built-in add -p: implement the "worktree" patch modes

This is a straight-forward port of 2f0896e (restore: support
--patch, 2019-04-25) which added support for `git restore -p`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

add-interactive.h

@@ -28,6 +28,7 @@ enum add_p_mode {
 	ADD_P_STASH,
 	ADD_P_RESET,
 	ADD_P_CHECKOUT,
+	ADD_P_WORKTREE,
 };
 
 int run_add_p(struct repository *r, enum add_p_mode mode,

add-patch.c

@@ -176,6 +176,49 @@ static struct patch_mode patch_mode_checkout_nothead = {
 			"the file\n"),
 };
 
+static struct patch_mode patch_mode_worktree_head = {
+	.diff_cmd = { "diff-index", NULL },
+	.apply_args = { "-R", NULL },
+	.apply_check_args = { "-R", NULL },
+	.is_reverse = 1,
+	.prompt_mode = {
+		N_("Discard mode change from index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Discard deletion from index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Discard this hunk from index and worktree [y,n,q,a,d%s,?]? "),
+	},
+	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
+			     "will immediately be marked for discarding."),
+	.help_patch_text =
+		N_("y - discard this hunk from worktree\n"
+		   "n - do not discard this hunk from worktree\n"
+		   "q - quit; do not discard this hunk or any of the remaining "
+			"ones\n"
+		   "a - discard this hunk and all later hunks in the file\n"
+		   "d - do not discard this hunk or any of the later hunks in "
+			"the file\n"),
+};
+
+static struct patch_mode patch_mode_worktree_nothead = {
+	.diff_cmd = { "diff-index", "-R", NULL },
+	.apply_args = { NULL },
+	.apply_check_args = { NULL },
+	.prompt_mode = {
+		N_("Apply mode change to index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Apply deletion to index and worktree [y,n,q,a,d%s,?]? "),
+		N_("Apply this hunk to index and worktree [y,n,q,a,d%s,?]? "),
+	},
+	.edit_hunk_hint = N_("If the patch applies cleanly, the edited hunk "
+			     "will immediately be marked for applying."),
+	.help_patch_text =
+		N_("y - apply this hunk to worktree\n"
+		   "n - do not apply this hunk to worktree\n"
+		   "q - quit; do not apply this hunk or any of the remaining "
+			"ones\n"
+		   "a - apply this hunk and all later hunks in the file\n"
+		   "d - do not apply this hunk or any of the later hunks in "
+			"the file\n"),
+};
+
 struct hunk_header {
 	unsigned long old_offset, old_count, new_offset, new_count;
 	/*
@@ -1551,6 +1594,13 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 			s.mode = &patch_mode_checkout_head;
 		else
 			s.mode = &patch_mode_checkout_nothead;
+	} else if (mode == ADD_P_WORKTREE) {
+		if (!revision)
+			s.mode = &patch_mode_checkout_index;
+		else if (!strcmp(revision, "HEAD"))
+			s.mode = &patch_mode_worktree_head;
+		else
+			s.mode = &patch_mode_worktree_nothead;
 	} else
 		s.mode = &patch_mode_add;
 	s.revision = revision;

builtin/add.c

@@ -208,6 +208,8 @@ int run_add_interactive(const char *revision, const char *patch_mode,
 			mode = ADD_P_RESET;
 		else if (!strcmp(patch_mode, "--patch=checkout"))
 			mode = ADD_P_CHECKOUT;
+		else if (!strcmp(patch_mode, "--patch=worktree"))
+			mode = ADD_P_WORKTREE;
 		else
 			die("'%s' not supported", patch_mode);