From 08e7ad94f99b5944405a40af5c28b9aa95e9c0b0 Mon Sep 17 00:00:00 2001
From: Joshua Haberman <jhaberman@gmail.com>
Date: Fri, 19 Aug 2011 22:30:13 -0700
Subject: Renamed lang_ext -> bindings, README updates.

---
 lang_ext/lua/upb.c | 1012 ----------------------------------------------------
 1 file changed, 1012 deletions(-)
 delete mode 100644 lang_ext/lua/upb.c

(limited to 'lang_ext/lua/upb.c')

diff --git a/lang_ext/lua/upb.c b/lang_ext/lua/upb.c
deleted file mode 100644
index fe523e7..0000000
--- a/lang_ext/lua/upb.c
+++ /dev/null
@@ -1,1012 +0,0 @@
-/*
- * upb - a minimalist implementation of protocol buffers.
- *
- * Copyright (c) 2009 Google Inc.  See LICENSE for details.
- * Author: Josh Haberman <jhaberman@gmail.com>
- *
- * A Lua extension for upb.
- */
-
-#include <stdlib.h>
-#include <math.h>
-#include <float.h>
-#include "lauxlib.h"
-#include "upb/def.h"
-#include "upb/msg.h"
-#include "upb/pb/glue.h"
-
-#if LUA_VERSION_NUM == 501
-#define lua_rawlen lua_objlen
-#endif
-
-static bool streql(const char *a, const char *b) { return strcmp(a, b) == 0; }
-
-static bool lupb_isint(double n) { return (double)(int)n == n; }
-
-static uint8_t lupb_touint8(lua_State *L, int narg, const char *name) {
-  lua_Number n = lua_tonumber(L, narg);
-  if (n > UINT8_MAX || n < 0 || rint(n) != n)
-    luaL_error(L, "Invalid %s", name);
-  return n;
-}
-
-static uint32_t lupb_touint32(lua_State *L, int narg, const char *name) {
-  lua_Number n = lua_tonumber(L, narg);
-  if (n > UINT32_MAX || n < 0 || rint(n) != n)
-    luaL_error(L, "Invalid %s", name);
-  return n;
-}
-
-static void lupb_pushstring(lua_State *L, upb_strref *ref) {
-  if (ref->ptr) {
-    lua_pushlstring(L, ref->ptr, ref->len);
-  } else {
-    // Lua requires a continguous string; must copy+allocate.
-    char *str = upb_strref_dup(ref);
-    lua_pushlstring(L, str, ref->len);
-    free(str);
-  }
-}
-
-static void lupb_pushvalue(lua_State *L, upb_value val, upb_fielddef *f) {
-  switch (f->type) {
-    case UPB_TYPE(INT32):
-    case UPB_TYPE(SINT32):
-    case UPB_TYPE(SFIXED32):
-    case UPB_TYPE(ENUM):
-      lua_pushnumber(L, upb_value_getint32(val)); break;
-    case UPB_TYPE(INT64):
-    case UPB_TYPE(SINT64):
-    case UPB_TYPE(SFIXED64):
-      lua_pushnumber(L, upb_value_getint64(val)); break;
-    case UPB_TYPE(UINT32):
-    case UPB_TYPE(FIXED32):
-      lua_pushnumber(L, upb_value_getuint32(val)); break;
-    case UPB_TYPE(UINT64):
-    case UPB_TYPE(FIXED64):
-      lua_pushnumber(L, upb_value_getuint64(val)); break;
-    case UPB_TYPE(DOUBLE):
-      lua_pushnumber(L, upb_value_getdouble(val)); break;
-    case UPB_TYPE(FLOAT):
-      lua_pushnumber(L, upb_value_getfloat(val)); break;
-    case UPB_TYPE(BOOL):
-      lua_pushboolean(L, upb_value_getbool(val)); break;
-    default: luaL_error(L, "internal error");
-  }
-}
-
-// Returns a scalar value (ie. not a submessage) as a upb_value.
-static upb_value lupb_getvalue(lua_State *L, int narg, upb_fielddef *f,
-                               upb_strref *ref) {
-  assert(!upb_issubmsg(f));
-  upb_value val;
-  if (upb_fielddef_type(f) == UPB_TYPE(BOOL)) {
-    if (!lua_isboolean(L, narg))
-      luaL_error(L, "Must explicitly pass true or false for boolean fields");
-    upb_value_setbool(&val, lua_toboolean(L, narg));
-  } else if (upb_fielddef_type(f) == UPB_TYPE(STRING)) {
-    size_t len;
-    ref->ptr = luaL_checklstring(L, narg, &len);
-    ref->len = len;
-    upb_value_setstrref(&val, ref);
-  } else {
-    // Numeric type.
-    lua_Number num = 0;
-    num = luaL_checknumber(L, narg);
-    switch (upb_fielddef_type(f)) {
-      case UPB_TYPE(INT32):
-      case UPB_TYPE(SINT32):
-      case UPB_TYPE(SFIXED32):
-      case UPB_TYPE(ENUM):
-        if (num > INT32_MAX || num < INT32_MIN || num != rint(num))
-          luaL_error(L, "Cannot convert %f to 32-bit integer", num);
-        upb_value_setint32(&val, num);
-        break;
-      case UPB_TYPE(INT64):
-      case UPB_TYPE(SINT64):
-      case UPB_TYPE(SFIXED64):
-        if (num > INT64_MAX || num < INT64_MIN || num != rint(num))
-          luaL_error(L, "Cannot convert %f to 64-bit integer", num);
-        upb_value_setint64(&val, num);
-        break;
-      case UPB_TYPE(UINT32):
-      case UPB_TYPE(FIXED32):
-        if (num > UINT32_MAX || num < 0 || num != rint(num))
-          luaL_error(L, "Cannot convert %f to unsigned 32-bit integer", num);
-        upb_value_setuint32(&val, num);
-        break;
-      case UPB_TYPE(UINT64):
-      case UPB_TYPE(FIXED64):
-        if (num > UINT64_MAX || num < 0 || num != rint(num))
-          luaL_error(L, "Cannot convert %f to unsigned 64-bit integer", num);
-        upb_value_setuint64(&val, num);
-        break;
-      case UPB_TYPE(DOUBLE):
-        if (num > DBL_MAX || num < -DBL_MAX) {
-          // This could happen if lua_Number was long double.
