[showing-off RFC/PATCH 26/26] diff.c: have a "machine parseable" move coloring

[Stefan Beller]

Ævar asked for it, this is how you would do it.
(plus documentation, tests, CLI knobs, options)

Signed-off-by: Stefan Beller <sbel...@google.com>
---
 diff.c | 15 +++++++++++----
 diff.h |  2 ++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/diff.c b/diff.c
index 7756f7610c..61caa057ff 100644
--- a/diff.c
+++ b/diff.c
@@ -997,6 +997,7 @@ static void emit_diff_symbol_from_struct(struct 
diff_options *o,
        static const char *nneof = " No newline at end of file\n";
        const char *context, *reset, *set, *meta, *fraginfo;
        struct strbuf sb = STRBUF_INIT;
+       int sign;
 
        enum diff_symbol s = eds->s;
        const char *line = eds->line;
@@ -1058,8 +1059,11 @@ static void emit_diff_symbol_from_struct(struct 
diff_options *o,
                default:
                        set = diff_get_color_opt(o, DIFF_FILE_NEW);
                }
+               sign = '+';
+               if (flags & DIFF_SYMBOL_MOVED_LINE && o->machine_readable_moves)
+                       sign = '*';
                reset = diff_get_color_opt(o, DIFF_RESET);
-               emit_line_ws_markup(o, set, reset, line, len, '+',
+               emit_line_ws_markup(o, set, reset, line, len, sign,
                                    flags & DIFF_SYMBOL_CONTENT_WS_MASK,
                                    flags & DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF);
                break;
@@ -1086,8 +1090,11 @@ static void emit_diff_symbol_from_struct(struct 
diff_options *o,
                default:
                        set = diff_get_color_opt(o, DIFF_FILE_OLD);
                }
+               sign = '-';
+               if (flags & DIFF_SYMBOL_MOVED_LINE && o->machine_readable_moves)
+                       sign = '_';
                reset = diff_get_color_opt(o, DIFF_RESET);
-               emit_line_ws_markup(o, set, reset, line, len, '-',
+               emit_line_ws_markup(o, set, reset, line, len, sign,
                                    flags & DIFF_SYMBOL_CONTENT_WS_MASK, 0);
                break;
        case DIFF_SYMBOL_WORDS_PORCELAIN:
@@ -5475,7 +5482,7 @@ static void diff_flush_patch_all_file_pairs(struct 
diff_options *o)
        static struct emitted_diff_symbols esm = EMITTED_DIFF_SYMBOLS_INIT;
        struct diff_queue_struct *q = &diff_queued_diff;
 
-       if (o->color_moved)
+       if (o->color_moved || o->machine_readable_moves)
                o->emitted_symbols = &esm;
 
        for (i = 0; i < q->nr; i++) {
@@ -5485,7 +5492,7 @@ static void diff_flush_patch_all_file_pairs(struct 
diff_options *o)
        }
 
        if (o->emitted_symbols) {
-               if (o->color_moved) {
+               if (o->color_moved || o->machine_readable_moves) {
                        struct hashmap add_lines, del_lines;
                        unsigned ignore_ws = DIFF_XDL_TST(o, IGNORE_WHITESPACE);
 
diff --git a/diff.h b/diff.h
index 98abd75521..b6c4d7ab0f 100644
--- a/diff.h
+++ b/diff.h
@@ -194,6 +194,8 @@ struct diff_options {
                COLOR_MOVED_ZEBRA = 2,
                COLOR_MOVED_ZEBRA_DIM = 3,
        } color_moved;
+
+       int machine_readable_moves;
 };
 
 void diff_emit_submodule_del(struct diff_options *o, const char *line);
-- 
2.12.2.575.gb14f27f917