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note |
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|
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description: |
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"Formatter for non-integral numbers" |
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|
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library: "Free implementation of ELKS library" |
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copyright: "Copyright (c) 2005, Eiffel Software and others" |
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license: "Eiffel Forum License v2 (see forum.txt)" |
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names: format_double; |
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date: "$Date$" |
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revision: "$Revision$" |
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|
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class FORMAT_DOUBLE |
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|
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inherit |
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FORMAT_INTEGER |
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rename |
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make as set_defaults, |
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split as split_integral, |
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formatted as fm_formatted |
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export {NONE} |
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fm_formatted |
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redefine |
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comma_separate, |
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underscore_separate, |
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remove_separator |
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end |
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|
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DOUBLE_MATH |
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export {NONE} |
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all |
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end |
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|
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create |
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make |
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|
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feature -- Initialization |
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|
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make (w, d: INTEGER) |
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require |
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reasonable_field: w >= 1 |
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reasonable_decimals: d <= w |
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do |
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set_defaults (w) |
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decimals := d |
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decimal := '.' |
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trailing_zeros_shown := True |
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ensure |
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blank_fill: fill_character = ' ' |
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show_sign_negative: show_sign_negative |
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no_separator: no_separator |
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width_set: width = w |
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right_justified: right_justified |
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leading_sign: leading_sign |
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decimals_set: decimals = d |
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decimal_point: decimal = '.' |
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trailing_zeros_shown: trailing_zeros_shown |
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end |
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|
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feature -- Access |
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|
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after_decimal_separate: BOOLEAN |
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-- Use separators after the decimal? |
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|
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decimals: INTEGER |
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-- Number of digits after the decimal point. |
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|
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zero_not_shown: BOOLEAN |
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-- Show 0.5 as .5 or 0.5? |
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|
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trailing_zeros_shown: BOOLEAN |
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-- Show 0.5000 as 0.5 or 0.5000? |
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|
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decimal: CHARACTER |
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-- What is used for the decimal |
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|
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feature -- Status setting |
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|
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point_decimal |
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-- Use . as the decimal point. |
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do |
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decimal := '.' |
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ensure |
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decimal = '.' |
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end |
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|
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comma_decimal |
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-- Use , as the decimal point. |
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do |
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decimal := ',' |
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ensure |
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decimal = ',' |
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end |
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|
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set_decimals (d: INTEGER) |
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-- `d' decimals to be displayed. |
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require |
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d <= width |
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do |
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decimals := d |
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ensure |
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decimals = d |
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end |
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|
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separate_after_decimal |
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-- Use separators after the decimal. |
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do |
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after_decimal_separate := True |
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ensure |
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after_decimal_separate |
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end |
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|
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no_separate_after_decimal |
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-- Do not use separators after the decimal. |
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do |
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after_decimal_separate := False |
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ensure |
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not after_decimal_separate |
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end |
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|
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underscore_separate |
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-- Set the separator to be underscore. |
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do |
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separator := '_' |
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separate_after_decimal |
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ensure then |
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after_decimal_separate |
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end |
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|
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comma_separate |
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-- Set the separator to be comma. |
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do |
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separator := ',' |
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separate_after_decimal |
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ensure then |
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after_decimal_separate |
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end |
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|
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remove_separator |
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-- Remove the separator. |
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do |
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separator := '%U' |
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no_separate_after_decimal |
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ensure then |
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not after_decimal_separate |
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end |
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|
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show_zero |
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-- Show 0.5 as 0.5 . |
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do |
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zero_not_shown := False |
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ensure |
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not zero_not_shown |
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end |
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|
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show_trailing_zeros |
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-- Show 0.5000 as 0.5000. |
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do |
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trailing_zeros_shown := True |
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ensure |
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trailing_zeros_shown_set: not trailing_zeros_shown |
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end |
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|
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hide_zero |
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-- Show 0.5 as .5 . |
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do |
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zero_not_shown := True |
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ensure |
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zero_not_shown |
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end |
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|
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hide_trailing_zeros |
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-- Show 0.5000 as 0.5, and 0.0000 as 0.0. |
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do |
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trailing_zeros_shown := False |
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ensure |
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trailing_zeros_shown_set: trailing_zeros_shown |
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end |
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|
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feature -- Conversion |
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|
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formatted (d: DOUBLE): STRING |
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-- Format `d'. |
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local |
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sign: INTEGER |
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integral, fraction: DOUBLE |
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ints, fracs: STRING |
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value: DOUBLE |
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do |
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value := d |
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sign := 1 |
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|
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if d < 0 then |
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sign := -1 |
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value := -value |
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end |
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|
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value := value + 5 * 10 ^(- decimals - 1) |
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|
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integral := floor (value) |
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fraction := floor ((value - integral) * 10 ^(decimals + 1)) |
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|
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if not no_separator then |
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ints := split_integral (integral.out) |
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if after_decimal_separate then |
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fracs := separate_fraction (pad_fraction (fraction)) |
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else |
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fracs := pad_fraction (fraction) |
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end |
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else |
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ints := integral.out |
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fracs := pad_fraction (fraction) |
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end |
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create Result.make (width) |
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if integral /= 0 or else not zero_not_shown then |
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Result.append (ints) |
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end |
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if not Result.has ('e') then |
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Result.extend (decimal) |
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if decimals > 0 then |
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Result.append (fracs) |
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end |
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if not ignore_sign then |
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Result := process_sign (Result, sign) |
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end |
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end |
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if justification /= No_justification and then Result.count < width then |
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Result := justify (Result) |
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end |
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ensure |
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exists: Result /= Void |
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correct_length: not_justified or Result.count >= width |
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end |
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|
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feature {NONE} -- Implementation |
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|
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pad_fraction (f: DOUBLE): STRING |
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-- Stretch or shrink `f' to length `decimals' . |
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local |
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i: INTEGER |
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do |
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Result := f.out |
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Result.remove_tail (1) |
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if Result.count > decimals then |
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Result := Result.substring (1, decimals) |
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else |
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from |
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until |
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Result.count = decimals |
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loop |
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Result.precede ('0') |
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end |
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end |
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if not trailing_zeros_shown then |
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-- Remove all but one trailing zero from the fraction part |
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from |
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i := Result.count |
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until |
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i = 1 or else Result.item (i) /= '0' |
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loop |
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Result.remove (i) |
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i := i - 1 |
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end |
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end |
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ensure |
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Result.count = decimals |
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end |
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|
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separate_fraction (s: STRING): STRING |
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-- Apply separators to the fraction. |
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require |
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efficiency: separator /= '%U' |
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local |
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count, sep_length: INTEGER |
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do |
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from |
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count := 1 |
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create Result.make (width) |
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until |
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count > s.count - 3 |
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loop |
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from |
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sep_length := 0 |
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until |
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sep_length = 3 |
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loop |
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Result.extend (s.item (count)) |
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count := count + 1 |
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sep_length := sep_length + 1 |
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end |
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Result.extend (separator) |
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end |
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from |
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until |
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count > s.count |
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loop |
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Result.extend (s.item (count)) |
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count := count + 1 |
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end |
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end |
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|
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invariant |
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separate_all: no_separator implies not after_decimal_separate |
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|
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end |
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