Added the migration count function.

src/drift/Drift.clj

@@ -7,6 +7,7 @@
   (:gen-class
     :methods [[init [java.util.List] Object]
               [migrate [Long java.util.List] Void]
+              [migrationCount [Long java.util.List] Integer]
               [currentVersion [] Long]
               [maxMigrationNumber [] Long]
               [addListener [drift.listener_protocol.ListenerProtocol] java.util.Collection]
@@ -18,6 +19,9 @@
 (defn -migrate [_ version other-args]
   (execute/migrate version other-args))
 
+(defn -migrationCount [_ version other-args]
+  (execute/migration-count version other-args))
+
 (defn -currentVersion [_]
   (long (version/current-db-version)))
 

src/drift/execute.clj

@@ -12,6 +12,13 @@
       (Long/parseLong version)
       version)
     Long/MAX_VALUE))
+
+(defn migration-count
+  "Returns the total number of migrations to run to update the database to the given version number."
+  [version remaining-args]
+  (core/with-init-config remaining-args
+    (fn []
+      (runner/migration-count (version-number version)))))
 
 (defn
   migrate [version remaining-args]

src/drift/runner.clj

@@ -97,6 +97,16 @@
       (logging/info "No changes were made to the database."))
     (logging/error (str "Invalid version number: " from-version " or " to-version ". No changes were made to the database."))))
 
+(defn migration-count
+  "Returns the total number of migrations to run to update the database to the given version number."
+  [version-number]
+  (if version-number
+    (let [db-version (version/current-db-version)
+          version-number-min (min (max version-number 0) (core/max-migration-number))]
+      (if (< db-version version-number-min)
+        (count (core/migration-namespaces-in-range (inc db-version) version-number-min))
+        (count (core/migration-namespaces-in-range db-version (inc version-number-min)))))))
+
 (defn 
 #^{ :doc "Updates the database to the given version number. If the version number is less than the current database 
 version number, then this function causes a roll back." }