Merge branch 'js/builtin-add-i-cmds'

"git add -i" that is getting rewritten in C has been extended to
cover subcommands other than the "patch".

* js/builtin-add-i-cmds:
  built-in add -i: offer the `quit` command
  built-in add -i: re-implement the `diff` command
  built-in add -i: implement the `patch` command
  built-in add -i: re-implement `add-untracked` in C
  built-in add -i: re-implement `revert` in C
  built-in add -i: implement the `update` command
  built-in add -i: prepare for multi-selection commands
  built-in add -i: allow filtering the modified files list
  add-interactive: make sure to release `rev.prune_data`

1 files changed, 560 insertions, 59 deletions

diff --git a/add-interactive.c b/add-interactive.c
index d6cb98cd40..f395d54c08 100644
--- a/add-interactive.c
+++ b/add-interactive.c
@@ -6,6 +6,9 @@
 #include "revision.h"
 #include "refs.h"
 #include "string-list.h"
+#include "lockfile.h"
+#include "dir.h"
+#include "run-command.h"
 
 struct add_i_state {
 	struct repository *r;
@@ -72,15 +75,17 @@ static void init_add_i_state(struct add_i_state *s, struct repository *r)
 struct prefix_item_list {
 	struct string_list items;
 	struct string_list sorted;
+	int *selected; /* for multi-selections */
 	size_t min_length, max_length;
 };
 #define PREFIX_ITEM_LIST_INIT \
-	{ STRING_LIST_INIT_DUP, STRING_LIST_INIT_NODUP, 1, 4 }
+	{ STRING_LIST_INIT_DUP, STRING_LIST_INIT_NODUP, NULL, 1, 4 }
 
 static void prefix_item_list_clear(struct prefix_item_list *list)
 {
 	string_list_clear(&list->items, 1);
 	string_list_clear(&list->sorted, 0);
+	FREE_AND_NULL(list->selected);
 }
 
 static void extend_prefix_length(struct string_list_item *p,
@@ -182,11 +187,12 @@ static ssize_t find_unique(const char *string, struct prefix_item_list *list)
 struct list_options {
 	int columns;
 	const char *header;
-	void (*print_item)(int i, struct string_list_item *item, void *print_item_data);
+	void (*print_item)(int i, int selected, struct string_list_item *item,
+			   void *print_item_data);
 	void *print_item_data;
 };
 
-static void list(struct add_i_state *s, struct string_list *list,
+static void list(struct add_i_state *s, struct string_list *list, int *selected,
 		 struct list_options *opts)
 {
 	int i, last_lf = 0;
@@ -199,7 +205,8 @@ static void list(struct add_i_state *s, struct string_list *list,
 				 "%s", opts->header);
 
 	for (i = 0; i < list->nr; i++) {
-		opts->print_item(i, list->items + i, opts->print_item_data);
+		opts->print_item(i, selected ? selected[i] : 0, list->items + i,
+				 opts->print_item_data);
 
 		if ((opts->columns) && ((i + 1) % (opts->columns))) {
 			putchar('\t');
@@ -218,6 +225,10 @@ struct list_and_choose_options {
 	struct list_options list_opts;
 
 	const char *prompt;
+	enum {
+		SINGLETON = (1<<0),
+		IMMEDIATE = (1<<1),
+	} flags;
 	void (*print_help)(struct add_i_state *s);
 };
 
@@ -225,7 +236,8 @@ struct list_and_choose_options {
 #define LIST_AND_CHOOSE_QUIT  (-2)
 
