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color: allow colors to be prefixed with "reset"

"reset" was previously treated as a standalone special color name
representing `\e[m`. Now, it can apply to other color properties,
allowing exact specifications without implicit attribute inheritance.

For example, "reset green" now renders `\e[;32m`, which is interpreted
as "reset everything; then set foreground to green". This means the
background and other attributes are also reset to their defaults.

Previously, this was impossible to represent in a single color:
"reset" could be specified alone, or a color with attributes, but some
thing like clearing a background color were impossible.

There is a separate change that introduces the "default" color name to
assist with that, but even then, the above could only to be represented
by explicitly disabling each of the attributes:
  green default no-bold no-dim no-italic no-ul no-blink no-reverse no-strike

Signed-off-by: Robert Estelle <robertestelle@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pull/948/merge
Robert Estelle 10 months ago committed by Junio C Hamano
parent
commit
de658515ae
  1. 5
      Documentation/config.txt
  2. 18
      color.c
  3. 1
      color.h
  4. 4
      t/t4026-color.sh

5
Documentation/config.txt

@ -288,6 +288,11 @@ The position of any attributes with respect to the colors
be turned off by prefixing them with `no` or `no-` (e.g., `noreverse`,
`no-ul`, etc).
+
The pseudo-attribute `reset` resets all colors and attributes before
applying the specified coloring. For example, `reset green` will result
in a green foreground and default background without any active
attributes.
+
An empty color string produces no color effect at all. This can be used
to avoid coloring specific elements without disabling color entirely.
+

18
color.c

@ -255,6 +255,7 @@ int color_parse_mem(const char *value, int value_len, char *dst)
const char *ptr = value;
int len = value_len;
char *end = dst + COLOR_MAXLEN;
unsigned int has_reset = 0;
unsigned int attr = 0;
struct color fg = { COLOR_UNSPECIFIED };
struct color bg = { COLOR_UNSPECIFIED };
@ -269,12 +270,7 @@ int color_parse_mem(const char *value, int value_len, char *dst)
return 0;
}
if (!strncasecmp(ptr, "reset", len)) {
xsnprintf(dst, end - dst, GIT_COLOR_RESET);
return 0;
}
/* [fg [bg]] [attr]... */
/* [reset] [fg [bg]] [attr]... */
while (len > 0) {
const char *word = ptr;
struct color c = { COLOR_UNSPECIFIED };
@ -291,6 +287,11 @@ int color_parse_mem(const char *value, int value_len, char *dst)
len--;
}
if (match_word(word, wordlen, "reset")) {
has_reset = 1;
continue;
}
if (!parse_color(&c, word, wordlen)) {
if (fg.type == COLOR_UNSPECIFIED) {
fg = c;
@ -316,13 +317,16 @@ int color_parse_mem(const char *value, int value_len, char *dst)
*dst++ = (x); \
} while(0)
if (attr || !color_empty(&fg) || !color_empty(&bg)) {
if (has_reset || attr || !color_empty(&fg) || !color_empty(&bg)) {
int sep = 0;
int i;
OUT('\033');
OUT('[');
if (has_reset)
sep++;
for (i = 0; attr; i++) {
unsigned bit = (1 << i);
if (!(attr & bit))

1
color.h

@ -6,6 +6,7 @@ struct strbuf;
/*
* The maximum length of ANSI color sequence we would generate:
* - leading ESC '[' 2
* - reset ';' .................1
* - attr + ';' 2 * num_attr (e.g. "1;")
* - no-attr + ';' 3 * num_attr (e.g. "22;")
* - fg color + ';' 17 (e.g. "38;2;255;255;255;")

4
t/t4026-color.sh

@ -60,6 +60,10 @@ test_expect_success 'fg bg attr...' '
color "blue bold dim ul blink reverse" "[1;2;4;5;7;34m"
'
test_expect_success 'reset fg bg attr...' '
color "reset blue bold dim ul blink reverse" "[;1;2;4;5;7;34m"
'
# note that nobold and nodim are the same code (22)
test_expect_success 'attr negation' '
color "nobold nodim noul noblink noreverse" "[22;24;25;27m"

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