protobuf/upb/handlers.h

/*
 * upb - a minimalist implementation of protocol buffers.
 *
 * Copyright (c) 2010-2012 Google Inc.  See LICENSE for details.
 * Author: Josh Haberman <jhaberman@gmail.com>
 *
 * A upb_handlers is like a virtual table for a upb_msgdef.  Each field of the
 * message can have associated functions that will be called when we are
 * parsing or visiting a stream of data.  This is similar to how handlers work
 * in SAX (the Simple API for XML).
 *
 * The handlers have no idea where the data is coming from, so a single set of
 * handlers could be used with two completely different data sources (for
 * example, a parser and a visitor over in-memory objects).  This decoupling is
 * the most important feature of upb, because it allows parsers and serializers
 * to be highly reusable.
 *
 * This is a mixed C/C++ interface that offers a full API to both languages.
 * See the top-level README for more information.
 */

#ifndef UPB_HANDLERS_H
#define UPB_HANDLERS_H

#include "upb/def.h"

#ifdef __cplusplus

struct upb_frametype;

namespace upb {

typedef upb_frametype FrameType;
class Handlers;

template <class T> class Handler;
typedef Handler<void *(*)(void *, const void *)> StartFieldHandler;
typedef Handler<bool(*)(void *, const void *)> EndFieldHandler;
typedef Handler<void *(*)(void *, const void *, size_t)> StartStringHandler;
typedef Handler<size_t(*)(void *, const void *, const char *, size_t)>
    StringHandler;

template <class T> struct ValueHandler {
  typedef Handler<bool(*)(void *, const void *, T)> H;
};

typedef ValueHandler<upb_int32_t>::H     Int32Handler;
typedef ValueHandler<upb_int64_t>::H     Int64Handler;
typedef ValueHandler<upb_uint32_t>::H    UInt32Handler;
typedef ValueHandler<upb_uint64_t>::H    UInt64Handler;
typedef ValueHandler<float>::H           FloatHandler;
typedef ValueHandler<double>::H          DoubleHandler;
typedef ValueHandler<bool>::H            BoolHandler;
template <class T> struct CanonicalType;

}  // namespace upb

typedef upb::FrameType upb_frametype;
typedef upb::Handlers upb_handlers;

#else  // #ifdef __cplusplus

struct upb_frametype;
struct upb_handlers;
struct upb_sinkframe;
typedef struct upb_frametype upb_frametype;
typedef struct upb_handlers upb_handlers;
typedef struct upb_sinkframe upb_sinkframe;

#endif  // #ifdef __cplusplus

typedef struct {
  void (*func)();
  const void *data;
} upb_handlers_tabent;

// All the different types of handlers that can be registered.
// Only needed for the advanced functions in upb::Handlers.
typedef enum {
  UPB_HANDLER_INT32,
  UPB_HANDLER_INT64,
  UPB_HANDLER_UINT32,
  UPB_HANDLER_UINT64,
  UPB_HANDLER_FLOAT,
  UPB_HANDLER_DOUBLE,
  UPB_HANDLER_BOOL,
  UPB_HANDLER_STARTSTR,
  UPB_HANDLER_STRING,
  UPB_HANDLER_ENDSTR,
  UPB_HANDLER_STARTSUBMSG,
  UPB_HANDLER_ENDSUBMSG,
  UPB_HANDLER_STARTSEQ,
  UPB_HANDLER_ENDSEQ,
} upb_handlertype_t;

#define UPB_HANDLER_MAX (UPB_HANDLER_ENDSEQ+1)

#define UPB_BREAK NULL

// A convenient definition for when no closure is needed.
extern char _upb_noclosure;
#define UPB_NO_CLOSURE &_upb_noclosure

// A selector refers to a specific field handler in the Handlers object
// (for example: the STARTSUBMSG handler for field "field15").
typedef int32_t upb_selector_t;

#ifdef __cplusplus

// A upb::Handlers object represents the set of handlers associated with a
// message in the graph of messages.  You can think of it as a big virtual
// table with functions corresponding to all the events that can fire while
// parsing or visiting a message of a specific type.
//
// Any handlers that are not set behave as if they had successfully consumed
// the value.  Any unset Start* handlers will propagate their closure to the
// inner frame.
//
// The easiest way to create the *Handler objects needed by the Set* methods is
// with the UpbBind() and UpbMakeHandler() macros; see below.
class upb::Handlers {
 public:
  typedef upb_selector_t Selector;
  typedef upb_handlertype_t Type;

