[Pcloud]StimProducer: Impl addAttachedStimBuffIfNotExists

Reduces code duplication, centralizes checking and enforces consistent
behaviour across producers.

Also reordered the writes to the sh_ptr<StimulusBuffer>s such that
the pointers are written last.

commonLibs/attachmentSupport/stimulusProducer.cpp

@@ -52,6 +52,28 @@ bool StimulusProducer::hasBufferWithQualeIfaceApi(
 	return false;
 }
 
+bool StimulusProducer::addAttachedStimulusBufferIfNotExists(
+	const std::shared_ptr<StimulusBuffer>& buffer)
+{
+	if (!buffer) { return false; }
+
+	auto it = std::find_if(
+		attachedStimulusBuffers.begin(),
+		attachedStimulusBuffers.end(),
+		[&](const std::shared_ptr<StimulusBuffer>& buf) {
+			return buf && buffer &&
+				buf->deviceAttachmentSpec && buffer->deviceAttachmentSpec &&
+				*(buf->deviceAttachmentSpec) == *(buffer->deviceAttachmentSpec);
+		});
+
+	if (it != attachedStimulusBuffers.end()) {
+		return false;
+	}
+
+	attachedStimulusBuffers.push_back(buffer);
+	return true;
+}
+
 void StimulusProducer::destroyAttachedStimulusBuffer(
 	const std::shared_ptr<StimulusBuffer>& buffer)
 {