[Forms] Separate out FormController

Separate out the controller for mct-form from its
directive definition, to allow reuse by the
mct-toolbar directive, WTD-684.

platform/forms/src/controllers/FormController.js

@@ -0,0 +1,57 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        // Default ng-pattern; any non whitespace
+        var NON_WHITESPACE = /\S/;
+
+        /**
+         * Controller for mct-form and mct-toolbar directives.
+         * @constructor
+         */
+        function FormController($scope) {
+            var regexps = [];
+
+            // ng-pattern seems to want a RegExp, and not a
+            // string (despite what documentation says) but
+            // we want form structure to be JSON-expressible,
+            // so we make RegExp's from strings as-needed
+            function getRegExp(pattern) {
+                // If undefined, don't apply a pattern
+                if (!pattern) {
+                    return NON_WHITESPACE;
+                }
+
+                // Just echo if it's already a regexp
+                if (pattern instanceof RegExp) {
+                    return pattern;
+                }
+
+                // Otherwise, assume a string
+                // Cache for easy lookup later (so we don't
+                // creat a new RegExp every digest cycle)
+                if (!regexps[pattern]) {
+                    regexps[pattern] = new RegExp(pattern);
+                }
+
+                return regexps[pattern];
+            }
+
+            // Publish the form state under the requested
+            // name in the parent scope
+            $scope.$watch("mctForm", function (mctForm) {
+                if ($scope.name) {
+                    $scope.$parent[$scope.name] = mctForm;
+                }
+            });
+
+            // Expose the regexp lookup
+            $scope.getRegExp = getRegExp;
+        }
+
+        return FormController;
+    }
+);