1 --[[--

2 text = -- text with the value formatted as decimal number

3 format.decimal(

4 value, -- a number, a fraction or nil

5 {

6 nil_as = nil_text, -- text to be returned for a nil value

7 digits = digits, -- digits before decimal point

8 precision = precision, -- digits after decimal point

9 decimal_shift = decimal_shift -- divide the value by 10^decimal_shift (setting true uses precision)

10 }

11 )

12

13 Formats a (floating point) number or a fraction as a decimal number. If a 'digits' option is set, the number of digits before the decimal point is increased up to the given count by preceding it with zeros. The digits after the decimal point are adjusted by the 'precision' parameter. The 'decimal_shift' parameter is useful, when fixed precision decimal numbers are stored as integers, as the given value will be divided by 10 to the power of the 'decimal_shift' value prior to formatting. Setting 'decimal_shift' to true will copy the value for 'precision'.

14

15 --]]--

16

17 function format.decimal(value, options)

18 -- TODO: more features

19 local options = options or {}

20 local special_chars = charset.get_data().special_chars

21 local f

22 if value == nil then

23 return options.nil_as or ""

24 elseif atom.has_type(value, atom.number) then

25 f = value

26 elseif atom.has_type(value, atom.fraction) then

27 f = value.float

28 else

29 error("Value passed to format.decimal(...) is neither a number nor a fraction nor nil.")

30 end

31 local digits = options.digits

32 local precision = options.precision or 0

33 local decimal_shift = options.decimal_shift or 0

34 if decimal_shift == true then

35 decimal_shift = precision

36 end

37 f = f / 10 ^ decimal_shift

38 local negative

39 local absolute

40 if f < 0 then

41 absolute = -f

42 negative = true

43 else

44 absolute = f

45 negative = false

46 end

47 absolute = absolute + 0.5 / 10 ^ precision

48 local int = math.floor(absolute)

49 if not atom.is_integer(int) then

50 if f > 0 then

51 return "+" .. special_chars.inf_sign

52 elseif f < 0 then

53 return minus_sign .. special_chars.inf_sign

54 else

55 return "NaN"

56 end

57 end

58 local int_str = tostring(int)

59 if digits then

60 while #int_str < digits do

61 int_str = "0" .. int_str

62 end

63 end

64 if precision > 0 then

65 local decimal_point =

66 options.decimal_point or

67 locale.get('decimal_point') or '.'

68 local frac_str = tostring(math.floor((absolute - int) * 10 ^ precision))

69 while #frac_str < precision do

70 frac_str = "0" .. frac_str

71 end

72 assert(#frac_str == precision, "Assertion failed in format.float(...).") -- should not happen

73 if negative then

74 return special_chars.minus_sign .. int_str .. decimal_point .. frac_str

75 elseif options.show_plus then

76 return "+" .. int_str .. decimal_point .. frac_str

77 else

78 return int_str .. decimal_point .. frac_str

79 end

80 else

81 if negative then

82 return special_chars.minus_sign .. int

83 elseif options.show_plus then

84 return "+" .. int_str

85 else

86 return int_str

87 end

88 end

89 end