From a6a80850b729eefaafac325256023ee92b21be34 Mon Sep 17 00:00:00 2001
From: Kirill Primak <vyivel@posteo.net>
Date: Mon, 9 Aug 2021 17:57:19 +0300
Subject: util: add wlr_addon

---
 include/wlr/util/addon.h | 43 ++++++++++++++++++++++++++++++++++++++++++
 util/addon.c             | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 util/meson.build         |  1 +
 3 files changed, 93 insertions(+)
 create mode 100644 include/wlr/util/addon.h
 create mode 100644 util/addon.c

diff --git a/include/wlr/util/addon.h b/include/wlr/util/addon.h
new file mode 100644
index 00000000..3ad71f54
--- /dev/null
+++ b/include/wlr/util/addon.h
@@ -0,0 +1,43 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
+#ifndef WLR_UTIL_ADDON_H
+#define WLR_UTIL_ADDON_H
+
+#include <wayland-server-core.h>
+
+struct wlr_addon_set {
+	// private state
+	struct wl_list addons;
+};
+
+struct wlr_addon;
+
+struct wlr_addon_interface {
+	const char *name;
+	void (*destroy)(struct wlr_addon *addon);
+};
+
+struct wlr_addon {
+	const struct wlr_addon_interface *impl;
+	// private state
+	const void *owner;
+	struct wl_list link;
+};
+
+void wlr_addon_set_init(struct wlr_addon_set *set);
+void wlr_addon_set_finish(struct wlr_addon_set *set);
+
+void wlr_addon_init(struct wlr_addon *addon, struct wlr_addon_set *set,
+		const void *owner, const struct wlr_addon_interface *impl);
+void wlr_addon_finish(struct wlr_addon *addon);
+
+struct wlr_addon *wlr_addon_find_by_owner(struct wlr_addon_set *set,
+		const void *owner);
+
+#endif
diff --git a/util/addon.c b/util/addon.c
new file mode 100644
index 00000000..7de54a73
--- /dev/null
+++ b/util/addon.c
@@ -0,0 +1,49 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <wayland-server-core.h>
+
+#include "wlr/util/addon.h"
+
+void wlr_addon_set_init(struct wlr_addon_set *set) {
+	wl_list_init(&set->addons);
+}
+
+void wlr_addon_set_finish(struct wlr_addon_set *set) {
+	struct wlr_addon *addon, *tmp;
+	wl_list_for_each_safe(addon, tmp, &set->addons, link) {
+		wlr_addon_finish(addon);
+		addon->impl->destroy(addon);
+	}
+}
+
+void wlr_addon_init(struct wlr_addon *addon, struct wlr_addon_set *set,
+		const void *owner, const struct wlr_addon_interface *impl) {
+	assert(owner);
+	struct wlr_addon *iter;
+	wl_list_for_each(iter, &set->addons, link) {
+		if (iter->owner == addon->owner) {
+			assert(0 && "Can't have two addons with the same owner");
+		}
+	}
+	wl_list_insert(&set->addons, &addon->link);
+	addon->owner = owner;
+	addon->impl = impl;
+}
+
+void wlr_addon_finish(struct wlr_addon *addon) {
+	if (addon->owner) {
+		addon->owner = NULL;
+		wl_list_remove(&addon->link);
+	}
+}
+
+struct wlr_addon *wlr_addon_find_by_owner(struct wlr_addon_set *set,
+		const void *owner) {
+	struct wlr_addon *addon;
+	wl_list_for_each(addon, &set->addons, link) {
+		if (addon->owner == owner) {
+			return addon;
+		}
+	}
+	return NULL;
+}
diff --git a/util/meson.build b/util/meson.build
index c2b46749..a416490f 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -1,4 +1,5 @@
 wlr_files += files(
+	'addon.c',
 	'array.c',
 	'box.c',
 	'global.c',
-- 
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