protobuf/upb/msg.h

/*
** Our memory representation for parsing tables and messages themselves.
** Functions in this file are used by generated code and possibly reflection.
**
** The definitions in this file are internal to upb.
**/

#ifndef UPB_MSG_H_
#define UPB_MSG_H_

#include <stdint.h>
#include <string.h>

#include "upb/table.int.h"
#include "upb/upb.h"

#include "upb/port_def.inc"

#ifdef __cplusplus
extern "C" {
#endif

#define PTR_AT(msg, ofs, type) (type*)((const char*)msg + ofs)

typedef void upb_msg;

/** upb_msglayout *************************************************************/

/* upb_msglayout represents the memory layout of a given upb_msgdef.  The
 * members are public so generated code can initialize them, but users MUST NOT
 * read or write any of its members. */

/* These aren't real labels according to descriptor.proto, but in the table we
 * use these for map/packed fields instead of UPB_LABEL_REPEATED. */
enum {
  _UPB_LABEL_MAP = 4,
  _UPB_LABEL_PACKED = 7  /* Low 3 bits are common with UPB_LABEL_REPEATED. */
};

typedef struct {
  uint32_t number;
  uint16_t offset;
  int16_t presence;      /* If >0, hasbit_index.  If <0, -oneof_index. */
  uint16_t submsg_index;  /* undefined if descriptortype != MESSAGE or GROUP. */
  uint8_t descriptortype;
  uint8_t label;
} upb_msglayout_field;

typedef struct upb_msglayout {
  const struct upb_msglayout *const* submsgs;
  const upb_msglayout_field *fields;
  /* Must be aligned to sizeof(void*).  Doesn't include internal members like
   * unknown fields, extension dict, pointer to msglayout, etc. */
  uint16_t size;
  uint16_t field_count;
  bool extendable;
} upb_msglayout;

/** upb_msg *******************************************************************/

/* Internal members of a upb_msg.  We can change this without breaking binary
 * compatibility.  We put these before the user's data.  The user's upb_msg*
 * points after the upb_msg_internal. */

/* Used when a message is not extendable. */
typedef struct {
  char *unknown;
  size_t unknown_len;
  size_t unknown_size;
} upb_msg_internal;

/* Used when a message is extendable. */
typedef struct {
  upb_inttable *extdict;
  upb_msg_internal base;
} upb_msg_internal_withext;

/* Maps upb_fieldtype_t -> memory size. */
extern char _upb_fieldtype_to_size[12];

/* Creates a new messages with the given layout on the given arena. */
upb_msg *_upb_msg_new(const upb_msglayout *l, upb_arena *a);

/* Clears the given message. */
void _upb_msg_clear(upb_msg *msg, const upb_msglayout *l);

/* Discards the unknown fields for this message only. */
void _upb_msg_discardunknown_shallow(upb_msg *msg);

/* Adds unknown data (serialized protobuf data) to the given message.  The data
 * is copied into the message instance. */
bool _upb_msg_addunknown(upb_msg *msg, const char *data, size_t len,
                         upb_arena *arena);

/* Returns a reference to the message's unknown data. */
const char *upb_msg_getunknown(const upb_msg *msg, size_t *len);

UPB_INLINE bool _upb_has_field(const void *msg, size_t idx) {
  return (*PTR_AT(msg, idx / 8, const char) & (1 << (idx % 8))) != 0;
}

UPB_INLINE bool _upb_sethas(const void *msg, size_t idx) {
  return (*PTR_AT(msg, idx / 8, char)) |= (char)(1 << (idx % 8));
}

UPB_INLINE bool _upb_clearhas(const void *msg, size_t idx) {
  return (*PTR_AT(msg, idx / 8, char)) &= (char)(~(1 << (idx % 8)));
}

UPB_INLINE bool _upb_has_oneof_field(const void *msg, size_t case_ofs, int32_t num) {
  return *PTR_AT(msg, case_ofs, int32_t) == num;
}

