Implemented upb_streamdata().

upb_streamdata() reads data from a upb_src until EOF
or error, passing all the data to a upb_sink.

core/upb_stream.c

@@ -0,0 +1,44 @@
+/*
+ * upb - a minimalist implementation of protocol buffers.
+ *
+ * Copyright (c) 2010 Joshua Haberman.  See LICENSE for details.
+ */
+
+#include "upb_stream.h"
+
+#include "upb_def.h"
+
+#define CHECKSRC(x) if(!x) goto src_err
+#define CHECKSINK(x) if(!x) goto sink_err
+
+void upb_streamdata(upb_src *src, upb_sink *sink, upb_status *status) {
+  upb_fielddef *f;
+  upb_string *str = NULL;
+  while((f = upb_src_getdef(src)) != NULL) {
+    CHECKSINK(upb_sink_putdef(sink, f));
+    if(f->type == UPB_TYPE(GROUP) || f->type == UPB_TYPE(MESSAGE)) {
+      // We always recurse into submessages, but the putdef above already told
+      // the sink that.
+    } else if(f->type == UPB_TYPE(STRING) || f->type == UPB_TYPE(BYTES)) {
+      str = upb_string_tryrecycle(str);
+      CHECKSRC(upb_src_getstr(src, str));
+      CHECKSINK(upb_sink_putstr(sink, str));
+    } else {
+      // Primitive type.
+      upb_value val;
+      CHECKSRC(upb_src_getval(src, upb_value_addrof(&val)));
+      CHECKSINK(upb_sink_putval(sink, val));
+    }
+  }
+  // If we're not EOF now, the loop terminated due to an error.
+  CHECKSRC(upb_src_eof(src));
+  return;
+
+src_err:
+  upb_copyerr(status, upb_src_status(src));
+  return;
+
+sink_err:
+  upb_copyerr(status, upb_sink_status(sink));
+  return;
+}