streaming.c: remove enum/function/vtbl indirection

Remove the indirection of discovering a function pointer to use via an
enum and virtual table. This refactors code added in
46bf043807c (streaming: a new API to read from the object store,
2011-05-11).

We can instead simply return an "open_istream_fn" for use from the
"istream_source()" selector function directly. This allows us to get
rid of the "incore", "loose" and "pack_non_delta" enum
variables. We'll return the functions instead.

The "stream_error" variable in that enum can likewise go in favor of
returning NULL, which is what the open_istream() was doing when it got
that value anyway.

We can thus remove the entire enum, and the "open_istream_tbl" virtual
table that (indirectly) referenced it.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/streaming.c b/streaming.c
index b0d439e47a73fef2318390ed6a5b8d394cde98f4..628369519b9fe0f4d61399167fb5bf767e68debf 100644 (file)
--- a/streaming.c
+++ b/streaming.c
@@ -8,13 +8,6 @@
 #include "replace-object.h"
 #include "packfile.h"
 
-enum input_source {
-       stream_error = -1,
-       incore = 0,
-       loose = 1,
-       pack_non_delta = 2
-};
-
 typedef int (*open_istream_fn)(struct git_istream *,
                               struct repository *,
                               struct object_info *,
@@ -424,16 +417,10 @@ static open_method_decl(incore)
  * static helpers variables and functions for users of streaming interface
  *****************************************************************************/
 
-static open_istream_fn open_istream_tbl[] = {
-       open_istream_incore,
-       open_istream_loose,
-       open_istream_pack_non_delta,
-};
-
-static enum input_source istream_source(struct repository *r,
-                                       const struct object_id *oid,
-                                       enum object_type *type,
-                                       struct object_info *oi)
+static open_istream_fn istream_source(struct repository *r,
+                                     const struct object_id *oid,
+                                     enum object_type *type,
+                                     struct object_info *oi)
 {
        unsigned long size;
        int status;
@@ -442,21 +429,20 @@ static enum input_source istream_source(struct repository *r,
        oi->sizep = &size;
        status = oid_object_info_extended(r, oid, oi, 0);
        if (status < 0)
-               return stream_error;
+               return NULL;
 
        switch (oi->whence) {
        case OI_LOOSE:
-               return loose;
+               return open_istream_loose;
        case OI_PACKED:
                if (!oi->u.packed.is_delta && big_file_threshold < size)
-                       return pack_non_delta;
+                       return open_istream_pack_non_delta;
                /* fallthru */
        default:
-               return incore;
+               return open_istream_incore;
        }
 }
 
-
 /****************************************************************
  * Users of streaming interface
  ****************************************************************/
@@ -482,13 +468,13 @@ struct git_istream *open_istream(struct repository *r,
        struct git_istream *st;
        struct object_info oi = OBJECT_INFO_INIT;
        const struct object_id *real = lookup_replace_object(r, oid);
-       enum input_source src = istream_source(r, real, type, &oi);
+       open_istream_fn open_fn = istream_source(r, real, type, &oi);
 
-       if (src < 0)
+       if (!open_fn)
                return NULL;
 
        st = xmalloc(sizeof(*st));
-       if (open_istream_tbl[src](st, r, &oi, real, type)) {
+       if (open_fn(st, r, &oi, real, type)) {
                if (open_istream_incore(st, r, &oi, real, type)) {
                        free(st);
                        return NULL;