-          luaL_error(L, "Cannot convert %f to double", num);
-        }
-        upb_value_setdouble(&val, num);
-        break;
-      case UPB_TYPE(FLOAT):
-        if (num > FLT_MAX || num < -FLT_MAX)
-          luaL_error(L, "Cannot convert %f to float", num);
-        upb_value_setfloat(&val, num);
-        break;
-    }
-  }
-  return val;
-}
-
-static void lupb_typecheck(lua_State *L, int narg, upb_fielddef *f) {
-  upb_strref ref;
-  lupb_getvalue(L, narg, f, &ref);
-}
-
-//static void lupb_msg_getorcreate(lua_State *L, upb_msg *msg, upb_msgdef *md);
-static void lupb_fielddef_getorcreate(lua_State *L, upb_fielddef *f);
-static upb_msgdef *lupb_msgdef_check(lua_State *L, int narg);
-static void lupb_msg_pushnew(lua_State *L, void *md);
-
-void lupb_checkstatus(lua_State *L, upb_status *s) {
-  if (!upb_ok(s)) {
-    upb_status_print(s, stderr);
-    // Need to copy the string to the stack, so we can free it and not leak
-    // it (since luaL_error() does not return).
-    char buf[strlen(s->str)+1];
-    strcpy(buf, s->str);
-    upb_status_uninit(s);
-    luaL_error(L, "%s", buf);
-  }
-  upb_status_uninit(s);
-}
-
-
-/* object cache ***************************************************************/
-
-// We cache all the lua objects (userdata) we vend in a weak table, indexed by
-// the C pointer of the object they are caching.
-
-static void *lupb_cache_getorcreate_size(
-    lua_State *L, void *cobj, const char *type, size_t size) {
-  // Lookup our cache in the registry (we don't put our objects in the registry
-  // directly because we need our cache to be a weak table).
-  void **obj = NULL;
-  lua_getfield(L, LUA_REGISTRYINDEX, "upb.objcache");
-  assert(!lua_isnil(L, -1));  // Should have been created by luaopen_upb.
-  lua_pushlightuserdata(L, cobj);
-  lua_rawget(L, -2);
-  // Stack: objcache, cached value.
-  if (lua_isnil(L, -1)) {
-    // Remove bad cached value and push new value.
-    lua_pop(L, 1);
-    // We take advantage of the fact that all of our objects are currently a
-    // single pointer, and thus have the same layout.
-    obj = lua_newuserdata(L, size);
-    *obj = cobj;
-    luaL_getmetatable(L, type);
-    assert(!lua_isnil(L, -1));  // Should have been created by luaopen_upb.
-    lua_setmetatable(L, -2);
-
-    // Set it in the cache.
-    lua_pushlightuserdata(L, cobj);
-    lua_pushvalue(L, -2);
-    lua_rawset(L, -4);
-  }
-  lua_insert(L, -2);
-  lua_pop(L, 1);
-  return obj;
-}
-
-// Most types are just 1 pointer and can use this helper.
-static bool lupb_cache_getorcreate(lua_State *L, void *cobj, const char *type) {
-  return lupb_cache_getorcreate_size(L, cobj, type, sizeof(void*)) != NULL;
-}
-
-static void lupb_cache_create(lua_State *L, void *cobj, const char *type) {
-  bool created =
-      lupb_cache_getorcreate_size(L, cobj, type, sizeof(void*)) != NULL;
-  (void)created;  // For NDEBUG
-  assert(created);
-}
-
-
-/* lupb_def *******************************************************************/
-
-// All the def types share the same C layout, even though they are different Lua
-// types with different metatables.
