9. Fine tuning

latexindent.pl operates by looking for the code blocks detailed in Table 2. The fine tuning of the details of such code blocks is controlled by the fineTuning field, detailed in Listing 586.

This field is for those that would like to peek under the bonnet/hood and make some fine tuning to latexindent.pl’s operating.

Warning

Making changes to the fine tuning may have significant consequences for your indentation scheme, proceed with caution!

Listing 586 fineTuning

fineTuning:
    environments:
      name: [a-zA-Z@\*0-9_\\]+
    ifElseFi:
      name: (?!@?if[a-zA-Z@]*?\{)@?if[a-zA-Z@]*?
    commands:
      name: [+a-zA-Z@\*0-9_\:]+?
    items:
      canBeFollowedBy: (?:\[[^]]*?\])|(?:<[^>]*?>)
    keyEqualsValuesBracesBrackets:
      name: [a-zA-Z@\*0-9_\/.:\#-]+[a-zA-Z@\*0-9_\/.\h\{\}:\#-]*?
      follow: (?:(?<!\\)\{)|,|(?:(?<!\\)\[)
    namedGroupingBracesBrackets:
      name: [0-9\.a-zA-Z@\*><]+?
      follow: \h|\R|\{|\[|\$|\)|\(
    UnNamedGroupingBracesBrackets:
      follow: \{|\[|,|&|\)|\(|\$
    arguments:
      before: (?:#\d\h*;?,?\/?)+|\<.*?\>
      between: _|\^|\*
    trailingComments:
      notPreceededBy: (?<!\\)
      afterComment: .*?
    modifyLineBreaks:
      doubleBackSlash: \\\\(?:\h*\[\h*\d+\h*[a-zA-Z]+\h*\])?
      comma: ','
      betterFullStop: |-
        (?x)                                # ignore spaces in the below
        (?:                                 #
          \.\)                              # .) 
          (?!\h*[a-z])                      # not *followed by* a-z
        )                                   #
        |                                   # OR
        (?:                                 #
          (?<!                              # not *preceded by*
            (?:                             #
              (?:[eE]\.[gG])                # e.g OR E.g OR e.G OR E.G
              |                             #
              (?:[iI]\.[eE])                # i.e OR I.e OR i.E OR I.E
              |                             #
              (?:etc)                       # etc
              |                             #
              (?:[wW]\.[rR]\.[tT])          # w.r.t OR W.r.t OR w.R.t OR w.r.T OR W.R.t OR W.r.T OR w.R.T OR W.R.T
            )                               #
          )                                 #
        )                                   # 
        \.                                  # .
        (?!                                 # not *followed by*
          (?:                               #
            [a-zA-Z0-9-~,]                  #
            |                               #
            \),                             # ),
            |                               #
            \)\.                            # ).
          )                                 #
        )                                   #

The fields given in Listing 586 are all regular expressions. This manual is not intended to be a tutorial on regular expressions; you might like to read, for example, (Friedl, n.d.) for a detailed covering of the topic.

We make the following comments with reference to Listing 586:

the environments:name field details that the name of an environment can contain:
1. a-z lower case letters
2. A-Z upper case letters
3. @ the @ ’letter’
4. \* stars
5. 0-9 numbers
6. _ underscores
7. \ backslashes
The + at the end means at least one of the above characters.
the ifElseFi:name field:
1. @? means that it can possibly begin with @
2. followed by if
3. followed by 0 or more characters from a-z, A-Z and @
4. the ? the end means non-greedy, which means ‘stop the match as soon as possible’
the keyEqualsValuesBracesBrackets contains some interesting syntax:
1. | means ‘or’
2. (?:(?<!\\)\{) the (?:...) uses a non-capturing group – you don’t necessarily need to worry about what this means, but just know that for the fineTuning feature you should only ever use non-capturing groups, and not capturing groups, which are simply (...)
3. (?<!\\)\{) means a { but it can not be immediately preceded by a \
in the arguments:before field
1. \d\h* means a digit (i.e. a number), followed by 0 or more horizontal spaces
2. ;?,? means possibly a semi-colon, and possibly a comma
3. \<.*?\> is designed for ’beamer’-type commands; the .*? means anything in between <...>
the modifyLineBreaks field refers to fine tuning settings detailed in Section 6. In particular:
1. betterFullStop is in relation to the one sentence per line routine, detailed in Section 6.2
2. doubleBackSlash is in relation to the DBSStartsOnOwnLine and DBSFinishesWithLineBreak polyswitches surrounding double backslashes, see Section 6.3.2
3. comma is in relation to the CommaStartsOnOwnLine and CommaFinishesWithLineBreak polyswitches surrounding commas in optional and mandatory arguments; see Table 3

