atom: cache result of get_atom

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/atom.h

@@ -0,0 +1,51 @@
+#include <xcb/xcb.h>
+
+#include "meta.h"
+#include "cache.h"
+
+// Splitted into 2 lists because of the limitation of our macros
+#define ATOM_LIST \
+	_NET_WM_WINDOW_OPACITY, \
+	_NET_FRAME_EXTENTS, \
+	WM_STATE, \
+	_NET_WM_NAME, \
+	_NET_WM_PID, \
+	WM_NAME, \
+	WM_CLASS, \
+	WM_TRANSIENT_FOR, \
+	WM_WINDOW_ROLE, \
+	WM_CLIENT_LEADER, \
+	_NET_ACTIVE_WINDOW, \
+	_COMPTON_SHADOW, \
+	_NET_WM_WINDOW_TYPE, \
+	_NET_WM_WINDOW_TYPE_DESKTOP, \
+	_NET_WM_WINDOW_TYPE_DOCK, \
+	_NET_WM_WINDOW_TYPE_TOOLBAR, \
+	_NET_WM_WINDOW_TYPE_MENU, \
+	_NET_WM_WINDOW_TYPE_UTILITY, \
+	_NET_WM_WINDOW_TYPE_SPLASH, \
+	_NET_WM_WINDOW_TYPE_DIALOG, \
+	_NET_WM_WINDOW_TYPE_NORMAL, \
+	_NET_WM_WINDOW_TYPE_DROPDOWN_MENU, \
+	_NET_WM_WINDOW_TYPE_POPUP_MENU, \
+	_NET_WM_WINDOW_TYPE_TOOLTIP, \
+	_NET_WM_WINDOW_TYPE_NOTIFICATION, \
+	_NET_WM_WINDOW_TYPE_COMBO, \
+	_NET_WM_WINDOW_TYPE_DND
+
+#define ATOM_DEF(x) xcb_atom_t a##x
+
+struct atom {
+	struct cache *c;
+	LIST_APPLY(ATOM_DEF, SEP_COLON, ATOM_LIST);
+};
+
+struct atom *init_atoms(xcb_connection_t *);
+
+static inline xcb_atom_t get_atom(struct atom *a, const char *key) {
+	return (xcb_atom_t)(intptr_t)cache_get(a->c, key, NULL);
+}
+
+static inline void destroy_atoms(struct atom *a) {
+	cache_free(a->c);
+}