#ifndef TREE_WALK_H

#define TREE_WALK_H

#include "cache.h"

#define MAX_TRAVERSE_TREES 8

/**

 * The tree walking API is used to traverse and inspect trees.

 */

/**

 * An entry in a tree. Each entry has a sha1 identifier, pathname, and mode.

 */

struct name_entry {

	struct object_id oid;

	const char *path;

	int pathlen;

	unsigned int mode;

};

/**

 * A semi-opaque data structure used to maintain the current state of the walk.

 */

struct tree_desc {

	/*

	 * pointer into the memory representation of the tree. It always

	 * points at the current entry being visited.

	 */

	const void *buffer;

	/* points to the current entry being visited. */

	struct name_entry entry;

	/* counts the number of bytes left in the `buffer`. */

	unsigned int size;

};

/**

 * Decode the entry currently being visited (the one pointed to by

 * `tree_desc's` `entry` member) and return the sha1 of the entry. The

 * `pathp` and `modep` arguments are set to the entry's pathname and mode

 * respectively.

 */

static inline const struct object_id *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned short *modep)

{

	*pathp = desc->entry.path;

	*modep = desc->entry.mode;

	return &desc->entry.oid;

}

/**

 * Calculate the length of a tree entry's pathname. This utilizes the

 * memory structure of a tree entry to avoid the overhead of using a

 * generic strlen().

 */

static inline int tree_entry_len(const struct name_entry *ne)

{

	return ne->pathlen;

}

/*

 * The _gently versions of these functions warn and return false on a

 * corrupt tree entry rather than dying,

 */

/**

 * Walk to the next entry in a tree. This is commonly used in conjunction

 * with `tree_entry_extract` to inspect the current entry.

 */

void update_tree_entry(struct tree_desc *);

int update_tree_entry_gently(struct tree_desc *);

/**

 * Initialize a `tree_desc` and decode its first entry. The buffer and

 * size parameters are assumed to be the same as the buffer and size

 * members of `struct tree`.

 */

void init_tree_desc(struct tree_desc *desc, const void *buf, unsigned long size);

int init_tree_desc_gently(struct tree_desc *desc, const void *buf, unsigned long size);

/*

 * Visit the next entry in a tree. Returns 1 when there are more entries

 * left to visit and 0 when all entries have been visited. This is

 * commonly used in the test of a while loop.

 */

int tree_entry(struct tree_desc *, struct name_entry *);

int tree_entry_gently(struct tree_desc *, struct name_entry *);

/**

 * Initialize a `tree_desc` and decode its first entry given the

 * object ID of a tree. Returns the `buffer` member if the latter

 * is a valid tree identifier and NULL otherwise.

 */

void *fill_tree_descriptor(struct repository *r,

			   struct tree_desc *desc,

			   const struct object_id *oid);

struct traverse_info;

typedef int (*traverse_callback_t)(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *);

/**

 * Traverse `n` number of trees in parallel. The `fn` callback member of

 * `traverse_info` is called once for each tree entry.

 */

int traverse_trees(struct index_state *istate, int n, struct tree_desc *t, struct traverse_info *info);

enum get_oid_result get_tree_entry_follow_symlinks(struct repository *r, struct object_id *tree_oid, const char *name, struct object_id *result, struct strbuf *result_path, unsigned short *mode);

/**

 * A structure used to maintain the state of a traversal.

 */

struct traverse_info {

	const char *traverse_path;

	/*

	 * points to the traverse_info which was used to descend into the

	 * current tree. If this is the top-level tree `prev` will point to

	 * a dummy traverse_info.

	 */

	struct traverse_info *prev;

	/* is the entry for the current tree (if the tree is a subtree). */

	const char *name;

	size_t namelen;

	unsigned mode;

	/* is the length of the full path for the current tree. */

	size_t pathlen;

	struct pathspec *pathspec;

	/* can be used by callbacks to maintain directory-file conflicts. */

	unsigned long df_conflicts;

	/* a callback called for each entry in the tree.

	 *

	 * The arguments passed to the traverse callback are as follows:

	 *

	 * - `n` counts the number of trees being traversed.

	 *

	 * - `mask` has its nth bit set if something exists in the nth entry.

	 *

	 * - `dirmask` has its nth bit set if the nth tree's entry is a directory.

	 *

	 * - `entry` is an array of size `n` where the nth entry is from the nth tree.

	 *

	 * - `info` maintains the state of the traversal.

	 *

	 * Returning a negative value will terminate the traversal. Otherwise the

	 * return value is treated as an update mask. If the nth bit is set the nth tree

	 * will be updated and if the bit is not set the nth tree entry will be the

	 * same in the next callback invocation.

	 */

	traverse_callback_t fn;

	/* can be anything the `fn` callback would want to use. */

	void *data;

	/* tells whether to stop at the first error or not. */

	int show_all_errors;

};

/**

 * Find an entry in a tree given a pathname and the sha1 of a tree to

 * search. Returns 0 if the entry is found and -1 otherwise. The third

 * and fourth parameters are set to the entry's sha1 and mode respectively.

 */

int get_tree_entry(struct repository *, const struct object_id *, const char *, struct object_id *, unsigned short *);

/**

 * Generate the full pathname of a tree entry based from the root of the

 * traversal. For example, if the traversal has recursed into another

 * tree named "bar" the pathname of an entry "baz" in the "bar"

 * tree would be "bar/baz".

 */

char *make_traverse_path(char *path, size_t pathlen, const struct traverse_info *info,

			 const char *name, size_t namelen);

/**

 * Convenience wrapper to `make_traverse_path` into a strbuf.

 */

void strbuf_make_traverse_path(struct strbuf *out,

			       const struct traverse_info *info,

			       const char *name, size_t namelen);

/**

 * Initialize a `traverse_info` given the pathname of the tree to start

 * traversing from.

 */

void setup_traverse_info(struct traverse_info *info, const char *base);

/**

 * Calculate the length of a pathname returned by `make_traverse_path`.

 * This utilizes the memory structure of a tree entry to avoid the

 * overhead of using a generic strlen().

 */

static inline size_t traverse_path_len(const struct traverse_info *info,

				       size_t namelen)

{

	return st_add(info->pathlen, namelen);

}

/* in general, positive means "kind of interesting" */

enum interesting {

	all_entries_not_interesting = -1, /* no, and no subsequent entries will be either */

	entry_not_interesting = 0,

	entry_interesting = 1,

	all_entries_interesting = 2 /* yes, and all subsequent entries will be */

};

enum interesting tree_entry_interesting(struct index_state *istate,

					const struct name_entry *,

					struct strbuf *, int,

					const struct pathspec *ps);

#endif