 /*
- * Returns the selected index.
+ * Returns the selected index in singleton mode, the number of selected items
+ * otherwise.
  *
  * If an error occurred, returns `LIST_AND_CHOOSE_ERROR`. Upon EOF,
  * `LIST_AND_CHOOSE_QUIT` is returned.
@@ -234,8 +246,19 @@ static ssize_t list_and_choose(struct add_i_state *s,
 			       struct prefix_item_list *items,
 			       struct list_and_choose_options *opts)
 {
+	int singleton = opts->flags & SINGLETON;
+	int immediate = opts->flags & IMMEDIATE;
+
 	struct strbuf input = STRBUF_INIT;
-	ssize_t res = LIST_AND_CHOOSE_ERROR;
+	ssize_t res = singleton ? LIST_AND_CHOOSE_ERROR : 0;
+
+	if (!singleton) {
+		free(items->selected);
+		CALLOC_ARRAY(items->selected, items->items.nr);
+	}
+
+	if (singleton && !immediate)
+		BUG("singleton requires immediate");
 
 	find_unique_prefixes(items);
 
@@ -244,15 +267,16 @@ static ssize_t list_and_choose(struct add_i_state *s,
 
 		strbuf_reset(&input);
 
-		list(s, &items->items, &opts->list_opts);
+		list(s, &items->items, items->selected, &opts->list_opts);
 
 		color_fprintf(stdout, s->prompt_color, "%s", opts->prompt);
-		fputs("> ", stdout);
+		fputs(singleton ? "> " : ">> ", stdout);
 		fflush(stdout);
 
 		if (strbuf_getline(&input, stdin) == EOF) {
 			putchar('\n');
-			res = LIST_AND_CHOOSE_QUIT;
+			if (immediate)
+				res = LIST_AND_CHOOSE_QUIT;
 			break;
 		}
 		strbuf_trim(&input);
@@ -268,7 +292,9 @@ static ssize_t list_and_choose(struct add_i_state *s,
 		p = input.buf;
 		for (;;) {
 			size_t sep = strcspn(p, " \t\r\n,");
-			ssize_t index = -1;
+			int choose = 1;
+			/* `from` is inclusive, `to` is exclusive */
+			ssize_t from = -1, to = -1;
 
 			if (!sep) {
 				if (!*p)
@@ -277,30 +303,70 @@ static ssize_t list_and_choose(struct add_i_state *s,
 				continue;
 			}
 
-			if (isdigit(*p)) {
+			/* Input that begins with '-'; de-select */
+			if (*p == '-') {
+				choose = 0;
+				p++;
+				sep--;
+			}
+
+			if (sep == 1 && *p == '*') {
+				from = 0;
+				to = items->items.nr;
+			} else if (isdigit(*p)) {
 				char *endp;
-				index = strtoul(p, &endp, 10) - 1;
-				if (endp != p + sep)
-					index = -1;
+				/*
+				 * A range can be specified like 5-7 or 5-.
+				 *
+				 * Note: `from` is 0-based while the user input
+				 * is 1-based, hence we have to decrement by
+				 * one. We do not have to decrement `to` even
+				 * if it is 0-based because it is an exclusive
+				 * boundary.
+				 */
+				from = strtoul(p, &endp, 10) - 1;
+				if (endp == p + sep)
+					to = from + 1;
+				else if (*endp == '-') {
+					to = strtoul(++endp, &endp, 10);
+					/* extra characters after the range? */
+					if (endp != p + sep)
+						from = -1;
+				}
 			}
 
 			if (p[sep])
 				p[sep++] = '\0';
-			if (index < 0)
-				index = find_unique(p, items);
+			if (from < 0) {
+				from = find_unique(p, items);
+				if (from >= 0)
+					to = from + 1;
+			}
 
-			if (index < 0 || index >= items->items.nr)
+			if (from < 0 || from >= items->items.nr ||
+			    (singleton && from + 1 != to)) {
 				color_fprintf_ln(stdout, s->error_color,
 						 _("Huh (%s)?"), p);
-			else {
-				res = index;
+				break;
+			} else if (singleton) {
+				res = from;
 				break;
 			}
 
+			if (to > items->items.nr)
+				to = items->items.nr;
+
+			for (; from < to; from++)
+				if (items->selected[from] != choose) {
+					items->selected[from] = choose;
+					res += choose ? +1 : -1;
+				}
+
 			p += sep;
 		}
 
-		if (res != LIST_AND_CHOOSE_ERROR)
+		if ((immediate && res != LIST_AND_CHOOSE_ERROR) ||
+		    !strcmp(input.buf, "*"))
 			break;
 	}
 
