Add vcs task with subtasks.

leiningen-core/src/leiningen/core/project.clj

@@ -127,6 +127,7 @@
   (cond (nil? left) right
         (nil? right) (remove-top-displace left)
 
+        ;; TODO: support :reverse?
         (top-displace? left) right
 
         (and (displace? left)   ;; Pick the rightmost

src/leiningen/vcs.clj

@@ -0,0 +1,40 @@
+(ns leiningen.vcs
+  (:require [clojure.java.io :as io]
+            [leiningen.core.eval :as eval]
+            [leiningen.core.main :as main]))
+
+;; TODO: make pom task use this ns
+
+(def supported-systems (atom [:git]))
+
+(defn uses-vcs [project vcs]
+  (let [vcs-dir (io/file (:root project) (str "." (name vcs)))]
+    (and (.exists vcs-dir) vcs)))
+
+(defn which-vcs [project & _]
+  (some (partial uses-vcs project) @supported-systems))
+
+(defmulti push "Push to your remote repository." which-vcs :default :none)
+
+(defmethod push :git [project]
+  (binding [eval/*dir* (:root project)]
+    (eval/sh "git" "push")
+    (eval/sh "git" "push" "--tags")))
+
+(defmulti tag "Apply a version control tag" which-vcs)
+
+(defmethod tag :git [project version]
+  (binding [eval/*dir* (:root project)]
+    (eval/sh "git" "tag" "-s" version "-m" (str "Release " version))))
+
+;; TODO: add a subtask to assert there are no uncommitted changes
+
+(defn- not-found [subtask]
+  (partial #'main/task-not-found (str "vcs " subtask)))
+
+(defn ^{:subtasks [#'push #'tag]} vcs
+  "Interact with the version control system."
+  [project subtask & args]
+  (let [subtasks (:subtasks (meta #'vcs) {})
+        [subtask-var] (filter #(= subtask (name (:name (meta %)))) subtasks)]
+    (apply (or subtask-var (not-found subtask)) project args)))