UPB_INLINE bool _upb_has_submsg_nohasbit(const void *msg, size_t ofs) {
  return *PTR_AT(msg, ofs, const void*) != NULL;
}

UPB_INLINE bool _upb_isrepeated(const upb_msglayout_field *field) {
  return (field->label & 3) == UPB_LABEL_REPEATED;
}

/** upb_array *****************************************************************/

/* Our internal representation for repeated fields.  */
typedef struct {
  uintptr_t data;   /* Tagged ptr: low 3 bits of ptr are lg2(elem size). */
  size_t len;   /* Measured in elements. */
  size_t size;  /* Measured in elements. */
} upb_array;

UPB_INLINE const void *_upb_array_constptr(const upb_array *arr) {
  return (void*)(arr->data & ~(uintptr_t)7);
}

UPB_INLINE void *_upb_array_ptr(upb_array *arr) {
  return (void*)_upb_array_constptr(arr);
}

/* Creates a new array on the given arena. */
upb_array *_upb_array_new(upb_arena *a, upb_fieldtype_t type);

/* Resizes the capacity of the array to be at least min_size. */
bool _upb_array_realloc(upb_array *arr, size_t min_size, upb_arena *arena);

/* Fallback functions for when the accessors require a resize. */
void *_upb_array_resize_fallback(upb_array **arr_ptr, size_t size,
                                 upb_fieldtype_t type, upb_arena *arena);
bool _upb_array_append_fallback(upb_array **arr_ptr, const void *value,
                                upb_fieldtype_t type, upb_arena *arena);

UPB_INLINE bool _upb_array_reserve(upb_array *arr, size_t size,
                                   upb_arena *arena) {
  if (arr->size < size) return _upb_array_realloc(arr, size, arena);
  return true;
}

UPB_INLINE bool _upb_array_resize(upb_array *arr, size_t size,
                                  upb_arena *arena) {
  if (!_upb_array_reserve(arr, size, arena)) return false;
  arr->len = size;
  return true;
}

UPB_INLINE const void *_upb_array_accessor(const void *msg, size_t ofs,
                                           size_t *size) {
  const upb_array *arr = *PTR_AT(msg, ofs, const upb_array*);
  if (arr) {
    if (size) *size = arr->len;
    return _upb_array_constptr(arr);
  } else {
    if (size) *size = 0;
    return NULL;
  }
}

UPB_INLINE void *_upb_array_mutable_accessor(void *msg, size_t ofs,
                                             size_t *size) {
  upb_array *arr = *PTR_AT(msg, ofs, upb_array*);
  if (arr) {
    if (size) *size = arr->len;
    return _upb_array_ptr(arr);
  } else {
    if (size) *size = 0;
    return NULL;
  }
}

UPB_INLINE void *_upb_array_resize_accessor(void *msg, size_t ofs, size_t size,
                                            upb_fieldtype_t type,
                                            upb_arena *arena) {
  upb_array **arr_ptr = PTR_AT(msg, ofs, upb_array*);
  upb_array *arr = *arr_ptr;
  if (!arr || arr->size < size) {
    return _upb_array_resize_fallback(arr_ptr, size, type, arena);
  }
  arr->len = size;
  return _upb_array_ptr(arr);
}


UPB_INLINE bool _upb_array_append_accessor(void *msg, size_t ofs,
                                           size_t elem_size,
                                           upb_fieldtype_t type,
                                           const void *value,
                                           upb_arena *arena) {
  upb_array **arr_ptr = PTR_AT(msg, ofs, upb_array*);
  upb_array *arr = *arr_ptr;
  void* ptr;
  if (!arr || arr->len == arr->size) {
    return _upb_array_append_fallback(arr_ptr, value, type, arena);
  }
  ptr = _upb_array_ptr(arr);
  memcpy(PTR_AT(ptr, arr->len * elem_size, char), value, elem_size);
  arr->len++;
  return true;
}

