get-csv: speed up with unsafe get-char.

I'm seeing about a 6% improvement in get-csv from this.

* stream.c (us_get_char, us_unget_char): New static functions,
which assume all arguments have correct type.
(get_csv): If we use source_opt, validate that it's a stream
with class_check. Use us_get_char and use_unget_char.

1 files changed, 17 insertions, 4 deletions

diff --git a/stream.c b/stream.c
index 20e5c933..1403f1b2 100644
--- a/stream.c
+++ b/stream.c
@@ -3086,6 +3086,12 @@ val get_char(val stream_in)
   return ops->get_char(stream);
 }
 
+static val us_get_char(val stream)
+{
+  struct strm_ops *ops = coerce(struct strm_ops *, stream->co.ops);
+  return ops->get_char(stream);
+}
+
 val get_byte(val stream_in)
 {
   val self = lit("get-byte");
@@ -3114,6 +3120,12 @@ val unget_char(val ch, val stream_in)
   return ops->unget_char(stream, ch);
 }
 
+static val us_unget_char(val ch, val stream)
+{
+  struct strm_ops *ops = coerce(struct strm_ops *, stream->co.ops);
+  return ops->unget_char(stream, ch);
+}
+
 val unget_byte(val byte, val stream_in)
 {
   val self = lit("unget-byte");
@@ -5424,24 +5436,25 @@ val make_byte_input_stream(val obj)
 
 val get_csv(val source_opt)
 {
+  val self = lit("get-csv");
   val source = if3(missingp(source_opt),
                    std_input,
                    if3(stringp(source_opt),
                        make_string_input_stream(source_opt),
-                       source_opt));
+                       (class_check(self, source_opt, stream_cls), source_opt)));
   val record = nil, field = nil;
   enum { init, rfield, qfield, quot } state = init;
   int done = 0;
 
   while (!done) {
-    val ch = get_char(source);
+    val ch = us_get_char(source);
 
     if (ch == chr('\r')) {
-      val ch2 = get_char(source);
+      val ch2 = us_get_char(source);
       if (ch2 == chr('\n'))
         ch = ch2;
       else if (ch2)
-        unget_char(ch2, source);
+        us_unget_char(ch2, source);
     } else if (ch == nil) {
       if (state == init)
         return nil;