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Added support for shared subscriptions #37

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Added support for shared subscriptions #37

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33 changes: 29 additions & 4 deletions nmqtt.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -1194,14 +1194,39 @@ proc publish*(ctx: MqttCtx, topic: string, message: string, qos=0, retain=false)
proc subscribe*(ctx: MqttCtx, topic: string, qos: int, callback: PubCallback.cb): Future[void] =
## Subscribe to a topic.
##
## Shared subscription topic filter must follow the format: $share/{ShareName}/{filter}
##
## Access the callback with:
## .. code-block::nim
## proc callbackName(topic: string, message: string) =
## echo "Topic: ", topic, ": ", message
let msgId = ctx.nextMsgId()
ctx.workQueue[msgId] = Work(wk: SubWork, msgId: msgId, topic: topic, qos: qos, typ: Subscribe)
ctx.pubCallbacks[topic] = PubCallback(cb: callback, qos: qos)
result = ctx.work()
proc verify_shared_subscription(topic: string): bool =
type InvalidSharedSubscriptionTopicFilter = object of ValueError
if topic.split("/", 2)[1].len == 0:
raise newException(InvalidSharedSubscriptionTopicFilter, "The ShareName must be at least 1 character long.")
if topic.split("/", 2)[2].len == 0:
raise newException(InvalidSharedSubscriptionTopicFilter, "The filter must be at least 1 character long.")
if count(topic, "/") < 2:
raise newException(InvalidSharedSubscriptionTopicFilter, "The ShareName must end with a / character.")
if "#" in topic.split("/", 2)[1] or "+" in topic.split("/", 2)[1]:
raise newException(InvalidSharedSubscriptionTopicFilter, "The ShareName must not include the characters + and #")
return true

var verification: bool = true

if topic.startsWith("$share"):
verification = verify_shared_subscription(topic)

if verification:
let msgId = ctx.nextMsgId()
ctx.workQueue[msgId] = Work(wk: SubWork, msgId: msgId, topic: topic, qos: qos, typ: Subscribe)
if topic.startsWith("$share"):
# get the actual topic to set the pubCallback
ctx.pubCallbacks[topic.split("/", 2)[2]] = PubCallback(cb: callback, qos: qos)
else:
# not a shared subscription
ctx.pubCallbacks[topic] = PubCallback(cb: callback, qos: qos)
result = ctx.work()

proc unsubscribe*(ctx: MqttCtx, topic: string): Future[void] =
## Unsubscribe to a topic.
Expand Down