added RepeatStream: allows you to repeat some stream for a number of times (or infinitely)

 * this currently also works for very long streams without precalculating stuff
 * On the other hand, after each iteration the target stream must be reinitialized.
   This is not safe in generator functions (FIXME).

1 files changed, 33 insertions, 0 deletions

diff --git a/applause.lua b/applause.lua
index a568a4a..d598a86 100644
--- a/applause.lua
+++ b/applause.lua
@@ -135,6 +135,10 @@ function Stream:sync()
 	return SyncedStream:new(self)
 end
 
+function Stream:rep(repeats)
+	return RepeatStream:new(self, repeats)
+end
+
 function Stream:map(fnc)
 	return MapStream:new(self, fnc)
 end
@@ -641,6 +645,35 @@ function ConcatStream:len()
 	return len
 end
 
+RepeatStream = DeriveClass(Stream, function(self, stream, repeats)
+	self.streams = {tostream(stream)}
+	self.repeats = repeats or math.huge
+end)
+
+function RepeatStream:tick()
+	local i = 1
+	local stream_tick = self.streams[1]:tick()
+	local repeats = self.repeats
+
+	return function()
+		while i <= repeats do
+			local sample = stream_tick()
+			if sample then return sample end
+
+			-- next iteration
+			i = i + 1
+			-- FIXME: The tick() method itself may be too
+			-- inefficient for realtime purposes.
+			-- Also, we may slowly leak memory.
+			stream_tick = self.streams[1]:tick()
+		end
+	end
+end
+
+function RepeatStream:len()
+	return self.streams[1]:len() * self.repeats
+end
+
 -- Ravel operation inspired by APL.
 -- This removes one level of nesting from nested streams
 -- (e.g. streams of streams), and is semantically similar