  // Any function pointer can be converted to this and converted back to its
  // correct type.
  typedef void GenericFunction();

  typedef void HandlersCallback(void *closure, upb_handlers *h);

  // Returns a new handlers object for the given frozen msgdef that will use
  // the given FrameType as its top-level state (can be NULL, for now).  A
  // single ref on the returned object will belong to the given owner.
  // Returns NULL if memory allocation failed.
  static Handlers* New(const MessageDef* m,
                       const FrameType* ft,
                       const void *owner);

  // Convenience function for registering a graph of handlers that mirrors the
  // graph of msgdefs for some message.  For "m" and all its children a new set
  // of handlers will be created and the given callback will be invoked,
  // allowing the client to register handlers for this message.  Note that any
  // subhandlers set by the callback will be overwritten.  A single ref on the
  // returned object will belong to the given owner.
  static const Handlers* NewFrozen(const MessageDef *m,
                                   const FrameType* ft,
                                   const void *owner,
                                   HandlersCallback *callback, void *closure);

  // Functionality from upb::RefCounted.
  bool IsFrozen() const;
  void Ref(const void* owner) const;
  void Unref(const void* owner) const;
  void DonateRef(const void *from, const void *to) const;
  void CheckRef(const void *owner) const;

  // Top-level frame type.
  const FrameType* frame_type() const;

  // Freezes the given set of handlers.  You may not freeze a handler without
  // also freezing any handlers they point to.  In the future we may want to
  // require that all fields of the submessage have had subhandlers set for
  // them.
  static bool Freeze(Handlers*const* handlers, int n, Status* s);

  // Returns the msgdef associated with this handlers object.
  const MessageDef* message_def() const;

  // Sets the startmsg handler for the message, which is defined as follows:
  //
  //   bool startmsg(MyType* closure) {
  //     // Called when the message begins.  Returns true if processing should
  //     // continue.
  //     return true;
  //   }
  //
  // TODO(haberman): change this to work with UpbMakeHandler and auto-deduce,
  // like all of the field handlers.
  template<class T, bool F(T*)> void SetStartMessageHandler();

  // Sets the endmsg handler for the message, which is defined as follows:
  //
  //   bool endmsg(MyType* closure, upb_status *status) {
  //     // Called when processing of this message ends, whether in success or
  //     // failure.  "status" indicates the final status of processing, and
  //     // can also be modified in-place to update the final status.
  //   }
  //
  // TODO(haberman): change this to work with UpbMakeHandler and auto-deduce,
  // like all of the field handlers.
  template<class T, bool F(T*, upb::Status*)> void SetEndMessageHandler();

  // Sets the value handler for the given field, which is defined as follows
  // (this is for an int32 field; other field types will pass their native
  // C/C++ type for "val"):
  //
  //   bool OnValue(MyClosure* c, const MyHandlerData* d, int32_t val) {
  //     // Called when the field's value is encountered.  "d" contains
  //     // whatever data was bound to this field when it was registered.
  //     // Returns true if processing should continue.
  //     return true;
  //   }
  //
  //   handers->SetInt32Handler(f, UpbBind(OnValue, new MyHandlerData(...)));
  //
  // The value type must exactly match f->type().
  // For example, a handler that takes an int32_t parameter may only be used for
  // fields of type UPB_TYPE_INT32 and UPB_TYPE_ENUM.
  //
  // Returns false if the handler failed to register; in this case the cleanup
  // handler (if any) will be called immediately.
  bool SetInt32Handler (const FieldDef* f,  const Int32Handler& h);
  bool SetInt64Handler (const FieldDef* f,  const Int64Handler& h);
  bool SetUInt32Handler(const FieldDef* f, const UInt32Handler& h);
  bool SetUInt64Handler(const FieldDef* f, const UInt64Handler& h);
  bool SetFloatHandler (const FieldDef* f,  const FloatHandler& h);
  bool SetDoubleHandler(const FieldDef* f, const DoubleHandler& h);
  bool SetBoolHandler  (const FieldDef* f,   const BoolHandler& h);

