Subject: [PATCH 11/20] merge-ort: add a preliminary simple process_entries() implementation

From: Elijah Newren <[email-masked]>
Date: Thu, 29 Oct 2020 20:41:22 -0700

Add a process_entries() implementation that just loops over the paths
and processes each one individually with an auxiliary process_entry()
call.  Add a basic process_entry() as well, which handles several cases
but leaves a few of the more involved ones with die-not-implemented
messages.  Also, although process_entries() is supposed to create a
tree, it does not yet have code to do so -- except in the special case
of merging completely empty trees.

Signed-off-by: Elijah Newren <[email-masked]>
---
 merge-ort.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 105 insertions(+), 1 deletion(-)

diff --git a/merge-ort.c b/merge-ort.c
index 2a402e18ed..f4bf1baf78 100644
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -324,10 +324,114 @@ static int detect_and_process_renames(struct merge_options *opt,
 	return clean;
 }
 
+/* Per entry merge function */
+static void process_entry(struct merge_options *opt,
+			  const char *path,
+			  struct conflict_info *ci)
+{
+	assert(!ci->merged.clean);
+	assert(ci->filemask >= 0 && ci->filemask <= 7);
+
+	if (ci->filemask == 0) {
+		/*
+		 * This is a placeholder for directories that were recursed
+		 * into; nothing to do in this case.
+		 */
+		return;
+	}
+
+	if (ci->df_conflict) {
+		die("Not yet implemented.");
+	}
+
+	/*
+	 * NOTE: Below there is a long switch-like if-elseif-elseif... block
+	 *       which the code goes through even for the df_conflict cases
+	 *       above.  Well, it will once we don't die-not-implemented above.
+	 */
+	if (ci->match_mask) {
+		ci->merged.clean = 1;
+		if (ci->match_mask == 6) {
+			/* stages[1] == stages[2] */
+			ci->merged.result.mode = ci->stages[1].mode;
+			oidcpy(&ci->merged.result.oid, &ci->stages[1].oid);
+		} else {
+			/* determine the mask of the side that didn't match */
+			unsigned int othermask = 7 & ~ci->match_mask;
+			int side = (othermask == 4) ? 2 : 1;
+
+			ci->merged.is_null = (ci->filemask == ci->match_mask);
+			ci->merged.result.mode = ci->stages[side].mode;
+			oidcpy(&ci->merged.result.oid, &ci->stages[side].oid);
+
+			assert(othermask == 2 || othermask == 4);
+			assert(ci->merged.is_null == !ci->merged.result.mode);
+		}
+	} else if (ci->filemask >= 6 &&
+		   (S_IFMT & ci->stages[1].mode) !=
+		   (S_IFMT & ci->stages[2].mode)) {
+		/*
+		 * Two different items from (file/submodule/symlink)
+		 */
+		die("Not yet implemented.");
+	} else if (ci->filemask >= 6) {
+		/*
+		 * TODO: Needs a two-way or three-way content merge, but we're
+		 * just being lazy and copying the version from HEAD and
+		 * leaving it as conflicted.
+		 */
+		ci->merged.clean = 0;
+		ci->merged.result.mode = ci->stages[1].mode;
+		oidcpy(&ci->merged.result.oid, &ci->stages[1].oid);
+	} else if (ci->filemask == 3 || ci->filemask == 5) {
+		/* Modify/delete */
+		die("Not yet implemented.");
+	} else if (ci->filemask == 2 || ci->filemask == 4) {
+		/* Added on one side */
+		int side = (ci->filemask == 4) ? 2 : 1;
+		ci->merged.result.mode = ci->stages[side].mode;
+		oidcpy(&ci->merged.result.oid, &ci->stages[side].oid);
+		ci->merged.clean = !ci->df_conflict && !ci->path_conflict;
+	} else if (ci->filemask == 1) {
+		/* Deleted on both sides */
+		ci->merged.is_null = 1;
+		ci->merged.result.mode = 0;
+		oidcpy(&ci->merged.result.oid, &null_oid);
+		ci->merged.clean = !ci->path_conflict;
+	}
+
+	/*
+	 * If still unmerged, record it separately.  This allows us to later
+	 * iterate over just unmerged entries when updating the index instead
+	 * of iterating over all entries.
+	 */
+	if (!ci->merged.clean)
+		strmap_put(&opt->priv->unmerged, path, ci);
+}
+
 static void process_entries(struct merge_options *opt,
 			    struct object_id *result_oid)
 {
-	die("Not yet implemented.");
+	struct hashmap_iter iter;
+	struct strmap_entry *e;
+
+	if (strmap_empty(&opt->priv->paths)) {
+		oidcpy(result_oid, opt->repo->hash_algo->empty_tree);
+		return;
+	}
+
+	strmap_for_each_entry(&opt->priv->paths, &iter, e) {
+		/*
+		 * WARNING: If ci->merged.clean is true, then ci does not
+		 * actually point to a conflict_info but a struct merge_info.
+		 */
+		struct conflict_info *ci = e->value;
+
+		if (!ci->merged.clean)
+			process_entry(opt, e->key, e->value);
+	}
+
+	die("Tree creation not yet implemented");
 }
 
 void merge_switch_to_result(struct merge_options *opt,
-- 
2.29.1.56.ga287c268e6.dirty