diff/status: introduce conflicts

When diffing against an index, return a new `GIT_DELTA_CONFLICTED`
delta type for items that are conflicted.  For a single file path,
only one delta will be produced (despite the fact that there are
multiple entries in the index).

Index iterators now have the (optional) ability to return conflicts
in the index.  Prior to this change, they would be omitted, and callers
(like diff) would omit conflicted index entries entirely.

1 files changed, 64 insertions, 13 deletions

diff --git a/src/diff.c b/src/diff.c
index f829fb07c..765956a29 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -327,6 +327,22 @@ static const char *diff_mnemonic_prefix(
 	return pfx;
 }
 
+static int diff_entry_cmp(const void *a, const void *b)
+{
+	const git_index_entry *entry_a = a;
+	const git_index_entry *entry_b = b;
+
+	return strcmp(entry_a->path, entry_b->path);
+}
+
+static int diff_entry_icmp(const void *a, const void *b)
+{
+	const git_index_entry *entry_a = a;
+	const git_index_entry *entry_b = b;
+
+	return strcasecmp(entry_a->path, entry_b->path);
+}
+
 static void diff_set_ignore_case(git_diff *diff, bool ignore_case)
 {
 	if (!ignore_case) {
@@ -335,7 +351,7 @@ static void diff_set_ignore_case(git_diff *diff, bool ignore_case)
 		diff->strcomp    = git__strcmp;
 		diff->strncomp   = git__strncmp;
 		diff->pfxcomp    = git__prefixcmp;
-		diff->entrycomp  = git_index_entry_cmp;
+		diff->entrycomp  = diff_entry_cmp;
 
 		git_vector_set_cmp(&diff->deltas, git_diff_delta__cmp);
 	} else {
@@ -344,7 +360,7 @@ static void diff_set_ignore_case(git_diff *diff, bool ignore_case)
 		diff->strcomp    = git__strcasecmp;
 		diff->strncomp   = git__strncasecmp;
 		diff->pfxcomp    = git__prefixcmp_icase;
-		diff->entrycomp  = git_index_entry_icmp;
+		diff->entrycomp  = diff_entry_icmp;
 
 		git_vector_set_cmp(&diff->deltas, git_diff_delta__casecmp);
 	}
@@ -731,8 +747,12 @@ static int maybe_modified(
 		new_is_workdir)
 		nmode = (nmode & ~MODE_BITS_MASK) | (omode & MODE_BITS_MASK);
 
+	/* if one side is a conflict, mark the whole delta as conflicted */
+	if (git_index_entry_stage(oitem) > 0 || git_index_entry_stage(nitem) > 0)
+		status = GIT_DELTA_CONFLICTED;
+
 	/* support "assume unchanged" (poorly, b/c we still stat everything) */
-	if ((oitem->flags & GIT_IDXENTRY_VALID) != 0)
+	else if ((oitem->flags & GIT_IDXENTRY_VALID) != 0)
 		status = GIT_DELTA_UNMODIFIED;
 
 	/* support "skip worktree" index bit */
@@ -875,9 +895,29 @@ static int iterator_advance(
 	const git_index_entry **entry,
 	git_iterator *iterator)
 {
-	int error;
+	const git_index_entry *prev_entry = *entry;
+	int cmp, error;
+
+	/* if we're looking for conflicts, we only want to report
+	 * one conflict for each file, instead of all three sides.
+	 * so if this entry is a conflict for this file, and the
+	 * previous one was a conflict for the same file, skip it.
+	 */
+	while ((error = git_iterator_advance(entry, iterator)) == 0) {
+		if (!(iterator->flags & GIT_ITERATOR_INCLUDE_CONFLICTS) ||
+			git_index_entry_stage(prev_entry) == 0 ||
+			git_index_entry_stage(*entry) == 0)
+			break;
+
+		cmp = (iterator->flags & GIT_ITERATOR_IGNORE_CASE) ?
+			strcasecmp(prev_entry->path, (*entry)->path) :
+			strcmp(prev_entry->path, (*entry)->path);
+
+		if (cmp)
+			break;
+	}
 
-	if ((error = git_iterator_advance(entry, iterator)) == GIT_ITEROVER) {
+	if (error == GIT_ITEROVER) {
 		*entry = NULL;
 		error = 0;
 	}
@@ -926,8 +966,12 @@ static int handle_unmatched_new_item(
 	/* check if this is a prefix of the other side */
 	contains_oitem = entry_is_prefixed(diff, info->oitem, nitem);
 
+	/* update delta_type if this item is conflicted */
+	if (git_index_entry_stage(nitem))
+		delta_type = GIT_DELTA_CONFLICTED;
+
 	/* update delta_type if this item is ignored */
-	if (git_iterator_current_is_ignored(info->new_iter))
+	else if (git_iterator_current_is_ignored(info->new_iter))
 		delta_type = GIT_DELTA_IGNORED;
 
 	if (nitem->mode == GIT_FILEMODE_TREE) {
@@ -1067,8 +1111,14 @@ static int handle_unmatched_new_item(
 static int handle_unmatched_old_item(
 	git_diff *diff, diff_in_progress *info)
 {
-	int error = diff_delta__from_one(diff, GIT_DELTA_DELETED, info->oitem);
-	if (error != 0)
+	git_delta_t delta_type = GIT_DELTA_DELETED;
+	int error;
+
+	/* update delta_type if this item is conflicted */
+	if (git_index_entry_stage(info->oitem))
+		delta_type = GIT_DELTA_CONFLICTED;
+
+	if ((error = diff_delta__from_one(diff, delta_type, info->oitem)) < 0)
 		return error;
 
 	/* if we are generating TYPECHANGE records then check for that
@@ -1234,6 +1284,8 @@ int git_diff_tree_to_index(
 {
 	int error = 0;
 	bool index_ignore_case = false;
+	git_iterator_flag_t iflag = GIT_ITERATOR_DONT_IGNORE_CASE |
+		GIT_ITERATOR_INCLUDE_CONFLICTS;
 
 	assert(diff && repo);
 
@@ -1243,10 +1295,8 @@ int git_diff_tree_to_index(
 	index_ignore_case = index->ignore_case;
 
 	DIFF_FROM_ITERATORS(
-		git_iterator_for_tree(
-			&a, old_tree, GIT_ITERATOR_DONT_IGNORE_CASE, pfx, pfx),
-		git_iterator_for_index(
-			&b, index, GIT_ITERATOR_DONT_IGNORE_CASE, pfx, pfx)
+		git_iterator_for_tree(&a, old_tree, iflag, pfx, pfx),
+		git_iterator_for_index(&b, index, iflag, pfx, pfx)
 	);
 
 	/* if index is in case-insensitive order, re-sort deltas to match */
@@ -1270,7 +1320,8 @@ int git_diff_index_to_workdir(
 		return error;
 
 	DIFF_FROM_ITERATORS(
-		git_iterator_for_index(&a, index, 0, pfx, pfx),
+		git_iterator_for_index(
+			&a, index, GIT_ITERATOR_INCLUDE_CONFLICTS, pfx, pfx),
 		git_iterator_for_workdir(
 			&b, repo, index, NULL, GIT_ITERATOR_DONT_AUTOEXPAND, pfx, pfx)
 	);