Added upb::FileDef, which represents the file defs are declared in.

It is entirely optional: MessageDef/EnumDef can still exist
on their own.  But this can represent a def's file when it is
desirable to do so (eg. for code generators).

This approach will require that we change the way we handle
extensions.  But I think it will be a good change overall.

Specifically, we previously handled extensions by duplicating
the extended message and then adding the extension as a regular
field to the duplicated message.  This required also duplicating
any messages that could reach the extended message.

In the new world we will need a way of declaring and looking up
extensions separately from the message being extended.

This change also involves some notable changes to the generated
code:

- files are now called foo.upbdefs.h instead of foo.upb.h.
  This reflects the fact that we might possibly generate several
  different output files for a .proto file, and this one is just
  for defs.

- we no longer generate selectors in the .h file.

- the upbdefs.c no longer vends a SymbolTable.  Now it vends the
  individual messages (and possibly a FileDef later).  I think this
  will compose better once we can generate files where one
  generated files imports another.

We also make the descriptor reader vend a list of FileDefs now.
This is the best conceptual match for parsing a FileDescriptorSet.

1 files changed, 13 insertions, 4 deletions

diff --git a/upb/symtab.h b/upb/symtab.h
index ffe9f73..9a41c03 100644
--- a/upb/symtab.h
+++ b/upb/symtab.h
@@ -108,12 +108,17 @@ class upb::SymbolTable {
    * only a few messages are changing.  We may want to add a way of adding a
    * tree of frozen defs to the symtab (perhaps an alternate constructor where
    * you pass the root of the tree?) */
-  bool Add(Def*const* defs, int n, void* ref_donor, upb_status* status);
+  bool Add(Def*const* defs, size_t n, void* ref_donor, Status* status);
 
   bool Add(const std::vector<Def*>& defs, void *owner, Status* status) {
     return Add((Def*const*)&defs[0], defs.size(), owner, status);
   }
 
+  /* Resolves all subdefs for messages in this file and attempts to freeze the
+   * file.  If this succeeds, adds all the symbols to this SymbolTable
+   * (replacing any existing ones with the same names). */
+  bool AddFile(FileDef* file, Status* s);
+
  private:
   UPB_DISALLOW_POD_OPS(SymbolTable, upb::SymbolTable)
 };
@@ -134,8 +139,9 @@ const upb_def *upb_symtab_resolve(const upb_symtab *s, const char *base,
 const upb_def *upb_symtab_lookup(const upb_symtab *s, const char *sym);
 const upb_msgdef *upb_symtab_lookupmsg(const upb_symtab *s, const char *sym);
 const upb_enumdef *upb_symtab_lookupenum(const upb_symtab *s, const char *sym);
-bool upb_symtab_add(upb_symtab *s, upb_def *const*defs, int n, void *ref_donor,
-                    upb_status *status);
+bool upb_symtab_add(upb_symtab *s, upb_def *const*defs, size_t n,
+                    void *ref_donor, upb_status *status);
+bool upb_symtab_addfile(upb_symtab *s, upb_filedef *file, upb_status* status);
 
 /* upb_symtab_iter i;
  * for(upb_symtab_begin(&i, s, type); !upb_symtab_done(&i);
@@ -177,9 +183,12 @@ inline const MessageDef *SymbolTable::LookupMessage(const char *sym) const {
   return upb_symtab_lookupmsg(this, sym);
 }
 inline bool SymbolTable::Add(
-    Def*const* defs, int n, void* ref_donor, upb_status* status) {
+    Def*const* defs, size_t n, void* ref_donor, Status* status) {
   return upb_symtab_add(this, (upb_def*const*)defs, n, ref_donor, status);
 }
+inline bool SymbolTable::AddFile(FileDef* file, Status* s) {
+  return upb_symtab_addfile(this, file, s);
+}
 }  /* namespace upb */
 #endif