is_last_evaluated_expression() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js lines 81–150

function is_last_evaluated_expression(path, node) {
	let i = path.length;

	while (i--) {
		const parent = path[i];

		if (parent.type === 'ConstTag') {
			// {@const ...} tags are treated as deriveds and its contents should all get the preserve-reactivity treatment
			return false;
		}

		// @ts-expect-error we could probably use a neater/more robust mechanism
		if (parent.metadata) {
			return true;
		}

		switch (parent.type) {
			case 'ArrayExpression':
				if (node !== parent.elements.at(-1)) return false;
				break;

			case 'AssignmentExpression':
			case 'BinaryExpression':
			case 'LogicalExpression':
				if (node === parent.left) return false;
				break;

			case 'CallExpression':
			case 'NewExpression':
				if (node !== parent.arguments.at(-1)) return false;
				break;

			case 'ConditionalExpression':
				if (node === parent.test) return false;
				break;

			case 'MemberExpression':
				if (parent.computed && node === parent.object) return false;
				break;

			case 'ObjectExpression':
				if (node !== parent.properties.at(-1)) return false;
				break;

			case 'Property':
				if (node === parent.key) return false;
				break;

			case 'SequenceExpression':
				if (node !== parent.expressions.at(-1)) return false;
				break;

			case 'TaggedTemplateExpression':
				if (node !== parent.quasi.expressions.at(-1)) return false;
				break;

			case 'TemplateLiteral':
				if (node !== parent.expressions.at(-1)) return false;
				break;

			case 'VariableDeclarator':
				return true;

			default:
				return false;
		}

		node = parent;
	}
}