-typedef struct {
-  upb_def *def;
-} lupb_def;
-
-static lupb_def *lupb_def_check(lua_State *L, int narg) {
-  void *ldef = luaL_checkudata(L, narg, "upb.msgdef");
-  if (!ldef) ldef = luaL_checkudata(L, narg, "upb.enumdef");
-  if (!ldef) luaL_typerror(L, narg, "upb def");
-  return ldef;
-}
-
-static void lupb_def_getorcreate(lua_State *L, upb_def *def, int owned) {
-  bool created = false;
-  switch(def->type) {
-    case UPB_DEF_MSG:
-      created = lupb_cache_getorcreate(L, def, "upb.msgdef");
-      break;
-    case UPB_DEF_ENUM:
-      created = lupb_cache_getorcreate(L, def, "upb.enumdef");
-      break;
-    default:
-      luaL_error(L, "unknown deftype %d", def->type);
-  }
-  if (!owned && created) {
-    upb_def_ref(def);
-  } else if (owned && !created) {
-    upb_def_unref(def);
-  }
-}
-
-
-/* lupb_fielddef **************************************************************/
-
-typedef struct {
-  upb_fielddef *field;
-} lupb_fielddef;
-
-static lupb_fielddef *lupb_fielddef_check(lua_State *L, int narg) {
-  lupb_fielddef *f = luaL_checkudata(L, narg, "upb.fielddef");
-  if (!f) luaL_typerror(L, narg, "upb fielddef");
-  return f;
-}
-
-static int lupb_fielddef_index(lua_State *L) {
-  lupb_fielddef *f = lupb_fielddef_check(L, 1);
-  const char *str = luaL_checkstring(L, 2);
-  if (streql(str, "name")) {
-    lua_pushstring(L, upb_fielddef_name(f->field));
-  } else if (streql(str, "number")) {
-    lua_pushinteger(L, upb_fielddef_number(f->field));
-  } else if (streql(str, "type")) {
-    lua_pushinteger(L, upb_fielddef_type(f->field));
-  } else if (streql(str, "label")) {
-    lua_pushinteger(L, upb_fielddef_label(f->field));
-  } else if (streql(str, "subdef")) {
-    lupb_def_getorcreate(L, upb_fielddef_subdef(f->field), false);
-  } else if (streql(str, "msgdef")) {
-    lupb_def_getorcreate(L, UPB_UPCAST(upb_fielddef_msgdef(f->field)), false);
-  } else {
-    luaL_error(L, "Invalid fielddef member '%s'", str);
-  }
-  return 1;
-}
-
-static void lupb_fielddef_set(lua_State *L, upb_fielddef *f,
-                              const char *field, int narg) {
-  if (!upb_fielddef_ismutable(f)) luaL_error(L, "fielddef is not mutable.");
-  if (streql(field, "name")) {
-    const char *name = lua_tostring(L, narg);
-    if (!name || !upb_fielddef_setname(f, name))
-      luaL_error(L, "Invalid name");
-  } else if (streql(field, "number")) {
-    if (!upb_fielddef_setnumber(f, lupb_touint32(L, narg, "number")))
-      luaL_error(L, "Invalid number");
-  } else if (streql(field, "type")) {
-    if (!upb_fielddef_settype(f, lupb_touint8(L, narg, "type")))
-      luaL_error(L, "Invalid type");
-  } else if (streql(field, "label")) {
-    if (!upb_fielddef_setlabel(f, lupb_touint8(L, narg, "label")))
-      luaL_error(L, "Invalid label");
-  } else if (streql(field, "type_name")) {
-    const char *name = lua_tostring(L, narg);
-    if (!name || !upb_fielddef_settypename(f, name))
-      luaL_error(L, "Invalid type_name");
-  } else if (streql(field, "default_value")) {
-    if (!upb_fielddef_type(f))
-      luaL_error(L, "Must set type before setting default_value");
-    upb_strref ref;
-    upb_fielddef_setdefault(f, lupb_getvalue(L, narg, f, &ref));
-  } else {
-    luaL_error(L, "Cannot set fielddef member '%s'", field);
-  }
-}
-
-static int lupb_fielddef_new(lua_State *L) {
-  upb_fielddef *f = upb_fielddef_new();
-  lupb_cache_create(L, f, "upb.fielddef");
-
-  if (lua_gettop(L) == 0) return 1;
-
-  // User can specify initialization values like so:
-  //   upb.FieldDef{label=upb.LABEL_REQUIRED, name="my_field", number=5,
-  //                type=upb.TYPE_INT32, default_value=12, type_name="Foo"}
-  luaL_checktype(L, 1, LUA_TTABLE);
-  // Iterate over table.
-  lua_pushnil(L);  // first key
-  while (lua_next(L, 1)) {
-    luaL_checktype(L, -2, LUA_TSTRING);
-    const char *key = lua_tostring(L, -2);
-    lupb_fielddef_set(L, f, key, -1);
-    lua_pop(L, 1);
-  }
-  return 1;
-}
-
-static void lupb_fielddef_getorcreate(lua_State *L, upb_fielddef *f) {
-  bool created = lupb_cache_getorcreate(L, f, "upb.fielddef");
-  if (created) upb_fielddef_ref(f);
-}
-
-static int lupb_fielddef_newindex(lua_State *L) {
-  lupb_fielddef *f = lupb_fielddef_check(L, 1);
-  lupb_fielddef_set(L, f->field, luaL_checkstring(L, 2), 3);
-  return 0;
-}
-
-static int lupb_fielddef_gc(lua_State *L) {
-  lupb_fielddef *lfielddef = lupb_fielddef_check(L, 1);
-  upb_fielddef_unref(lfielddef->field);
-  return 0;
-}
-
-static const struct luaL_Reg lupb_fielddef_mm[] = {
-  {"__gc", lupb_fielddef_gc},
-  {"__index", lupb_fielddef_index},
-  {"__newindex", lupb_fielddef_newindex},
-  {NULL, NULL}
-};
-
-
-/* lupb_msgdef ****************************************************************/
-
-static upb_msgdef *lupb_msgdef_check(lua_State *L, int narg) {
-  lupb_def *ldef = luaL_checkudata(L, narg, "upb.msgdef");
-  luaL_argcheck(L, ldef != NULL, narg, "upb msgdef expected");
-  return upb_downcast_msgdef(ldef->def);
-}
-
-static int lupb_msgdef_gc(lua_State *L) {
-  lupb_def *ldef = luaL_checkudata(L, 1, "upb.msgdef");
-  upb_def_unref(ldef->def);
-  return 0;
-}
-
-static int lupb_msgdef_call(lua_State *L) {
-  upb_msgdef *md = lupb_msgdef_check(L, 1);
-  lupb_msg_pushnew(L, md);
-  return 1;
-}
-
-static int lupb_msgdef_new(lua_State *L) {
-  upb_msgdef *md = upb_msgdef_new();
-  lupb_cache_create(L, md, "upb.msgdef");
-
-  if (lua_gettop(L) == 0) return 1;
-
-  // User can specify initialization values like so:
-  //   upb.MessageDef{fqname="MyMessage", extstart=8000, fields={...}}
-  luaL_checktype(L, 1, LUA_TTABLE);
-  // Iterate over table.
