astro/dist/runtime/server/render/head-propagation/runtime.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

import { collectPropagatedHeadParts } from "../../../../core/head-propagation/buffer.js";
import { getPropagationHint as getHint, isPropagatingHint } from "../../../../core/head-propagation/resolver.js";
import { shouldRenderInstruction as shouldRenderInstructionByPolicy } from "../../../../core/head-propagation/policy.js";
import { isHeadAndContent } from "../astro/head-and-content.js";
/** Facade helper used by runtime adapters to read effective hint resolution. */
export function getPropagationHint(result, factory) {
	return getHint(result, factory);
}
/**
* Registers an instance in the propagation set when its hint requires buffering.
*
* @example
* A runtime-created component with `propagation: 'self'` is registered so its
* styles can be collected before head flush.
*/
export function registerIfPropagating(result, factory, instance) {
	// Fast path: explicit runtime hint is cheapest and most common for dynamic entries.
	if (factory.propagation === "self" || factory.propagation === "in-tree") {
		// The runtime set supports both AstroComponentInstance and ServerIslandComponent,
		// and integrations may push objects that satisfy this minimal `init()` contract.
		result._metadata.propagators.add(instance);
		return;
	}
	// Otherwise fall back to metadata (`.astro` compile/build analysis).
	if (factory.moduleId) {
		const hint = result.componentMetadata.get(factory.moduleId)?.propagation;
		if (isPropagatingHint(hint ?? "none")) {
			result._metadata.propagators.add(instance);
		}
	}
}
/**
* Initializes all registered propagators and appends the head parts they emit
* to `extraHead`. See `collectPropagatedHeadParts` for `awaitPendingSlots`.
*/
export async function bufferPropagatedHead(result, options = {}) {
	const collected = await collectPropagatedHeadParts({
		propagators: result._metadata.propagators,
		result,
		isHeadAndContent,
		awaitPendingSlots: options.awaitPendingSlots
	});
	result._metadata.extraHead.push(...collected);
}
/** Facade helper for render instruction gating (`head` vs `maybe-head`). */
export function shouldRenderInstruction(type, state) {
	return shouldRenderInstructionByPolicy(type, state);
}
/** Projects `SSRResult` into the minimal state needed by instruction policy. */
export function getInstructionRenderState(result) {
	return {
		hasRenderedHead: result._metadata.hasRenderedHead,
		headInTree: result._metadata.headInTree,
		partial: result.partial
	};
}