Sync from internal Google development.

Many improvements, too many to mention.  One significant
perf regression warrants investigation:

omitfp.parsetoproto2_googlemessage1.upb_jit: 343 -> 252 (-26.53)
plain.parsetoproto2_googlemessage1.upb_jit: 334 -> 251 (-24.85)

25% regression for this benchmark is bad, but since I don't think
there's any fundamental design issue that caused it I'm going to
go ahead with the commit anyway.  Can investigate and fix later.

Other benchmarks were neutral or showed slight improvement.

1 files changed, 35 insertions, 12 deletions

diff --git a/bindings/cpp/upb/handlers.hpp b/bindings/cpp/upb/handlers.hpp
index d356a33..a366c3d 100644
--- a/bindings/cpp/upb/handlers.hpp
+++ b/bindings/cpp/upb/handlers.hpp
@@ -15,11 +15,16 @@
 
 #include "upb/handlers.h"
 
+#include "upb/upb.hpp"
+
 namespace upb {
 
 typedef upb_fieldtype_t FieldType;
 typedef upb_flow_t Flow;
+typedef upb_sflow_t SubFlow;
 class MessageHandlers;
+class MessageDef;
+class FieldDef;
 
 class FieldHandlers : public upb_fhandlers {
  public:
@@ -68,12 +73,11 @@ class FieldHandlers : public upb_fhandlers {
   MessageHandlers* GetSubMessageHandlers() const;
   // If set to >=0, the given hasbit will be set after the value callback is
   // called (offset relative to the current closure).
-  int32_t GetValueHasbit() const { return upb_fhandlers_getvaluehasbit(this); }
-  void SetValueHasbit(int32_t bit) { upb_fhandlers_setvaluehasbit(this, bit); }
+  int32_t GetHasbit() const { return upb_fhandlers_gethasbit(this); }
+  void SetHasbit(int32_t bit) { upb_fhandlers_sethasbit(this, bit); }
 
  private:
-  FieldHandlers();  // Only created by upb::Handlers.
-  ~FieldHandlers(); // Only destroyed by refcounting.
+  UPB_DISALLOW_CONSTRUCT_AND_DESTRUCT(FieldHandlers);
 };
 
 class MessageHandlers : public upb_mhandlers {
@@ -81,6 +85,13 @@ class MessageHandlers : public upb_mhandlers {
   typedef upb_startmsg_handler StartMessageHandler;
   typedef upb_endmsg_handler EndMessageHandler;
 
+  static MessageHandlers* Cast(upb_mhandlers* mh) {
+    return static_cast<MessageHandlers*>(mh);
+  }
+  static const MessageHandlers* Cast(const upb_mhandlers* mh) {
+    return static_cast<const MessageHandlers*>(mh);
+  }
+
   // The MessageHandlers will live at least as long as the upb::Handlers to
   // which it belongs, but can be Ref'd/Unref'd to make it live longer (which
   // will prolong the life of the underlying upb::Handlers also).
@@ -89,7 +100,7 @@ class MessageHandlers : public upb_mhandlers {
 
   // Functions to set this message's handlers.
   // These return "this" so they can be conveniently chained, eg.
-  //   handlers->NewMessage()
+  //   handlers->NewMessageHandlers()
   //       ->SetStartMessageHandler(&StartMessage)
   //       ->SetEndMessageHandler(&EndMessage);
   MessageHandlers* SetStartMessageHandler(StartMessageHandler* h) {
@@ -111,13 +122,13 @@ class MessageHandlers : public upb_mhandlers {
   FieldHandlers* NewFieldHandlersForSubmessage(uint32_t n, const char *name,
                                                FieldType type, bool repeated,
                                                MessageHandlers* subm) {
+    (void)name;
     return static_cast<FieldHandlers*>(
         upb_mhandlers_newfhandlers_subm(this, n, type, repeated, subm));
   }
 
  private:
-  MessageHandlers();  // Only created by upb::Handlers.
-  ~MessageHandlers(); // Only destroyed by refcounting.
+  UPB_DISALLOW_CONSTRUCT_AND_DESTRUCT(MessageHandlers);
 };
 
 class Handlers : public upb_handlers {
@@ -134,17 +145,29 @@ class Handlers : public upb_handlers {
     return static_cast<MessageHandlers*>(upb_handlers_newmhandlers(this));
   }
 
+  // Convenience function for registering handlers for all messages and fields
+  // in a MessageDef and all its children.  For every registered message,
+  // OnMessage will be called on the visitor with newly-created MessageHandlers
+  // and MessageDef. Likewise with OnField will be called with newly-created
+  // FieldHandlers and FieldDef for each field.
+  class MessageRegistrationVisitor {
+   public:
+    virtual ~MessageRegistrationVisitor() {}
+    virtual void OnMessage(MessageHandlers* mh, const MessageDef* m) = 0;
+    virtual void OnField(FieldHandlers* fh, const FieldDef* f) = 0;
+  };
+  MessageHandlers* RegisterMessageDef(const MessageDef& m,
+                                      MessageRegistrationVisitor* visitor);
+
  private:
-  Handlers();  // Only created by Handlers::New().
-  ~Handlers(); // Only destroyed by refcounting.
+  UPB_DISALLOW_CONSTRUCT_AND_DESTRUCT(Handlers);
 };
 
-
-MessageHandlers* FieldHandlers::GetMessageHandlers() const {
+inline MessageHandlers* FieldHandlers::GetMessageHandlers() const {
   return static_cast<MessageHandlers*>(upb_fhandlers_getmsg(this));
 }
 
-MessageHandlers* FieldHandlers::GetSubMessageHandlers() const {
+inline MessageHandlers* FieldHandlers::GetSubMessageHandlers() const {
   return static_cast<MessageHandlers*>(upb_fhandlers_getsubmsg(this));
 }