-  lua_pushnil(L);  // first key
-  while (lua_next(L, 1)) {
-    luaL_checktype(L, -2, LUA_TSTRING);
-    const char *key = lua_tostring(L, -2);
-
-    if (streql(key, "fqname")) {  // fqname="MyMessage"
-      const char *fqname = lua_tostring(L, -1);
-      if (!fqname || !upb_def_setfqname(UPB_UPCAST(md), fqname))
-        luaL_error(L, "Invalid fqname");
-    } else if (streql(key, "fields")) {  // fields={...}
-      // Iterate over the list of fields.
-      lua_pushnil(L);
-      luaL_checktype(L, -2, LUA_TTABLE);
-      while (lua_next(L, -2)) {
-        lupb_fielddef *f = lupb_fielddef_check(L, -1);
-        if (!upb_msgdef_addfield(md, f->field)) {
-          // TODO: more specific error.
-          luaL_error(L, "Could not add field.");
-        }
-        lua_pop(L, 1);
-      }
-    } else {
-      // TODO: extrange=
-      luaL_error(L, "Unknown initializer key '%s'", key);
-    }
-    lua_pop(L, 1);
-  }
-  return 1;
-}
-
-static int lupb_msgdef_fqname(lua_State *L) {
-  upb_msgdef *m = lupb_msgdef_check(L, 1);
-  lua_pushstring(L, m->base.fqname);
-  return 1;
-}
-
-static int lupb_msgdef_fieldbyname(lua_State *L) {
-  upb_msgdef *m = lupb_msgdef_check(L, 1);
-  upb_fielddef *f = upb_msgdef_ntof(m, luaL_checkstring(L, 2));
-  if (f) {
-    lupb_fielddef_getorcreate(L, f);
-  } else {
-    lua_pushnil(L);
-  }
-  return 1;
-}
-
-static int lupb_msgdef_fieldbynum(lua_State *L) {
-  upb_msgdef *m = lupb_msgdef_check(L, 1);
-  int num = luaL_checkint(L, 2);
-  upb_fielddef *f = upb_msgdef_itof(m, num);
-  if (f) {
-    lupb_fielddef_getorcreate(L, f);
-  } else {
-    lua_pushnil(L);
-  }
-  return 1;
-}
-
-static const struct luaL_Reg lupb_msgdef_mm[] = {
-  {"__call", lupb_msgdef_call},
-  {"__gc", lupb_msgdef_gc},
-  {NULL, NULL}
-};
-
-static const struct luaL_Reg lupb_msgdef_m[] = {
-  {"fieldbyname", lupb_msgdef_fieldbyname},
-  {"fieldbynum", lupb_msgdef_fieldbynum},
-  {"fqname", lupb_msgdef_fqname},
-  {NULL, NULL}
-};
-
-
-/* lupb_enumdef ***************************************************************/
-
-static upb_enumdef *lupb_enumdef_check(lua_State *L, int narg) {
-  lupb_def *ldef = luaL_checkudata(L, narg, "upb.enumdef");
-  return upb_downcast_enumdef(ldef->def);
-}
-
-static int lupb_enumdef_gc(lua_State *L) {
-  upb_enumdef *e = lupb_enumdef_check(L, 1);
-  upb_def_unref(UPB_UPCAST(e));
-  return 0;
-}
-
-static int lupb_enumdef_name(lua_State *L) {
-  upb_enumdef *e = lupb_enumdef_check(L, 1);
-  lua_pushstring(L, e->base.fqname);
-  return 1;
-}
-
-static const struct luaL_Reg lupb_enumdef_mm[] = {
-  {"__gc", lupb_enumdef_gc},
-  {NULL, NULL}
-};
-
-static const struct luaL_Reg lupb_enumdef_m[] = {
-  {"name", lupb_enumdef_name},
-  {NULL, NULL}
-};
-
-
-/* lupb_symtab ****************************************************************/
-
-typedef struct {
-  upb_symtab *symtab;
-} lupb_symtab;
-
-static upb_accessor_vtbl *lupb_accessor(upb_fielddef *f);
-
-// Inherits a ref on the symtab.
-// Checks that narg is a proper lupb_symtab object.  If it is, leaves its
-// metatable on the stack for cache lookups/updates.
-lupb_symtab *lupb_symtab_check(lua_State *L, int narg) {
-  return luaL_checkudata(L, narg, "upb.symtab");
-}
-
-// narg is a lua table containing a list of defs to add.
-void lupb_symtab_doadd(lua_State *L, upb_symtab *s, int narg) {
-  luaL_checktype(L, narg, LUA_TTABLE);
-  // Iterate over table twice.  First iteration to count entries and
-  // check constraints.
-  int n = 0;
-  lua_pushnil(L);  // first key
-  while (lua_next(L, narg)) {
-    lupb_def_check(L, -1);
-    ++n;
-    lua_pop(L, 1);
-  }
-
-  // Second iteration to build deflist and layout.
