Mass API rename and clang-reformat (#485)

* Wave 1: upb_fielddef.

* upb_fielddef itself.

* upb_oneofdef.

* upb_msgdef.

* ExtensionRange.

* upb_enumdef

* upb_enumvaldef

* upb_filedef

* upb_methoddef

* upb_servicedef

* upb_symtab

* upb_defpool_init

* upb_wellknown and upb_syntax_t

* Some constants.

* upb_status

* upb_strview

* upb_arena

* upb.h constants

* reflection

* encode

* JSON decode.

* json encode.

* msg_internal.

* Formatted with clang-format.

* Some naming fixups and comment reformatting.

* More refinements.

* A few more stragglers.

* Fixed PyObject_HEAD with semicolon. Removed TODO entries.
diff --git a/python/descriptor_pool.c b/python/descriptor_pool.c
index 7a39403..95e14fe 100644
--- a/python/descriptor_pool.c
+++ b/python/descriptor_pool.c
@@ -27,21 +27,21 @@
 
 #include "python/descriptor_pool.h"
 
+#include "google/protobuf/descriptor.upbdefs.h"
 #include "python/convert.h"
 #include "python/descriptor.h"
 #include "python/message.h"
 #include "python/protobuf.h"
 #include "upb/def.h"
 #include "upb/util/def_to_proto.h"
-#include "google/protobuf/descriptor.upbdefs.h"
 
 // -----------------------------------------------------------------------------
 // DescriptorPool
 // -----------------------------------------------------------------------------
 
 typedef struct {
-  PyObject_HEAD
-  upb_symtab* symtab;
+  PyObject_HEAD;
+  upb_DefPool* symtab;
   PyObject* db;  // The DescriptorDatabase underlying this pool.  May be NULL.
 } PyUpb_DescriptorPool;
 
@@ -50,10 +50,10 @@
   return s->default_pool;
 }
 
-const upb_msgdef* PyUpb_DescriptorPool_GetFileProtoDef(void) {
+const upb_MessageDef* PyUpb_DescriptorPool_GetFileProtoDef(void) {
   PyUpb_ModuleState* s = PyUpb_ModuleState_Get();
   if (!s->c_descriptor_symtab) {
-    s->c_descriptor_symtab = upb_symtab_new();
+    s->c_descriptor_symtab = upb_DefPool_New();
   }
   return google_protobuf_FileDescriptorProto_getmsgdef(s->c_descriptor_symtab);
 }
@@ -61,7 +61,7 @@
 static PyObject* PyUpb_DescriptorPool_DoCreateWithCache(
     PyTypeObject* type, PyObject* db, PyUpb_WeakMap* obj_cache) {
   PyUpb_DescriptorPool* pool = (void*)PyType_GenericAlloc(type, 0);
-  pool->symtab = upb_symtab_new();
+  pool->symtab = upb_DefPool_New();
   pool->db = db;
   Py_XINCREF(pool->db);
   PyUpb_WeakMap_Add(obj_cache, pool->symtab, &pool->ob_base);
@@ -74,7 +74,7 @@
                                                 PyUpb_ObjCache_Instance());
 }
 
-upb_symtab* PyUpb_DescriptorPool_GetSymtab(PyObject* pool) {
+upb_DefPool* PyUpb_DescriptorPool_GetSymtab(PyObject* pool) {
   return ((PyUpb_DescriptorPool*)pool)->symtab;
 }
 
@@ -89,7 +89,7 @@
   return 0;
 }
 
-PyObject* PyUpb_DescriptorPool_Get(const upb_symtab* symtab) {
+PyObject* PyUpb_DescriptorPool_Get(const upb_DefPool* symtab) {
   PyObject* pool = PyUpb_ObjCache_Get(symtab);
   assert(pool);
   return pool;
@@ -97,7 +97,7 @@
 
 static void PyUpb_DescriptorPool_Dealloc(PyUpb_DescriptorPool* self) {
   PyUpb_DescriptorPool_Clear(self);
-  upb_symtab_free(self->symtab);
+  upb_DefPool_Free(self->symtab);
   PyUpb_ObjCache_Delete(self->symtab);
   PyUpb_Dealloc(self);
 }
@@ -158,18 +158,16 @@
   return ret;
 }
 
