path: root/libparc/parc/algol/parc_Chunker.h

/*
 * Copyright (c) 2017 Cisco and/or its affiliates.
 * 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.
 */

/**
 * @file parc_Chunker.h
 * @ingroup ContentObject
 * @brief A Chunker is an object that breaks up a large piece of data from a `PARCBuffer`
 *        or a file and provides an iterator to walk over the chunks in sequential order.
 *
 */

#ifndef libparc_parc_Chunker_h
#define libparc_parc_Chunker_h

#include <parc/algol/parc_Object.h>
#include <parc/algol/parc_Iterator.h>

struct parc_chunker;
/**
 * @typedef PARCChunker
 * @brief The PARC Chunker
 */
typedef struct parc_chunker PARCChunker;

typedef struct PARCChunkerInterface {
    /**
     * @see parcChunker_ForwardIterator
     */
    void *(*ForwardIterator)(const void *original);

    /**
     * @see parcChunker_ReverseIterator
     */
    void *(*ReverseIterator)(const void *original);

    /**
     * @see parcChunker_GetChunkSize
     */
    size_t (*GetChunkSize)(const void *original);
} PARCChunkerInterface;

/**
 * Create a new chunker from the given concrete instance.
 *
 * @param [in] instance A `PARCChunker` instance.
 * @param [in] interface The interface implementation of the chunker.
 *
 * @retval PARCChunker A newly allocated `PARCChunker`
 * @retval NULL An error occurred.
 *
 * Example
 * @code
 * {
 *     PARCBuffer *dataToChunk = ...
 *     PARCChunkerBuffer *bufferChunker = parcBufferChunker_Create(dataToChunk, 32);
 *     PARCChunker *chunker = parcChunker_Create(bufferCunker, &PARCBufferChunkerAsChunker);
 * }
 */
PARCChunker *parcChunker_Create(PARCObject *instance, PARCChunkerInterface *interface);

/**
 * Create a new chunker to segment data contained in a file.
 *
 * @param [in] fileName The name of a file from which to read.
 * @param [in] chunkSize The size per chunk.
 *
 * @retval PARCChunker A newly allocated `PARCChunker`
 * @retval NULL An error occurred.
 *
 * Example
 * @code
 * {
 *     char *bigFileName = "big_file.bin";
 *     PARCChunker *chunker = parcChunker_CreateFromBuffer(bigFileName, 32);
 * }
 */
//PARCChunker *parcChunker_CreateFromFile(char *fileName, size_t maxDataSize);

/**
 * Increase the number of references to a `PARCChunker` instance.
 *
 * Note that new `PARCChunker` is not created,
 * only that the given `PARCChunker` reference count is incremented.
 * Discard the reference by invoking {@link parcChunker_Release}.
 *
 * @param [in] chunker A pointer to the original `PARCChunker`.
 * @return The value of the input parameter @p chunker.
 *
 * Example:
 * @code
 * {
 *     PARCChunker *original = ...
 *
 *     PARCChunker *reference = parcChunker_Acquire(original);
 *
 *     parcChunker_Release(&original);
 *     parcChunker_Release(&reference);
 * }
 * @endcode
 *
 * @see parcChunker_Release
 */
PARCChunker *parcChunker_Acquire(const PARCChunker *chunker);

/**
 * Release a previously acquired reference to the specified instance,
 * decrementing the reference count for the instance.
 *
 * The pointer to the instance is set to NULL as a side-effect of this function.
 *
 * If the invocation causes the last reference to the instance to be released,
 * the instance is deallocated and the instance's implementation will perform
 * additional cleanup and release other privately held references.
 *
 * @param [in,out] chunkerP A pointer to a pointer to the instance to release.
 *
 *
 * Example:
 * @code
 * {
 *     ...
 *
 *     PARCChunker *chunker = parcChunker_Acquire(instance);
 *
 *     parcChunker_Release(&chunker);
 * }
 * @endcode
 */
void parcChunker_Release(PARCChunker **chunkerP);

/**
 * Determine if two `PARCChunker` instances are equal.
 *
 * The following equivalence relations on non-null `PARCChunker` instances are maintained:
 *
 *  * It is reflexive: for any non-null reference value x, `parcChunker_Equals(x, x)`
 *      must return true.
 *
 *  * It is symmetric: for any non-null reference values x and y,
 *    `parcChunker_Equals(x, y)` must return true if and only if
 *        `parcChunker_Equals(y, x)` returns true.
 *
 *  * It is transitive: for any non-null reference values x, y, and z, if
 *        `parcChunker_Equals(x, y)` returns true and
 *        `parcChunker_Equals(y, z)` returns true,
 *        then  `parcChunker_Equals(x, z)` must return true.
 *
 *  * It is consistent: for any non-null reference values x and y, multiple
 *      invocations of `parcChunker_Equals(x, y)` consistently return true or
 *      consistently return false.
 *
 *  * For any non-null reference value x, `parcChunker_Equals(x, NULL)` must
 *      return false.
 *
 * @param chunkerA A pointer to a `PARCChunker` instance.
 * @param chunkerB A pointer to a `PARCChunker` instance.
 * @return true if the two `PARCChunker` instances are equal.
 *
 * Example:
 * @code
 * {
 *     PARCBuffer *dataToChunk = ...
 *     PARCChunker *chunkerA = ...
 *     PARCChunker *chunkerB = ...
 *
 *     bool equals = parcChunker_Equals(chunkerA, chunkerB);
 * }
 * @endcode
 */
bool parcChunker_Equals(const PARCChunker *chunkerA, const PARCChunker *chunkerB);

/**
 * Return an iterator to traverse the chunks of the underlying data in sequential order.
 *
 * This function can only be called once per chunker instance since the iterator
 * will mutate internal state of the chunker.
 *
 * @param [in] chunker A `PARCChunker` instance.
 *
 * @return a `PARCIterator` that traverses the chunks of the underlying data.
 *
 * Example
 * @code
 * {
 *     PARCBuffer *dataToChunk = ...
 *     PARCBufferChunker *chunker = ...
 *
 *     PARCIterator *itr = parcChunker_ForwardIterator(chunker);
 *
 *     // use the iterator to traverse the chunker
 * }
 * @endcode
 */
PARCIterator *parcChunker_ForwardIterator(const PARCChunker *chunker);

/**
 * Return an iterator to traverse the chunks of the underlying data in sequential order.
 *
 * This function can only be called once per chunker instance since the iterator
 * will mutate internal state of the chunker.
 *
 * @param [in] chunker A `PARCChunker` instance.
 *
 * @return a `PARCIterator` that traverses the chunks of the underlying data.
 *
 * Example
 * @code
 * {
 *     PARCBuffer *dataToChunk = ...
 *     PARCChunker *chunker = ...
 *
 *     PARCIterator *itr = parcChunker_ReverseIterator(chunker);
 *
 *     // use the iterator to traverse the chunker
 * }
 * @endcode
 */
PARCIterator *parcChunker_ReverseIterator(const PARCChunker *chunker);

/**
 * Get the chunk size of a `PARCChunker.`
 *
 * @param [in] chunker A `PARCChunker` instance.
 *
 * @return the chunk size
 *
 * Example
 * @code
 * {
 *     PARCBuffer *dataToChunk = ...
 *     PARCChunker *chunker = ...
 *
 *     size_t chunkSize = parcChunker_GetChunkSize(chunker);
 * }
 * @endcode
 */
size_t parcChunker_GetChunkSize(const PARCChunker *chunker);
#endif // libparc_parc_Chunker_h