-  upb_def **defs = malloc(n * sizeof(*defs));
-  n = 0;
-  lua_pushnil(L);  // first key
-  while (lua_next(L, 1)) {
-    upb_def *def = lupb_def_check(L, -1)->def;
-    defs[n++] = def;
-    upb_msgdef *md = upb_dyncast_msgdef(def);
-    if (md) {
-      upb_msg_iter i;
-      for(i = upb_msg_begin(md); !upb_msg_done(i); i = upb_msg_next(md, i)) {
-        upb_fielddef *f = upb_msg_iter_field(i);
-        upb_fielddef_setaccessor(f, lupb_accessor(f));
-      }
-      upb_msgdef_layout(md);
-    }
-    lua_pop(L, 1);
-  }
-
-  upb_status status = UPB_STATUS_INIT;
-  upb_symtab_add(s, defs, n, &status);
-  free(defs);
-  lupb_checkstatus(L, &status);
-}
-
-static int lupb_symtab_new(lua_State *L) {
-  upb_symtab *s = upb_symtab_new();
-  lupb_cache_create(L, s, "upb.symtab");
-  if (lua_gettop(L) == 0) return 1;
-  lupb_symtab_doadd(L, s, 1);
-  return 1;
-}
-
-static int lupb_symtab_add(lua_State *L) {
-  lupb_symtab *s = lupb_symtab_check(L, 1);
-  lupb_symtab_doadd(L, s->symtab, 2);
-  return 0;
-}
-
-static int lupb_symtab_gc(lua_State *L) {
-  lupb_symtab *s = lupb_symtab_check(L, 1);
-  upb_symtab_unref(s->symtab);
-  return 0;
-}
-
-static int lupb_symtab_lookup(lua_State *L) {
-  lupb_symtab *s = lupb_symtab_check(L, 1);
-  for (int i = 2; i <= lua_gettop(L); i++) {
-    upb_def *def = upb_symtab_lookup(s->symtab, luaL_checkstring(L, i));
-    if (def) {
-      lupb_def_getorcreate(L, def, true);
-    } else {
-      lua_pushnil(L);
-    }
-    lua_replace(L, i);
-  }
-  return lua_gettop(L) - 1;
-}
-
-static int lupb_symtab_getdefs(lua_State *L) {
-  lupb_symtab *s = lupb_symtab_check(L, 1);
-  upb_deftype_t type = luaL_checkint(L, 2);
-  int count;
-  upb_def **defs = upb_symtab_getdefs(s->symtab, &count, type);
-
-  // Create the table in which we will return the defs.
-  lua_createtable(L, count, 0);
-  for (int i = 0; i < count; i++) {
-    upb_def *def = defs[i];
-    lupb_def_getorcreate(L, def, true);
-    lua_rawseti(L, -2, i + 1);
-  }
-  free(defs);
-  return 1;
-}
-
-static const struct luaL_Reg lupb_symtab_m[] = {
-  {"add", lupb_symtab_add},
-  {"getdefs", lupb_symtab_getdefs},
-  {"lookup", lupb_symtab_lookup},
-  {NULL, NULL}
-};
-
-static const struct luaL_Reg lupb_symtab_mm[] = {
-  {"__gc", lupb_symtab_gc},
-  {NULL, NULL}
-};
-
-
-/* lupb_msg********************************************************************/
-
-// Messages are userdata.  Primitive values (numbers and bools, and their
-// hasbits) are stored right in the userdata.  Other values are stored using
-// integer entries in the environment table and no hasbits are used (since
-// "nil" in the environment table can indicate "not present").
-//
-// The environment table looks like:
-//   {msgdef, <string, submessage, and array fields>}
-
-// Must pass a upb_fielddef as the pointer.
-static void lupb_array_pushnew(lua_State *L, void *f);
-
-static void *lupb_msg_check(lua_State *L, int narg, upb_msgdef **md) {
-  void *msg = luaL_checkudata(L, narg, "upb.msg");
-  luaL_argcheck(L, msg != NULL, narg, "msg expected");
-  // If going all the way to the environment table for the msgdef is an
-  // efficiency issue, we could put the pointer right in the userdata.
-  lua_getfenv(L, narg);
-  lua_rawgeti(L, -1, 1);
-  // Shouldn't have to check msgdef userdata validity, environment table can't
-  // be accessed from Lua.
-  lupb_def *lmd = lua_touserdata(L, -1);
-  *md = upb_downcast_msgdef(lmd->def);
-  return msg;
-}
-
-static void lupb_msg_pushnew(lua_State *L, void *md) {
-  void *msg = lua_newuserdata(L, upb_msgdef_size(md));
-  luaL_getmetatable(L, "upb.msg");
-  assert(!lua_isnil(L, -1));  // Should have been created by luaopen_upb.
-  lua_setmetatable(L, -2);
-  upb_msg_clear(msg, md);
-  lua_getfenv(L, -1);
-  lupb_cache_getorcreate(L, md, "upb.msgdef");
-  lua_rawseti(L, -2, 1);
-  lua_pop(L, 1);  // Pop the fenv.
-}
-
-static int lupb_msg_new(lua_State *L) {
-  upb_msgdef *md = lupb_msgdef_check(L, 1);
-  lupb_msg_pushnew(L, md);
-  return 1;
-}
-
-static int lupb_msg_index(lua_State *L) {
-  upb_msgdef *md;
-  void *m = lupb_msg_check(L, 1, &md);
-  upb_fielddef *f = upb_msgdef_ntof(md, luaL_checkstring(L, 2));
-  if (!f) luaL_argerror(L, 2, "not a field name");
-  if (upb_isprimitivetype(upb_fielddef_type(f))) {
-    upb_value v = upb_msg_has(m, f) ? upb_msg_get(m, f) : upb_fielddef_default(f);
-    lupb_pushvalue(L, v, f);
-  } else {
-    lua_getfenv(L, 1);
-    lua_rawgeti(L, -1, f->offset);
-    if (lua_isnil(L, -1)) {
-      // Need to lazily create array, string, or submessage.
