Re: Top level block scalar without indentation

Hi Oren,

Thanks for the clarification! I created a ticket for this.

  http://pyyaml.org/ticket/288


> auto-detect does not return 0, it returns at least 1, but since we start
> with -1 this results with an overall 0 indentation (since production 207
> uses -1 and not 0).

Is YAML 1.1 same?

In YAML 1.1 spec, the rule [117] max(-1, 0) set n = 0.
So I think [166] detect(m) must return 0, not 1..

  [117] c-l+block-scalar(n) ::= c-l+folded(max(n,0)) | c-l+literal(max(n,0))
  [175] c-l+literal(n) ::= c-b-block-header(literal,m,t)
                                    l-literal-content(n+m,t)

I'm not sure I'm understanding these parametered production rules..

Anyway, I hope I can use top level block scalar with libyaml.


2013/4/14 Oren Ben-Kiki <[email protected]>:
> Well, example 9.5 is pretty explicit in what the spec says. Note that the
> auto-detect does not return 0, it returns at least 1, but since we start
> with -1 this results with an overall 0 indentation (since production 207
> uses -1 and not 0).
>
> The same logic holds for both of your samples; example 9.3 shows an
> unindented plain at the top level.
>
> Oren.
>
>
>
> On Sat, Apr 13, 2013 at 2:10 PM, KOSEKI Kengo <[email protected]> wrote:
>>
>> Hi,
>>
>> I noticed that LibYAML doesn't parse block scalar without indentation.
>>
>>   Sample: 1
>>   ---
>>   XXX
>>   YYY
>>   ZZZ
>>
>>   Sample: 2
>>   --- |
>>   XXX
>>   YYY
>>   ZZZ
>>
>> I expected that these samples would be parsed like this:
>>
>>   [{"Sample": 1}, "XXX YYY ZZZ"]
>>   [{"Sample": 2}, "XXX\nYYY\nZZZ\n"]
>>
>> LibYAML can parse Sample 1 but not Sample 2.
>>
>>   $ ./run-parser Sample1.yaml
>>   [1] Parsing 'Sample1.yaml': SUCCESS (11 events)
>>
>>   $ ./run-parser Sample2.yaml
>>   [1] Parsing 'Sample2.yaml': FAILURE (10 events)
>>
>> PyYAML returned error.
>>
>>   expected '<document start>', but found '<scalar>'
>>
>>
>> I checked some implementations. The results are:
>>
>>   Syck (YAML 1.0) - Ruby
>>     Sample1 ... PASS
>>     Sample2 ... PASS
>>
>>   YAML.pm (YAML 1.0) - Perl
>>     Sample1 ... FAIL
>>     Sample2 ... PASS
>>
>>   PyYAML (YAML 1.1) - Python / LibYAML
>>     Sample1 ... PASS
>>     Sample2 ... FAIL
>>
>>   Psych     (YAML 1.1) - Ruby / LibYAML
>>     Sample1 ... PASS
>>     Sample2 ... FAIL
>>
>>   SnakeYAML (YAML 1.1) - Java / based on LibYAML
>>     Sample1 ... PASS
>>     Sample2 ... FAIL
>>
>>   JS-YAML (YAML 1.2) - JavaScript
>>     Sample1 ... PASS
>>     Sample2 ... PASS
>>
>>   Yamerl (YAML 1.2) - Erlang
>>     Sample1 ... PASS
>>     Sample2 ... PASS
>>
>>
>> My questions are:
>>
>>   (1) Which parsers are implemented properly, at this point?
>>   (2) Is there possibility that LibYAML support Sample2?
>>       At YAML 1.1 trunk or future 1.2 branch?
>>
>>
>> In YAML 1.0 spec, Example 4.21 says:
>>
>>   --- |
>>   Usually top level nodes are not indented.
>>
>> In YAML 1.2 spec, Example 9.5 says:
>>
>>   %YAML 1.2
>>   --- |
>>   %!PS-Adobe-2.0
>>   ...
>>
>>   %YAML 1.2
>>   ---
>>   !!str "%!PS-Adobe-2.0\n"
>>   ...
>>
>> I couldn't find an example like these in the YAML 1.1 spec.
>> It may be determined by [161] detect(m) being able to return 0 or not.
>>
>>
>> I found this message.
>>
>>  * http://osdir.com/ml/text.yaml.general/2008-07/msg00001.html
>>
>> > The spec requires that continuation lines of a flow scalar are indented
>> > with at least one space. LibYAML relaxes this rule by allowing
>> > multi-line flow scalars not to be indented,
>>
>> So I realized that the Sample1 result was came from relaxing
>> the spec. But how about the block scalar, Sample 2?
>>
>>
>> I think this notation is important, because this enable to append
>> metadata to the plain text.
>>
>> An email will be represented like this.
>>
>>   Date: 2013-04-13 20:10:53+09:00
>>   Subject: Top level block scalar without indentation
>>   From: [email protected]
>>   To: [email protected]
>>   --- |
>>   Hi,
>>   I noticed that ...
>>
>>
>> Using template engine to generate HTML.
>>
>>   title: YAML block scalar
>>   template: blog
>>   published: 2013-04-13
>>   --- |
>>   <article>
>>     <h1>xxxxxx</h1>
>>     <pre>
>>       Here must
>>       be written in
>>       multi lines.
>>     </pre>
>>   </article>
>>
>>
>> Best regards,
>>
>> --
>> koseki
>>
>>
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>
>



-- 
koseki

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