Implement xas_object_call_table

Changes:

    * Implement xas_object_call_table as a static structure to allow
      creating a static dispatch table on a per-compilation-unit basis

    * Refactor xas_object to provide a single pointer to a
      xas_object_call_table

    * Refactor all object implementations to use xas_object_call_table

1 files changed, 9 insertions, 5 deletions

diff --git a/src/vox.c b/src/vox.c
index 775aee9..421ac00 100644
--- a/src/vox.c
+++ b/src/vox.c
@@ -277,6 +277,14 @@ static int vox_generate(xas_vox *vox, ...) {
     return xas_vox_generate(vox);
 }
 
+static xas_object_call_table call_table = {
+    .start      = (xas_object_start_callback)vox_generate,
+    .stop       = (xas_object_stop_callback)vox_stop,
+    .set_gain   = (xas_object_set_gain_callback)set_gain,
+    .stream_new = (xas_object_stream_new_callback)xas_vox_stream_new,
+    .destroy    = (xas_object_destroy_callback)xas_vox_destroy
+};
+
 xas_vox *xas_vox_new_args(xas_audio_format format,
                               size_t buffer_size,
                               const char *text2wave_path,
@@ -288,11 +296,7 @@ xas_vox *xas_vox_new_args(xas_audio_format format,
         goto error_malloc_vox;
     }
 
-    vox->obj.start      = (xas_object_start_callback)vox_generate;
-    vox->obj.stop       = (xas_object_stop_callback)vox_stop;
-    vox->obj.set_gain   = (xas_object_set_gain_callback)set_gain;
-    vox->obj.stream_new = (xas_object_stream_new_callback)xas_vox_stream_new;
-    vox->obj.destroy    = (xas_object_destroy_callback)xas_vox_destroy;
+    vox->obj.table = &call_table;
 
     vox->text2wave_path = text2wave_path;