-bool PyUpb_DescriptorPool_CheckNoDatabase(PyObject* _self) {
-  return true;
-}
+bool PyUpb_DescriptorPool_CheckNoDatabase(PyObject* _self) { return true; }
 
 static bool PyUpb_DescriptorPool_LoadDependentFiles(
     PyUpb_DescriptorPool* self, google_protobuf_FileDescriptorProto* proto) {
   size_t n;
-  const upb_strview* deps =
+  const upb_StringView* deps =
       google_protobuf_FileDescriptorProto_dependency(proto, &n);
   for (size_t i = 0; i < n; i++) {
-    const upb_filedef* dep =
-        upb_symtab_lookupfile2(self->symtab, deps[i].data, deps[i].size);
+    const upb_FileDef* dep = upb_DefPool_FindFileByNameWithSize(
+        self->symtab, deps[i].data, deps[i].size);
     if (!dep) {
       PyObject* filename =
           PyUnicode_FromStringAndSize(deps[i].data, deps[i].size);
@@ -185,7 +183,7 @@
 static PyObject* PyUpb_DescriptorPool_DoAddSerializedFile(
     PyObject* _self, PyObject* serialized_pb) {
   PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
-  upb_arena* arena = upb_arena_new();
+  upb_Arena* arena = upb_Arena_New();
   if (!arena) PYUPB_RETURN_OOM;
   PyObject* result = NULL;
 
@@ -202,9 +200,9 @@
     goto done;
   }
 
-  upb_strview name = google_protobuf_FileDescriptorProto_name(proto);
-  const upb_filedef* file =
-      upb_symtab_lookupfile2(self->symtab, name.data, name.size);
+  upb_StringView name = google_protobuf_FileDescriptorProto_name(proto);
+  const upb_FileDef* file =
+      upb_DefPool_FindFileByNameWithSize(self->symtab, name.data, name.size);
 
   if (file) {
     // If the existing file is equal to the new file, then silently ignore the
@@ -215,7 +213,7 @@
       PyErr_SetNone(PyExc_MemoryError);
       goto done;
     }
-    const upb_msgdef* m = PyUpb_DescriptorPool_GetFileProtoDef();
+    const upb_MessageDef* m = PyUpb_DescriptorPool_GetFileProtoDef();
     if (PyUpb_Message_IsEqual(proto, existing, m)) {
       Py_INCREF(Py_None);
       result = Py_None;
@@ -227,21 +225,22 @@
     if (!PyUpb_DescriptorPool_LoadDependentFiles(self, proto)) goto done;
   }
 
-  upb_status status;
-  upb_status_clear(&status);
+  upb_Status status;
+  upb_Status_Clear(&status);
 
-  const upb_filedef* filedef = upb_symtab_addfile(self->symtab, proto, &status);
+  const upb_FileDef* filedef =
+      upb_DefPool_AddFile(self->symtab, proto, &status);
   if (!filedef) {
     PyErr_Format(PyExc_TypeError,
                  "Couldn't build proto file into descriptor pool: %s",
-                 upb_status_errmsg(&status));
+                 upb_Status_ErrorMessage(&status));
     goto done;
   }
 
   result = PyUpb_FileDescriptor_Get(filedef);
 
