Method parseFunction

pkg/filter/ql/parser.go:494–543

parseFunction parses a function call. This method assumes the function name and LPAREN have been consumed.

(name string)

// parseFunction parses a function call. This method assumes
// the function name and LPAREN have been consumed.
func (p *Parser) parseFunction(name string) (*Function, error) {
	name = strings.ToLower(name)
	args := make([]Expr, 0)

	// If there's a right paren then just return immediately.
	// This is the case for functions without arguments
	if tok, _, _ := p.scan(); tok == Rparen {
		fn := &Function{Name: name}
		if err := fn.validate(); err != nil {
			return nil, err
		}
		return fn, nil
	}
	p.unscan()

	arg, err := p.ParseExpr()
	if err != nil {
		return nil, err
	}
	args = append(args, arg)

	// Parse additional function arguments if there is a comma.
	for {
		// If there's not a comma, stop parsing arguments.
		if tok, _, _ := p.scanIgnoreWhitespace(); tok != Comma {
			p.unscan()
			break
		}

		// Parse an expression argument.
		arg, err := p.ParseExpr()
		if err != nil {
			return nil, err
		}
		args = append(args, arg)
	}

	// There should be a right parentheses at the end.
	if tok, pos, lit := p.scan(); tok != Rparen {
		return nil, newParseError(tokstr(tok, lit), []string{")"}, pos, p.expr)
	}

	fn := &Function{Name: name, Args: args}

	if err := fn.validate(); err != nil {
		return nil, err
	}

	return fn, nil
}

// parseDuration parses a string and returns a duration literal.
func (p *Parser) parseDuration() (time.Duration, error) {