Adding byte counting ports

collects/meta/props

@@ -1800,6 +1800,7 @@ path/s is either such a string or a list of them.
 "collects/tests/units/test-runtime.rktl" drdr:command-line (racket "-f" *)
 "collects/tests/units/test-unit-contracts.rktl" drdr:command-line (racket "-f" *)
 "collects/tests/units/test-unit.rktl" drdr:command-line (racket "-f" *)
+"collects/tests/unstable/byte-counting-port.rkt" responsible (jay)
 "collects/tests/unstable/generics.rkt" responsible (jay)
 "collects/tests/unstable/srcloc.rktl" responsible (cce) drdr:command-line (racket "-f" *)
 "collects/tests/utils" responsible (unknown)
@@ -1839,6 +1840,7 @@ path/s is either such a string or a list of them.
 "collects/typed/rackunit/gui.rkt" drdr:command-line (gracket "-t" *)
 "collects/typed-scheme" responsible (samth)
 "collects/unstable" responsible (jay samth cce ryanc)
+"collects/unstable/byte-counting-port.rkt" responsible (jay)
 "collects/unstable/debug.rkt" responsible (samth)
 "collects/unstable/gui/notify.rkt" drdr:command-line (gracket-text "-t" *)
 "collects/unstable/gui/prefs.rkt" drdr:command-line (gracket-text "-t" *)
@@ -1846,6 +1848,7 @@ path/s is either such a string or a list of them.
 "collects/unstable/match.rkt" responsible (samth)
 "collects/unstable/mutated-vars.rkt" responsible (samth)
 "collects/unstable/poly-c.rkt" responsible (samth)
+"collects/unstable/scribblings/byte-counting-port.scrbl" responsible (jay)
 "collects/unstable/scribblings/debug.scrbl" responsible (samth)
 "collects/unstable/scribblings/hash.scrbl" responsible (samth)
 "collects/unstable/scribblings/match.scrbl" responsible (samth)

collects/tests/unstable/byte-counting-port.rkt

@@ -0,0 +1,15 @@
+#lang racket
+(require unstable/byte-counting-port
+         tests/eli-tester)
+
+(define name (gensym))
+(define cp (make-byte-counting-port name))
+(test
+ (object-name cp) => name
+ (for/fold ([l 0])
+   ([i (in-range 100)])
+   (define n (random 25))
+   (test
+    (file-position cp) => l
+    (write-bytes (make-bytes n) cp))
+   (+ l n)))

collects/unstable/byte-counting-port.rkt

@@ -0,0 +1,17 @@
+#lang racket
+
+(define (make-byte-counting-port [name 'byte-counting-port])
+  (define location 0)
+  (define (write-out bs starting ending opt1 opt2)
+    (define how-many-written (- ending starting))
+    (set! location (+ location how-many-written))
+    how-many-written)
+  (define close void)
+  (define (get-location)
+    (values #f #f location))
+  (make-output-port name always-evt write-out close 
+                    #f #f #f
+                    get-location))
+
+(provide/contract
+ [make-byte-counting-port (any/c . -> . output-port?)])

collects/unstable/scribblings/byte-counting-port.scrbl

@@ -0,0 +1,15 @@
+#lang scribble/manual
+@(require "utils.rkt" (for-label racket unstable/byte-counting-port))
+
+@title{Byte Counting Ports}
+
+@defmodule[unstable/byte-counting-port]
+
+@unstable[@author+email["Jay McCarthy" "jay@racket-lang.org"]]
+
+This library provides an output port constructor like @racket[open-output-nowhere], except it counts how many bytes have been written (available through @racket[file-position].)
+
+@defproc[(make-byte-counting-port [name any/c 'byte-counting-port])
+         output-port?]{
+Creates and returns an output port that discards all output sent to it (without blocking.) The @racket[name] argument is used as the port's name. The total number bytes written is available through @racket[file-position].}
+                      

collects/unstable/scribblings/unstable.scrbl

@@ -95,6 +95,7 @@ Keep documentation and tests up to date.
 @include-section["generics.scrbl"]
 @include-section["markparam.scrbl"]
 @include-section["debug.scrbl"]
+@include-section["byte-counting-port.scrbl"]
 
 @;{--------}