@@ -310,10 +376,11 @@ static ssize_t list_and_choose(struct add_i_state *s,
 
 struct adddel {
 	uintmax_t add, del;
-	unsigned seen:1, binary:1;
+	unsigned seen:1, unmerged:1, binary:1;
 };
 
 struct file_item {
+	size_t prefix_length;
 	struct adddel index, worktree;
 };
 
@@ -344,10 +411,12 @@ static int pathname_entry_cmp(const void *unused_cmp_data,
 }
 
 struct collection_status {
-	enum { FROM_WORKTREE = 0, FROM_INDEX = 1 } phase;
+	enum { FROM_WORKTREE = 0, FROM_INDEX = 1 } mode;
 
 	const char *reference;
 
+	unsigned skip_unseen:1;
+	size_t unmerged_count, binary_count;
 	struct string_list *files;
 	struct hashmap file_map;
 };
@@ -370,11 +439,14 @@ static void collect_changes_cb(struct diff_queue_struct *q,
 		int hash = strhash(name);
 		struct pathname_entry *entry;
 		struct file_item *file_item;
-		struct adddel *adddel;
+		struct adddel *adddel, *other_adddel;
 
 		entry = hashmap_get_entry_from_hash(&s->file_map, hash, name,
 						    struct pathname_entry, ent);
 		if (!entry) {
+			if (s->skip_unseen)
+				continue;
+
 			add_file_item(s->files, name);
 
 			entry = xcalloc(sizeof(*entry), 1);
@@ -385,37 +457,64 @@ static void collect_changes_cb(struct diff_queue_struct *q,
 		}
 
 		file_item = entry->item;
-		adddel = s->phase == FROM_INDEX ?
+		adddel = s->mode == FROM_INDEX ?
 			&file_item->index : &file_item->worktree;
+		other_adddel = s->mode == FROM_INDEX ?
+			&file_item->worktree : &file_item->index;
 		adddel->seen = 1;
 		adddel->add = stat.files[i]->added;
 		adddel->del = stat.files[i]->deleted;
-		if (stat.files[i]->is_binary)
+		if (stat.files[i]->is_binary) {
+			if (!other_adddel->binary)
+				s->binary_count++;
 			adddel->binary = 1;
+		}
+		if (stat.files[i]->is_unmerged) {
+			if (!other_adddel->unmerged)
+				s->unmerged_count++;
+			adddel->unmerged = 1;
+		}
 	}
 	free_diffstat_info(&stat);
 }
 
-static int get_modified_files(struct repository *r, struct string_list *files,
-			      const struct pathspec *ps)
+enum modified_files_filter {
+	NO_FILTER = 0,
+	WORKTREE_ONLY = 1,
+	INDEX_ONLY = 2,
+};
+
+static int get_modified_files(struct repository *r,
+			      enum modified_files_filter filter,
+			      struct prefix_item_list *files,
+			      const struct pathspec *ps,
+			      size_t *unmerged_count,
+			      size_t *binary_count)
 {
 	struct object_id head_oid;
 	int is_initial = !resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
 					     &head_oid, NULL);
-	struct collection_status s = { FROM_WORKTREE };
+	struct collection_status s = { 0 };
+	int i;
 
 	if (discard_index(r->index) < 0 ||
 	    repo_read_index_preload(r, ps, 0) < 0)
 		return error(_("could not read index"));
 
-	string_list_clear(files, 1);
-	s.files = files;
+	prefix_item_list_clear(files);
+	s.files = &files->items;
 	hashmap_init(&s.file_map, pathname_entry_cmp, NULL, 0);
 
-	for (s.phase = FROM_WORKTREE; s.phase <= FROM_INDEX; s.phase++) {
+	for (i = 0; i < 2; i++) {
 		struct rev_info rev;
 		struct setup_revision_opt opt = { 0 };
 