 done:
-  upb_arena_free(arena);
+  upb_Arena_Free(arena);
   return result;
 }
 
@@ -249,9 +248,9 @@
                                             PyObject* file_desc) {
   PyObject* subargs = PyTuple_New(0);
   if (!PyUpb_CMessage_Check(file_desc)) return NULL;
-  const upb_msgdef* m = PyUpb_CMessage_GetMsgdef(file_desc);
+  const upb_MessageDef* m = PyUpb_CMessage_GetMsgdef(file_desc);
   const char* file_proto_name = "google.protobuf.FileDescriptorProto";
-  if (strcmp(upb_msgdef_fullname(m), file_proto_name) != 0) {
+  if (strcmp(upb_MessageDef_FullName(m), file_proto_name) != 0) {
     return PyErr_Format(PyExc_TypeError, "Can only add FileDescriptorProto");
   }
   PyObject* serialized =
@@ -272,7 +271,7 @@
  * Adds the given serialized FileDescriptorProto to the pool.
  */
 static PyObject* PyUpb_DescriptorPool_AddSerializedFile(
-    PyObject * _self, PyObject * serialized_pb) {
+    PyObject* _self, PyObject* serialized_pb) {
   PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
   if (self->db) {
     PyErr_SetString(
@@ -310,10 +309,10 @@
   const char* name = PyUpb_GetStrData(arg);
   if (!name) return NULL;
 
-  const upb_filedef* file = upb_symtab_lookupfile(self->symtab, name);
+  const upb_FileDef* file = upb_DefPool_FindFileByName(self->symtab, name);
   if (file == NULL && self->db) {
     if (!PyUpb_DescriptorPool_TryLoadFilename(self, arg)) return NULL;
-    file = upb_symtab_lookupfile(self->symtab, name);
+    file = upb_DefPool_FindFileByName(self->symtab, name);
   }
   if (file == NULL) {
     return PyErr_Format(PyExc_KeyError, "Couldn't find file %.200s", name);
@@ -335,10 +334,11 @@
   const char* name = PyUpb_GetStrData(arg);
   if (!name) return NULL;
 
-  const upb_fielddef* field = upb_symtab_lookupext(self->symtab, name);
+  const upb_FieldDef* field =
+      upb_DefPool_FindExtensionByName(self->symtab, name);
   if (field == NULL && self->db) {
     if (!PyUpb_DescriptorPool_TryLoadSymbol(self, arg)) return NULL;
-    field = upb_symtab_lookupext(self->symtab, name);
+    field = upb_DefPool_FindExtensionByName(self->symtab, name);
   }
   if (field == NULL) {
     return PyErr_Format(PyExc_KeyError, "Couldn't find extension %.200s", name);
@@ -360,10 +360,10 @@
   const char* name = PyUpb_GetStrData(arg);
   if (!name) return NULL;
 
-  const upb_msgdef* m = upb_symtab_lookupmsg(self->symtab, name);
+  const upb_MessageDef* m = upb_DefPool_FindMessageByName(self->symtab, name);
   if (m == NULL && self->db) {
     if (!PyUpb_DescriptorPool_TryLoadSymbol(self, arg)) return NULL;
-    m = upb_symtab_lookupmsg(self->symtab, name);
+    m = upb_DefPool_FindMessageByName(self->symtab, name);
   }
   if (m == NULL) {
     return PyErr_Format(PyExc_KeyError, "Couldn't find message %.200s", name);
@@ -397,14 +397,13 @@
   if (!name) return NULL;
 
   size_t parent_size;
-  const char* child =
-      PyUpb_DescriptorPool_SplitSymbolName(name, &parent_size);
-  const upb_fielddef* f = NULL;
+  const char* child = PyUpb_DescriptorPool_SplitSymbolName(name, &parent_size);
+  const upb_FieldDef* f = NULL;
   if (child) {
-    const upb_msgdef* parent =
-        upb_symtab_lookupmsg2(self->symtab, name, parent_size);
+    const upb_MessageDef* parent =
+        upb_DefPool_FindMessageByNameWithSize(self->symtab, name, parent_size);
     if (parent) {
-      f = upb_msgdef_ntofz(parent, child);
+      f = upb_MessageDef_FindFieldByName(parent, child);
     }
   }
 
@@ -428,10 +427,10 @@
   const char* name = PyUpb_GetStrData(arg);
   if (!name) return NULL;
 
