read_attribute() — svelte Function Reference

Source Code

packages/svelte/src/compiler/phases/1-parse/state/element.js lines 501–696

function read_attribute(parser) {
	const start = parser.index;

	if (parser.eat('{')) {
		parser.allow_whitespace();

		if (parser.eat('@attach')) {
			parser.require_whitespace();

			const expression = read_expression(parser);
			parser.allow_whitespace();
			parser.eat('}', true);

			/** @type {AST.AttachTag} */
			const attachment = {
				type: 'AttachTag',
				start,
				end: parser.index,
				expression,
				metadata: {
					expression: new ExpressionMetadata()
				}
			};

			return attachment;
		}

		if (parser.eat('...')) {
			const expression = read_expression(parser);

			parser.allow_whitespace();
			parser.eat('}', true);

			/** @type {AST.SpreadAttribute} */
			const spread = {
				type: 'SpreadAttribute',
				start,
				end: parser.index,
				expression,
				metadata: {
					expression: new ExpressionMetadata()
				}
			};

			return spread;
		} else {
			const id = parser.read_identifier();

			if (id.name === '') {
				if (
					parser.loose &&
					(parser.match('#') || parser.match('/') || parser.match('@') || parser.match(':'))
				) {
					// We're likely in an unclosed opening tag and did read part of a block.
					// Return null to not crash the parser so it can continue with closing the tag.
					return null;
				} else if (parser.loose && parser.match('}')) {
					// Likely in the middle of typing, just created the shorthand
				} else {
					e.attribute_empty_shorthand(start);
				}
			}

			parser.allow_whitespace();
			parser.eat('}', true);

			/** @type {AST.ExpressionTag} */
			const expression = {
				type: 'ExpressionTag',
				start: id.start,
				end: id.end,
				expression: id,
				metadata: {
					expression: new ExpressionMetadata()
				}
			};

			return create_attribute(id.name, id.loc, start, parser.index, expression);
		}
	}