-      if (upb_isseq(f)) {
-        lupb_array_pushnew(L, f);
-      } else if (upb_isstring(f)) {
-        // TODO: (need to figure out default string ownership).
-      } else if (upb_issubmsg(f)) {
-        lupb_msg_pushnew(L, upb_downcast_msgdef(upb_fielddef_subdef(f)));
-      } else {
-        luaL_error(L, "internal error");
-      }
-      lua_rawseti(L, -2, f->offset);
-    }
-  }
-  return 1;
-}
-
-static int lupb_msg_newindex(lua_State *L) {
-  upb_msgdef *md;
-  void *m = lupb_msg_check(L, 1, &md);
-  upb_fielddef *f = upb_msgdef_ntof(md, luaL_checkstring(L, 2));
-  if (!f) luaL_error(L, "not a field name");
-  if (upb_isprimitivetype(upb_fielddef_type(f))) {
-    if (lua_isnil(L, 3))
-      upb_msg_clearbit(m, f);
-    else
-      upb_msg_set(m, f, lupb_getvalue(L, 3, f, NULL));
-  } else {
-    if (!lua_isnil(L, 3)) lupb_typecheck(L, 3, f);
-    lua_getfenv(L, 1);
-    lua_pushvalue(L, 3);
-    lua_rawseti(L, -1, f->offset);
-  }
-  return 0;
-}
-
-static const struct luaL_Reg lupb_msg_mm[] = {
-  {"__index", lupb_msg_index},
-  {"__newindex", lupb_msg_newindex},
-  {NULL, NULL}
-};
-
-// Functions that operate on msgdefs but do not live in the msgdef namespace.
-static int lupb_clear(lua_State *L) {
-  upb_msgdef *md;
-  void *m = lupb_msg_check(L, 1, &md);
-  upb_msg_clear(m, md);
-  return 0;
-}
-
-static int lupb_has(lua_State *L) {
-  upb_msgdef *md;
-  void *m = lupb_msg_check(L, 1, &md);
-  upb_fielddef *f = upb_msgdef_ntof(md, luaL_checkstring(L, 2));
-  if (!f) luaL_argerror(L, 2, "not a field name");
-  lua_pushboolean(L, upb_msg_has(m, f));
-  return 1;
-}
-
-static int lupb_msgdef(lua_State *L) {
-  upb_msgdef *md;
-  lupb_msg_check(L, 1, &md);
-  lupb_def_getorcreate(L, UPB_UPCAST(md), false);
-  return 1;
-}
-
-// Accessors for arrays, strings, and submessages need access to the current
-// userdata's environment table, which can only be stored in Lua space.
-// Options for storing it are:
-//
-// - put the env tables for all messages and arrays in the registry, keyed by
-//   userdata pointer (light userdata), or by a reference using luaL_ref().
-//   Then we can just let upb's parse stack track the stack of env tables.
-//   Easy but requires all messages and arrays to be in the registry, which
-//   seems too heavyweight.
-//
-// - store the stack of env tables in the Lua stack.  Convenient, but requires
-//   special code to handle resumable decoders.
-//
-// There is also the question of how to obtain the lua_State* pointer.
-// The main options for this are:
-//
-// - make our closure point to a struct:
-//     struct { void *msg; lua_State *L; }
-//   But then we can't use standard accessors, which expect the closure
-//   to point to the data itself.  Using the standard accessors for
-//   primitive values is both a simplicity and a performance win.
-//
-// - store a lua_State* pointer inside each userdata.  Convenient and
-//   efficient, but makes every message sizeof(void*) larger.
-//   Currently we take this route.
-//
-// - use thread-local storage.  Convenient and efficient, but not portable.
-
-typedef void createfunc_t(lua_State *L, void *param);
-
-static upb_sflow_t lupb_msg_start(void *m, upb_fielddef *f, bool array,
-                                  createfunc_t *pushnew, void *param) {
-  lua_State *L = *(lua_State**)m;
-  int offset = array ? lua_rawlen(L, -1) : f->offset;
-  if (!lua_checkstack(L, 3)) luaL_error(L, "stack full");
-  lua_rawgeti(L, -1, offset);
-  if (lua_isnil(L, -1)) {
-    lua_pop(L, 1);
-    pushnew(L, param);
-    lua_pushvalue(L, -1);
-    lua_rawseti(L, -3, offset);
-  }
-  void *subval = lua_touserdata(L, -1);
-  lua_getfenv(L, -1);
-  lua_replace(L, -2);  // Replace subval userdata with fenv.
-  return UPB_CONTINUE_WITH(subval);
-}
-
-static upb_flow_t lupb_msg_string(void *m, upb_value fval, upb_value val,
-                                  bool array) {
-  // Could add lazy materialization of strings here.
