3203 - testable interface for reading a file

This commit was written by Stephen Malina. Thanks also to Stephen for
running into the bug of commit 3202.

1 files changed, 31 insertions, 0 deletions

diff --git a/088file.mu b/088file.mu
new file mode 100644
index 00000000..25263fa9
--- /dev/null
+++ b/088file.mu
@@ -0,0 +1,31 @@
+# Wrappers around file-system primitives that take a 'filesystem' object and
+# are thus easier to test.
+
+container filesystem [
+  {data: (address table (address array character) (address array character))}
+]
+
+def start-reading fs:address:filesystem, filename:address:array:character -> contents:address:source:character [
+  local-scope
+  load-ingredients
+  x:number/file <- $open-file-for-reading filename
+  contents:address:source:character, sink:address:sink:character <- new-channel 30
+  $print [sink: ], sink, 10/newline
+  chan:address:channel:character <- get *sink, chan:offset
+  $print [chan in start-reading: ], chan, 10/newline
+  start-running transmit x, sink
+]
+
+def transmit file:number, sink:address:sink:character -> file:number, sink:address:sink:character [
+  local-scope
+  load-ingredients
+  {
+    c:character <- $read-from-file file
+    break-unless c
+    sink <- write sink, c
+    loop
+  }
+  $print [closing chan after reading file], 10/newline
+  sink <- close sink
+  $print [returning from 'transmit'], 10/newline
+]