+		if (filter == INDEX_ONLY)
+			s.mode = (i == 0) ? FROM_INDEX : FROM_WORKTREE;
+		else
+			s.mode = (i == 0) ? FROM_WORKTREE : FROM_INDEX;
+		s.skip_unseen = filter && i;
+
 		opt.def = is_initial ?
 			empty_tree_oid_hex() : oid_to_hex(&head_oid);
 
@@ -429,17 +528,24 @@ static int get_modified_files(struct repository *r, struct string_list *files,
 		if (ps)
 			copy_pathspec(&rev.prune_data, ps);
 
-		if (s.phase == FROM_INDEX)
+		if (s.mode == FROM_INDEX)
 			run_diff_index(&rev, 1);
 		else {
 			rev.diffopt.flags.ignore_dirty_submodules = 1;
 			run_diff_files(&rev, 0);
 		}
+
+		if (ps)
+			clear_pathspec(&rev.prune_data);
 	}
 	hashmap_free_entries(&s.file_map, struct pathname_entry, ent);
+	if (unmerged_count)
+		*unmerged_count = s.unmerged_count;
+	if (binary_count)
+		*binary_count = s.binary_count;
 
 	/* While the diffs are ordered already, we ran *two* diffs... */
-	string_list_sort(files);
+	string_list_sort(&files->items);
 
 	return 0;
 }
@@ -474,43 +580,401 @@ static int is_valid_prefix(const char *prefix, size_t prefix_len)
 }
 
 struct print_file_item_data {
-	const char *modified_fmt;
-	struct strbuf buf, index, worktree;
+	const char *modified_fmt, *color, *reset;
+	struct strbuf buf, name, index, worktree;
+	unsigned only_names:1;
 };
 
-static void print_file_item(int i, struct string_list_item *item,
+static void print_file_item(int i, int selected, struct string_list_item *item,
 			    void *print_file_item_data)
 {
 	struct file_item *c = item->util;
 	struct print_file_item_data *d = print_file_item_data;
+	const char *highlighted = NULL;
 
 	strbuf_reset(&d->index);
 	strbuf_reset(&d->worktree);
 	strbuf_reset(&d->buf);
 
+	/* Format the item with the prefix highlighted. */
+	if (c->prefix_length > 0 &&
+	    is_valid_prefix(item->string, c->prefix_length)) {
+		strbuf_reset(&d->name);
+		strbuf_addf(&d->name, "%s%.*s%s%s", d->color,
+			    (int)c->prefix_length, item->string, d->reset,
+			    item->string + c->prefix_length);
+		highlighted = d->name.buf;
+	}
+
+	if (d->only_names) {
+		printf("%c%2d: %s", selected ? '*' : ' ', i + 1,
+		       highlighted ? highlighted : item->string);
+		return;
+	}
+
 	render_adddel(&d->worktree, &c->worktree, _("nothing"));
 	render_adddel(&d->index, &c->index, _("unchanged"));
-	strbuf_addf(&d->buf, d->modified_fmt,
-		    d->index.buf, d->worktree.buf, item->string);
 
-	printf(" %2d: %s", i + 1, d->buf.buf);
+	strbuf_addf(&d->buf, d->modified_fmt, d->index.buf, d->worktree.buf,
+		    highlighted ? highlighted : item->string);
+
+	printf("%c%2d: %s", selected ? '*' : ' ', i + 1, d->buf.buf);
 }
 
 static int run_status(struct add_i_state *s, const struct pathspec *ps,
-		      struct string_list *files, struct list_options *opts)
+		      struct prefix_item_list *files,
+		      struct list_and_choose_options *opts)
 {
-	if (get_modified_files(s->r, files, ps) < 0)
+	if (get_modified_files(s->r, NO_FILTER, files, ps, NULL, NULL) < 0)
+		return -1;
+
+	list(s, &files->items, NULL, &opts->list_opts);
+	putchar('\n');
+
+	return 0;
+}
+
+static int run_update(struct add_i_state *s, const struct pathspec *ps,
+		      struct prefix_item_list *files,
+		      struct list_and_choose_options *opts)
+{
+	int res = 0, fd;
+	size_t count, i;
+	struct lock_file index_lock;
+
+	if (get_modified_files(s->r, WORKTREE_ONLY, files, ps, NULL, NULL) < 0)
 		return -1;
 
