Added in:<channels> search predicate (#2634)

Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/messages/search/ChannelPredicate.hpp

@@ -0,0 +1,38 @@
+#pragma once
+
+#include "messages/search/MessagePredicate.hpp"
+
+namespace chatterino {
+
+/**
+ * @brief MessagePredicate checking for the channel a message was sent in.
+ *
+ * This predicate will only allow messages that are sent in a list of channels,
+ * specified by their names.
+ */
+class ChannelPredicate : public MessagePredicate
+{
+public:
+    /**
+     * @brief Create a ChannelPredicate with a list of channels to search for.
+     *
+     * @param channels a list of channel names that a message should be sent in
+     */
+    ChannelPredicate(const QStringList &channels);
+
+    /**
+     * @brief Checks whether the message was sent in any of the channels passed
+     *        in the constructor.
+     *
+     * @param message the message to check
+     * @return true if the message was sent in one of the specified channels,
+     *         false otherwise
+     */
+    bool appliesTo(const Message &message);
+
+private:
+    /// Holds the channel names that will be searched for
+    QStringList channels_;
+};
+
+}  // namespace chatterino