[cxml-devel] RNG question

[Cyrus Harmon]

Wow. Thanks!

On Mar 6, 2012, at 10:20 AM, David Lichteblau wrote:

> Quoting Cyrus Harmon (ch-lisp at bobobeach.com):
>> Is the former invalid RNC or is cxml-rng's parser barfing where it
>> shouldn't?  A complete, minimal-ish example is shown below and
>> attempting to parse it gives:
> 
> The RNC is invalid:
> 
> | There is no notion of operator precedence. It is an error for patterns
> | to combine the |, &, , and - operators without using parentheses to
> | make the grouping explicit. For example, foo | bar, baz is not allowed;
> | instead, either (foo | bar), baz or foo | (bar, baz) must be used. A
> | similar restriction applies to name classes and the use of the | and -
> | operators.
> 
> The fun part: The spec has not one but two BNFs.
> 
> The first BNF is incorrect and you're supposed to basically ignore it.
> The second BNF correct but much less readable:
> 
> | These restrictions are not expressed in the above EBNF but
> | they are made explicit in the BNF in Section 1.
> 
> 
> d.