-  upb_fielddef *f = upb_value_getfielddef(fval);
-  lua_State *L = *(lua_State**)m;
-  int offset = array ? lua_rawlen(L, -1) : f->offset;
-  if (!lua_checkstack(L, 1)) luaL_error(L, "stack full");
-  lupb_pushstring(L, upb_value_getstrref(val));
-  lua_rawseti(L, -2, offset);
-  return UPB_CONTINUE;
-}
-
-static upb_sflow_t lupb_msg_startseq(void *m, upb_value fval) {
-  upb_fielddef *f = upb_value_getfielddef(fval);
-  return lupb_msg_start(m, f, false, lupb_array_pushnew, f);
-}
-
-static upb_sflow_t lupb_msg_startsubmsg(void *m, upb_value fval) {
-  upb_fielddef *f = upb_value_getfielddef(fval);
-  return lupb_msg_start(m, f, false, lupb_msg_pushnew, upb_fielddef_subdef(f));
-}
-
-static upb_sflow_t lupb_msg_startsubmsg_r(void *a, upb_value fval) {
-  upb_fielddef *f = upb_value_getfielddef(fval);
-  return lupb_msg_start(a, f, true, lupb_msg_pushnew, upb_fielddef_subdef(f));
-}
-
-static upb_flow_t lupb_msg_stringval(void *m, upb_value fval, upb_value val) {
-  return lupb_msg_string(m, fval, val, false);
-}
-
-static upb_flow_t lupb_msg_stringval_r(void *a, upb_value fval, upb_value val) {
-  return lupb_msg_string(a, fval, val, true);
-}
-
-#define STDMSG(type, size) static upb_accessor_vtbl vtbl = { \
-    &lupb_msg_startsubmsg, \
-    &upb_stdmsg_set ## type, \
-    &lupb_msg_startseq, \
-    &lupb_msg_startsubmsg_r, \
-    &upb_stdmsg_set ## type ## _r, \
-    &upb_stdmsg_has, \
-    &upb_stdmsg_getptr, \
-    &upb_stdmsg_get ## type, \
-    &upb_stdmsg_seqbegin, \
-    &upb_stdmsg_ ## size ## byte_seqnext, \
-    &upb_stdmsg_seqget ## type};
-
-#define RETURN_STDMSG(type, size) { STDMSG(type, size); return &vtbl; }
-
-static upb_accessor_vtbl *lupb_accessor(upb_fielddef *f) {
-  switch (f->type) {
-    case UPB_TYPE(DOUBLE): RETURN_STDMSG(double, 8)
-    case UPB_TYPE(FLOAT): RETURN_STDMSG(float, 4)
-    case UPB_TYPE(UINT64):
-    case UPB_TYPE(FIXED64): RETURN_STDMSG(uint64, 8)
-    case UPB_TYPE(INT64):
-    case UPB_TYPE(SFIXED64):
-    case UPB_TYPE(SINT64): RETURN_STDMSG(int64, 8)
-    case UPB_TYPE(INT32):
-    case UPB_TYPE(SINT32):
-    case UPB_TYPE(ENUM):
-    case UPB_TYPE(SFIXED32): RETURN_STDMSG(int32, 4)
-    case UPB_TYPE(UINT32):
-    case UPB_TYPE(FIXED32): RETURN_STDMSG(uint32, 4)
-    case UPB_TYPE(BOOL): { STDMSG(bool, 1); return &vtbl; }
-    case UPB_TYPE(GROUP):
-    case UPB_TYPE(MESSAGE): RETURN_STDMSG(ptr, 8)  // TODO: 32-bit
-    case UPB_TYPE(STRING):
-    case UPB_TYPE(BYTES): {
-      STDMSG(ptr, 8);
-      vtbl.set = &lupb_msg_stringval;
-      vtbl.append = &lupb_msg_stringval_r;
-      return &vtbl;
-    }
-  }
-  return NULL;
-}
-
-
-/* lupb_array ****************************************************************/
-
-// Array: we store all elements in the environment table.  Could optimize by
-// storing primitive arrays in our own memory; this would be significantly more
-// space efficient.  Lua array elements are 16 bytes each; our own array would
-// be 1/4 the space for 32-bit integers, or 1/16 the space for booleans.
-//
-// The first element of the environment table stores our type (which will be
-// either an integer from upb.TYPE_* or a upb.msgdef), the remaining elements
-// store the elements.  We always keep all elements contiguous so we can use
-// lua_objlen()/lua_rawlen() (for Lua 5.1/5.2 respectively) to report its len).
-
-// narg is offset of environment table.
-static size_t lupb_array_getlen(lua_State *L, int narg) {
-  return lua_rawlen(L, narg) - 1;
-}
-
-static void lupb_array_check(lua_State *L, int narg) {
-  if (!luaL_checkudata(L, narg, "upb.array"))
-    luaL_typerror(L, narg, "upb array");
-}
-
-static void lupb_array_pushnew(lua_State *L, void *f) {
-  (void)L;
-  (void)f;
-}
-
-static int lupb_array_new(lua_State *L) {
-  (void)L;
-  return 0;
-}
-
-static int lupb_array_len(lua_State *L) {
-  lupb_array_check(L, 1);
-  lua_getfenv(L, 1);
-  lua_pushnumber(L, lupb_array_getlen(L, -1));
-  return 1;
-}
-
-static int lupb_array_index(lua_State *L) {
-  assert(lua_gettop(L) == 2);  // __index should always be called with 2 args.
-  lupb_array_check(L, 1);
-  lua_Number num = luaL_checknumber(L, 2);
-  if (!lupb_isint(num)) luaL_typerror(L, 2, "integer");
-
-  lua_getfenv(L, 1);
-  size_t len = lupb_array_getlen(L, -1);
-  if (num < 1 || num > len) luaL_error(L, "array bounds check failed");
-  lua_rawgeti(L, -1, num + 1);
-  return 1;
-}
-
-static int lupb_array_newindex(lua_State *L) {
-  assert(lua_gettop(L) == 3);  // __newindex should always be called with 3 args.
