Add resp_stream_is_complete()

To determine if there is data remaining on the stream. Fixes #559

NAMESPACE

@@ -119,6 +119,7 @@ export(resp_retry_after)
 export(resp_status)
 export(resp_status_desc)
 export(resp_stream_aws)
+export(resp_stream_is_complete)
 export(resp_stream_lines)
 export(resp_stream_raw)
 export(resp_stream_sse)

NEWS.md

@@ -1,5 +1,6 @@
 # httr2 (development version)
 
+* `resp_stream_is_complete()` tells you if there is still data remaining to be streamed (#559).
 * `url_parse()` now uses `curl::curl_parse_url()` which is much faster and more correct (#577).
 * `req_retry()` now defaults to `max_tries = 2` with a message.
   Set to `max_tries = 1` to disable retries.

R/resp-stream.R

@@ -10,6 +10,9 @@
 #' * `resp_stream_aws()` retrieves a single event from an AWS stream
 #'   (i.e. mime type `application/vnd.amazon.eventstream``).
 #'
+#' Use `resp_stream_is_complete()` to determine if there is further data
+#' waiting on the stream.
+#'
 #' @returns
 #' * `resp_stream_raw()`: a raw vector.
 #' * `resp_stream_lines()`: a character vector.
@@ -80,6 +83,14 @@ resp_stream_sse <- function(resp, max_size = Inf) {
   }
 }
 
+#' @export
+#' @rdname resp_stream_raw
+resp_stream_is_complete <- function(resp) {
+  check_response(resp)
+
+  !isIncomplete(resp$body)
+}
+
 #' @export
 #' @param ... Not used; included for compatibility with generic.
 #' @rdname resp_stream_raw

tests/testthat/test-resp-stream.R

@@ -16,6 +16,24 @@ test_that("can stream bytes from a connection", {
   expect_length(out, 0)
 })
 
+test_that("can determine if a stream is complete (blocking)", {
+  resp <- request_test("/stream-bytes/2048") %>% req_perform_connection()
+  withr::defer(close(resp))
+
+  expect_false(resp_stream_is_complete(resp))
+  resp_stream_raw(resp, kb = 2)
+  expect_true(resp_stream_is_complete(resp))
+})
+
+test_that("can determine if a stream is complete (non-blocking)", {
+  resp <- request_test("/stream-bytes/2048") %>% req_perform_connection(blocking = FALSE)
+  withr::defer(close(resp))
+
+  expect_false(resp_stream_is_complete(resp))
+  resp_stream_raw(resp, kb = 2)
+  expect_true(resp_stream_is_complete(resp))
+})
+
 test_that("can't read from a closed connection", {
   resp <- request_test("/stream-bytes/1024") %>% req_perform_connection()
   close(resp)