  // Convenience versions that look up the field by name first.  These return
  // false if no field with this name exists, or for any of the other reasons
  // that the FieldDef* version returns false.
  bool SetInt32Handler (const char *name,   const Int32Handler& h);
  bool SetInt64Handler (const char *name,   const Int64Handler& h);
  bool SetUInt32Handler(const char *name,  const UInt32Handler& h);
  bool SetUInt64Handler(const char *name,  const UInt64Handler& h);
  bool SetFloatHandler (const char *name,   const FloatHandler& h);
  bool SetDoubleHandler(const char *name,  const DoubleHandler& h);
  bool SetBoolHandler  (const char *name,    const BoolHandler& h);

  // Like the previous, but templated on the type on the value (ie. int32).
  // This is mostly useful to call from other templates.  To call this you must
  // specify the template parameter explicitly, ie:
  //   h->SetValueHandler<T>(f, UpbBind(MyHandler<T>, MyData));
  template <class T>
  bool SetValueHandler(
      const FieldDef *f,
      const typename ValueHandler<typename CanonicalType<T>::Type>::H& handler);
  template <class T>
  bool SetValueHandler(
      const char *name,
      const typename ValueHandler<typename CanonicalType<T>::Type>::H& handler);

  // Sets handlers for a string field, which are defined as follows:
  //
  //   MySubClosure* startstr(MyClosure* c, const MyHandlerData* d,
  //                          size_t size_hint) {
  //     // Called when a string value begins.  The return value indicates the
  //     // closure for the string.  "size_hint" indicates the size of the
  //     // string if it is known, however if the string is length-delimited
  //     // and the end-of-string is not available size_hint will be zero.
  //     // This case is indistinguishable from the case where the size is
  //     // known to be zero.
  //     //
  //     // TODO(haberman): is it important to distinguish these cases?
  //     // If we had ssize_t as a type we could make -1 "unknown", but
  //     // ssize_t is POSIX (not ANSI) and therefore less portable.
  //     // In practice I suspect it won't be important to distinguish.
  //     return closure;
  //   }
  //
  //   size_t str(MyClosure* closure, const MyHandlerData* d,
  //              const char *str, size_t len) {
  //     // Called for each buffer of string data; the multiple physical buffers
  //     // are all part of the same logical string.  The return value indicates
  //     // how many bytes were consumed.  If this number is less than "len",
  //     // this will also indicate that processing should be halted for now,
  //     // like returning false or UPB_BREAK from any other callback.  If
  //     // number is greater than "len", the excess bytes will be skipped over
  //     // and not passed to the callback.
  //     return len;
  //   }
  //
  //   bool endstr(MyClosure* c, const MyHandlerData* d) {
  //     // Called when a string value ends.  Return value indicates whether
  //     // processing should continue.
  //     return true;
  //   }
  bool SetStartStringHandler(const FieldDef* f, const StartStringHandler& h);
  bool SetStringHandler(const FieldDef* f, const StringHandler& h);
  bool SetEndStringHandler(const FieldDef* f, const EndFieldHandler& h);

  // Convenience versions that look up the field by name first.  These return
  // false if no field with this name exists, or for any of the other reasons
  // that the FieldDef* version returns false.
  bool SetStartStringHandler(const char* name, const StartStringHandler& h);
  bool SetStringHandler(const char* name, const StringHandler& h);
  bool SetEndStringHandler(const char* name, const EndFieldHandler& h);

  // Sets the startseq handler, which is defined as follows:
  //
  //   MySubClosure *startseq(MyClosure* c, const MyHandlerData* d) {
  //     // Called when a sequence (repeated field) begins.  The returned
  //     // pointer indicates the closure for the sequence (or UPB_BREAK
  //     // to interrupt processing).
  //     return closure;
  //   }
  //
  //   h->SetStartSequenceHandler(f, UpbBind(startseq, new MyHandlerData(...)));
  //
  // Returns "false" if "f" does not belong to this message or is not a
  // repeated field.
  bool SetStartSequenceHandler(const FieldDef* f, const StartFieldHandler& h);
  bool SetStartSequenceHandler(const char* name, const StartFieldHandler& h);