/** upb_map *******************************************************************/

/* Right now we use strmaps for everything.  We'll likely want to use
 * integer-specific maps for integer-keyed maps.*/
typedef struct {
  /* Size of key and val, based on the map type.  Strings are represented as '0'
   * because they must be handled specially. */
  char key_size;
  char val_size;

  upb_strtable table;
} upb_map;

/* Map entries aren't actually stored, they are only used during parsing.  For
 * parsing, it helps a lot if all map entry messages have the same layout.
 * The compiler and def.c must ensure that all map entries have this layout. */
typedef struct {
  upb_msg_internal internal;
  union {
    upb_strview str;  /* For str/bytes. */
    upb_value val;    /* For all other types. */
  } k;
  union {
    upb_strview str;  /* For str/bytes. */
    upb_value val;    /* For all other types. */
  } v;
} upb_map_entry;

/* Creates a new map on the given arena with this key/value type. */
upb_map *_upb_map_new(upb_arena *a, size_t key_size, size_t value_size);

/* Converting between internal table representation and user values.
 *
 * _upb_map_tokey() and _upb_map_fromkey() are inverses.
 * _upb_map_tovalue() and _upb_map_fromvalue() are inverses.
 *
 * These functions account for the fact that strings are treated differently
 * from other types when stored in a map.
 */

UPB_INLINE upb_strview _upb_map_tokey(const void *key, size_t size) {
  if (size == UPB_MAPTYPE_STRING) {
    return *(upb_strview*)key;
  } else {
    return upb_strview_make((const char*)key, size);
  }
}

UPB_INLINE void _upb_map_fromkey(upb_strview key, void* out, size_t size) {
  if (size == UPB_MAPTYPE_STRING) {
    memcpy(out, &key, sizeof(key));
  } else {
    memcpy(out, key.data, size);
  }
}

UPB_INLINE upb_value _upb_map_tovalue(const void *val, size_t size,
                                      upb_arena *a) {
  upb_value ret = {0};
  if (size == UPB_MAPTYPE_STRING) {
    upb_strview *strp = (upb_strview*)upb_arena_malloc(a, sizeof(*strp));
    *strp = *(upb_strview*)val;
    memcpy(&ret, &strp, sizeof(strp));
  } else {
    memcpy(&ret, val, size);
  }
  return ret;
}

UPB_INLINE void _upb_map_fromvalue(upb_value val, void* out, size_t size) {
  if (size == UPB_MAPTYPE_STRING) {
    const upb_strview *strp = (const upb_strview*)upb_value_getptr(val);
    memcpy(out, strp, sizeof(upb_strview));
  } else {
    memcpy(out, &val, size);
  }
}

/* Map operations, shared by reflection and generated code. */

UPB_INLINE size_t _upb_map_size(const upb_map *map) {
  return map->table.t.count;
}

UPB_INLINE bool _upb_map_get(const upb_map *map, const void *key,
                             size_t key_size, void *val, size_t val_size) {
  upb_value tabval;
  upb_strview k = _upb_map_tokey(key, key_size);
  bool ret = upb_strtable_lookup2(&map->table, k.data, k.size, &tabval);
  if (ret && val) {
    _upb_map_fromvalue(tabval, val, val_size);
  }
  return ret;
}

UPB_INLINE void* _upb_map_next(const upb_map *map, size_t *iter) {
  upb_strtable_iter it;
  it.t = &map->table;
  it.index = *iter;
  upb_strtable_next(&it);
  *iter = it.index;
  if (upb_strtable_done(&it)) return NULL;
  return (void*)str_tabent(&it);
}

UPB_INLINE bool _upb_map_set(upb_map *map, const void *key, size_t key_size,
                             void *val, size_t val_size, upb_arena *arena) {
  upb_strview strkey = _upb_map_tokey(key, key_size);
  upb_value tabval = _upb_map_tovalue(val, val_size, arena);
  upb_alloc *a = upb_arena_alloc(arena);

