Permissible characters in ConTeXt reference labels

Permissible characters in ConTeXt reference labels

[Mark Szepieniec]

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I'm trying to fix a problem in pandoc (see
https://github.com/jgm/pandoc/pull/1589) where it doesn't properly sanitize
the reference labels in ConTeXt output, causing errors during compilation
when a label contains '#' for example. Note that this sanitizing is needed
in addition to the regular backslash escaping used for control characters:
'\#' is still illegal in a label for example.

In the sanitizer function I'm writing, I'd like to properly escape all
illegal characters, but I couldn't find an explicit list of allowed or
illegal characters. Based on some testing I've conducted (see attached
file), I've arrived at the following set:

\#[]",{}%()|=

1) Does this look like a reasonable set? Are there other characters or
sequences that should be included, or are worth testing?

2) I was told (see
https://groups.google.com/forum/#!topic/pandoc-discuss/tYpXMUkmbEY) that if
the characters " and , didn't work, it would count as a ConTeXt bug, is
there any truth to that? Please let me know if any further info is needed
on my part.

3) Does anyone see issues with this general approach? I'm relatively new to
ConTeXt, so I might be missing either a huge problem, or an obviously
easier way to do this.

Thanks,

Mark

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Re: Permissible characters in ConTeXt reference labels

[Mark Szepieniec]

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Bump...

If it's not too much trouble, I would greatly appreciate some feedback on
this before I propose it to be merged into pandoc; even a "looks good to
me" from one of the ConTeXt gurus would be very helpful.

Thanks in advance,

Mark

On Tue, Sep 9, 2014 at 12:20 AM, Mark Szepieniec <mszepien@gmail.com> wrote:

> I'm trying to fix a problem in pandoc (see
> https://github.com/jgm/pandoc/pull/1589) where it doesn't properly
> sanitize the reference labels in ConTeXt output, causing errors during
> compilation when a label contains '#' for example. Note that this
> sanitizing is needed in addition to the regular backslash escaping used for
> control characters: '\#' is still illegal in a label for example.
>
> In the sanitizer function I'm writing, I'd like to properly escape all
> illegal characters, but I couldn't find an explicit list of allowed or
> illegal characters. Based on some testing I've conducted (see attached
> file), I've arrived at the following set:
>
> \#[]",{}%()|=
>
> 1) Does this look like a reasonable set? Are there other characters or
> sequences that should be included, or are worth testing?
>
> 2) I was told (see
> https://groups.google.com/forum/#!topic/pandoc-discuss/tYpXMUkmbEY) that
> if the characters " and , didn't work, it would count as a ConTeXt bug, is
> there any truth to that? Please let me know if any further info is needed
> on my part.
>
> 3) Does anyone see issues with this general approach? I'm relatively new
> to ConTeXt, so I might be missing either a huge problem, or an obviously
> easier way to do this.
>
> Thanks,
>
> Mark
>

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___________________________________________________________________________________

Re: Permissible characters in ConTeXt reference labels

[Hans Hagen]

On 9/18/2014 12:06 AM, Mark Szepieniec wrote:
> Bump...
>
> If it's not too much trouble, I would greatly appreciate some feedback
> on this before I propose it to be merged into pandoc; even a "looks good
> to me" from one of the ConTeXt gurus would be very helpful.
>
> Thanks in advance,
>
> Mark
>
> On Tue, Sep 9, 2014 at 12:20 AM, Mark Szepieniec <mszepien@gmail.com
> <mailto:mszepien@gmail.com>> wrote:
>
>     I'm trying to fix a problem in pandoc (see
>     https://github.com/jgm/pandoc/pull/1589) where it doesn't properly
>     sanitize the reference labels in ConTeXt output, causing errors
>     during compilation when a label contains '#' for example. Note that
>     this sanitizing is needed in addition to the regular backslash
>     escaping used for control characters: '\#' is still illegal in a
>     label for example.
>
>     In the sanitizer function I'm writing, I'd like to properly escape
>     all illegal characters, but I couldn't find an explicit list of
>     allowed or illegal characters. Based on some testing I've conducted
>     (see attached file), I've arrived at the following set:
>
>     \#[]",{}%()|=

it depends on where these characters end up in

#  : always tricky as it denotes an argument, so escape
[] : depends if it gets fed into a macro that uses [] as delimiters
{} : only an issue when not balanced
%  : escaping needed as it's comment otherwise
() : depends on where it ends up, like []
|  : is special in context so needs escaping
\  : of course that one needs escaping

