protobuf/upb.h

/*
 * upb - a minimalist implementation of protocol buffers.

 * Copyright (c) 2009 Joshua Haberman.  See LICENSE for details.
 *
 * This file contains shared definitions that are widely used across upb.
 */

#ifndef UPB_H_
#define UPB_H_

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>  /* for size_t. */
#include <string.h>

#ifdef __cplusplus
extern "C" {
#endif

/* Branch prediction hints for GCC. */
#ifdef __GNUC__
#define likely(x)       __builtin_expect((x),1)
#define unlikely(x)     __builtin_expect((x),0)
#else
#define likely(x)       (x)
#define unlikely(x)     (x)
#endif

/* inline if possible, emit standalone code if required. */
#ifndef INLINE
#define INLINE static inline
#endif

/* The maximum that any submessages can be nested.  Matches proto2's limit. */
#define UPB_MAX_NESTING 64

/* The maximum number of fields that any one .proto type can have. */
#define UPB_MAX_FIELDS (1<<16)

/* Nested type names are separated by periods. */
#define UPB_SYMBOL_SEPARATOR '.'
#define UPB_SYMBOL_MAX_LENGTH 256

#define UPB_INDEX(base, i, m) (void*)((char*)(base) + ((i)*(m)))

INLINE uint32_t max(uint32_t a, uint32_t b) { return a > b ? a : b; }

/* Value type as defined in a .proto file.  The values of this are defined by
 * google_protobuf_FieldDescriptorProto_Type (from descriptor.proto).
 * Note that descriptor.proto reserves "0" for errors, and we use it to
 * represent exceptional circumstances. */
typedef uint8_t upb_field_type_t;

/* Label (optional, repeated, required) as defined in a .proto file.  The values
 * of this are defined by google.protobuf.FieldDescriptorProto.Label (from
 * descriptor.proto). */
typedef uint8_t  upb_label_t;

struct upb_type_info {
  uint8_t align;
  uint8_t size;
  uint8_t expected_wire_type;
};

/* Contains information for all .proto types.  Indexed by upb_field_type_t. */
extern struct upb_type_info upb_type_info[];

/* A pointer to a .proto value.  The owner must have an out-of-band way of
 * knowing the type, so it knows which union member to use. */
union upb_value {
  double   _double;
  float    _float;
  int32_t  int32;
  int64_t  int64;
  uint32_t uint32;
  uint64_t uint64;
  bool     _bool;
  struct upb_string **string;
  struct upb_array **array;
  void     *message;
};

union upb_value_ptr {
  double   *_double;
  float    *_float;
  int32_t  *int32;
  int64_t  *int64;
  uint32_t *uint32;
  uint64_t *uint64;
  bool     *_bool;
  struct upb_string **string;
  struct upb_array **array;
  void     **message;
  void     *_void;
};

union upb_symbol_ref {
  struct upb_msg *msg;
  struct upb_enum *_enum;
  struct upb_svc *svc;
};

/* The number of a field, eg. "optional string foo = 3". */
typedef int32_t upb_field_number_t;

/* Status codes used as a return value.  Codes >0 are not fatal and can be
 * resumed. */
typedef enum upb_status {
  UPB_STATUS_OK = 0,

  // The input byte stream ended in the middle of a record.
  UPB_STATUS_NEED_MORE_DATA = 1,

  // The user value callback opted to stop parsing.
  UPB_STATUS_USER_CANCELLED = 2,

  // A varint did not terminate before hitting 64 bits.
  UPB_ERROR_UNTERMINATED_VARINT = -1,

  // A submessage or packed array ended in the middle of data.
  UPB_ERROR_BAD_SUBMESSAGE_END = -2,

  // Input was nested more than UPB_MAX_NESTING deep.
  UPB_ERROR_STACK_OVERFLOW = -3,

  // The input data caused the pb's offset (a size_t) to overflow.
  UPB_ERROR_OVERFLOW = -4,

  // An "end group" tag was encountered in an inappropriate place.
  UPB_ERROR_SPURIOUS_END_GROUP = -5,

  UPB_ERROR_ILLEGAL = -6
} upb_status_t;

#define UPB_CHECK(func) do { \
  upb_status_t status = func; \
  if(status != UPB_STATUS_OK) return status; \
  } while (0)

#ifdef __cplusplus
}  /* extern "C" */
#endif

#endif  /* UPB_H_ */