commands: allow __focused__ for con_id criterion

sway/criteria.c

@@ -361,8 +361,17 @@ static char *get_focused_prop(enum criteria_token token) {
 			}
 		}
 		break;
-	case T_CON_ID: // These do not support __focused__
-	case T_CON_MARK:
+	case T_CON_ID:
+		if (view->swayc == NULL) {
+			return NULL;
+		}
+		size_t id = view->swayc->id;
+		int len = snprintf(NULL, 0, "%zu", id) + 1;
+		char *id_str = malloc(len);
+		snprintf(id_str, len, "%zu", id);
+		value = id_str;
+		break;
+	case T_CON_MARK: // These do not support __focused__
 	case T_FLOATING:
 #ifdef HAVE_XWAYLAND
 	case T_ID:
@@ -425,7 +434,7 @@ static bool parse_token(struct criteria *criteria, char *name, char *value) {
 	case T_CON_ID:
 		criteria->con_id = strtoul(effective_value, &endptr, 10);
 		if (*endptr != 0) {
-			error = strdup("The value for 'con_id' should be numeric");
+			error = strdup("The value for 'con_id' should be '__focused__' or numeric");
 		}
 		break;
 	case T_CON_MARK:

sway/sway.5.scd

@@ -582,7 +582,9 @@ The following attributes may be matched with:
 	the currently focused window.
 
 *con\_id*
-	Compare against the internal container ID, which you can find via IPC.
+	Compare against the internal container ID, which you can find via IPC. If
+	value is \_\_focused\_\_, then the id must be the same as that of the
+	currently focused window.
 
 *con\_mark*
 	Compare against the window marks. Can be a regular expression.