Function parseMatch

src/parser/syntaxes/expressions.ts:446–488

* ```abnf * Match = "match" Expr "{" [(MatchCase *(SEP MatchCase) [SEP DefaultCase] [SEP]) / DefaultCase [SEP]] "}" * ```

(s: ITokenStream)

 * ```
*/
function parseMatch(s: ITokenStream): Ast.Match {
	const startPos = s.getPos();

	s.expect(TokenKind.MatchKeyword);
	s.next();
	const about = parseExpr(s, false);

	s.expect(TokenKind.OpenBrace);
	s.next();

	if (s.is(TokenKind.NewLine)) {
		s.next();
	}

	const qs: Ast.Match['qs'] = [];
	let x: Ast.Match['default'];
	if (s.is(TokenKind.CaseKeyword)) {
		qs.push(parseMatchCase(s));
		let sep = parseOptionalSeparator(s);
		while (s.is(TokenKind.CaseKeyword)) {
			if (!sep) {
				throw new AiScriptSyntaxError('separator expected', s.getPos());
			}
			qs.push(parseMatchCase(s));
			sep = parseOptionalSeparator(s);
		}
		if (s.is(TokenKind.DefaultKeyword)) {
			if (!sep) {
				throw new AiScriptSyntaxError('separator expected', s.getPos());
			}
			x = parseDefaultCase(s);
			parseOptionalSeparator(s);
		}
	} else if (s.is(TokenKind.DefaultKeyword)) {
		x = parseDefaultCase(s);
		parseOptionalSeparator(s);
	}

	s.expect(TokenKind.CloseBrace);
	s.next();

	return NODE('match', { about, qs, default: x }, startPos, s.getPos());
}

/**
 * ```abnf