Refinement of upb_bytesrc interface.

Added a upb_byteregion that tracks a region of
the input buffer; decoders use this instead of
using a upb_bytesrc directly.  upb_byteregion
is also used as the way of passing a string to
a upb_handlers callback.  This symmetry makes
decoders compose better; if you want to take
a parsed string and decode it as something else,
you can take the string directly from the callback
and feed it as input to another parser.

A commented-out version of a pinning interface
is present; I decline to actually implement it
(and accept its extra complexity) until/unless
it is clear that it is actually a win.  But it
is included as a proof-of-concept, to show that
it fits well with the existing interface.

1 files changed, 8 insertions, 5 deletions

diff --git a/upb/pb/glue.c b/upb/pb/glue.c
index 37b86d9..3176355 100644
--- a/upb/pb/glue.c
+++ b/upb/pb/glue.c
@@ -23,7 +23,7 @@ void upb_strtomsg(const char *str, size_t len, void *msg, const upb_msgdef *md,
   upb_accessors_reghandlers(h, md);
   upb_decoder_init(&d, h);
   upb_handlers_unref(h);
-  upb_decoder_reset(&d, upb_stringsrc_bytesrc(&strsrc), 0, UINT64_MAX, msg);
+  upb_decoder_reset(&d, upb_stringsrc_allbytes(&strsrc), msg);
   upb_decoder_decode(&d, status);
 
   upb_stringsrc_uninit(&strsrc);
@@ -84,16 +84,19 @@ upb_def **upb_load_defs_from_descriptor(const char *str, size_t len, int *n,
   upb_handlers_unref(h);
   upb_descreader r;
   upb_descreader_init(&r);
-  upb_decoder_reset(&d, upb_stringsrc_bytesrc(&strsrc), 0, UINT64_MAX, &r);
+  upb_decoder_reset(&d, upb_stringsrc_allbytes(&strsrc), &r);
 
   upb_decoder_decode(&d, status);
+  upb_stringsrc_uninit(&strsrc);
+  upb_decoder_uninit(&d);
+  if (!upb_ok(status)) {
+    upb_descreader_uninit(&r);
+    return NULL;
+  }
   upb_def **defs = upb_descreader_getdefs(&r, n);
   upb_def **defscopy = malloc(sizeof(upb_def*) * (*n));
   memcpy(defscopy, defs, sizeof(upb_def*) * (*n));
-
   upb_descreader_uninit(&r);
-  upb_stringsrc_uninit(&strsrc);
-  upb_decoder_uninit(&d);
 
   // Set default accessors and layouts on all messages.
   for(int i = 0; i < *n; i++) {