  /* TODO(haberman): add overwrite operation to minimize number of lookups. */
  upb_strtable_remove3(&map->table, strkey.data, strkey.size, NULL, a);
  return upb_strtable_insert3(&map->table, strkey.data, strkey.size, tabval, a);
}

UPB_INLINE bool _upb_map_delete(upb_map *map, const void *key, size_t key_size) {
  upb_strview k = _upb_map_tokey(key, key_size);
  return upb_strtable_remove3(&map->table, k.data, k.size, NULL, NULL);
}

UPB_INLINE void _upb_map_clear(upb_map *map) {
  upb_strtable_clear(&map->table);
}

/* Message map operations, these get the map from the message first. */

UPB_INLINE size_t _upb_msg_map_size(const upb_msg *msg, size_t ofs) {
  upb_map *map = *UPB_PTR_AT(msg, ofs, upb_map *);
  return map ? _upb_map_size(map) : 0;
}

UPB_INLINE bool _upb_msg_map_get(const upb_msg *msg, size_t ofs,
                                 const void *key, size_t key_size, void *val,
                                 size_t val_size) {
  upb_map *map = *UPB_PTR_AT(msg, ofs, upb_map *);
  if (!map) return false;
  return _upb_map_get(map, key, key_size, val, val_size);
}

UPB_INLINE void *_upb_msg_map_next(const upb_msg *msg, size_t ofs,
                                   size_t *iter) {
  upb_map *map = *UPB_PTR_AT(msg, ofs, upb_map *);
  if (!map) return NULL;
  return _upb_map_next(map, iter);
}

UPB_INLINE bool _upb_msg_map_set(upb_msg *msg, size_t ofs, const void *key,
                                 size_t key_size, void *val, size_t val_size,
                                 upb_arena *arena) {
  upb_map **map = PTR_AT(msg, ofs, upb_map *);
  if (!*map) {
    *map = _upb_map_new(arena, key_size, val_size);
  }
  return _upb_map_set(*map, key, key_size, val, val_size, arena);
}

UPB_INLINE bool _upb_msg_map_delete(upb_msg *msg, size_t ofs, const void *key,
                                    size_t key_size) {
  upb_map *map = *UPB_PTR_AT(msg, ofs, upb_map *);
  if (!map) return false;
  return _upb_map_delete(map, key, key_size);
}

UPB_INLINE void _upb_msg_map_clear(upb_msg *msg, size_t ofs) {
  upb_map *map = *UPB_PTR_AT(msg, ofs, upb_map *);
  if (!map) return;
  _upb_map_clear(map);
}

/* Accessing map key/value from a pointer, used by generated code only. */

UPB_INLINE void _upb_msg_map_key(const void* msg, void* key, size_t size) {
  const upb_tabent *ent = (const upb_tabent*)msg;
  uint32_t u32len;
  upb_strview k;
  k.data = upb_tabstr(ent->key, &u32len);
  k.size = u32len;
  _upb_map_fromkey(k, key, size);
}

UPB_INLINE void _upb_msg_map_value(const void* msg, void* val, size_t size) {
  const upb_tabent *ent = (const upb_tabent*)msg;
  upb_value v;
  _upb_value_setval(&v, ent->val.val);
  _upb_map_fromvalue(v, val, size);
}

UPB_INLINE void _upb_msg_map_set_value(void* msg, const void* val, size_t size) {
  upb_tabent *ent = (upb_tabent*)msg;
  /* This is like _upb_map_tovalue() except the entry already exists so we can
   * reuse the allocated upb_strview for string fields. */
  if (size == UPB_MAPTYPE_STRING) {
    upb_strview *strp = (upb_strview*)ent->val.val;
    memcpy(strp, val, sizeof(*strp));
  } else {
    memcpy(&ent->val.val, val, size);
  }
}

#undef PTR_AT

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

#include "upb/port_undef.inc"

#endif /* UPB_MSG_H_ */