  // Sets the startsubmsg handler for the given field, which is defined as
  // follows:
  //
  //   MySubClosure* startsubmsg(MyClosure* c, const MyHandlerData* d) {
  //     // Called when a submessage begins.  The returned pointer indicates the
  //     // closure for the sequence (or UPB_BREAK to interrupt processing).
  //     return closure;
  //   }
  //
  //   h->SetStartSubMessageHandler(f, UpbBind(startsubmsg,
  //                                           new MyHandlerData(...)));
  //
  // Returns "false" if "f" does not belong to this message or is not a
  // submessage/group field.
  bool SetStartSubMessageHandler(const FieldDef* f, const StartFieldHandler& h);
  bool SetStartSubMessageHandler(const char* name, const StartFieldHandler& h);

  // Sets the endsubmsg handler for the given field, which is defined as
  // follows:
  //
  //   bool endsubmsg(MyClosure* c, const MyHandlerData* d) {
  //     // Called when a submessage ends.  Returns true to continue processing.
  //     return true;
  //   }
  //
  // Returns "false" if "f" does not belong to this message or is not a
  // submessage/group field.
  bool SetEndSubMessageHandler(const FieldDef *f, const EndFieldHandler &h);
  bool SetEndSubMessageHandler(const char *name, const EndFieldHandler &h);

  // Starts the endsubseq handler for the given field, which is defined as
  // follows:
  //
  //   bool endseq(MyClosure* c, const MyHandlerData* d) {
  //     // Called when a sequence ends.  Returns true continue processing.
  //     return true;
  //   }
  //
  // Returns "false" if "f" does not belong to this message or is not a
  // repeated field.
  bool SetEndSequenceHandler(const FieldDef* f, const EndFieldHandler& h);
  bool SetEndSequenceHandler(const char* name, const EndFieldHandler& h);

  // Sets or gets the object that specifies handlers for the given field, which
  // must be a submessage or group.  Returns NULL if no handlers are set.
  bool SetSubHandlers(const FieldDef* f, const Handlers* sub);
  const Handlers* GetSubHandlers(const FieldDef* f) const;

  // Equivalent to GetSubHandlers, but takes the STARTSUBMSG selector for the
  // field.
  const Handlers* GetSubHandlers(Selector startsubmsg) const;

  // A selector refers to a specific field handler in the Handlers object
  // (for example: the STARTSUBMSG handler for field "field15").
  // On success, returns true and stores the selector in "s".
  // If the FieldDef or Type are invalid, returns false.
  // The returned selector is ONLY valid for Handlers whose MessageDef
  // contains this FieldDef.
  static bool GetSelector(const FieldDef* f, Type type, Selector* s);

  // Given a START selector of any kind, returns the corresponding END selector.
  static Selector GetEndSelector(Selector start_selector);

  // Returns the function pointer for this handler.  It is the client's
  // responsibility to cast to the correct function type before calling it.
  GenericFunction* GetHandler(Selector selector);

  // Returns the handler data that was registered with this handler.
  const void* GetHandlerData(Selector selector);

  // Could add any of the following functions as-needed, with some minor
  // implementation changes:
  //
  // const FieldDef* GetFieldDef(Selector selector);
  // static bool IsSequence(Selector selector);

 private:
  UPB_DISALLOW_POD_OPS(Handlers);

#else
struct upb_handlers {
#endif
  upb_refcounted base;
  const upb_msgdef *msg;
  const upb_frametype *ft;
  bool (*startmsg)(void*);
  bool (*endmsg)(void*, upb_status*);
  struct {
    void *ptr;
    void (*cleanup)(void*);
  } *cleanup;
  size_t cleanup_len, cleanup_size;
  upb_handlers_tabent table[1];  // Dynamically-sized field handler array.
};