-	list(s, files, opts);
+	if (!files->items.nr) {
+		putchar('\n');
+		return 0;
+	}
+
+	opts->prompt = N_("Update");
+	count = list_and_choose(s, files, opts);
+	if (count <= 0) {
+		putchar('\n');
+		return 0;
+	}
+
+	fd = repo_hold_locked_index(s->r, &index_lock, LOCK_REPORT_ON_ERROR);
+	if (fd < 0) {
+		putchar('\n');
+		return -1;
+	}
+
+	for (i = 0; i < files->items.nr; i++) {
+		const char *name = files->items.items[i].string;
+		if (files->selected[i] &&
+		    add_file_to_index(s->r->index, name, 0) < 0) {
+			res = error(_("could not stage '%s'"), name);
+			break;
+		}
+	}
+
+	if (!res && write_locked_index(s->r->index, &index_lock, COMMIT_LOCK) < 0)
+		res = error(_("could not write index"));
+
+	if (!res)
+		printf(Q_("updated %d path\n",
+			  "updated %d paths\n", count), (int)count);
+
+	putchar('\n');
+	return res;
+}
+
+static void revert_from_diff(struct diff_queue_struct *q,
+			     struct diff_options *opt, void *data)
+{
+	int i, add_flags = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
+
+	for (i = 0; i < q->nr; i++) {
+		struct diff_filespec *one = q->queue[i]->one;
+		struct cache_entry *ce;
+
+		if (!(one->mode && !is_null_oid(&one->oid))) {
+			remove_file_from_index(opt->repo->index, one->path);
+			printf(_("note: %s is untracked now.\n"), one->path);
+		} else {
+			ce = make_cache_entry(opt->repo->index, one->mode,
+					      &one->oid, one->path, 0, 0);
+			if (!ce)
+				die(_("make_cache_entry failed for path '%s'"),
+				    one->path);
+			add_index_entry(opt->repo->index, ce, add_flags);
+		}
+	}
+}
+
+static int run_revert(struct add_i_state *s, const struct pathspec *ps,
+		      struct prefix_item_list *files,
+		      struct list_and_choose_options *opts)
+{
+	int res = 0, fd;
+	size_t count, i, j;
+
+	struct object_id oid;
+	int is_initial = !resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &oid,
+					     NULL);
+	struct lock_file index_lock;
+	const char **paths;
+	struct tree *tree;
+	struct diff_options diffopt = { NULL };
+
+	if (get_modified_files(s->r, INDEX_ONLY, files, ps, NULL, NULL) < 0)
+		return -1;
+
+	if (!files->items.nr) {
+		putchar('\n');
+		return 0;
+	}
+
+	opts->prompt = N_("Revert");
+	count = list_and_choose(s, files, opts);
+	if (count <= 0)
+		goto finish_revert;
+
+	fd = repo_hold_locked_index(s->r, &index_lock, LOCK_REPORT_ON_ERROR);
+	if (fd < 0) {
+		res = -1;
+		goto finish_revert;
+	}
+
+	if (is_initial)
+		oidcpy(&oid, s->r->hash_algo->empty_tree);
+	else {
+		tree = parse_tree_indirect(&oid);
+		if (!tree) {
+			res = error(_("Could not parse HEAD^{tree}"));
+			goto finish_revert;
+		}
+		oidcpy(&oid, &tree->object.oid);
+	}
+
+	ALLOC_ARRAY(paths, count + 1);
+	for (i = j = 0; i < files->items.nr; i++)
+		if (files->selected[i])
+			paths[j++] = files->items.items[i].string;
+	paths[j] = NULL;
+
+	parse_pathspec(&diffopt.pathspec, 0,
+		       PATHSPEC_PREFER_FULL | PATHSPEC_LITERAL_PATH,
+		       NULL, paths);
+
+	diffopt.output_format = DIFF_FORMAT_CALLBACK;
+	diffopt.format_callback = revert_from_diff;
+	diffopt.flags.override_submodule_config = 1;
+	diffopt.repo = s->r;
+
+	if (do_diff_cache(&oid, &diffopt))
+		res = -1;
+	else {
+		diffcore_std(&diffopt);
+		diff_flush(&diffopt);
+	}
+	free(paths);
+	clear_pathspec(&diffopt.pathspec);
+
+	if (!res && write_locked_index(s->r->index, &index_lock,
+				       COMMIT_LOCK) < 0)
+		res = -1;
+	else
+		res = repo_refresh_and_write_index(s->r, REFRESH_QUIET, 0, 1,
+						   NULL, NULL, NULL);
+
+	if (!res)
+		printf(Q_("reverted %d path\n",
+			  "reverted %d paths\n", count), (int)count);
+
+finish_revert:
 	putchar('\n');
+	return res;
+}
 
