rehype-optimize-static.ts — astro Source File

Source Code

import type { RehypePlugin } from '@astrojs/markdown-remark';
import { SKIP, visit } from 'estree-util-visit';
import type { Element, RootContent, RootContentMap } from 'hast';
import { toHtml } from 'hast-util-to-html';
import type {} from 'mdast-util-mdx';
import type { MdxJsxFlowElementHast, MdxJsxTextElementHast } from 'mdast-util-mdx-jsx';

// Alias as the main hast node
type Node = RootContent;
// Nodes that have the `children` property
type ParentNode = Element | MdxJsxFlowElementHast | MdxJsxTextElementHast;
// Nodes that can have its children optimized as a single HTML string
type OptimizableNode = Element | MdxJsxFlowElementHast | MdxJsxTextElementHast;

export interface OptimizeOptions {
	ignoreElementNames?: string[];
}

interface ElementMetadata {
	parent: ParentNode;
	index: number;
}

const exportConstComponentsRe = /export\s+const\s+components\s*=/;

/**
 * For MDX only, collapse static subtrees of the hast into `set:html`. Subtrees
 * do not include any MDX elements.
 *
 * This optimization reduces the JS output as more content are represented as a
 * string instead, which also reduces the AST size that Rollup holds in memory.
 */
export const rehypeOptimizeStatic: RehypePlugin<[OptimizeOptions?]> = (options) => {
	return (tree) => {
		// A set of non-static components to avoid collapsing when walking the tree
		// as they need to be preserved as JSX to be rendered dynamically.
		const ignoreElementNames = new Set<string>(options?.ignoreElementNames);

		// Find `export const components = { ... }` and get it's object's keys to be
		// populated into `ignoreElementNames`. This configuration is used to render
		// some HTML elements as custom components, and we also want to avoid collapsing them.
		for (const child of tree.children) {
			if (child.type === 'mdxjsEsm' && exportConstComponentsRe.test(child.value)) {
				const keys = getExportConstComponentObjectKeys(child);
				if (keys) {
					for (const key of keys) {
						ignoreElementNames.add(key);
					}
				}
				break;
			}
		}

		// All possible elements that could be the root of a subtree
		const allPossibleElements = new Set<OptimizableNode>();
		// The current collapsible element stack while traversing the tree
		const elementStack: Node[] = [];
		// Metadata used by `findElementGroups` later
		const elementMetadatas = new WeakMap<OptimizableNode, ElementMetadata>();

// ... (241 more lines)