Function parsePratt

src/parser/syntaxes/expressions.ts:710–762

(s: ITokenStream, minBp: number)

type OpInfo = PrefixInfo | InfixInfo | PostfixInfo;

function parsePratt(s: ITokenStream, minBp: number): Ast.Expression {
	// pratt parsing
	// https://matklad.github.io/2020/04/13/simple-but-powerful-pratt-parsing.html

	let left: Ast.Expression;

	const tokenKind = s.getTokenKind();
	const prefix = operators.find((x): x is PrefixInfo => x.opKind === 'prefix' && x.kind === tokenKind);
	if (prefix != null) {
		left = parsePrefix(s, prefix.bp);
	} else {
		left = parseAtom(s, false);
	}

	while (true) {
		// 改行のエスケープ
		if (s.is(TokenKind.BackSlash)) {
			s.next();
			s.expect(TokenKind.NewLine);
			s.next();
		}

		const tokenKind = s.getTokenKind();

		const postfix = operators.find((x): x is PostfixInfo => x.opKind === 'postfix' && x.kind === tokenKind);
		if (postfix != null) {
			if (postfix.bp < minBp) {
				break;
			}

			if ([TokenKind.OpenBracket, TokenKind.OpenParen].includes(tokenKind) && s.getToken().hasLeftSpacing) {
				// 前にスペースがある場合は後置演算子として処理しない
			} else {
				left = parsePostfix(s, left);
				continue;
			}
		}

		const infix = operators.find((x): x is InfixInfo => x.opKind === 'infix' && x.kind === tokenKind);
		if (infix != null) {
			if (infix.lbp < minBp) {
				break;
			}

			left = parseInfix(s, left, infix.rbp);
			continue;
		}

		break;
	}

	return left;
}

//#endregion Pratt parsing