+static int get_untracked_files(struct repository *r,
+			       struct prefix_item_list *files,
+			       const struct pathspec *ps)
+{
+	struct dir_struct dir = { 0 };
+	size_t i;
+	struct strbuf buf = STRBUF_INIT;
+
+	if (repo_read_index(r) < 0)
+		return error(_("could not read index"));
+
+	prefix_item_list_clear(files);
+	setup_standard_excludes(&dir);
+	add_pattern_list(&dir, EXC_CMDL, "--exclude option");
+	fill_directory(&dir, r->index, ps);
+
+	for (i = 0; i < dir.nr; i++) {
+		struct dir_entry *ent = dir.entries[i];
+
+		if (index_name_is_other(r->index, ent->name, ent->len)) {
+			strbuf_reset(&buf);
+			strbuf_add(&buf, ent->name, ent->len);
+			add_file_item(&files->items, buf.buf);
+		}
+	}
+
+	strbuf_release(&buf);
 	return 0;
 }
 
+static int run_add_untracked(struct add_i_state *s, const struct pathspec *ps,
+		      struct prefix_item_list *files,
+		      struct list_and_choose_options *opts)
+{
+	struct print_file_item_data *d = opts->list_opts.print_item_data;
+	int res = 0, fd;
+	size_t count, i;
+	struct lock_file index_lock;
+
+	if (get_untracked_files(s->r, files, ps) < 0)
+		return -1;
+
+	if (!files->items.nr) {
+		printf(_("No untracked files.\n"));
+		goto finish_add_untracked;
+	}
+
+	opts->prompt = N_("Add untracked");
+	d->only_names = 1;
+	count = list_and_choose(s, files, opts);
+	d->only_names = 0;
+	if (count <= 0)
+		goto finish_add_untracked;
+
+	fd = repo_hold_locked_index(s->r, &index_lock, LOCK_REPORT_ON_ERROR);
+	if (fd < 0) {
+		res = -1;
+		goto finish_add_untracked;
+	}
+
+	for (i = 0; i < files->items.nr; i++) {
+		const char *name = files->items.items[i].string;
+		if (files->selected[i] &&
+		    add_file_to_index(s->r->index, name, 0) < 0) {
+			res = error(_("could not stage '%s'"), name);
+			break;
+		}
+	}
+
+	if (!res &&
+	    write_locked_index(s->r->index, &index_lock, COMMIT_LOCK) < 0)
+		res = error(_("could not write index"));
+
+	if (!res)
+		printf(Q_("added %d path\n",
+			  "added %d paths\n", count), (int)count);
+
+finish_add_untracked:
+	putchar('\n');
+	return res;
+}
+
+static int run_patch(struct add_i_state *s, const struct pathspec *ps,
+		     struct prefix_item_list *files,
+		     struct list_and_choose_options *opts)
+{
+	int res = 0;
+	ssize_t count, i, j;
+	size_t unmerged_count = 0, binary_count = 0;
+
+	if (get_modified_files(s->r, WORKTREE_ONLY, files, ps,
+			       &unmerged_count, &binary_count) < 0)
+		return -1;
+
+	if (unmerged_count || binary_count) {
+		for (i = j = 0; i < files->items.nr; i++) {
+			struct file_item *item = files->items.items[i].util;
+
+			if (item->index.binary || item->worktree.binary) {
+				free(item);
+				free(files->items.items[i].string);
+			} else if (item->index.unmerged ||
+				 item->worktree.unmerged) {
+				color_fprintf_ln(stderr, s->error_color,
+						 _("ignoring unmerged: %s"),
+						 files->items.items[i].string);
+				free(item);
+				free(files->items.items[i].string);
+			} else
+				files->items.items[j++] = files->items.items[i];
+		}
+		files->items.nr = j;
+	}
+
+	if (!files->items.nr) {
+		if (binary_count)
+			fprintf(stderr, _("Only binary files changed.\n"));
+		else
+			fprintf(stderr, _("No changes.\n"));
