- From: Bjoern Hoehrmann <derhoermi@gmx.net>
- Date: Fri, 21 Feb 2014 21:03:34 +0100
- To: bugzilla@jessica.w3.org
- Cc: www-svg@w3.org
* bugzilla@jessica.w3.org wrote: >https://www.w3.org/Bugs/Public/show_bug.cgi?id=24769 >http://www.w3.org/TR/SVG2/single-page.html#paths-PathDataBNF > >There is no description in the text on how this BNF is to be used. For example, >are the rules for the BNF alternatives to be parsed as 'first match wins'? > >If so, then the following rules won't produce good results, as the may match >part of a floating point number as an integer before matching the >floating-point-constant rule: > >nonnegative-number: > integer-constant > | floating-point-constant >number: > sign? integer-constant > | sign? floating-point-constant An `integer-constant` is a `digit-sequence` while a `floating-point- constant` is either a `fractional-constant` followed by an optional exponent, or a `digit-sequence` followed by a mandatory exponent. A `fractional-constant` must include `.`, so either a `.` or an expo- nent's `e` resolve the choice, and it does not seem like either is a prefix to a following rule. Could you give an example string that has more than one parse tree? Certainly `integer-constant` is prefix of `floating-point-constant` but there isn't an obvious advantage to putting it last, automated tools that prefer some order can re-arrange them as they see fit, and to a human reader less to more complex ordering might actually be the better. -- Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de Am Badedeich 7 · Telefon: +49(0)160/4415681 · http://www.bjoernsworld.de 25899 Dagebüll · PGP Pub. KeyID: 0xA4357E78 · http://www.websitedev.de/
Received on Friday, 21 February 2014 20:03:53 UTC