Refactor duplicate code into a named function. (#1158)

* Refactor duplicate code into a named function.

* Promise not to change the client

by making the client pointer point to a const UA_Client.

src/client/ua_client_highlevel_subscriptions.c

@@ -49,14 +49,20 @@ UA_Client_Subscriptions_new(UA_Client *client, UA_SubscriptionSettings settings,
     return UA_STATUSCODE_GOOD;
 }
 
-/* remove the subscription remotely */
-UA_StatusCode
-UA_Client_Subscriptions_remove(UA_Client *client, UA_UInt32 subscriptionId) {
-    UA_Client_Subscription *sub;
+static UA_Client_Subscription *findSubscription(const UA_Client *client, UA_UInt32 subscriptionId)
+{
+    UA_Client_Subscription *sub = NULL;
     LIST_FOREACH(sub, &client->subscriptions, listEntry) {
         if(sub->subscriptionID == subscriptionId)
             break;
     }
+    return sub;
+}
+
+/* remove the subscription remotely */
+UA_StatusCode
+UA_Client_Subscriptions_remove(UA_Client *client, UA_UInt32 subscriptionId) {
+    UA_Client_Subscription *sub = findSubscription(client, subscriptionId);
     if(!sub)
         return UA_STATUSCODE_BADSUBSCRIPTIONIDINVALID;
 
@@ -110,11 +116,7 @@ UA_Client_Subscriptions_addMonitoredItem(UA_Client *client, UA_UInt32 subscripti
                                          UA_NodeId nodeId, UA_UInt32 attributeID,
                                          UA_MonitoredItemHandlingFunction hf,
                                          void *hfContext, UA_UInt32 *newMonitoredItemId) {
-    UA_Client_Subscription *sub;
-    LIST_FOREACH(sub, &client->subscriptions, listEntry) {
-        if(sub->subscriptionID == subscriptionId)
-            break;
-    }
+    UA_Client_Subscription *sub = findSubscription(client, subscriptionId);
     if(!sub)
         return UA_STATUSCODE_BADSUBSCRIPTIONIDINVALID;
 
@@ -179,11 +181,7 @@ UA_Client_Subscriptions_addMonitoredItem(UA_Client *client, UA_UInt32 subscripti
 UA_StatusCode
 UA_Client_Subscriptions_removeMonitoredItem(UA_Client *client, UA_UInt32 subscriptionId,
                                             UA_UInt32 monitoredItemId) {
-    UA_Client_Subscription *sub;
-    LIST_FOREACH(sub, &client->subscriptions, listEntry) {
-        if(sub->subscriptionID == subscriptionId)
-            break;
-    }
+    UA_Client_Subscription *sub = findSubscription(client, subscriptionId);
     if(!sub)
         return UA_STATUSCODE_BADSUBSCRIPTIONIDINVALID;
 
@@ -227,12 +225,7 @@ UA_Client_processPublishResponse(UA_Client *client, UA_PublishRequest *request,
     if(response->responseHeader.serviceResult != UA_STATUSCODE_GOOD)
         return;
 
-    /* Find the subscription */
-    UA_Client_Subscription *sub;
-    LIST_FOREACH(sub, &client->subscriptions, listEntry) {
-        if(sub->subscriptionID == response->subscriptionId)
-            break;
-    }
+    UA_Client_Subscription *sub = findSubscription(client, response->subscriptionId);
     if(!sub)
         return;