git/object.h
Michael Haggerty 1506510c17 object_array_remove_duplicates(): rewrite to reduce copying
The old version copied one entry to its destination position, then
deleted any matching entries from the tail of the array.  This
required the tail of the array to be copied multiple times.  It didn't
affect the complexity of the algorithm because the whole tail has to
be searched through anyway.  But all the copying was unnecessary.

Instead, check for the existence of an entry with the same name in the
*head* of the list before copying an entry to its final position.
This way each entry has to be copied at most one time.

Extract a helper function contains_name() to do a bit of the work.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-05-28 09:25:01 -07:00

108 lines
3.3 KiB
C

#ifndef OBJECT_H
#define OBJECT_H
struct object_list {
struct object *item;
struct object_list *next;
};
struct object_array {
unsigned int nr;
unsigned int alloc;
struct object_array_entry {
struct object *item;
const char *name;
unsigned mode;
} *objects;
};
#define OBJECT_ARRAY_INIT { 0, 0, NULL }
#define TYPE_BITS 3
#define FLAG_BITS 27
/*
* The object type is stored in 3 bits.
*/
struct object {
unsigned parsed : 1;
unsigned used : 1;
unsigned type : TYPE_BITS;
unsigned flags : FLAG_BITS;
unsigned char sha1[20];
};
extern const char *typename(unsigned int type);
extern int type_from_string(const char *str);
extern unsigned int get_max_object_index(void);
extern struct object *get_indexed_object(unsigned int);
/*
* This can be used to see if we have heard of the object before, but
* it can return "yes we have, and here is a half-initialised object"
* for an object that we haven't loaded/parsed yet.
*
* When parsing a commit to create an in-core commit object, its
* parents list holds commit objects that represent its parents, but
* they are expected to be lazily initialized and do not know what
* their trees or parents are yet. When this function returns such a
* half-initialised objects, the caller is expected to initialize them
* by calling parse_object() on them.
*/
struct object *lookup_object(const unsigned char *sha1);
extern void *create_object(const unsigned char *sha1, int type, void *obj);
/*
* Returns the object, having parsed it to find out what it is.
*
* Returns NULL if the object is missing or corrupt.
*/
struct object *parse_object(const unsigned char *sha1);
/*
* Like parse_object, but will die() instead of returning NULL. If the
* "name" parameter is not NULL, it is included in the error message
* (otherwise, the sha1 hex is given).
*/
struct object *parse_object_or_die(const unsigned char *sha1, const char *name);
/* Given the result of read_sha1_file(), returns the object after
* parsing it. eaten_p indicates if the object has a borrowed copy
* of buffer and the caller should not free() it.
*/
struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p);
/** Returns the object, with potentially excess memory allocated. **/
struct object *lookup_unknown_object(const unsigned char *sha1);
struct object_list *object_list_insert(struct object *item,
struct object_list **list_p);
int object_list_contains(struct object_list *list, struct object *obj);
/* Object array handling .. */
void add_object_array(struct object *obj, const char *name, struct object_array *array);
void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode);
typedef int (*object_array_each_func_t)(struct object_array_entry *, void *);
/*
* Apply want to each entry in array, retaining only the entries for
* which the function returns true. Preserve the order of the entries
* that are retained.
*/
void object_array_filter(struct object_array *array,
object_array_each_func_t want, void *cb_data);
/*
* Remove from array all but the first entry with a given name.
* Warning: this function uses an O(N^2) algorithm.
*/
void object_array_remove_duplicates(struct object_array *array);
void clear_object_flags(unsigned flags);
#endif /* OBJECT_H */