Introduce "--add" for marking windows.

In order to keep compatibility to before allowing multiple marks on a window,
we introduce a flag "--add" that must be set to put more than one mark on a
window. The default, which is also available as "--replace", keeps the old
behavior of overwriting a mark when setting a new one.

fixes #2014

src/commands.c

@@ -1003,10 +1003,10 @@ void cmd_workspace_name(I3_CMD, const char *name) {
 }
 
 /*
- * Implementation of 'mark [--toggle] <mark>'
+ * Implementation of 'mark [--add|--replace] [--toggle] <mark>'
  *
  */
-void cmd_mark(I3_CMD, const char *mark, const char *toggle) {
+void cmd_mark(I3_CMD, const char *mark, const char *mode, const char *toggle) {
     HANDLE_EMPTY_MATCH;
 
     owindow *current = TAILQ_FIRST(&owindows);
@@ -1022,10 +1022,12 @@ void cmd_mark(I3_CMD, const char *mark, const char *toggle) {
     }
 
     DLOG("matching: %p / %s\n", current->con, current->con->name);
+
+    mark_mode_t mark_mode = (mode == NULL || strcmp(mode, "--replace") == 0) ? MM_REPLACE : MM_ADD;
     if (toggle != NULL) {
-        con_mark_toggle(current->con, mark);
+        con_mark_toggle(current->con, mark, mark_mode);
     } else {
-        con_mark(current->con, mark);
+        con_mark(current->con, mark, mark_mode);
     }
 
     cmd_output->needs_tree_render = true;

src/con.c

@@ -540,14 +540,14 @@ bool con_has_mark(Con *con, const char *mark) {
  * Otherwise, the mark is assigned to the container.
  *
  */
-void con_mark_toggle(Con *con, const char *mark) {
+void con_mark_toggle(Con *con, const char *mark, mark_mode_t mode) {
     assert(con != NULL);
     DLOG("Toggling mark \"%s\" on con = %p.\n", mark, con);
 
     if (con_has_mark(con, mark)) {
         con_unmark(mark);
     } else {
-        con_mark(con, mark);
+        con_mark(con, mark, mode);
     }
 }
 
@@ -555,11 +555,19 @@ void con_mark_toggle(Con *con, const char *mark) {
  * Assigns a mark to the container.
  *
  */
-void con_mark(Con *con, const char *mark) {
+void con_mark(Con *con, const char *mark, mark_mode_t mode) {
     assert(con != NULL);
     DLOG("Setting mark \"%s\" on con = %p.\n", mark, con);
 
     con_unmark(mark);
+    if (mode == MM_REPLACE) {
+        DLOG("Removing all existing marks on con = %p.\n", con);
+
+        mark_t *current;
+        TAILQ_FOREACH(current, &(con->marks_head), marks) {
+            con_unmark(current->name);
+        }
+    }
 
     mark_t *new = scalloc(1, sizeof(mark_t));
     new->name = sstrdup(mark);

src/load_layout.c

@@ -246,7 +246,7 @@ static int json_string(void *ctx, const unsigned char *val, size_t len) {
         char *mark;
         sasprintf(&mark, "%.*s", (int)len, val);
 
-        con_mark(json_node, mark);
+        con_mark(json_node, mark, MM_ADD);
     } else {
         if (strcasecmp(last_key, "name") == 0) {
             json_node->name = scalloc(len + 1, 1);
@@ -354,7 +354,7 @@ static int json_string(void *ctx, const unsigned char *val, size_t len) {
             char *buf = NULL;
             sasprintf(&buf, "%.*s", (int)len, val);
 
-            con_mark(json_node, buf);
+            con_mark(json_node, buf, MM_REPLACE);
         } else if (strcasecmp(last_key, "floating") == 0) {
             char *buf = NULL;
             sasprintf(&buf, "%.*s", (int)len, val);