-  lupb_array_check(L, 1);
-  lua_Number num = luaL_checknumber(L, 2);
-  if (rint(num) != num) luaL_typerror(L, 2, "integer");
-
-  lua_getfenv(L, 1);
-  size_t len = lupb_array_getlen(L, -1);
-  // We only allow extending the index one beyond the end.
-  if (num < 1 || num > len + 1) luaL_error(L, "array bounds check failed");
-  lua_pushvalue(L, 3);
-  lua_rawseti(L, -2, num);
-  return 0;
-}
-
-static const struct luaL_Reg lupb_array_mm[] = {
-  {"__len", lupb_array_len},
-  {"__index", lupb_array_index},
-  {"__newindex", lupb_array_newindex},
-  {NULL, NULL}
-};
-
-/* lupb toplevel **************************************************************/
-
-static const struct luaL_Reg lupb_toplevel_m[] = {
-  {"SymbolTable", lupb_symtab_new},
-  {"MessageDef", lupb_msgdef_new},
-  {"FieldDef", lupb_fielddef_new},
-
-  {"Message", lupb_msg_new},
-  {"Array", lupb_array_new},
-
-  {"clear", lupb_clear},
-  {"msgdef", lupb_msgdef},
-  {"has", lupb_has},
-
-  {NULL, NULL}
-};
-
-// Register the given type with the given methods and metamethods.
-static void lupb_register_type(lua_State *L, const char *name,
-                               const luaL_Reg *m, const luaL_Reg *mm) {
-  luaL_newmetatable(L, name);
-  luaL_register(L, NULL, mm);  // Register all mm in the metatable.
-  lua_createtable(L, 0, 0);
-  if (m) {
-    // Methods go in the mt's __index method.  This implies that you can't
-    // implement __index and also set methods yourself.
-    luaL_register(L, NULL, m);
-    lua_setfield(L, -2, "__index");
-  }
-  lua_pop(L, 1);  // The mt.
-}
-
-static void lupb_setfieldi(lua_State *L, const char *field, int i) {
-  lua_pushnumber(L, i);
-  lua_setfield(L, -2, field);
-}
-
-int luaopen_upb(lua_State *L) {
-  lupb_register_type(L, "upb.msgdef", lupb_msgdef_m, lupb_msgdef_mm);
-  lupb_register_type(L, "upb.enumdef", lupb_enumdef_m, lupb_enumdef_mm);
-  lupb_register_type(L, "upb.fielddef", NULL, lupb_fielddef_mm);
-  lupb_register_type(L, "upb.symtab", lupb_symtab_m, lupb_symtab_mm);
-
-  lupb_register_type(L, "upb.msg", NULL, lupb_msg_mm);
-  lupb_register_type(L, "upb.array", NULL, lupb_msg_mm);
-
-  // Create our object cache.
-  lua_createtable(L, 0, 0);
-  lua_createtable(L, 0, 1);  // Cache metatable.
-  lua_pushstring(L, "v");    // Values are weak.
-  lua_setfield(L, -2, "__mode");
-  lua_setfield(L, LUA_REGISTRYINDEX, "upb.objcache");
-
-  luaL_register(L, "upb", lupb_toplevel_m);
-
-  // Register constants.
-  lupb_setfieldi(L, "LABEL_OPTIONAL", UPB_LABEL(OPTIONAL));
-  lupb_setfieldi(L, "LABEL_REQUIRED", UPB_LABEL(REQUIRED));
-  lupb_setfieldi(L, "LABEL_REPEATED", UPB_LABEL(REPEATED));
-
-  lupb_setfieldi(L, "TYPE_DOUBLE", UPB_TYPE(DOUBLE));
-  lupb_setfieldi(L, "TYPE_FLOAT", UPB_TYPE(FLOAT));
-  lupb_setfieldi(L, "TYPE_INT64", UPB_TYPE(INT64));
-  lupb_setfieldi(L, "TYPE_UINT64", UPB_TYPE(UINT64));
-  lupb_setfieldi(L, "TYPE_INT32", UPB_TYPE(INT32));
-  lupb_setfieldi(L, "TYPE_FIXED64", UPB_TYPE(FIXED64));
-  lupb_setfieldi(L, "TYPE_FIXED32", UPB_TYPE(FIXED32));
-  lupb_setfieldi(L, "TYPE_BOOL", UPB_TYPE(BOOL));
-  lupb_setfieldi(L, "TYPE_STRING", UPB_TYPE(STRING));
-  lupb_setfieldi(L, "TYPE_GROUP", UPB_TYPE(GROUP));
-  lupb_setfieldi(L, "TYPE_MESSAGE", UPB_TYPE(MESSAGE));
-  lupb_setfieldi(L, "TYPE_BYTES", UPB_TYPE(BYTES));
-  lupb_setfieldi(L, "TYPE_UINT32", UPB_TYPE(UINT32));
-  lupb_setfieldi(L, "TYPE_ENUM", UPB_TYPE(ENUM));
-  lupb_setfieldi(L, "TYPE_SFIXED32", UPB_TYPE(SFIXED32));
-  lupb_setfieldi(L, "TYPE_SFIXED64", UPB_TYPE(SFIXED64));
-  lupb_setfieldi(L, "TYPE_SINT32", UPB_TYPE(SINT32));
-  lupb_setfieldi(L, "TYPE_SINT64", UPB_TYPE(SINT64));
-
-  return 1;  // Return package table.
-}
-- 
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