Formatting references in LaTeX (with a filter?)

Formatting references in LaTeX (with a filter?)

[Thomas Hodgson]

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I currently put something like this at the end of my markdown files:

```
# References {-}
\setlength{\parindent}{-0.2in}
\setlength{\leftskip}{0.2in}
\setlength{\parskip}{8pt}
\vspace*{-0.2in}
\noindent
```

This gives me what I want when I use Pandoc to convert the MD to a PDF. I 
would like to avoid the five lines of LaTeX if possible (just for 
neatness). If I use `--include-after` the material comes after the 
bibliography. Should I look in to writing a filter? The first problem thatI 
saw is that when I looked at the AST I saw that the references are an 
ordinary header called 'References'. Is it possible to write the filter so 
that some LaTeX comes immediately after it?

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Re: Formatting references in LaTeX (with a filter?)

[John MacFarlane]

+++ Thomas Hodgson [Nov 21 14 09:03 ]:
>I currently put something like this at the end of my markdown files:
>
>```
># References {-}
>\setlength{\parindent}{-0.2in}
>\setlength{\leftskip}{0.2in}
>\setlength{\parskip}{8pt}
>\vspace*{-0.2in}
>\noindent
>```
>
>This gives me what I want when I use Pandoc to convert the MD to a PDF. I
>would like to avoid the five lines of LaTeX if possible (just for
>neatness). If I use `--include-after` the material comes after the
>bibliography. Should I look in to writing a filter? The first problem thatI
>saw is that when I looked at the AST I saw that the references are an
>ordinary header called 'References'. Is it possible to write the filter so
>that some LaTeX comes immediately after it?

Sure, the easiest approach would be just to write a function with
type Pandoc -> Pandoc, like

insertLatexLines :: Pandoc -> Pandoc
insertLatexLines (Pandoc meta bs) =
  Pandoc meta (bs ++ [RawBlock (Format "latex") latexLines])
  where latexLines = "\\setlength...etc."

then toJSONFilter insertLatexLines.

Then, just make sure to put this filter BEFORE pandoc-citeproc
when you call pandoc:

pandoc -F ./insertLatexLines -F pandoc-citeproc

Re: Formatting references in LaTeX (with a filter?)

[Aaron O'Leary]

On Fri 21 Nov, John MacFarlane wrote:
> when you call pandoc:
> 
> pandoc -F ./insertLatexLines -F pandoc-citeproc

Today I learned that you can use multiple filters! Thanks!

Re: Formatting references in LaTeX (with a filter?)

[Thomas Hodgson]

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Thank-you both. That's just what I was after.

On Friday, 21 November 2014 18:28:09 UTC, Aaron O'leary wrote:
>
> On Fri 21 Nov, John MacFarlane wrote: 
> > when you call pandoc: 
> > 
> > pandoc -F ./insertLatexLines -F pandoc-citeproc 
>
> Today I learned that you can use multiple filters! Thanks! 
>

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Re: Formatting references in LaTeX (with a filter?)

[BPJ]

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Sure, it saves you a lot of time!

A tip: you can use classes on Header/Code/CodeBlock/Span/Div elements and
have filters look at them to indicate which filter should act on them; not
least an earlier filter can 'call the attention' of a later filter this
way, and even have a last filter which removes temporary 'wrapper'
spans/divs by giving them a special class which it recognises or by ending
such filtering classes in a special character sequence.

/bpj
Den 21 nov 2014 19:28 skrev "Aaron O'Leary" <aaron.oleary-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:

> On Fri 21 Nov, John MacFarlane wrote:
> > when you call pandoc:
> >
> > pandoc -F ./insertLatexLines -F pandoc-citeproc
>
> Today I learned that you can use multiple filters! Thanks!
>
> --
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> .
> For more options, visit https://groups.google.com/d/optout.
>

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Re: Formatting references in LaTeX (with a filter?)

[nickbart1980-Re5JQEeQqe8AvxtiuMwx3w]

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Could pandoc do this automatically, depending on whether the CSL style file 
specifies

  <bibliography hanging-indent="true" …> or

  <bibliography hanging-indent="false"  …>

("false" is the default)?

See http://citationstyles.org/downloads/specification.html#whitespace

On Saturday, 22 November 2014 15:40:22 UTC, BPJ wrote:
>
> Sure, it saves you a lot of time!
>
> A tip: you can use classes on Header/Code/CodeBlock/Span/Div elements and 
> have filters look at them to indicate which filter should act on them; not 
> least an earlier filter can 'call the attention' of a later filter this 
> way, and even have a last filter which removes temporary 'wrapper' 
> spans/divs by giving them a special class which it recognises or by ending 
> such filtering classes in a special character sequence.
>
> /bpj
> Den 21 nov 2014 19:28 skrev "Aaron O'Leary" <aaron....-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org 
> <javascript:>>:
>
>> On Fri 21 Nov, John MacFarlane wrote:
>> > when you call pandoc:
>> >
>> > pandoc -F ./insertLatexLines -F pandoc-citeproc
>>
>> Today I learned that you can use multiple filters! Thanks!
>>
>> --
>> You received this message because you are subscribed to the Google Groups 
>> "pandoc-discuss" group.
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to pandoc-discus...-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org <javascript:>.
>> To post to this group, send email to pandoc-...-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org 
>> <javascript:>.
>> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/pandoc-discuss/20141121182803.GA26159%40tk422.wireless.leeds.ac.uk
>> .
>> For more options, visit https://groups.google.com/d/optout.
>>
>

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Re: Formatting references in LaTeX (with a filter?)