>     1) Does this look like a reasonable set? Are there other characters
>     or sequences that should be included, or are worth testing?

keep in mind that escapes should end up unescaped at some point

>     2) I was told (see
>     https://groups.google.com/forum/#!topic/pandoc-discuss/tYpXMUkmbEY)
>     that if the characters " and , didn't work, it would count as a
>     ConTeXt bug, is there any truth to that? Please let me know if any
>     further info is needed on my part.

well, define bug ... one can say the same of < and > in xml -)

if the result ends up in a comma separated list then , can be an issue 
but one can always wrap an argument in {} to hide that

>     3) Does anyone see issues with this general approach? I'm relatively
>     new to ConTeXt, so I might be missing either a huge problem, or an
>     obviously easier way to do this.

i don't know ... i never used pandoc input

Hans

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Re: Permissible characters in ConTeXt reference labels

[Aditya Mahajan]

On Thu, 18 Sep 2014, Hans Hagen wrote:

> On 9/18/2014 12:06 AM, Mark Szepieniec wrote:
>> Bump...
>> 
>> If it's not too much trouble, I would greatly appreciate some feedback
>> on this before I propose it to be merged into pandoc; even a "looks good
>> to me" from one of the ConTeXt gurus would be very helpful.
>> 
>> Thanks in advance,
>> 
>> Mark
>> 
>> On Tue, Sep 9, 2014 at 12:20 AM, Mark Szepieniec <mszepien@gmail.com
>> <mailto:mszepien@gmail.com>> wrote:
>>
>>     I'm trying to fix a problem in pandoc (see
>>     https://github.com/jgm/pandoc/pull/1589) where it doesn't properly
>>     sanitize the reference labels in ConTeXt output, causing errors
>>     during compilation when a label contains '#' for example. Note that
>>     this sanitizing is needed in addition to the regular backslash
>>     escaping used for control characters: '\#' is still illegal in a
>>     label for example.

(LaTeX label) = (ConTeXt reference). What Mark mean was references such as

\section[...]{...} or \startplacefigure[reference={...}].

>>     In the sanitizer function I'm writing, I'd like to properly escape
>>     all illegal characters, but I couldn't find an explicit list of
>>     allowed or illegal characters. Based on some testing I've conducted
>>     (see attached file), I've arrived at the following set:
>>
>>     \#[]",{}%()|=
>
> it depends on where these characters end up in
>
> #  : always tricky as it denotes an argument, so escape
> [] : depends if it gets fed into a macro that uses [] as delimiters
> {} : only an issue when not balanced
> %  : escaping needed as it's comment otherwise
> () : depends on where it ends up, like []
> |  : is special in context so needs escaping
> \  : of course that one needs escaping
>
>>     1) Does this look like a reasonable set? Are there other characters
>>     or sequences that should be included, or are worth testing?
>
> keep in mind that escapes should end up unescaped at some point
>
>>     2) I was told (see
>>     https://groups.google.com/forum/#!topic/pandoc-discuss/tYpXMUkmbEY)
>>     that if the characters " and , didn't work, it would count as a
>>     ConTeXt bug, is there any truth to that? Please let me know if any
>>     further info is needed on my part.
>
> well, define bug ... one can say the same of < and > in xml -)

Since I made that comment on the pandoc mailing list, let me explain.

Consider:

\section["some" reference]{Title}

Given how " behaves elsewhere in ConTeXt, a user would expect the above to 
be a valid input. If it is not, then it is bug (or atleast, surprising).

