/*
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 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
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 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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 */

#ifndef INCLUDE_git_revwalk_h__
#define INCLUDE_git_revwalk_h__

#include "git_common.h"
#include "git_odb.h"
#include "git_commit.h"

/**
 * @file git_revwalk.h
 * @brief Git revision traversal routines
 * @defgroup git_revwalk Git revision traversal routines
 * @ingroup Git
 * @{
 */
GIT_BEGIN_DECL

/** Configuration of a revision pool. */
typedef struct git_revp_attr git_revp_attr;

/**
 * Allocate an empty pool configuration.
 *
 * The resulting configuration is identical to passing NULL
 * to git_revp_alloc().
 *
 * @return a new configuration block.
 *         NULL if there is insufficient memory.
 */
GIT_EXTERN(git_revp_attr*) git_revp_attr_alloc(void);

/**
 * Setup the application's per-commit data allocation.
 *
 * If size is non-zero the requested number of bytes is allocated
 * alongside every git_commit used by the revision pool, allowing
 * constant-time access to per-commit application data.
 *
 * If init is not NULL the function is invoked with the commit and
 * the application data pointer, allowing the function to populate
 * the application's data space the first time the commit is parsed
 * into the pool.  Space available within the application data is
 * not initialized.  Subsequent resets do not invoke this method.
 *
 * If init is NULL and size is non-zero the application data space
 * is cleared during the first parse.
 *
 * @param attr the pool configuration to adjust.
 * @param size number of bytes required by the application on
 *        each rev_commit instance within the pool.
 * @param init optional callback function to initialize the
 *        application data space.  If NULL the application
 *        space will be zeroed.  If supplied the application
 *        space may contain random garbage.
 */
GIT_EXTERN(void) git_revp_attr_appdata(
	git_revp_attr *attr,
	size_t size,
	int (*init)(git_commit *, void *));

/**
 * Free a pool configuration.
 * @param attr the configuration to free.  No-op if NULL.
 */
GIT_EXTERN(void) git_revp_attr_free(git_revp_attr *attr);

/**
 * Allocate a new revision traversal pool.
 *
 * The configuration is copied during allocation.  Changes
 * to the configuration after allocation do not affect the pool
 * returned by this function.  Callers may safely free the
 * passed configuration after the function completes.
 *
 * @param db the database objects are read from.
 * @param attr configuration for the pool.
 *        NULL to use a default configuration.
 * @return the new traversal handle; NULL if memory is exhausted.
 */
GIT_EXTERN(git_revp*) git_revp_alloc(
	git_odb *db,
	const git_revp_attr *attr);

/**
 * Reset the traversal machinary for reuse.
 * @param pool traversal handle to reset.
 */
GIT_EXTERN(void) git_revp_reset(git_revp *pool);

/**
 * Mark an object to start traversal from.
 * @param pool the pool being used for the traversal.
 * @param commit the commit the commit to start from.
 */
GIT_EXTERN(void) git_revp_pushc(git_revp *pool, git_commit *commit);

/**
 * Mark a commit (and its ancestors) uninteresting for the output.
 * @param pool the pool being used for the traversal.
 * @param commit the commit the commit to start from.
 */
GIT_EXTERN(void) git_revp_hidec(git_revp *pool, git_commit *commit);

/**
 * Get the next commit from the revision traversal.
 * @param pool the pool to pop the commit from.
 * @return next commit; NULL if there is no more output.
 */
GIT_EXTERN(git_commit*) git_revp_nextc(git_revp *pool);

/**
 * Free a revwalk previously allocated.
 * @param pool traversal handle to close.  If NULL nothing occurs.
 */
GIT_EXTERN(void) git_revp_free(git_revp *pool);

/** @} */
GIT_END_DECL
#endif