[nickbart1980-Re5JQEeQqe8AvxtiuMwx3w]

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I have been using an approach similar to the one mentioned by the OP, in my 
case putting `\hangindent1.5em\hangafter1\noindent` (lifted from 
`hanging.sty`) right after `# References` for some time, too. While this 
works for most cases, it fails when additional text is inserted after the 
reference list, e.g., when creating multi-part bibliographies by stitching 
together latex fragments.

The problem is that the scope of `\hangindent1.5em\hangafter1\noindent` is 
not (and cannot be) limited and thus messes with the formatting of 
subsequent text. In the case of a multi-part bibliography, e.g., the 
vertical space before subsequent section headers is greatly reduced.

My feeling is that the proper way to deal with the formatting of reference 
list entries in pandoc is to have the latex writer wrap all reference list 
entries (but not the `# References` header) in a latex environment, e.g.:

`\begin{pandocreferences}
... [reference list entries]
\end{pandocreferences}`

which could be defined in the default.latex template, adapted from 
`hanging.sty`, as:

`\newenvironment{pandocreferences}[1]{\setlength{\parindent}{\z@} 
\everypar={\hangindent1.5em\hangafter1\noindent}}{\par}`

BTW, I feel this should definitely be part of pandoc's core functionality 
and should not be relegated to a filter.

What's more, this approach could be used to start coping with formatting 
directives from CSL styles files (well, at least hanging-indent true vs. 
false), e.g.

IF CSL STYLE FILE CONTAINS <bibliography hanging-indent="true" …>
THEN
`\newenvironment{pandocreferences}[1]{\setlength{\parindent}{\z@} 
\everypar={\hangindent1.5em\hangafter1\noindent}}{\par}`
ELSE
`\newenvironment{pandocreferences}[1]{\setlength{\parindent}{\z@} 
\everypar={\hangindent0em\hangafter1\noindent}}{\par}`
ENDIF

To implement additional CSL options such as `second-field-align` 
(http://citationstyles.org/downloads/specification.html#whitespace) it 
might also be useful to look into the way biblatex formats reference list 
entries. Apparently it uses `\defbibenvironment` to define a *list* 
environment, and since `second-field-align` is essentially a list format, 
and ordinary hanging indent can also be formatted using latex lists, this 
might have advantages. I have not been able to figure out from manual or 
source what exactly biblatex does though, but maybe a biblatex expert could 
help us out ...



On Saturday, 22 November 2014 16:32:25 UTC, nickba...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org wrote:
>
> Could pandoc do this automatically, depending on whether the CSL style 
> file specifies
>
>   <bibliography hanging-indent="true" …> or
>
>   <bibliography hanging-indent="false"  …>
>
> ("false" is the default)?
>
> See http://citationstyles.org/downloads/specification.html#whitespace
>
> On Saturday, 22 November 2014 15:40:22 UTC, BPJ wrote:
>>
>> Sure, it saves you a lot of time!
>>
>> A tip: you can use classes on Header/Code/CodeBlock/Span/Div elements and 
>> have filters look at them to indicate which filter should act on them; not 
>> least an earlier filter can 'call the attention' of a later filter this 
>> way, and even have a last filter which removes temporary 'wrapper' 
>> spans/divs by giving them a special class which it recognises or by ending 
>> such filtering classes in a special character sequence.
>>
>> /bpj
>> Den 21 nov 2014 19:28 skrev "Aaron O'Leary" <aaron....-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>
>>> On Fri 21 Nov, John MacFarlane wrote:
>>> > when you call pandoc:
>>> >
>>> > pandoc -F ./insertLatexLines -F pandoc-citeproc
>>>
>>> Today I learned that you can use multiple filters! Thanks!
>>>
>>> --
>>> You received this message because you are subscribed to the Google 
>>> Groups "pandoc-discuss" group.
>>> To unsubscribe from this group and stop receiving emails from it, send 
>>> an email to pandoc-discus...-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> To post to this group, send email to pandoc-...-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> To view this discussion on the web visit 
>>> https://groups.google.com/d/msgid/pandoc-discuss/20141121182803.GA26159%40tk422.wireless.leeds.ac.uk
>>> .
>>> For more options, visit https://groups.google.com/d/optout.
>>>
>>

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Re: Formatting references in LaTeX (with a filter?)

[Aaron O'Leary]

On Fri 21 Nov, Thomas Hodgson wrote:
> Is it possible to write the filter so that some LaTeX comes
> immediately after it?

In python you can do it like this:

    import pandocfilters as pf

    reference_formatting = r"""\setlength{\parindent}{-0.2in}
    \setlength{\leftskip}{0.2in}
    \setlength{\parskip}{8pt}
    \vspace*{-0.2in}
    \noindent
    """

    format_block = pf.RawBlock('latex', reference_formatting)

    def ref(key, value, format, meta):
        if key == 'Header' and value[2][0]['c'] == 'References':
            return [pf.Header(*value), format_block]

    if __name__ == '__main__':
        pf.toJSONFilter(ref)


This scans the document looking for a header called 'References', then
puts a block of latex after that header. You can add `and format == 'latex'`
to the if statement to have it only active when you are outputting
latex.