as_iterator.h

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/* 
 * Copyright 2008-2018 Aerospike, Inc.
 *
 * Portions may be licensed to Aerospike, Inc. under one or more contributor
 * license agreements.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

#pragma once

#include <aerospike/as_std.h>
#include <aerospike/as_util.h>
#include <aerospike/as_val.h>

#ifdef __cplusplus
extern "C" {
#endif

/******************************************************************************
 *  TYPES
 ******************************************************************************/

struct as_iterator_hooks_s;

/**
 *  Iterator Object
 */
typedef struct as_iterator_s {

    /**
     *  @private
     *  If TRUE, then free this instance.
     */
    bool free;

    /**
     *  Data for the iterator.
     */
    void * data;

    /**
     *  Hooks for subtypes of as_iterator.
     */
    const struct as_iterator_hooks_s * hooks;

} as_iterator;

/**
 *  Iterator Function Hooks
 */
typedef struct as_iterator_hooks_s {

    /**
     *  Releases the subtype of as_iterator.
     */
    bool (* destroy)(as_iterator *);

    /**
     *  Tests whether there is another element in the iterator.
     */
    bool (* has_next)(const as_iterator *);

    /**
     *  Read the next value.
     */
    const as_val * (* next)(as_iterator *);

} as_iterator_hooks;

/******************************************************************************
 *  INSTANCE FUNCTIONS
 ******************************************************************************/

/**
 *  Initialize a stack allocated iterator.
 */
AS_EXTERN as_iterator * as_iterator_init(as_iterator * iterator, bool free, void * data, const as_iterator_hooks * hooks);

/**
 *  Destroys the iterator and releasing associated resources.
 */
AS_EXTERN void as_iterator_destroy(as_iterator * iterator);

/******************************************************************************
 *  VALUE FUNCTIONS
 ******************************************************************************/

/**
 *  Tests if there are more values available in the iterator.
 *
 *  @param iterator     The iterator to be tested.
 *
 *  @return true if there are more values, otherwise false.
 */
static inline bool as_iterator_has_next(const as_iterator * iterator)
{
    return as_util_hook(has_next, false, iterator);
}

/**
 *  Attempts to get the next value from the iterator.
 *  This will return the next value, and iterate past the value.
 *
 *  @param iterator     The iterator to get the next value from.
 *
 *  @return the next value available in the iterator.
 */
static inline const as_val * as_iterator_next(as_iterator * iterator)
{
    return as_util_hook(next, NULL, iterator);
}

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