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# bson_t

BSON Document Abstraction

## Synopsis

    #include <bson/bson.h>

    /**
     * bson_empty:
     * @b: a bson_t.
     *
     * Checks to see if @b is an empty BSON document. An empty BSON document is
     * a 5 byte document which contains the length (4 bytes) and a single NUL
     * byte indicating end of fields.
     */
    #define bson_empty(b) /* ... */

    /**
     * bson_empty0:
     *
     * Like bson_empty() but treats NULL the same as an empty bson_t document.
     */
    #define bson_empty0(b) /* ... */

    /**
     * bson_clear:
     *
     * Easily free a bson document and set it to NULL. Use like:
     *
     * bson_t *doc = bson_new();
     * bson_clear (&doc);
     * BSON_ASSERT (doc == NULL);
     */
    #define bson_clear(bptr) /* ... */

    /**
     * BSON_MAX_SIZE:
     *
     * The maximum size in bytes of a BSON document.
     */
    #define BSON_MAX_SIZE /* ... */

    #define BSON_APPEND_ARRAY(b, key, val) \
       bson_append_array (b, key, (int) strlen (key), val)

    #define BSON_APPEND_ARRAY_BEGIN(b, key, child) \
       bson_append_array_begin (b, key, (int) strlen (key), child)

    #define BSON_APPEND_BINARY(b, key, subtype, val, len) \
       bson_append_binary (b, key, (int) strlen (key), subtype, val, len)

    #define BSON_APPEND_BINARY_UNINIT(b, key, subtype, val, len) \
       bson_append_binary_uninit (b, key, (int) strlen (key), subtype, val, len)

    #define BSON_APPEND_BOOL(b, key, val) \
       bson_append_bool (b, key, (int) strlen (key), val)

    #define BSON_APPEND_CODE(b, key, val) \
       bson_append_code (b, key, (int) strlen (key), val)

    #define BSON_APPEND_CODE_WITH_SCOPE(b, key, val, scope) \
       bson_append_code_with_scope (b, key, (int) strlen (key), val, scope)

    #define BSON_APPEND_DBPOINTER(b, key, coll, oid) \
       bson_append_dbpointer (b, key, (int) strlen (key), coll, oid)

    #define BSON_APPEND_DOCUMENT_BEGIN(b, key, child) \
       bson_append_document_begin (b, key, (int) strlen (key), child)

    #define BSON_APPEND_DOUBLE(b, key, val) \
       bson_append_double (b, key, (int) strlen (key), val)

    #define BSON_APPEND_DOCUMENT(b, key, val) \
       bson_append_document (b, key, (int) strlen (key), val)

    #define BSON_APPEND_INT32(b, key, val) \
       bson_append_int32 (b, key, (int) strlen (key), val)

    #define BSON_APPEND_INT64(b, key, val) \
       bson_append_int64 (b, key, (int) strlen (key), val)

    #define BSON_APPEND_MINKEY(b, key) \
       bson_append_minkey (b, key, (int) strlen (key))

    #define BSON_APPEND_DECIMAL128(b, key, val) \
       bson_append_decimal128 (b, key, (int) strlen (key), val)

    #define BSON_APPEND_MAXKEY(b, key) \
       bson_append_maxkey (b, key, (int) strlen (key))

    #define BSON_APPEND_NULL(b, key) bson_append_null (b, key, (int) strlen (key))

    #define BSON_APPEND_OID(b, key, val) \
       bson_append_oid (b, key, (int) strlen (key), val)

    #define BSON_APPEND_REGEX(b, key, val, opt) \
       bson_append_regex (b, key, (int) strlen (key), val, opt)

    #define BSON_APPEND_UTF8(b, key, val) \
       bson_append_utf8 (b, key, (int) strlen (key), val, (int) strlen (val))

    #define BSON_APPEND_SYMBOL(b, key, val) \
       bson_append_symbol (b, key, (int) strlen (key), val, (int) strlen (val))

