process_children() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/fragment.js lines 19–136

export function process_children(nodes, initial, is_element, context) {
	const within_bound_contenteditable = context.state.metadata.bound_contenteditable;
	let prev = initial;
	let skipped = 0;

	/** @typedef {Array<AST.Text | AST.ExpressionTag>} Sequence */
	/** @type {Sequence} */
	let sequence = [];

	/** @param {boolean} is_text */
	function get_node(is_text) {
		if (skipped === 0) {
			return prev(is_text);
		}

		return b.call(
			'$.sibling',
			prev(false),
			(is_text || skipped !== 1) && b.literal(skipped),
			is_text && b.true
		);
	}

	/**
	 * @param {boolean} is_text
	 * @param {string} name
	 * @param {SourceLocation | null} [loc]
	 */
	function flush_node(is_text, name, loc) {
		const expression = get_node(is_text);
		let id = expression;

		if (id.type !== 'Identifier') {
			id = b.id(context.state.scope.generate(name), loc);
			context.state.init.push(b.var(id, expression));
		}

		prev = () => id;
		skipped = 1; // the next node is `$.sibling(id)`

		return id;
	}

	/**
	 * @param {Sequence} sequence
	 */
	function flush_sequence(sequence) {
		if (sequence.every((node) => node.type === 'Text')) {
			skipped += 1;
			context.state.template.push_text(sequence);
			return;
		}

		context.state.template.push_text([{ type: 'Text', data: ' ', raw: ' ', start: -1, end: -1 }]);

		const { has_state, value } = build_template_chunk(sequence, context);

		// if this is a standalone `{expression}`, make sure we handle the case where
		// no text node was created because the expression was empty during SSR
		const is_text = sequence.length === 1;
		const id = flush_node(is_text, 'text');

		const update = b.stmt(b.call('$.set_text', id, value));

		if (has_state && !within_bound_contenteditable) {
			context.state.update.push(update);
		} else {
			context.state.init.push(b.stmt(b.assignment('=', b.member(id, 'nodeValue'), value)));
		}
	}

	for (const node of nodes) {
		if (node.type === 'Text' || node.type === 'ExpressionTag') {
			sequence.push(node);
		} else {
			if (sequence.length > 0) {
				flush_sequence(sequence);
				sequence = [];
			}

			let child_state = context.state;