Complete floating point literals

[Timon Gehr]

KennyTM~ wrote:
> No special case needed. Just complicate the grammar to
>
>     // in terms of regex: [0-9][0-9_]*
>
>     DecimalDigits:
>        DecimalDigit
>        DecimalDigit DecimalDigitsOrUnderscores
>
>     DecimalDigitsOrUnderscores:
>        DecimalDigitOrUnderscore
>        DecimalDigitOrUnderscore DecimalDigitsOrUnderscores
>
>     DecimalDigit:
>        0
>        NonZeroDigit
>
>     DecimalDigitOrUnderscore
>        _
>        DecimalDigit
>
> (similar for HexDigits)

I don't get what you are saying here.

The change turns this:
DecimalFloat:
  LeadingDecimal .
  LeadingDecimal . DecimalDigits
  DecimalDigits . DecimalDigits DecimalExponent
  . Decimal
  . Decimal DecimalExponent
  LeadingDecimal DecimalExponent

into this:
DecimalFloat:
  LeadingDecimal . LeadingDecimal
  DecimalDigits . LeadingDecimal DecimalExponent
  LeadingDecimal DecimalExponent

(similarly for hex)

That is making the grammar *simpler* in my book.

> is enough to get rid of leading underscores. (See also
> http://d.puremagic.com/issues/show_bug.cgi?id=2734) But I'd prefer
> keeping the grammar simple and require the programmer to add '(' ')'
>
>      (1)._1;
>      (4)._0f;
>      (0xf).deep-2;
>
> or a space ' '
>
>      1 ._1;
>      4 ._0f;
>      0xf .deep-2;
>
> if they really meant to.

That is quite ugly.

Cheers,
-Timon