    #define BSON_APPEND_TIME_T(b, key, val) \
       bson_append_time_t (b, key, (int) strlen (key), val)

    #define BSON_APPEND_TIMEVAL(b, key, val) \
       bson_append_timeval (b, key, (int) strlen (key), val)

    #define BSON_APPEND_DATE_TIME(b, key, val) \
       bson_append_date_time (b, key, (int) strlen (key), val)

    #define BSON_APPEND_TIMESTAMP(b, key, val, inc) \
       bson_append_timestamp (b, key, (int) strlen (key), val, inc)

    #define BSON_APPEND_UNDEFINED(b, key) \
       bson_append_undefined (b, key, (int) strlen (key))

    #define BSON_APPEND_VALUE(b, key, val) \
       bson_append_value (b, key, (int) strlen (key), (val))

    typedef struct {
       uint32_t flags;       /* Internal flags for the bson_t. */
       uint32_t len;         /* Length of BSON data. */
       uint8_t padding[120]; /* Padding for stack allocation. */
    } bson_t;

## Description

The bson_t structure represents a BSON document. This structure manages the underlying BSON encoded buffer. For mutable documents, it can append new data to the document.

## Performance Notes

The bson_t structure attempts to use an inline allocation within the structure to speed up performance of small documents. When this internal buffer has been exhausted, a heap allocated buffer will be dynamically allocated. Therefore, it is essential to call bson_destroy() on allocated documents.

## Duplicate Keys

The BSON specification allows BSON documents to have duplicate keys. Documents are stored as an ordered list of key-value pairs. A bson_t may contain duplicate keys. Applications should refrain from generating such documents, because MongoDB server behavior is undefined when a BSON document contains duplicate keys.

## Functions

- bson_append_array()
- bson_append_array_begin()
- bson_append_array_unsafe_begin()
- bson_append_array_end()
- bson_append_binary()
- bson_append_binary_uninit()
- bson_append_bool()
- bson_append_code()
- bson_append_code_with_scope()
- bson_append_date_time()
- bson_append_dbpointer()
- bson_append_decimal128()
- bson_append_document()
- bson_append_document_begin()
- bson_append_document_end()
- bson_append_double()
- bson_append_int32()
- bson_append_int64()
- bson_append_iter()
- bson_append_maxkey()
- bson_append_minkey()
- bson_append_now_utc()
- bson_append_null()
- bson_append_oid()
- bson_append_regex()
- bson_append_regex_w_len()
- bson_append_symbol()
- bson_append_time_t()
- bson_append_timestamp()
- bson_append_timeval()
- bson_append_undefined()
- bson_append_utf8()
- bson_append_value()
- bson_array_as_canonical_extended_json()
- bson_array_as_legacy_extended_json()
- bson_array_as_relaxed_extended_json()
- bson_as_canonical_extended_json()
- bson_as_json_with_opts()
- bson_as_legacy_extended_json()
- bson_as_relaxed_extended_json()
- bson_compare()
- bson_concat()
- bson_copy()
- bson_copy_to()
- bson_copy_to_excluding_noinit()
- bson_copy_to_excluding_noinit_va()
- bson_count_keys()
- bson_destroy()
- bson_destroy_with_steal()
- bson_equal()
- bson_get_data()
- bson_has_field()
- bson_init()
- bson_init_from_json()
- bson_init_static()
- bson_json_mode_t
- bson_json_opts_t
- bson_new()
- bson_new_from_buffer()
- bson_new_from_data()
- bson_new_from_json()
- bson_reinit()
- bson_reserve_buffer()
- bson_sized_new()
- bson_steal()
- bson_validate()
- bson_validate_with_error()
- bson_validate_with_error_and_offset()

## Example

    static void
    create_on_heap (void)
    {
       bson_t *b = bson_new ();

       BSON_APPEND_INT32 (b, "foo", 123);
       BSON_APPEND_UTF8 (b, "bar", "foo");
       BSON_APPEND_DOUBLE (b, "baz", 1.23f);

       bson_destroy (b);
    }