#ifdef __cplusplus

namespace upb {

// Convenience macros for creating a Handler object that is wrapped with a
// type-safe wrapper function that converts the "void*" parameters/returns
// of the underlying C API into nice C++ function.
//
// Sample usage:
//   bool OnValue(MyClosure* c, const MyHandlerData* d, int32_t val) {
//     // do stuff ...
//     return true;
//   }
//
//   // Handler that doesn't need any data bound to it.
//   bool OnValue(MyClosure* c, int32_t val) {
//     // do stuff ...
//     return true;
//   }
//
//   // Takes ownership of the MyHandlerData.
//   handlers->SetInt32Handler(f1, UpbBind(OnValue, new MyHandlerData(...)));
//   handlers->SetInt32Handler(f2, UpbMakeHandler(OnValue));

#ifdef UPB_CXX11

// In C++11, the "template" disambiguator can appear even outside templates,
// so all calls can safely use this pair of macros.

#define UpbMakeHandler(f) \
    upb::MakeHandler(upb::MatchWrapper(f).template Wrapper<f>)

// We have to be careful to only evaluate "d" once.
#define UpbBind(f, d) \
    upb::BindHandler(upb::MatchWrapper(f).template Wrapper<f>, f, (d))

#else

// Prior to C++11, the "template" disambiguator may only appear inside a
// template, so the regular macro must not use "template"

#define UpbMakeHandler(f) \
    upb::MakeHandler(upb::MatchWrapper(f).Wrapper<f>)

#define UpbBind(f, d) \
    upb::BindHandler(upb::MatchWrapper(f).Wrapper<f>, f, (d))

#endif  // UPB_CXX11

// This macro must be used in C++98 for calls from inside a template.  But we
// define this variant in all cases; code that wants to be compatible with both
// C++98 and C++11 should always use this macro when calling from a template.
#define UpbMakeHandlerT(f) \
    upb::MakeHandler(upb::MatchWrapper(f).template Wrapper<f>)

#define UpbBindT(f, d) \
    upb::BindHandler(upb::MatchWrapper(f).template Wrapper<f>, f, (d))


// FieldHandler: a struct that contains the (handler, data, deleter) tuple that
// is used by all field-level handlers.  Users could Make() these directly but
// it's more convenient to use the Upb{Bind,Make}ValueHandler macros.
//
// This class is intentionally not copyable or assignable; it can only be
// constructed as a temporary object with Make() and then must be registered as
// a handler (this is enforced with the assert() in the destructor).
template <class T> class Handler {
 public:
  // The underlying, non-type-safe handler function signature that upb uses
  // internally.
  typedef T FuncPtr;

  ~Handler() { assert(registered_); }

  static Handler<T> Make(FuncPtr h, void* hd, void (*fr)(void*)) {
    return Handler<T>(h, hd, fr);
  }

 private:
  friend class Handlers;

  Handler(FuncPtr h, void *d, void (*c)(void *))
      : handler_(h), data_(d), cleanup_(c), registered_(false) {}
  Handler(const Handler&);
  void operator=(const Handler&);

  FuncPtr handler_;
  void *data_;
  void (*cleanup_)(void*);
  mutable bool registered_;

  // Noisy friend declarations; these are all of the "Bind" functions,
  // two for each type of handler.  They need to be friends so that
  // they can call the copy constructor to return a temporary.

  template <class T1>
  friend typename ValueHandler<T1>::H MakeHandler(bool (*wrapper)(void *,
                                                                  const void *,
                                                                  T1));

  template <class C, class D, class T1, class T2>
  friend typename ValueHandler<T1>::H BindHandler(
      bool (*wrapper)(void *, const void *, T1), bool (*h)(C *, const D *, T2),
      D *data);

  friend StartFieldHandler MakeHandler(void* (*wrapper)(void *, const void *));

  template <class R, class C, class D>
  friend StartFieldHandler BindHandler(void *(*wrapper)(void *, const void *),
                                       R *(*h)(C *, const D *), D *data);

  friend EndFieldHandler MakeHandler(bool (*wrapper)(void *, const void *));

  template <class C, class D>
  friend EndFieldHandler BindHandler(bool (*wrapper)(void *, const void *),
                                     bool (*h)(C *, const D *), D *data);

  friend StringHandler MakeHandler(size_t (*wrapper)(void *, const void *,
                                                     const char *, size_t));

  template <class C, class D>
  friend StringHandler BindHandler(
      size_t (*wrapper)(void *, const void *, const char *, size_t),
      size_t (*h)(C *, const D *, const char *, size_t), D *data);

  friend StartStringHandler MakeHandler(void *(*wrapper)(void *, const void *,
                                                         size_t));

  template <class R, class C, class D>
  friend StartStringHandler BindHandler(void *(*wrapper)(void *, const void *,
                                                         size_t),
                                        R *(*h)(C *, const D *, size_t),
                                        D *data);
};