-  const upb_enumdef* e = upb_symtab_lookupenum(self->symtab, name);
+  const upb_EnumDef* e = upb_DefPool_FindEnumByName(self->symtab, name);
   if (e == NULL && self->db) {
     if (!PyUpb_DescriptorPool_TryLoadSymbol(self, arg)) return NULL;
-    e = upb_symtab_lookupenum(self->symtab, name);
+    e = upb_DefPool_FindEnumByName(self->symtab, name);
   }
   if (e == NULL) {
     return PyErr_Format(PyExc_KeyError, "Couldn't find enum %.200s", name);
@@ -457,14 +456,15 @@
   const char* child = PyUpb_DescriptorPool_SplitSymbolName(name, &parent_size);
 
   if (child) {
-    const upb_msgdef* parent =
-        upb_symtab_lookupmsg2(self->symtab, name, parent_size);
+    const upb_MessageDef* parent =
+        upb_DefPool_FindMessageByNameWithSize(self->symtab, name, parent_size);
     if (parent == NULL && self->db) {
       if (!PyUpb_DescriptorPool_TryLoadSymbol(self, arg)) return NULL;
-      parent = upb_symtab_lookupmsg2(self->symtab, name, parent_size);
+      parent = upb_DefPool_FindMessageByNameWithSize(self->symtab, name,
+                                                     parent_size);
     }
     if (parent) {
-      const upb_oneofdef* o = upb_msgdef_ntooz(parent, child);
+      const upb_OneofDef* o = upb_MessageDef_FindOneofByName(parent, child);
       return PyUpb_OneofDescriptor_Get(o);
     }
   }
@@ -479,7 +479,7 @@
   const char* name = PyUpb_GetStrData(arg);
   if (!name) return NULL;
 
-  const upb_servicedef* s = upb_symtab_lookupservice(self->symtab, name);
+  const upb_ServiceDef* s = upb_DefPool_FindServiceByName(self->symtab, name);
   if (s == NULL) {
     return PyErr_Format(PyExc_KeyError, "Couldn't find enum %.200s", name);
   }
@@ -494,10 +494,10 @@
   const char* name = PyUpb_GetStrData(arg);
   if (!name) return NULL;
 
-  const upb_filedef* f = upb_symtab_lookupfileforsym(self->symtab, name);
+  const upb_FileDef* f = upb_DefPool_FindFileByNameforsym(self->symtab, name);
   if (f == NULL && self->db) {
     if (!PyUpb_DescriptorPool_TryLoadSymbol(self, arg)) return NULL;
-    f = upb_symtab_lookupfileforsym(self->symtab, name);
+    f = upb_DefPool_FindFileByNameforsym(self->symtab, name);
   }
   if (f == NULL) {
     return PyErr_Format(PyExc_KeyError, "Couldn't find symbol %.200s", name);
@@ -515,7 +515,7 @@
     return NULL;
   }
 
-  const upb_fielddef* f = upb_symtab_lookupextbynum(
+  const upb_FieldDef* f = upb_DefPool_FindExtensionByNumber(
       self->symtab, PyUpb_Descriptor_GetDef(message_descriptor), number);
   if (f == NULL) {
     return PyErr_Format(PyExc_KeyError, "Couldn't find Extension %d", number);
@@ -527,9 +527,9 @@
 static PyObject* PyUpb_DescriptorPool_FindAllExtensions(PyObject* _self,
                                                         PyObject* msg_desc) {
   PyUpb_DescriptorPool* self = (PyUpb_DescriptorPool*)_self;
-  const upb_msgdef* m = PyUpb_Descriptor_GetDef(msg_desc);
+  const upb_MessageDef* m = PyUpb_Descriptor_GetDef(msg_desc);
   size_t n;
-  const upb_fielddef** ext = upb_symtab_getallexts(self->symtab, m, &n);
+  const upb_FieldDef** ext = upb_DefPool_GetAllExtensions(self->symtab, m, &n);
   PyObject* ret = PyList_New(n);
   for (size_t i = 0; i < n; i++) {
     PyObject* field = PyUpb_FieldDescriptor_Get(ext[i]);