Type 4 – Arrays

CBOR arrays, just like byte strings and strings, can be encoded either as definite, or as indefinite.

Corresponding cbor_type

CBOR_TYPE_ARRAY

Number of allocations (definite)

Two plus any manipulations with the data

Number of allocations (indefinite)

Two plus logarithmically many reallocations relative to additions

Storage requirements (definite)

(sizeof(cbor_item_t) + 1) * size

Storage requirements (indefinite)

<= sizeof(cbor_item_t) + sizeof(cbor_item_t) * size * BUFFER_GROWTH

Examples

0x9f        Start indefinite array
    0x01        Unsigned integer 1
    0xff        "Break" control token
0x9f        Start array, 1B length follows
0x20        Unsigned integer 32
    ...        32 items follow

Streaming indefinite arrays

Please refer to Streaming & indefinite items.

Getting metadata

size_t cbor_array_size(const cbor_item_t *item)

Get the number of members.

param item[borrow]:

An array

return:

The number of members

size_t cbor_array_allocated(const cbor_item_t *item)

Get the size of the allocated storage.

param item[borrow]:

An array

return:

The size of the allocated storage (number of items)

bool cbor_array_is_definite(const cbor_item_t *item)

Is the array definite?

param item[borrow]:

An array

return:

Is the array definite?

bool cbor_array_is_indefinite(const cbor_item_t *item)

Is the array indefinite?

param item[borrow]:

An array

return:

Is the array indefinite?

Reading data

cbor_item_t **cbor_array_handle(const cbor_item_t *item)

Get the array contents.

The items may be reordered and modified as long as references remain consistent.

param item[borrow]:

An array

return:

cbor_array_size items

cbor_item_t *cbor_array_get(const cbor_item_t *item, size_t index)

Get item by index.

param item[borrow]:

An array

param index:

The index

return:

incref The item, or NULL in case of boundary violation

Creating new items

cbor_item_t *cbor_new_definite_array(size_t size)

Create new definite array.

param size:

Number of slots to preallocate

return:

new array or NULL upon malloc failure

cbor_item_t *cbor_new_indefinite_array()

Create new indefinite array.

return:

new array or NULL upon malloc failure

Modifying items

bool cbor_array_push(cbor_item_t *array, cbor_item_t *pushee)

Append to the end.

For indefinite items, storage may be realloacted. For definite items, only the preallocated capacity is available.

param array[borrow]:

An array

param pushee[incref]:

The item to push

return:

true on success, false on failure

bool cbor_array_replace(cbor_item_t *item, size_t index, cbor_item_t *value)

Replace item at an index.

The item being replace will be cbor_decref ‘ed.

param item[borrow]:

An array

param value[incref]:

The item to assign

param index:

The index, first item is 0.

return:

true on success, false on allocation failure.

bool cbor_array_set(cbor_item_t *item, size_t index, cbor_item_t *value)

Set item by index.

Creating arrays with holes is not possible

param item[borrow]:

An array

param value[incref]:

The item to assign

param index:

The index, first item is 0.

return:

true on success, false on allocation failure.