}  // namespace upb

extern "C" {
#endif  // __cplusplus

// Native C API.
typedef void upb_handlers_callback(void *closure, upb_handlers *h);
typedef void upb_handlerfree(void *d);
typedef void upb_func();

typedef bool upb_startmsg_handler(void *c);
typedef bool upb_endmsg_handler(void *c, upb_status *status);
typedef void* upb_startfield_handler(void *c, const void *hd);
typedef bool upb_endfield_handler(void *c, const void *hd);
typedef bool upb_int32_handler(void *c, const void *hd, int32_t val);
typedef bool upb_int64_handler(void *c, const void *hd, int64_t val);
typedef bool upb_uint32_handler(void *c, const void *hd, uint32_t val);
typedef bool upb_uint64_handler(void *c, const void *hd, uint64_t val);
typedef bool upb_float_handler(void *c, const void *hd, float val);
typedef bool upb_double_handler(void *c, const void *hd, double val);
typedef bool upb_bool_handler(void *c, const void *hd, bool val);
typedef void* upb_startstr_handler(void *c, const void *hd, size_t size_hint);
typedef size_t upb_string_handler(void *c, const void *hd, const char *buf,
                                  size_t n);

upb_handlers *upb_handlers_new(const upb_msgdef *m,
                               const upb_frametype *ft,
                               const void *owner);
const upb_handlers *upb_handlers_newfrozen(const upb_msgdef *m,
                                           const upb_frametype *ft,
                                           const void *owner,
                                           upb_handlers_callback *callback,
                                           void *closure);

// From upb_refcounted.
bool upb_handlers_isfrozen(const upb_handlers *h);
void upb_handlers_ref(const upb_handlers *h, const void *owner);
void upb_handlers_unref(const upb_handlers *h, const void *owner);
void upb_handlers_donateref(const upb_handlers *h, const void *from,
                            const void *to);
void upb_handlers_checkref(const upb_handlers *h, const void *owner);

const upb_msgdef *upb_handlers_msgdef(const upb_handlers *h);
const upb_frametype *upb_handlers_frametype(const upb_handlers *h);
void upb_handlers_setstartmsg(upb_handlers *h, upb_startmsg_handler *handler);
upb_startmsg_handler *upb_handlers_getstartmsg(const upb_handlers *h);
void upb_handlers_setendmsg(upb_handlers *h, upb_endmsg_handler *handler);
upb_endmsg_handler *upb_handlers_getendmsg(const upb_handlers *h);
bool upb_handlers_setint32(upb_handlers *h, const upb_fielddef *f,
                           upb_int32_handler *handler, void *d,
                           upb_handlerfree *fr);
bool upb_handlers_setint64(upb_handlers *h, const upb_fielddef *f,
                           upb_int64_handler *handler, void *d,
                           upb_handlerfree *fr);
bool upb_handlers_setuint32(upb_handlers *h, const upb_fielddef *f,
                            upb_uint32_handler *handler, void *d,
                            upb_handlerfree *fr);
bool upb_handlers_setuint64(upb_handlers *h, const upb_fielddef *f,
                            upb_uint64_handler *handler, void *d,
                            upb_handlerfree *fr);
bool upb_handlers_setfloat(upb_handlers *h, const upb_fielddef *f,
                           upb_float_handler *handler, void *d,
                           upb_handlerfree *fr);
bool upb_handlers_setdouble(upb_handlers *h, const upb_fielddef *f,
                            upb_double_handler *handler, void *d,
                            upb_handlerfree *fr);
bool upb_handlers_setbool(upb_handlers *h, const upb_fielddef *f,
                          upb_bool_handler *handler, void *d,
                          upb_handlerfree *fr);
bool upb_handlers_setstartstr(upb_handlers *h, const upb_fielddef *f,
                              upb_startstr_handler *handler, void *d,
                              upb_handlerfree *fr);
bool upb_handlers_setstring(upb_handlers *h, const upb_fielddef *f,
                            upb_string_handler *handler, void *d,
                            upb_handlerfree *fr);
bool upb_handlers_setendstr(upb_handlers *h, const upb_fielddef *f,
                            upb_endfield_handler *handler, void *d,
                            upb_handlerfree *fr);
bool upb_handlers_setstartseq(upb_handlers *h, const upb_fielddef *f,
                              upb_startfield_handler *handler, void *d,
                              upb_handlerfree *fr);
bool upb_handlers_setstartsubmsg(upb_handlers *h, const upb_fielddef *f,
                                 upb_startfield_handler *handler, void *d,
                                 upb_handlerfree *fr);
bool upb_handlers_setendsubmsg(upb_handlers *h, const upb_fielddef *f,
                               upb_endfield_handler *handler, void *d,
                               upb_handlerfree *fr);
bool upb_handlers_setendseq(upb_handlers *h, const upb_fielddef *f,
                            upb_endfield_handler *handler, void *d,
                            upb_handlerfree *fr);
bool upb_handlers_setsubhandlers(upb_handlers *h, const upb_fielddef *f,
                                 const upb_handlers *sub);
const upb_handlers *upb_handlers_getsubhandlers(const upb_handlers *h,
                                                const upb_fielddef *f);
const upb_handlers *upb_handlers_getsubhandlers_sel(const upb_handlers *h,
                                                    upb_selector_t sel);
upb_func *upb_handlers_gethandler(const upb_handlers *h, upb_selector_t s);
const void *upb_handlers_gethandlerdata(const upb_handlers *h,
                                        upb_selector_t s);

