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BSON_ITER_INIT_FROM_DATA_AT_OFFSET(3) libbson BSON_ITER_INIT_FROM_DATA_AT_OFFSET(3)

NAME

bson_iter_init_from_data_at_offset - bson_iter_init_from_data_at_offset()

SYNOPSIS

bool
bson_iter_init_from_data_at_offset (bson_iter_t *iter,


                                    const uint8_t *data,


                                    size_t length,


                                    uint32_t offset,


                                    uint32_t keylen);


PARAMETERS

  • iter: A bson_iter_t.
  • data: A buffer to initialize with. This is not validated.
  • length: The length of data in bytes. This is not validated.
  • offset: The offset of the field to start iterating. This is not validated. This should be an offset previously obtained from bson_iter_offset().
  • keylen: The string length of the key of the field to start iterating. This is not validated. This should be a length previously obtained from bson_iter_key_len().

DESCRIPTION

Creates a bson_iter_t and starts iteration on a field at the offset.

bson_iter_init_from_data_at_offset is useful for situations where the progress of a bson_iter_t must be saved and restored without relying on the bson_iter_t data layout. Saving the progress could be accomplished by:

  • Saving the current field's key length with bson_iter_key_len()
  • Saving the current offset with bson_iter_offset()
  • Saving the data pointer of the iterated bson_t with bson_get_data()
  • Saving the data length of the iterated bson_t with the len struct field

Then later, these saved values can be passed to bson_iter_init_from_data_at_offset() to reconstruct the bson_iter_t in constant time.

SEE ALSO

  • bson_iter_key_len()
  • bson_iter_offset()
  • bson_get_data()

RETURNS

Returns true if the iter was successfully initialized.

AUTHOR

MongoDB, Inc

COPYRIGHT

2017-present, MongoDB, Inc

June 4, 2021 1.17.6