It is not obvious from Listing 586, but each of the follow, before and between fields allow trailing comments, line breaks, and horizontal spaces between each character.

Warning

For the fineTuning feature you should only ever use non-capturing groups, such as (?:...) and not capturing groups, which are (...)

Example 161

As a demonstration, consider the file given in Listing 587, together with its default output using the command

latexindent.pl finetuning1.tex

is given in Listing 588.

Listing 587 finetuning1.tex

\mycommand{
    \rule{G -> +H[-G]CL}
    \rule{H -> -G[+H]CL}
    \rule{g -> +h[-g]cL}
    \rule{h -> -g[+h]cL}
}

Listing 588 finetuning1.tex default

\mycommand{
\rule{G -> +H[-G]CL}
\rule{H -> -G[+H]CL}
\rule{g -> +h[-g]cL}
\rule{h -> -g[+h]cL}
}

It’s clear from Listing 588 that the indentation scheme has not worked as expected. We can fine tune the indentation scheme by employing the settings given in Listing 590 and running the command

latexindent.pl finetuning1.tex -l=fine-tuning1.yaml

and the associated (desired) output is given in Listing 589.

Listing 589 finetuning1.tex using Listing 590

\mycommand{
	\rule{G -> +H[-G]CL}
	\rule{H -> -G[+H]CL}
	\rule{g -> +h[-g]cL}
	\rule{h -> -g[+h]cL}
}

Listing 590 finetuning1.yaml

fineTuning:
    arguments:
      between: '_|\^|\*|\->|\-|\+|h|H|g|G'

Example 162

Let’s have another demonstration; consider the file given in Listing 591, together with its default output using the command

latexindent.pl finetuning2.tex

is given in Listing 592.

Listing 591 finetuning2.tex

@misc{ wikilatex,
author = "{Wikipedia contributors}",
title = "LaTeX --- {Wikipedia}{,}",
note = "[Online; accessed 3-March-2020]"
}

Listing 592 finetuning2.tex default

@misc{ wikilatex,
author = "{Wikipedia contributors}",
title = "LaTeX --- {Wikipedia}{,}",
note = "[Online; accessed 3-March-2020]"
}

It’s clear from Listing 592 that the indentation scheme has not worked as expected. We can fine tune the indentation scheme by employing the settings given in Listing 594 and running the command

latexindent.pl finetuning2.tex -l=fine-tuning2.yaml

and the associated (desired) output is given in Listing 593.

Listing 593 finetuning2.tex using Listing 594

@misc{ wikilatex,
	author = "{Wikipedia contributors}",
	title = "LaTeX --- {Wikipedia}{,}",
	note = "[Online; accessed 3-March-2020]"
}

Listing 594 finetuning2.yaml

fineTuning:
    NamedGroupingBracesBrackets:
      follow: '\h|\R|\{|\[|\$|\)|\(|"'
    UnNamedGroupingBracesBrackets: 
      follow: '\{|\[|,|&|\)|\(|\$|"'
    arguments:
      between: '_|\^|\*|---'

In particular, note that the settings in Listing 594 specify that NamedGroupingBracesBrackets and UnNamedGroupingBracesBrackets can follow " and that we allow --- between arguments.

