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[PATCH 17/20] merge-ort: add implementation of checkout()

From
Elijah Newren <newren@gmail.com>
Date
Oct 30, 2020, 03:41 UTC
Message-ID
<20201030034131.1479968-18-newren@gmail.com>
In-Reply-To
<20201030034131.1479968-1-newren@gmail.com>

Since merge-ort creates a tree for its output, when there are no conflicts, updating the working tree and index is as simple as using the unpack_trees() machinery with a twoway_merge (i.e. doing the equivalent of a "checkout" operation).

If there were conflicts in the merge, then since the tree we created included all the conflict markers, then using the unpack_trees machinery in this manner will still update the working tree correctly. Further, all index entries corresponding to cleanly merged files will also be updated correctly by this procedure. Index entries corresponding to unmerged entries will appear as though the user had run "git add -u" after the merge to accept all files as-is with conflict markers.

Thus, after running unpack_trees(), there needs to be a separate step for updating the entries in the index corresponding to unmerged files. This will be the job for the function record_unmerged_index_entries(), which will be implemented in a subsequent commit.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-ort.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)
diff --git a/merge-ort.c b/merge-ort.c
index a5b97adfc4..4da671d647 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -19,9 +19,11 @@
 
 #include "diff.h"
 #include "diffcore.h"
+#include "dir.h"
 #include "object-store.h"
 #include "strmap.h"
 #include "tree.h"
+#include "unpack-trees.h"
 #include "xdiff-interface.h"
 
 struct merge_options_internal {
@@ -663,7 +665,48 @@ static int checkout(struct merge_options *opt,
 		    struct tree *prev,
 		    struct tree *next)
 {
-	die("Not yet implemented.");
+	/* Switch the index/working copy from old to new */
+	int ret;
+	struct tree_desc trees[2];
+	struct unpack_trees_options unpack_opts;
+
+	memset(&unpack_opts, 0, sizeof(unpack_opts));
+	unpack_opts.head_idx = -1;
+	unpack_opts.src_index = opt->repo->index;
+	unpack_opts.dst_index = opt->repo->index;
+
+	setup_unpack_trees_porcelain(&unpack_opts, "merge");
+
+	/*
+	 * NOTE: if this were just "git checkout" code, we would probably
+	 * read or refresh the cache and check for an unmerged index, but
+	 * builtin/merge.c or sequencer.c really needs to read the index
+	 * and check for unmerged entries before starting merging for a
+	 * good user experience (no sense waiting for merges/rebases before
+	 * erroring out), so there's no reason to duplicate that work here.
+	 */
+
+	/* 2-way merge to the new branch */
+	unpack_opts.update = 1;
+	unpack_opts.merge = 1;
+	unpack_opts.quiet = 0; /* FIXME: sequencer might want quiet? */
+	unpack_opts.verbose_update = (opt->verbosity > 2);
+	unpack_opts.fn = twoway_merge;
+	if (1/* FIXME: opts->overwrite_ignore*/) {
+		unpack_opts.dir = xcalloc(1, sizeof(*unpack_opts.dir));
+		unpack_opts.dir->flags |= DIR_SHOW_IGNORED;
+		setup_standard_excludes(unpack_opts.dir);
+	}
+	parse_tree(prev);
+	init_tree_desc(&trees[0], prev->buffer, prev->size);
+	parse_tree(next);
+	init_tree_desc(&trees[1], next->buffer, next->size);
+
+	ret = unpack_trees(2, trees, &unpack_opts);
+	clear_unpack_trees_porcelain(&unpack_opts);
+	dir_clear(unpack_opts.dir);
+	FREE_AND_NULL(unpack_opts.dir);
+	return ret;
 }
 
 static int record_unmerged_index_entries(struct merge_options *opt,
-- 
2.29.1.56.ga287c268e6.dirty
Previous: Elijah NewrenNext: Elijah Newren
Message 16 of 22 in “fundamentals of merge-ort implementation”
  1. 00/20 fundamentals of merge-ort implementationElijah Newren, Oct 30, 2020
  2. 07/20 merge-ort: avoid repeating fill_tree_descriptor() on the same treeElijah Newren, Oct 30, 2020
  3. 04/20 merge-ort: use histogram diffElijah Newren, Oct 30, 2020
  4. 01/20 merge-ort: setup basic internal data structuresElijah Newren, Oct 30, 2020
  5. 02/20 merge-ort: add some high-level algorithm structureElijah Newren, Oct 30, 2020
  6. 06/20 merge-ort: implement a very basic collect_merge_info()Elijah Newren, Oct 30, 2020
  7. 13/20 merge-ort: step 1 of tree writing -- record basenames, modes, and oidsElijah Newren, Oct 30, 2020
  8. 11/20 merge-ort: add a preliminary simple process_entries() implementationElijah Newren, Oct 30, 2020
  9. 12/20 merge-ort: have process_entries operate in a defined orderElijah Newren, Oct 30, 2020
  10. 10/20 merge-ort: avoid recursing into identical treesElijah Newren, Oct 30, 2020
  11. 14/20 merge-ort: step 2 of tree writing -- function to create tree objectElijah Newren, Oct 30, 2020
  12. 15/20 merge-ort: step 3 of tree writing -- handling subdirectories as we goElijah Newren, Oct 30, 2020
  13. 20/20 merge-ort: free data structures in merge_finalize()Elijah Newren, Oct 30, 2020
  14. 19/20 merge-ort: add implementation of record_unmerged_index_entries()Elijah Newren, Oct 30, 2020
  15. 18/20 tree: enable cmp_cache_name_compare() to be used elsewhereElijah Newren, Oct 30, 2020
  16. 17/20 merge-ort: add implementation of checkout()Elijah Newren, Oct 30, 2020
  17. 16/20 merge-ort: basic outline for merge_switch_to_result()Elijah Newren, Oct 30, 2020
  18. 05/20 merge-ort: add an err() function similar to one from merge-recursiveElijah Newren, Oct 30, 2020
  19. 09/20 merge-ort: record stage and auxiliary info for every pathElijah Newren, Oct 30, 2020
  20. 03/20 merge-ort: port merge_start() from merge-recursiveElijah Newren, Oct 30, 2020
  21. 08/20 merge-ort: compute a few more useful fields for collect_merge_infoElijah Newren, Oct 30, 2020
  22. Elijah NewrenOct 30, 2020

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