Just like the minimax, I thought that adding colors to the output of my Tic Tac Toe would be easy. And just like the minimax, it was a lot more difficult than I thought it would be.

The first thing was to create a namespace to deal with the colors:

(ns ttt.colors)

(defn color-code
  [code-string]
  (let [escape (char 27)]
    (str escape code-string)))

(def colors-code-list
  (mapv color-code ["[31m" "[32m" "[33m" "[34m" "[35m" "[36m" "[37m"]))

(def colors-key-list [:red :green :yellow :blue :purple :cyan :default])

(def ansi-colors
  (zipmap colors-key-list colors-code-list))

(defn colorize
  [color string]
  (str (color ansi-colors) string (:default ansi-colors)))

It is very simple and everything would work OK, if it was not the fact that I had the output centralized based on the string length, and the ANSI color code would add to the string length. As the ANSI code was not be displayed, the centralization got messy.

Counting a colorful string length

After a long while, I came up with some functions that would find the color sequence and count the string length without them:

(def color-re #"\[\d?;?\d*m")

(defn color-code-list
  [message-string]
    (re-seq color-re message-string))

(defn color-code-length
  [message-string]
  (if-let [color-list (color-code-list message-string)
           escape-chars (count color-list)]
    (+ escape-chars (count (string/join color-list)))
    0))

(defn message-length
  [message]
  (- (count message) (color-code-length message)))

Removing colors from a string

The game worked fine, and the centralization was normal, but all the tests that would deal with strings wouldn’t pass. The tests were expecting things like "Player 'x' moved to position 5", but it as getting "Player '\[33mx\[37m' moved to position 5". The solution was to write a helper that would clean the strings specifically for the tests:

(defn remove-color
  [string]
  (let [escape (char 27)]
    (loop [string string
           code-list (color-code-list color-re string)]
      (if (empty? code-list)
        string
        (recur (string/replace string (str escape (first code-list)) "")
               (rest code-list))))))

apprenticeship

clojure