+		return 0;
+	}
+
+	opts->prompt = N_("Patch update");
+	count = list_and_choose(s, files, opts);
+	if (count >= 0) {
+		struct argv_array args = ARGV_ARRAY_INIT;
+
+		argv_array_pushl(&args, "git", "add--interactive", "--patch",
+				 "--", NULL);
+		for (i = 0; i < files->items.nr; i++)
+			if (files->selected[i])
+				argv_array_push(&args,
+						files->items.items[i].string);
+		res = run_command_v_opt(args.argv, 0);
+		argv_array_clear(&args);
+	}
+
+	return res;
+}
+
+static int run_diff(struct add_i_state *s, const struct pathspec *ps,
+		    struct prefix_item_list *files,
+		    struct list_and_choose_options *opts)
+{
+	int res = 0;
+	ssize_t count, i;
+
+	struct object_id oid;
+	int is_initial = !resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &oid,
+					     NULL);
+	if (get_modified_files(s->r, INDEX_ONLY, files, ps, NULL, NULL) < 0)
+		return -1;
+
+	if (!files->items.nr) {
+		putchar('\n');
+		return 0;
+	}
+
+	opts->prompt = N_("Review diff");
+	opts->flags = IMMEDIATE;
+	count = list_and_choose(s, files, opts);
+	opts->flags = 0;
+	if (count >= 0) {
+		struct argv_array args = ARGV_ARRAY_INIT;
+
+		argv_array_pushl(&args, "git", "diff", "-p", "--cached",
+				 oid_to_hex(!is_initial ? &oid :
+					    s->r->hash_algo->empty_tree),
+				 "--", NULL);
+		for (i = 0; i < files->items.nr; i++)
+			if (files->selected[i])
+				argv_array_push(&args,
+						files->items.items[i].string);
+		res = run_command_v_opt(args.argv, 0);
+		argv_array_clear(&args);
+	}
+
+	putchar('\n');
+	return res;
+}
+
 static int run_help(struct add_i_state *s, const struct pathspec *unused_ps,
-		    struct string_list *unused_files,
-		    struct list_options *unused_opts)
+		    struct prefix_item_list *unused_files,
+		    struct list_and_choose_options *unused_opts)
 {
 	color_fprintf_ln(stdout, s->help_color, "status        - %s",
 			 _("show paths with changes"));
@@ -528,9 +992,29 @@ static int run_help(struct add_i_state *s, const struct pathspec *unused_ps,
 	return 0;
 }
 
+static void choose_prompt_help(struct add_i_state *s)
+{
+	color_fprintf_ln(stdout, s->help_color, "%s",
+			 _("Prompt help:"));
+	color_fprintf_ln(stdout, s->help_color, "1          - %s",
+			 _("select a single item"));
+	color_fprintf_ln(stdout, s->help_color, "3-5        - %s",
+			 _("select a range of items"));
+	color_fprintf_ln(stdout, s->help_color, "2-3,6-9    - %s",
+			 _("select multiple ranges"));
+	color_fprintf_ln(stdout, s->help_color, "foo        - %s",
+			 _("select item based on unique prefix"));
+	color_fprintf_ln(stdout, s->help_color, "-...       - %s",
+			 _("unselect specified items"));
+	color_fprintf_ln(stdout, s->help_color, "*          - %s",
+			 _("choose all items"));
+	color_fprintf_ln(stdout, s->help_color, "           - %s",
+			 _("(empty) finish selecting"));
+}
+
 typedef int (*command_t)(struct add_i_state *s, const struct pathspec *ps,
-			 struct string_list *files,
-			 struct list_options *opts);
+			 struct prefix_item_list *files,
+			 struct list_and_choose_options *opts);
 
 struct command_item {
 	size_t prefix_length;
@@ -541,7 +1025,8 @@ struct print_command_item_data {
 	const char *color, *reset;
 };
 
