icons: use a compact array

a lot of the extension use the same icon. this can be exploited via
having an array with all the unique icons and then storing a single byte
index into the unique array.

when using `O_EMOJI` this results in around ~1.7KiB drop in the total
table size. `O_NERD` and `O_ICONS` get roughly ~0.5KiB savings.

src/icons-hash.c

@@ -152,6 +152,28 @@ main(void)
 	icon_max = MAX(icon_max, strlen(exec_icon.icon) + 1);
 	icon_max = MAX(icon_max, strlen(file_icon.icon) + 1);
 
+	const char *uniq[ARRLEN(icons_ext)] = {0};
+	size_t uniq_head = 0;
+	for (size_t i = 0; i < ARRLEN(icons_ext); ++i) {
+		if (icons_ext[i].icon[0] == 0) continue;
+		int isuniq = 1;
+		for (size_t k = 0; k < uniq_head; ++k) {
+			if (strcmp(uniq[k], icons_ext[i].icon) == 0) {
+				isuniq = 0;
+				break;
+			}
+		}
+		if (isuniq) {
+			assert(uniq_head < ARRLEN(uniq));
+			uniq[uniq_head++] = icons_ext[i].icon;
+		}
+	}
+	assert(uniq_head < (unsigned char)-1);
+
+	log("uniq icons: %6zu\n", uniq_head);
+	log("no-compact: %6zu bytes\n", ARRLEN(table) * icon_max);
+	log("compaction: %6zu bytes\n", uniq_head * icon_max + ARRLEN(table));
+
 	printf("#ifndef INCLUDE_ICONS_GENERATED\n");
 	printf("#define INCLUDE_ICONS_GENERATED\n\n");
 
@@ -167,12 +189,22 @@ main(void)
 	printf("struct icon_pair { const char match[%zu]; const char icon[%zu]; unsigned char color; };\n\n",
 	       match_max, icon_max);
 
-	printf("static const struct icon_pair icons_ext[%zu] = {\n", ARRLEN(table));
+	printf("static const char icons_ext_uniq[%zu][%zu] = {\n", uniq_head, icon_max);
+	for (size_t i = 0; i < uniq_head; ++i)
+		printf("\t\"%s\",\n", uniq[i]);
+	printf("};\n\n");
+
+	printf("static const struct {\n\tconst char match[%zu];"
+	       "\n\tunsigned char idx;\n\tunsigned char color;\n} icons_ext[%zu] = {\n",
+	        match_max, ARRLEN(table));
 	for (size_t i = 0; i < ARRLEN(table); ++i) {
 		if (table[i].icon == NULL || table[i].icon[0] == '\0') /* skip empty entries */
 			continue;
-		printf("\t[%zu] = {\"%s\", \"%s\", %hhu },\n", i,
-		       table[i].match, table[i].icon, table[i].color);
+		int k;
+		for (k = 0; k < uniq_head; ++k) if (strcmp(table[i].icon, uniq[k]) == 0) break;
+		assert(k < uniq_head);
+		printf("\t[%3zu] = {\"%s\", %d, %hhu },\n",
+		       i, table[i].match, k, table[i].color);
 	}
 	printf("};\n\n");
 

src/icons.h

@@ -167,9 +167,11 @@ static const unsigned char init_colors[] = { COLOR_LIST };
 	struct icon_pair { const char *match; const char *icon; unsigned char color; };
 #endif
 
-static const struct icon_pair dir_icon  = {"", ICON_DIRECTORY, 0};
-static const struct icon_pair file_icon = {"", ICON_FILE, 0};
-static const struct icon_pair exec_icon = {"", ICON_EXEC, 0};
+struct icon { const char *icon; unsigned char color; };
+
+static const struct icon dir_icon  = {ICON_DIRECTORY, 0};
+static const struct icon file_icon = {ICON_FILE, 0};
+static const struct icon exec_icon = {ICON_EXEC, 0};
 
 static const struct icon_pair icons_name[] = {
 	{".git",        ICON_GIT,       0},

src/nnn.c

@@ -3961,16 +3961,14 @@ static char *get_lsperms(mode_t mode)
 }
 
 #ifdef ICONS_ENABLED
-static const struct icon_pair *get_icon(const struct entry *ent)
+static struct icon get_icon(const struct entry *ent)
 {
-	ushort_t i = 0;
-
-	for (; i < ELEMENTS(icons_name); ++i)
+	for (size_t i = 0; i < ELEMENTS(icons_name); ++i)
 		if (strcasecmp(ent->name, icons_name[i].match) == 0)
-			return &icons_name[i];
+			return (struct icon){ icons_name[i].icon, icons_name[i].color };
 
 	if (ent->flags & DIR_OR_DIRLNK)
-		return &dir_icon;
+		return dir_icon;
 
 	char *tmp = xextension(ent->name, ent->nlen);
 
@@ -3979,29 +3977,27 @@ static const struct icon_pair *get_icon(const struct entry *ent)
 		for (k = 0; k < ICONS_PROBE_MAX; ++k) {
 			z = (h + k) % ELEMENTS(icons_ext);
 			if (strcasecmp(tmp, icons_ext[z].match) == 0)
-				return &icons_ext[z];
+				return (struct icon){ icons_ext_uniq[icons_ext[z].idx], icons_ext[z].color };
 		}
 	}
 
 	/* If there's no match and the file is executable, icon that */
 	if (ent->mode & 0100)
-		return &exec_icon;
-
-	return &file_icon;
+		return exec_icon;
+	return file_icon;
 }
 
 static void print_icon(const struct entry *ent, const int attrs)
 {
-	const struct icon_pair *picon = get_icon(ent);
-
+	const struct icon icon = get_icon(ent);
 	addstr(ICON_PADDING_LEFT);
-	if (picon->color)
-		attron(COLOR_PAIR(C_UND + 1 + picon->color));
+	if (icon.color)
+		attron(COLOR_PAIR(C_UND + 1 + icon.color));
 	else if (attrs)
 		attron(attrs);
-	addstr(picon->icon);
-	if (picon->color)
-		attroff(COLOR_PAIR(C_UND + 1 + picon->color));
+	addstr(icon.icon);
+	if (icon.color)
+		attroff(COLOR_PAIR(C_UND + 1 + icon.color));
 	else if (attrs)
 		attroff(attrs);
 	addstr(ICON_PADDING_RIGHT);