// "Static" methods
bool upb_handlers_freeze(upb_handlers *const *handlers, int n, upb_status *s);
upb_handlertype_t upb_handlers_getprimitivehandlertype(const upb_fielddef *f);
bool upb_handlers_getselector(const upb_fielddef *f, upb_handlertype_t type,
                              upb_selector_t *s);
UPB_INLINE upb_selector_t upb_handlers_getendselector(upb_selector_t start) {
  return start + 1;
}

// Internal-only.
uint32_t upb_handlers_selectorbaseoffset(const upb_fielddef *f);
uint32_t upb_handlers_selectorcount(const upb_fielddef *f);
#ifdef __cplusplus
}  // extern "C"
#endif

// Convenience versions of the above that first look up the field by name.
#define DEFINE_NAME_SETTER(slot, type) \
  UPB_INLINE bool upb_handlers_set ## slot ## _n( \
      upb_handlers *h, const char *name, type val, \
      void *d, upb_handlerfree *fr) { \
    const upb_fielddef *f = upb_msgdef_ntof(upb_handlers_msgdef(h), name); \
    if (!f) return false; \
    return upb_handlers_set ## slot(h, f, val, d, fr); \
  }
DEFINE_NAME_SETTER(int32, upb_int32_handler*);
DEFINE_NAME_SETTER(int64, upb_int64_handler*);
DEFINE_NAME_SETTER(uint32, upb_uint32_handler*);
DEFINE_NAME_SETTER(uint64, upb_uint64_handler*);
DEFINE_NAME_SETTER(float, upb_float_handler*);
DEFINE_NAME_SETTER(double, upb_double_handler*);
DEFINE_NAME_SETTER(bool, upb_bool_handler*);
DEFINE_NAME_SETTER(startstr, upb_startstr_handler*);
DEFINE_NAME_SETTER(string, upb_string_handler*);
DEFINE_NAME_SETTER(endstr, upb_endfield_handler*);
DEFINE_NAME_SETTER(startseq, upb_startfield_handler*);
DEFINE_NAME_SETTER(startsubmsg, upb_startfield_handler*);
DEFINE_NAME_SETTER(endsubmsg, upb_endfield_handler*);
DEFINE_NAME_SETTER(endseq, upb_endfield_handler*);

#undef DEFINE_NAME_SETTER

#include "upb/handlers-inl.h"

#endif  // UPB_HANDLERS_H