git/unpack-trees.h
Junio C Hamano da165f470e unpack-trees.c: prepare for looking ahead in the index
This prepares but does not yet implement a look-ahead in the index entries
when traverse-trees.c decides to give us tree entries in an order that
does not match what is in the index.

A case where a look-ahead in the index is necessary happens when merging
branch B into branch A while the index matches the current branch A, using
a tree O as their common ancestor, and these three trees looks like this:

   O        A       B
   t                t
   t-i      t-i     t-i
   t-j      t-j
            t/1
            t/2

The traverse_trees() function gets "t", "t-i" and "t" from trees O, A and
B first, and notices that A may have a matching "t" behind "t-i" and "t-j"
(indeed it does), and tells A to give that entry instead.  After unpacking
blob "t" from tree B (as it hasn't changed since O in B and A removed it,
it will result in its removal), it descends into directory "t/".

The side that walked index in parallel to the tree traversal used to be
implemented with one pointer, o->pos, that points at the next index entry
to be processed.  When this happens, the pointer o->pos still points at
"t-i" that is the first entry.  We should be able to skip "t-i" and "t-j"
and locate "t/1" from the index while the recursive invocation of
traverse_trees() walks and match entries found there, and later come back
to process "t-i".

While that look-ahead is not implemented yet, this adds a flag bit,
CE_UNPACKED, to mark the entries in the index that has already been
processed.  o->pos pointer has been renamed to o->cache_bottom and it
points at the first entry that may still need to be processed.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-01-07 14:59:54 -08:00

58 lines
1.4 KiB
C

#ifndef UNPACK_TREES_H
#define UNPACK_TREES_H
#define MAX_UNPACK_TREES 8
struct unpack_trees_options;
typedef int (*merge_fn_t)(struct cache_entry **src,
struct unpack_trees_options *options);
struct unpack_trees_error_msgs {
const char *would_overwrite;
const char *not_uptodate_file;
const char *not_uptodate_dir;
const char *would_lose_untracked;
const char *bind_overlap;
};
struct unpack_trees_options {
unsigned int reset,
merge,
update,
index_only,
nontrivial_merge,
trivial_merges_only,
verbose_update,
aggressive,
skip_unmerged,
initial_checkout,
diff_index_cached,
gently;
const char *prefix;
int cache_bottom;
struct dir_struct *dir;
merge_fn_t fn;
struct unpack_trees_error_msgs msgs;
int head_idx;
int merge_size;
struct cache_entry *df_conflict_entry;
void *unpack_data;
struct index_state *dst_index;
struct index_state *src_index;
struct index_state result;
};
extern int unpack_trees(unsigned n, struct tree_desc *t,
struct unpack_trees_options *options);
int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o);
int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o);
int bind_merge(struct cache_entry **src, struct unpack_trees_options *o);
int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o);
#endif