PHPHub 中 blade 模板中如何使用的{{$currentUser}}?

今天拜读了下phphub源码，在layout/default.blade.php文件中

<script>
            Config = {
                'cdnDomain': '{{ get_cdn_domain() }}',
                'user_id': {{ $currentUser ? $currentUser->id : 0 }},
                'user_avatar': {!! $currentUser ? '"'.$currentUser->present()->gravatar() . '"' : '""' !!},
                'user_link': {!! $currentUser ? '"'. route('users.show', $currentUser->id) . '"' : '""' !!},
                'user_badge': '{{ $currentUser ? ($currentUser->present()->hasBadge() ? $currentUser->present()->badgeName() : '') : '' }}',
                'user_badge_link': "{{ $currentUser ? (route('roles.show', [$currentUser->present()->badgeID()])) : '' }}",
                'routes': {
                    'notificationsCount' : '{{ route('notifications.count') }}',
                    'upload_image' : '{{ route('upload_image') }}'
                },
                'token': '{{ csrf_token() }}',
                'environment': '{{ app()->environment() }}',
                'following_users': [],
                'qa_category_id': '{{ config('phphub.qa_category_id') }}'
            };

            var ShowCrxHint = '{{isset($show_crx_hint) ? $show_crx_hint : 'no'}}';
        </script>

代码中 {{ $currentUser ? $currentUser->id : 0 }} 是如何使用的 currentUser 变量的呢？如何传入的对象？