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, 30 insertions, 23 deletions

diff --git a/tools/upbc.lua b/tools/upbc.lua
index a248318..5db5fba 100644
--- a/tools/upbc.lua
+++ b/tools/upbc.lua
@@ -12,40 +12,47 @@ local dump_cinit = require "dump_cinit"
 local upb = require "upb"
 
 local src = arg[1]
-local outbase = arg[2]
-local basename = arg[3]
 
-if not (src and outbase and basename) then
-  print("Usage: upbc <binary descriptor> <output filename base> <symbol prefix>")
+if not src then
+  print("Usage: upbc <binary descriptor>")
   return 1
 end
 
-local hfilename = outbase .. ".upb.h"
-local cfilename = outbase .. ".upb.c"
-
-if os.getenv("UPBC_VERBOSE") then
-  print("upbc:")
-  print(string.format("  source file=%s", src))
-  print(string.format("  output file base=%s", outbase))
-  print(string.format("  hfilename=%s", hfilename))
-  print(string.format("  cfilename=%s", cfilename))
+function strip_proto(filename)
+  return string.gsub(filename, '%.proto$','')
 end
 
 -- Open input/output files.
 local f = assert(io.open(src, "r"), "couldn't open input file " .. src)
 local descriptor = f:read("*all")
+local files = upb.load_descriptor(descriptor)
 local symtab = upb.SymbolTable()
-symtab:load_descriptor(descriptor)
 
-os.execute(string.format("mkdir -p `dirname %s`", outbase))
-local hfile = assert(io.open(hfilename, "w"), "couldn't open " .. hfilename)
-local cfile = assert(io.open(cfilename, "w"), "couldn't open " .. cfilename)
+for _, file in ipairs(files) do
+  symtab:add_file(file)
+  local outbase = strip_proto(file:name())
+
+  local hfilename = outbase .. ".upbdefs.h"
+  local cfilename = outbase .. ".upbdefs.c"
+
+  if os.getenv("UPBC_VERBOSE") then
+    print("upbc:")
+    print(string.format("  source file=%s", src))
+    print(string.format("  output file base=%s", outbase))
+    print(string.format("  hfilename=%s", hfilename))
+    print(string.format("  cfilename=%s", cfilename))
+  end
 
-local happend = dump_cinit.file_appender(hfile)
-local cappend = dump_cinit.file_appender(cfile)
+  os.execute(string.format("mkdir -p `dirname %s`", outbase))
+  local hfile = assert(io.open(hfilename, "w"), "couldn't open " .. hfilename)
+  local cfile = assert(io.open(cfilename, "w"), "couldn't open " .. cfilename)
 
--- Dump defs
-dump_cinit.dump_defs(symtab, basename, happend, cappend)
+  local happend = dump_cinit.file_appender(hfile)
+  local cappend = dump_cinit.file_appender(cfile)
 
-hfile:close()
-cfile:close()
+  -- Dump defs
+  dump_cinit.dump_defs(file, happend, cappend)
+
+  hfile:close()
+  cfile:close()
+end