io.encodings.string: make binary decode/encode nop

Fixes #319.

basis/io/encodings/string/string-tests.factor

@@ -1,10 +1,11 @@
 ! Copyright (C) 2008 Daniel Ehrenberg.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: strings io.encodings.utf8 io.encodings.utf16
-io.encodings.string tools.test ;
+io.encodings.string tools.test io.encodings.binary ;
 IN: io.encodings.string.tests
 
 [ "hello" ] [ "hello" utf8 decode ] unit-test
+[ B{ 0 1 22 255 } ] [ B{ 0 1 22 255 } binary decode ] unit-test
 [ "he" ] [ "\0h\0e" utf16be decode ] unit-test
 
 [ "hello" ] [ "hello" utf8 encode >string ] unit-test

basis/io/encodings/string/string.factor

@@ -1,16 +1,23 @@
 ! Copyright (C) 2008 Daniel Ehrenberg.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: byte-vectors io io.encodings io.streams.byte-array
-io.streams.string kernel locals sbufs sequences ;
+io.streams.string kernel locals sbufs sequences io.private
+io.encodings.binary ;
 IN: io.encodings.string
 
 :: decode ( byte-array encoding -- string )
-    byte-array encoding <byte-reader> :> reader
-    byte-array length encoding guess-decoded-length <sbuf> :> buf
-    [ reader stream-read1 dup ] [ buf push ] while drop
-    buf "" like ; inline
+    encoding binary eq? [ byte-array ] [
+        byte-array encoding <byte-reader> :> reader
+        byte-array length
+        encoding guess-decoded-length
+        reader stream-exemplar-growable new-resizable :> buf
+        [ reader stream-read1 dup ] [ buf push ] while drop
+        buf reader stream-exemplar like
+    ] if ; inline
 
 :: encode ( string encoding -- byte-array )
-    string length encoding guess-encoded-length <byte-vector> :> vec
-    string vec encoding <encoder> stream-write
-    vec B{ } like ; inline
+    encoding binary eq? [ string ] [
+        string length encoding guess-encoded-length <byte-vector> :> vec
+        string vec encoding <encoder> stream-write
+        vec B{ } like
+    ] if ; inline