Method parseOrderByCommand

parser/parser.go:445–494

parseOrderByCommand - Return ast.OrderByCommand created from tokens and validate the syntax Example of input parsable to the ast.OrderByCommand: ORDER BY colName ASC

()

// Example of input parsable to the ast.OrderByCommand:
// ORDER BY colName ASC
func (parser *Parser) parseOrderByCommand() (ast.Command, error) {
	// token.ORDER already at current position in parser
	orderCommand := &ast.OrderByCommand{Token: parser.currentToken}

	// token.ORDER no longer needed
	parser.nextToken()

	err := validateTokenAndSkip(parser, []token.Type{token.BY})
	if err != nil {
		return nil, err
	}

	// ensure that loop below will execute at least once
	err = validateToken(parser.currentToken.Type, []token.Type{token.IDENT})
	if err != nil {
		return nil, err
	}

	// array of SortPattern
	for parser.currentToken.Type == token.IDENT {
		// Get column name
		err = validateToken(parser.currentToken.Type, []token.Type{token.IDENT})
		if err != nil {
			return nil, err
		}
		columnName := parser.currentToken
		parser.nextToken()

		// Get ASC or DESC
		err = validateToken(parser.currentToken.Type, []token.Type{token.ASC, token.DESC})
		if err != nil {
			return nil, err
		}
		order := parser.currentToken
		parser.nextToken()

		// append sortPattern
		orderCommand.SortPatterns = append(orderCommand.SortPatterns, ast.SortPattern{ColumnName: columnName, Order: order})

		if parser.currentToken.Type != token.COMMA {
			break
		}
		// Ignore token.COMMA
		parser.nextToken()
	}

	parser.skipIfCurrentTokenIsSemicolon()

	return orderCommand, nil
}

// parseLimitCommand - Return ast.LimitCommand created from tokens and validate the syntax
//