return function (elem) {
if (elem[$rendering] || !elem[$connected]) {
return;
}
// Flag as rendering. This prevents anything from trying to render - or
// queueing a render - while there is a pending render.
elem[$rendering] = true;
// Call the updated() callback to see if we should render.
let shouldRender = true;
if (updated) {
const prev = elem[$props];
elem[$props] = props(elem);
shouldRender = updated(elem, prev);
}
// Even though this would ideally be checked in the updated() callback,
// it may not be, so we ensure that there is a point in proceeding.
if (!render) {
elem[$rendering] = false;
return;
}
// Try and get the current shadow root (will be setup if not).
let sr = elem[$shadowRoot];
// Setup the shadow root if it hasn't been setup yet.
if (!sr) {
if (shadowDomV1) {
sr = elem.attachShadow({ mode: 'open' });
} else if (shadowDomV0) {
sr = elem.createShadowRoot();
} else {
sr = elem;
}
elem[$shadowRoot] = sr;
}
if (shouldRender) {
patchInner(sr, render, elem);
if (rendered) {
rendered(elem);
}
}
elem[$rendering] = false;
};
return function (elem) {
if (!render) {
return;
}
if (!elem[shadowRoot]) {
let sr;
if (shadowDomV1) {
sr = elem.attachShadow({ mode: 'open' });
} else if (shadowDomV0) {
sr = elem.createShadowRoot();
} else {
sr = elem;
}
elem[shadowRoot] = sr;
}
patchInner(elem[shadowRoot], render, elem);
};