Example 163

You can tweak the fineTuning using the -y switch, but to be sure to use quotes appropriately. For example, starting with the code in Listing 595 and running the following command

latexindent.pl -m -y='modifyLineBreaks:oneSentencePerLine:manipulateSentences: 1, modifyLineBreaks:oneSentencePerLine:sentencesBeginWith:a-z: 1, fineTuning:modifyLineBreaks:betterFullStop: "(?:\.|;|:(?![a-z]))|(?:(?<!(?:(?:e\.g)|(?:i\.e)|(?:etc))))\.(?!(?:[a-z]|[A-Z]|\-|~|\,|[0-9]))"' issue-243.tex -o=+-mod1

gives the output shown in Listing 596.

Listing 595 finetuning3.tex

We go; you see: this sentence \cite{tex:stackexchange} finishes here.

Listing 596 finetuning3.tex using -y switch

We go;
you see:
this sentence \cite{tex:stackexchange} finishes here.

Example 164

We can tweak the fineTuning for how trailing comments are classified. For motivation, let’s consider the code given in Listing 597

Listing 597 finetuning4.tex

some before text
 \href{Handbook%20for%30Spoken%40document.pdf}{my document}
some after text 

We will compare the settings given in Listing 598 and Listing 599.

Listing 598 href1.yaml

modifyLineBreaks:
    textWrapOptions:
        columns: -1
        blocksEndBefore:
           verbatim: 0
        blocksFollow:
           verbatim: 0

removeTrailingWhitespace:
    beforeProcessing: 1

Listing 599 href2.yaml

fineTuning:
    trailingComments:
      notPreceededBy: '(?:(?<!Handbook)(?<!for)(?<!Spoken))'

modifyLineBreaks:
    textWrapOptions:
        columns: -1
        blocksEndBefore:
           verbatim: 0
        blocksFollow:
           verbatim: 0

removeTrailingWhitespace:
    beforeProcessing: 1

Upon running the following commands

latexindent.pl -m finetuning4.tex -o=+-mod1 -l=href1
latexindent.pl -m finetuning4.tex -o=+-mod2 -l=href2

we receive the respective output in Listing 600 and Listing 601.

Listing 600 finetuning4.tex using Listing 598

some before text \href{Handbooksome after text%20for%30Spoken%40document.pdf}{my document}

Listing 601 finetuning4.tex using Listing 599

some before text \href{Handbook%20for%30Spoken%40document.pdf}{my document} some after text

We note that in:

Listing 600 the trailing comments are assumed to be everything following the first comment symbol, which has meant that everything following it has been moved to the end of the line; this is undesirable, clearly!
Listing 601 has fine-tuned the trailing comment matching, and says that % cannot be immediately preceded by the words ‘Handbook’, ‘for’ or ‘Spoken’, which means that none of the % symbols have been treated as trailing comments, and the output is desirable.

Example 165

Another approach to this situation, which does not use fineTuning, is to use noIndentBlock which we discussed in Listing 60; using the settings in Listing 602 and running the command

latexindent.pl -m finetuning4.tex -o=+-mod3 -l=href3

then we receive the same output given in Listing 601.

Listing 602 href3.yaml

modifyLineBreaks:
    textWrapOptions:
        columns: -1
        blocksEndBefore:
           verbatim: 0
        blocksFollow:
           verbatim: 0

noIndentBlock:
    href:
        begin: '\\href\{[^}]*?\}\{'
        body: '[^}]*?'
        end: '\}'

With reference to the body field in Listing 602, we note that the body field can be interpreted as: the fewest number of zero or more characters that are not right braces. This is an example of character class.

Example 166

We can use the fineTuning field to assist in the formatting of bibliography files.

Starting with the file in Listing 603 and running the command

latexindent.pl bib1.tex -o=+-mod1

gives the output in Listing 604.

Listing 603 bib1.bib

@online{paulo,
title="arararule,indent.yaml",
author="PauloCereda",
date={2013-05-23},
urldate={2021-03-19},
keywords={contributor},}

Listing 604 bib1-mod1.bib

@online{paulo,
	title="arararule,indent.yaml",
	author="PauloCereda",
	date={2013-05-23},
	urldate={2021-03-19},
	keywords={contributor},}

Let’s assume that we would like to format the output so as to align the = symbols. Using the settings in Listing 606 and running the command

latexindent.pl bib1.bib -l bibsettings1.yaml -o=+-mod2

gives the output in Listing 605.

