs, where the first item is the abbreviation
+; and the second is the original pronoun row.
+(defn abbreviate
+  [sorted-table]
+  (loop [acc nil
+         prev nil
+         row (first sorted-table)
+         todo (rest sorted-table)]
+    (let [next (first todo)
+          abbrev (disambiguate prev row next)
+          pair (list abbrev row)
+          acc2 (conj acc pair)]
+      (if (empty? todo) (reverse acc2)
+          (recur acc2 row next (rest todo))))))