Re: Possible bug with null document in libyaml

Hi Kirill,

>> BTW, I do not think a YAML 1.1 library will accept "x" as a valid YAML 
>> stream if the library strictly implements the specification. In YAML 
>> 1.1, a plain scalar node must be followed by s-l-comments that contains 
>> at least one line break. So, "x\n" is a valid document but "x" is not.
> 
> I don't think any pre-YAML 1.2 processors uses the grammar described in 
> the spec as the basis for the parser.

I read that Oren modified the spec in YAML 1.2 to accept an input without
a line break at the end of the stream merely for JSON compatibility. 
I thought that YAML 1.1 spec refused such an input not accidentally but 
intentionally.

http://sourceforge.net/mailarchive/forum.php?thread_name=200e06280904252219i1da33755h200bdac14058ba36%40mail.gmail.com&forum_name=yaml-core

Anyway, as I wrote, I don't think so, too, except for the reference 
parser. ;p


>> According to the spec, this change was done for JSON compatibility.
>> A YAML 1.2 processor seems to be required to construct a null object 
>> from an empty node.
>>
>> In this point, YAML 1.2 is completely incompatible from YAML 1.1.
>> Please compare example 7.3 in YAML 1.2 spec with example 8.13 in YAML 
>> 1.1 spec.
>>
> 
> I don't think it's the correct interpretation of the spec.  I'd say that 
> YAML 1.2 provide a recommended scheme for tag resolution, while YAML 1.1 
> doesn't, leaving the decision of choosing the default scheme to the 
> processor authors.  I believe all existing YAML producers interpret an 
> empty plain scalar as a null value unless instructed otherwise.

Fmm, I didn't know that.

I don't understand how we can interprete YAML 1.1 spec as you wrote 
with provided example 8.13 and 8.15, but if only I misinterpreted 
the spec, I'm happier to hear that. I was affraid to have the 
possible incompatibility between YAML 1.1 and 1.2.

Best,
Osamu Takeuchi


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