built-in add -p: show different prompts for mode changes and deletions

Just like the Perl version, we now helpfully ask the user whether they
want to stage a mode change, or a deletion.

Note that we define the prompts in an array, in preparation for a later
patch that changes those prompts to yet different versions for `git
reset -p`, `git stash -p` and `git checkout -p` (which all call the `git
add -p` machinery to do the actual work).

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

Author: dscho

add-patch.c

@@ -7,6 +7,16 @@
 #include "color.h"
 #include "diff.h"
 
+enum prompt_mode_type {
+	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK
+};
+
+static const char *prompt_mode[] = {
+	N_("Stage mode change [y,n,a,d%s,?]? "),
+	N_("Stage deletion [y,n,a,d%s,?]? "),
+	N_("Stage this hunk [y,n,a,d%s,?]? ")
+};
+
 struct hunk_header {
 	unsigned long old_offset, old_count, new_offset, new_count;
 	/*
@@ -390,6 +400,7 @@ static int patch_update_file(struct add_p_state *s,
 	char ch;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	int colored = !!s->colored.len;
+	enum prompt_mode_type prompt_mode_type;
 
 	if (!file_diff->hunk_nr)
 		return 0;
@@ -434,9 +445,16 @@ static int patch_update_file(struct add_p_state *s,
 			strbuf_addstr(&s->buf, ",j");
 		if (hunk_index + 1 < file_diff->hunk_nr)
 			strbuf_addstr(&s->buf, ",J");
+
+		if (file_diff->deleted)
+			prompt_mode_type = PROMPT_DELETION;
+		else if (file_diff->mode_change && !hunk_index)
+			prompt_mode_type = PROMPT_MODE_CHANGE;
+		else
+			prompt_mode_type = PROMPT_HUNK;
+
 		color_fprintf(stdout, s->s.prompt_color,
-			      _("Stage this hunk [y,n,a,d%s,?]? "),
-			      s->buf.buf);
+			      _(prompt_mode[prompt_mode_type]), s->buf.buf);
 		fflush(stdout);
 		if (strbuf_getline(&s->answer, stdin) == EOF)
 			break;