Method parseOrderExpr

parser/parser_table.go:957–1013

(pos Pos)

}

func (p *Parser) parseOrderExpr(pos Pos) (*OrderExpr, error) {
	// parse column expr
	columnExpr, err := p.parseExpr(pos)
	if err != nil {
		return nil, err
	}

	var alias *Ident
	if p.matchKeyword(KeywordAs) {
		// It should be a subquery instead of an order by alias if the `AS` is followed by `SELECT` keyword.
		if nextToken, err := p.lexer.peekToken(); err == nil && nextToken.ToString() == KeywordSelect {
			return &OrderExpr{
				OrderPos: pos,
				Expr:     columnExpr,
			}, nil
		}
		// consume the `AS` keyword
		_ = p.lexer.consumeToken()
		alias, err = p.parseIdent()
		if err != nil {
			return nil, err
		}
	} else if p.matchKeyword(KeywordTtl) {
		return &OrderExpr{
			OrderPos: pos,
			Expr:     columnExpr,
		}, nil
	}

	direction := OrderDirectionNone
	switch {
	case p.matchKeyword(KeywordAsc), p.matchKeyword(KeywordAscending):
		direction = OrderDirectionAsc
		_ = p.lexer.consumeToken()
	case p.matchKeyword(KeywordDesc), p.matchKeyword(KeywordDescending):
		direction = OrderDirectionDesc
		_ = p.lexer.consumeToken()
	}

	// Parse optional WITH FILL clause
	var fill *Fill
	if p.tryConsumeKeywords(KeywordWith, KeywordFill) {
		fillPos := p.Pos()
		fill, err = p.parseFillClause(fillPos)
		if err != nil {
			return nil, err
		}
	}

	return &OrderExpr{
		OrderPos:  pos,
		Alias:     alias,
		Expr:      columnExpr,
		Direction: direction,
		Fill:      fill,
	}, nil
}