The same goes for

\section[some, reference]{Title}

> if the result ends up in a comma separated list then , can be an issue but 
> one can always wrap an argument in {} to hide that
>
>>     3) Does anyone see issues with this general approach? I'm relatively
>>     new to ConTeXt, so I might be missing either a huge problem, or an
>>     obviously easier way to do this.
>
> i don't know ... i never used pandoc input

Aditya
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Re: Permissible characters in ConTeXt reference labels

[Mark Szepieniec]

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OK, thanks both of you, its looks like I need to sanitize all mentioned
characters, since the reference strings will generally originate from
formats other than ConTeXt, and we don't want ConTeXt to do any processing
on them, aside from comparisons to resolve references.

As for Aditya's examples, the first results in a compilation error on my
test file, while the second compiles without error, and gives the expected
result.

On Thu, Sep 18, 2014 at 4:26 AM, Aditya Mahajan <adityam@umich.edu> wrote:

> On Thu, 18 Sep 2014, Hans Hagen wrote:
>
>  On 9/18/2014 12:06 AM, Mark Szepieniec wrote:
>>
>>> Bump...
>>>
>>> If it's not too much trouble, I would greatly appreciate some feedback
>>> on this before I propose it to be merged into pandoc; even a "looks good
>>> to me" from one of the ConTeXt gurus would be very helpful.
>>>
>>> Thanks in advance,
>>>
>>> Mark
>>>
>>> On Tue, Sep 9, 2014 at 12:20 AM, Mark Szepieniec <mszepien@gmail.com
>>> <mailto:mszepien@gmail.com>> wrote:
>>>
>>>     I'm trying to fix a problem in pandoc (see
>>>     https://github.com/jgm/pandoc/pull/1589) where it doesn't properly
>>>     sanitize the reference labels in ConTeXt output, causing errors
>>>     during compilation when a label contains '#' for example. Note that
>>>     this sanitizing is needed in addition to the regular backslash
>>>     escaping used for control characters: '\#' is still illegal in a
>>>     label for example.
>>>
>>
> (LaTeX label) = (ConTeXt reference). What Mark mean was references such as
>
> \section[...]{...} or \startplacefigure[reference={...}].
>
>      In the sanitizer function I'm writing, I'd like to properly escape
>>>     all illegal characters, but I couldn't find an explicit list of
>>>     allowed or illegal characters. Based on some testing I've conducted
>>>     (see attached file), I've arrived at the following set:
>>>
>>>     \#[]",{}%()|=
>>>
>>
>> it depends on where these characters end up in
>>
>> #  : always tricky as it denotes an argument, so escape
>> [] : depends if it gets fed into a macro that uses [] as delimiters
>> {} : only an issue when not balanced
>> %  : escaping needed as it's comment otherwise
>> () : depends on where it ends up, like []
>> |  : is special in context so needs escaping
>> \  : of course that one needs escaping
>>
>>      1) Does this look like a reasonable set? Are there other characters
>>>     or sequences that should be included, or are worth testing?
>>>
>>
>> keep in mind that escapes should end up unescaped at some point
>>
>>      2) I was told (see
>>>     https://groups.google.com/forum/#!topic/pandoc-discuss/tYpXMUkmbEY)
>>>     that if the characters " and , didn't work, it would count as a
>>>     ConTeXt bug, is there any truth to that? Please let me know if any
>>>     further info is needed on my part.
>>>
>>
>> well, define bug ... one can say the same of < and > in xml -)
>>
>
> Since I made that comment on the pandoc mailing list, let me explain.
>
> Consider:
>
> \section["some" reference]{Title}
>
> Given how " behaves elsewhere in ConTeXt, a user would expect the above to
> be a valid input. If it is not, then it is bug (or atleast, surprising).
>
> The same goes for
>
> \section[some, reference]{Title}
>
>  if the result ends up in a comma separated list then , can be an issue
>> but one can always wrap an argument in {} to hide that
>>
>>      3) Does anyone see issues with this general approach? I'm relatively
>>>     new to ConTeXt, so I might be missing either a huge problem, or an
>>>     obviously easier way to do this.
>>>
>>
>> i don't know ... i never used pandoc input
>>
>
> Aditya
>
> ____________________________________________________________
> _______________________
> If your question is of interest to others as well, please add an entry to
> the Wiki!
>
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/
> listinfo/ntg-context
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> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
> ____________________________________________________________
> _______________________
>

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