new file mode 100644

@@ -0,0 +1,35 @@

+.Stream <- setRefClass("Stream", contains = "Consumer")

+

+.Stream$methods(

+    yield=function()

+    {

+        .self$inputPipe$yield()

+    

+    })

+

+setMethod(length, "Stream",

+    function(x)

+{

+    i <- 0L

+    inp <- x

+    while (extends(class(inp), "Consumer")) {

+        inp <- inp$inputPipe

+        i <- i + 1L

+    }

+    i

+})

+

+setMethod("[[", c("Stream", "numeric"),

+    function(x, i, j, ...)

+{

+    i <- as.integer(i)

+    len <- length(x)

+    if (1L != length(i) || 0 >= i || len < i)

+        stop("'i' must be integer(1), 0 < i <= length(x)")

+    inp <- x$inputPipe

+    while (extends(class(inp), "Consumer") && 1L < i) {

+        inp <- inp$inputPipe

+        i <- i - 1L

+    }

+    inp

+})