RenderTag() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/2-analyze/visitors/RenderTag.js lines 14–68

export function RenderTag(node, context) {
	validate_opening_tag(node, context.state, '@');

	node.metadata.path = [...context.path];

	const expression = unwrap_optional(node.expression);
	const callee = expression.callee;

	const binding = callee.type === 'Identifier' ? context.state.scope.get(callee.name) : null;

	node.metadata.dynamic = binding?.kind !== 'normal';

	/**
	 * If we can't unambiguously resolve this to a declaration, we
	 * must assume the worst and link the render tag to every snippet
	 */
	let resolved = callee.type === 'Identifier' && is_resolved_snippet(binding);

	if (binding?.initial?.type === 'SnippetBlock') {
		// if this render tag unambiguously references a local snippet, our job is easy
		node.metadata.snippets.add(binding.initial);
	}

	context.state.analysis.snippet_renderers.set(node, resolved);
	context.state.analysis.uses_render_tags = true;

	const raw_args = unwrap_optional(node.expression).arguments;
	for (const arg of raw_args) {
		if (arg.type === 'SpreadElement') {
			e.render_tag_invalid_spread_argument(arg);
		}
	}

	if (
		callee.type === 'MemberExpression' &&
		callee.property.type === 'Identifier' &&
		['bind', 'apply', 'call'].includes(callee.property.name)
	) {
		e.render_tag_invalid_call_expression(node);
	}

	mark_subtree_dynamic(context.path);

	context.visit(callee, { ...context.state, expression: node.metadata.expression });

	for (const arg of expression.arguments) {
		const metadata = new ExpressionMetadata();
		node.metadata.arguments.push(metadata);

		context.visit(arg, {
			...context.state,
			expression: metadata
		});
	}
}