NAME

bson_visitor_t - The bson_visitor_t structure provides a series of callbacks that can be called while iterating a BSON document. This may simplify the conversion of a bson_t to a higher level language structure.

SYNOPSIS

#include <bson.h>

typedef struct
{
   bool (*visit_before)     (const bson_iter_t *iter,
                             const char        *key,
                             void              *data);
   bool (*visit_after)      (const bson_iter_t *iter,
                             const char        *key,
                             void              *data);
   void (*visit_corrupt)    (const bson_iter_t *iter,
                             void              *data);
   bool (*visit_double)     (const bson_iter_t *iter,
                             const char        *key,
                             double             v_double,
                             void              *data);
   bool (*visit_utf8)       (const bson_iter_t *iter,
                             const char        *key,
                             size_t             v_utf8_len,
                             const char        *v_utf8,
                             void              *data);
   bool (*visit_document)   (const bson_iter_t *iter,
                             const char        *key,
                             const bson_t      *v_document,
                             void              *data);
   bool (*visit_array)      (const bson_iter_t *iter,
                             const char        *key,
                             const bson_t      *v_array,
                             void              *data);
   bool (*visit_binary)     (const bson_iter_t *iter,
                             const char        *key,
                             bson_subtype_t     v_subtype,
                             size_t             v_binary_len,
                             const uint8_t     *v_binary,
                             void              *data);
   bool (*visit_undefined)  (const bson_iter_t *iter,
                             const char        *key,
                             void              *data);
   bool (*visit_oid)        (const bson_iter_t *iter,
                             const char        *key,
                             const bson_oid_t  *v_oid,
                             void              *data);
   bool (*visit_bool)       (const bson_iter_t *iter,
                             const char        *key,
                             bool               v_bool,
                             void              *data);
   bool (*visit_date_time)  (const bson_iter_t *iter,
                             const char        *key,
                             int64_t            msec_since_epoch,
                             void              *data);
   bool (*visit_null)       (const bson_iter_t *iter,
                             const char        *key,
                             void              *data);
   bool (*visit_regex)      (const bson_iter_t *iter,
                             const char        *key,
                             const char        *v_regex,
                             const char        *v_options,
                             void              *data);
   bool (*visit_dbpointer)  (const bson_iter_t *iter,
                             const char        *key,
                             size_t             v_collection_len,
                             const char        *v_collection,
                             const bson_oid_t  *v_oid,
                             void              *data);
   bool (*visit_code)       (const bson_iter_t *iter,
                             const char        *key,
                             size_t             v_code_len,
                             const char        *v_code,
                             void              *data);
   bool (*visit_symbol)     (const bson_iter_t *iter,
                             const char        *key,
                             size_t             v_symbol_len,
                             const char        *v_symbol,
                             void              *data);
   bool (*visit_codewscope) (const bson_iter_t *iter,
                             const char        *key,
                             size_t             v_code_len,
                             const char        *v_code,
                             const bson_t      *v_scope,
                             void              *data);
   bool (*visit_int32)      (const bson_iter_t *iter,
                             const char        *key,
                             int32_t            v_int32,
                             void              *data);
   bool (*visit_timestamp)  (const bson_iter_t *iter,
                             const char        *key,
                             uint32_t           v_timestamp,
                             uint32_t           v_increment,
                             void              *data);
   bool (*visit_int64)      (const bson_iter_t *iter,
                             const char        *key,
                             int64_t            v_int64,
                             void              *data);
   bool (*visit_maxkey)     (const bson_iter_t *iter,
                             const char        *key,
                             void              *data);
   bool (*visit_minkey)     (const bson_iter_t *iter,
                             const char        *key,
                             void              *data);

   void *padding[9];
} bson_visitor_t;

DESCRIPTION

The bson_visitor_t structure provides a series of callbacks that can be called while iterating a BSON document. This may simplify the conversion of a bson_t to a higher level language structure.

EXAMPLE

#include <bson.h>
#include <stdio.h>

static bool
my_visit_before (const bson_iter_t *iter,
                 const char        *key,
                 void              *data)
{
   int *count = (int *)data;

   (*count)++;

   /* returning true stops further iteration of the document */

   return false; 
}

static void
count_fields (bson_t *doc)
{
   bson_visitor_t visitor;
   bson_iter_t iter;
   int count = 0;

   visitor.visit_before = my_visit_before;

   if (bson_iter_init (&iter, doc)) {
      bson_iter_visit_all (&iter, &visitor, &count);
   }

   printf ("Found %d fields.\n", count);
}

COLOPHON

This page is part of libbson. Please report any bugs at https://jira.mongodb.org/browse/CDRIVER.