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import QtQuick 1.1

QtObject {
    id: root
    property bool checked: false
    property variant value: null
    property QtObject exclusiveGroup: null
    property bool enabled: false

    onEnabledChanged: {
        if (!enabled) {
            exclusiveGroup = null;
            checked = false;
        }
    }

    function toggle() {
        if (!enabled)
            return;
        if (!exclusiveGroup) {
            checked = !checked;
        } else {
            // In an exclusive group, there is no 'checked = false'. The invariant
            // of the group doesn't allow to "uncheck" the checked item. Note that
            // the group watches for changes in the checked variable of its items.
            checked = true;
        }
    }

    onExclusiveGroupChanged: {
        if (exclusiveGroup) {
            enabled = true;
            // Note that we don't need to remove the previous group,
            // since it is watching the 'exclusiveGroup' property changes
            // in this item and will automatically remove us.
            exclusiveGroup.__add(root);
        }
    }

    Component.onDestruction: {
        // If there's a previous group, it will be watching for
        // this change and will remove this item.
        exclusiveGroup = null;
    }
}