func float()

in starlark/library.go [379:435]

• 56 lines of code
• 24 McCabe index (conditional complexity)

func float(thread *Thread, b *Builtin, args Tuple, kwargs []Tuple) (Value, error) {
	if len(kwargs) > 0 {
		return nil, fmt.Errorf("float does not accept keyword arguments")
	}
	if len(args) == 0 {
		return Float(0.0), nil
	}
	if len(args) != 1 {
		return nil, fmt.Errorf("float got %d arguments, wants 1", len(args))
	}
	switch x := args[0].(type) {
	case Bool:
		if x {
			return Float(1.0), nil
		} else {
			return Float(0.0), nil
		}
	case Int:
		return x.finiteFloat()
	case Float:
		return x, nil
	case String:
		if x == "" {
			return nil, fmt.Errorf("float: empty string")
		}
		// +/- NaN or Inf or Infinity (case insensitive)?
		s := string(x)
		switch x[len(x)-1] {
		case 'y', 'Y':
			if strings.EqualFold(s, "infinity") || strings.EqualFold(s, "+infinity") {
				return inf, nil
			} else if strings.EqualFold(s, "-infinity") {
				return neginf, nil
			}
		case 'f', 'F':
			if strings.EqualFold(s, "inf") || strings.EqualFold(s, "+inf") {
				return inf, nil
			} else if strings.EqualFold(s, "-inf") {
				return neginf, nil
			}
		case 'n', 'N':
			if strings.EqualFold(s, "nan") || strings.EqualFold(s, "+nan") || strings.EqualFold(s, "-nan") {
				return nan, nil
			}
		}
		f, err := strconv.ParseFloat(s, 64)
		if math.IsInf(f, 0) {
			return nil, fmt.Errorf("floating-point number too large")
		}
		if err != nil {
			return nil, fmt.Errorf("invalid float literal: %s", s)
		}
		return Float(f), nil
	default:
		return nil, fmt.Errorf("float got %s, want number or string", x.Type())
	}
}