From a899df2a122238a9b0700a6cd4bdc1508946fc8c Mon Sep 17 00:00:00 2001
From: Nico Rehwaldt <git_nikku@nixis.de>
Date: Thu, 29 Jan 2015 14:03:17 +0100
Subject: [PATCH] chore(modeling/rules): reduce complexity

Related to #176
---
 lib/features/modeling/rules/ModelingRules.js | 31 +++++++++++++-------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/lib/features/modeling/rules/ModelingRules.js b/lib/features/modeling/rules/ModelingRules.js
index 164f7fa8..65ef1e2e 100644
--- a/lib/features/modeling/rules/ModelingRules.js
+++ b/lib/features/modeling/rules/ModelingRules.js
@@ -17,31 +17,40 @@ ModelingRules.prototype = Object.create(RuleProvider.prototype);
 
 ModelingRules.prototype.init = function() {
 
+  function nonExistantOrLabel(element) {
+    return !element || element.labelTarget;
+  }
+
+  function isSame(a, b) {
+    return a === b;
+  }
+
   // rules
 
   function canConnect(source, target, connection) {
 
-    if (!source || source.labelTarget || !target || target.labelTarget) {
+    if (nonExistantOrLabel(source) || nonExistantOrLabel(target)) {
       return null;
     }
 
-    var sourceBo = source.businessObject,
-        targetBo = target.businessObject,
-        connectionBo = connection && connection.businessObject;
-
-    if (sourceBo.$parent !== targetBo.$parent) {
-      return false;
-    }
-
     // See https://github.com/bpmn-io/bpmn-js/issues/178
     // as a workround we disallow connections with same
     // target and source element.
     // This rule must be removed if a auto layout for this
     // connections is implemented.
-    if (sourceBo === targetBo) {
+    if (isSame(source, target)) {
       return false;
     }
 
+    // only move between the same parent
+    if (!isSame(source.parent, target.parent)) {
+      return false;
+    }
+
+    var sourceBo = source.businessObject,
+        targetBo = target.businessObject,
+        connectionBo = connection && connection.businessObject;
+
     if (connectionBo && connectionBo.$instanceOf('bpmn:SequenceFlow')) {
 
       if (!sourceBo.$instanceOf('bpmn:FlowNode') ||
@@ -165,7 +174,7 @@ ModelingRules.prototype.init = function() {
     // into source
     var t = target;
     while (t) {
-      if (t === source) {
+      if (isSame(t, source)) {
         return false;
       }