1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/reverse_seq.clj	Tue Oct 18 01:17:49 2011 -0700
     1.3 @@ -0,0 +1,43 @@
     1.4 +(ns coderloop.reverse-seq
     1.5 +  (:use [clojure.contrib
     1.6 +	 [duck-streams :only [file-str read-lines]]
     1.7 +	 [str-utils :only [re-split]]])
     1.8 +  (:use rlm.shell-inspect)
     1.9 +  (:use [clojure [string :only [trim]]]))
    1.10 +
    1.11 +(def c (file-str "/home/r/coderloop-test/reversesequence-c.in"))
    1.12 +(def a (file-str "/home/r/coderloop-test/reversesequence-a.in"))
    1.13 +(def b (file-str "/home/r/coderloop-test/reversesequence-b.in"))
    1.14 +
    1.15 +(defn test-trace-map []
    1.16 +  (= [:a :b :c :d :e]
    1.17 +       (trace-map {:a :b :d :e :c :d :b :c})))
    1.18 +
    1.19 +
    1.20 +(defn read-name-map
    1.21 +  "takes a file of pairs of names and returns a map from the first
    1.22 +   element in those pairs to the second element in the pairs."   
    1.23 +  [#^java.io.File file]
    1.24 +  (let [pairs  (map #(re-split #"\W+" (trim %)) (read-lines file))]
    1.25 +    (zipmap (map first pairs) (map second pairs))))
    1.26 +
    1.27 +(defn start-linked-map
    1.28 +  "takes a map-representing-a-list and finds the beginning of that list"
    1.29 +  [m]
    1.30 +  (first (remove (set (vals m)) (keys m))))
    1.31 +
    1.32 +(defn trace-map
    1.33 +  "chains through a map-representing-a-list, building a list along the way."
    1.34 +  [m]
    1.35 +  (loop [index (start-linked-map m)
    1.36 +	 chain (vector index)]
    1.37 +    (let [new-index (get m index ::sentinel)]
    1.38 +      (if (= new-index ::sentinel)
    1.39 +	chain
    1.40 +	(recur  new-index (conj chain new-index))))))
    1.41 +
    1.42 +
    1.43 +
    1.44 +(if (command-line?)
    1.45 +  (dorun
    1.46 +   (map println (reverse (trace-map (read-name-map (file-str (first *command-line-args*))))))))