Ufdjrw

I have a map representing information about a subversion commit.

Example contents:

(def commit 
 :repository "/var/group1/project1"
 :revision-number "1234"
 :author "toolkit"
 etc..

I would like to change the repository based on a prefix match, so that:

/var/group1 maps to http://foo/group1
/var/group2 maps to http://bar/group2

I have created 2 functions like:

(defn replace-fn [prefix replacement]
 (fn [str]
 (if (.startsWith str prefix)
 (.replaceFirst str prefix replacement)
 str)))

(def replace-group1 (replace-fn "/var/group1" "http://foo/group1"))
(def replace-group2 (replace-fn "/var/group2" "http://bar/group2"))

And now I have to apply them:

(defn fix-repository [:keys [repository] :as commit]
 (assoc commit :repository
 (replace-group1
 (replace-group2 repository))))

But this means I have to add an extra wrapper in my fix-repository for each new replacement.

I would like to simply:

• Given a commit map


• Extract the :repository value


• Loop through a list of replacement prefixes


• If any prefix matches, replace :repository value with the new string


• Otherwise, leave the :repository value alone.

I can't seem to build the right loop, reduce, or other solution to this.

How about something like this?

(defn replace-any-prefix [replacements-list string]
 (or (first
 (filter identity
 (map (fn [[p r]]
 (when (.startsWith string p)
 (.replaceFirst string p r)))
 replacements-list)))
 string)))

(update-in commit
 [:repository]
 (partial replace-any-prefix
 [["/var/group1" "http://foo/group1"]
 ["/var/group2" "http:/foo/group2"]]))

Documentation for update-in: http://clojuredocs.org/clojure_core/clojure.core/update-in

You can use function composition:

(def commit 
 :repository "/var/group2/project1"
 :revision-number "1234"
 :author "toolkit")

(defn replace-fn [prefix replacement]
 (fn [str]
 (if (.startsWith str prefix)
 (.replaceFirst str prefix replacement)
 str)))

(def replacements
 (comp (replace-fn "/var/group1" "http://foo/group1")
 (replace-fn "/var/group2" "http://foo/group2")))

(defn fix-repository [commit replacements]
 (update-in commit [:repository] replacements))

(fix-repository commit replacements)