-static void print_command_item(int i, struct string_list_item *item,
+static void print_command_item(int i, int selected,
+			       struct string_list_item *item,
 			       void *print_command_item_data)
 {
 	struct print_command_item_data *d = print_command_item_data;
@@ -574,25 +1059,33 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 	struct print_command_item_data data = { "[", "]" };
 	struct list_and_choose_options main_loop_opts = {
 		{ 4, N_("*** Commands ***"), print_command_item, &data },
-		N_("What now"), command_prompt_help
+		N_("What now"), SINGLETON | IMMEDIATE, command_prompt_help
 	};
 	struct {
 		const char *string;
 		command_t command;
 	} command_list[] = {
 		{ "status", run_status },
+		{ "update", run_update },
+		{ "revert", run_revert },
+		{ "add untracked", run_add_untracked },
+		{ "patch", run_patch },
+		{ "diff", run_diff },
+		{ "quit", NULL },
 		{ "help", run_help },
 	};
 	struct prefix_item_list commands = PREFIX_ITEM_LIST_INIT;
 
 	struct print_file_item_data print_file_item_data = {
-		"%12s %12s %s", STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
+		"%12s %12s %s", NULL, NULL,
+		STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
 	};
-	struct list_options opts = {
-		0, NULL, print_file_item, &print_file_item_data
+	struct list_and_choose_options opts = {
+		{ 0, NULL, print_file_item, &print_file_item_data },
+		NULL, 0, choose_prompt_help
 	};
 	struct strbuf header = STRBUF_INIT;
-	struct string_list files = STRING_LIST_INIT_DUP;
+	struct prefix_item_list files = PREFIX_ITEM_LIST_INIT;
 	ssize_t i;
 	int res = 0;
 
@@ -613,11 +1106,13 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 		data.color = s.prompt_color;
 		data.reset = s.reset_color;
 	}
+	print_file_item_data.color = data.color;
+	print_file_item_data.reset = data.reset;
 
 	strbuf_addstr(&header, "      ");
 	strbuf_addf(&header, print_file_item_data.modified_fmt,
 		    _("staged"), _("unstaged"), _("path"));
-	opts.header = header.buf;
+	opts.list_opts.header = header.buf;
 
 	if (discard_index(r->index) < 0 ||
 	    repo_read_index(r) < 0 ||
@@ -628,21 +1123,27 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 	res = run_status(&s, ps, &files, &opts);
 
 	for (;;) {
+		struct command_item *util;
+
 		i = list_and_choose(&s, &commands, &main_loop_opts);
-		if (i == LIST_AND_CHOOSE_QUIT) {
+		if (i < 0 || i >= commands.items.nr)
+			util = NULL;
+		else
+			util = commands.items.items[i].util;
+
+		if (i == LIST_AND_CHOOSE_QUIT || (util && !util->command)) {
 			printf(_("Bye.\n"));
 			res = 0;
 			break;
 		}
-		if (i != LIST_AND_CHOOSE_ERROR) {
-			struct command_item *util =
-				commands.items.items[i].util;
+
+		if (util)
 			res = util->command(&s, ps, &files, &opts);
-		}
 	}
 
-	string_list_clear(&files, 1);
+	prefix_item_list_clear(&files);
 	strbuf_release(&print_file_item_data.buf);
+	strbuf_release(&print_file_item_data.name);
 	strbuf_release(&print_file_item_data.index);
 	strbuf_release(&print_file_item_data.worktree);
 	strbuf_release(&header);