Listing 605 bib1.bib using Listing 606

@online{paulo,
	title    = "arararule,indent.yaml",
	author   = "PauloCereda",
	date     = {2013-05-23},
	urldate  = {2021-03-19},
	keywords = {contributor},}

Listing 606 bibsettings1.yaml

lookForAlignDelims:
   online: 
      delimiterRegEx: '(=)'

fineTuning:
    keyEqualsValuesBracesBrackets:
      follow: '(?:(?<!\\)\{)|(?:(?<!\\)\[)'
    UnNamedGroupingBracesBrackets: 
      follow: '\{|\[|,|&|\)|\(|\$|='

Some notes about Listing 606:

we have populated the lookForAlignDelims field with the online command, and have used the delimiterRegEx, discussed in Section 5.5.4;
we have tweaked the keyEqualsValuesBracesBrackets code block so that it will not be found following a comma; this means that, in contrast to the default behaviour, the lines such as date={2013-05-23}, will not be treated as key-equals-value braces;
the adjustment to keyEqualsValuesBracesBrackets necessitates the associated change to the UnNamedGroupingBracesBrackets field so that they will be searched for following = symbols.

Example 167

We can build upon Listing 606 for slightly more complicated bibliography files.

Starting with the file in Listing 607 and running the command

latexindent.pl bib2.bib -l bibsettings1.yaml -o=+-mod1

gives the output in Listing 608.

Listing 607 bib2.bib

@online{cmh:videodemo,
title="Videodemonstrationofpl.latexindentonyoutube",
url="https://www.youtube.com/watch?v=wo38aaH2F4E&spfreload=10",
urldate={2017-02-21},
}

Listing 608 bib2-mod1.bib

@online{cmh:videodemo,
	title   = "Videodemonstrationofpl.latexindentonyoutube",
	url     = "https://www.youtube.com/watch?v               = wo38aaH2F4E&spfreload = 10",
	urldate = {2017-02-21},
}

The output in Listing 608 is not ideal, as the = symbol within the url field has been incorrectly used as an alignment delimiter.

We address this by tweaking the delimiterRegEx field in Listing 609.

Listing 609 bibsettings2.yaml

lookForAlignDelims:
   online: 
      delimiterRegEx: '(?<!v)(?<!spfreload)(=)'

Upon running the command

latexindent.pl bib2.bib -l bibsettings1.yaml,bibsettings2.yaml -o=+-mod2

we receive the desired output in Listing 610.

Listing 610 bib2-mod2.bib

@online{cmh:videodemo,
	title   = "Videodemonstrationofpl.latexindentonyoutube",
	url     = "https://www.youtube.com/watch?v=wo38aaH2F4E&spfreload=10",
	urldate = {2017-02-21},
}

With reference to Listing 609 we note that the delimiterRegEx has been adjusted so that = symbols are used as the delimiter, but only when they are not preceded by either v or spfreload.

Example 168

We can use the fineTuning settings to tweak how latexindent.pl finds trailing comments. We begin with the file in Listing 611

Listing 611 finetuning5.tex

\chapter{chapter text} % 123
chapter text
\section{section text} % 456
section text
% end
% end

Using the settings in Listing 613 and running the command

latexindent.pl finetuning5.tex -l=fine-tuning3.yaml

gives the output in Listing 612.

Listing 612 finetuning5-mod1.tex

\chapter{chapter text} % 123
	chapter text
	\section{section text} % 456
		section text
	% end
% end

Listing 613 finetuning3.yaml

fineTuning:
    trailingComments:
      notPreceededBy: (?<!\\)
      afterComment: (?!(?:\hend)).*?

specialBeginEnd:
  customSection:
    begin: \\(?:section|chapter)
    end: \%\h+end
  specialBeforeCommand: 1

The settings in Listing 613 detail that trailing comments can not be followed by a single space, and then the text ‘end’. This means that the specialBeginEnd routine will be able to find the pattern % end as the end part. The trailing comments 123 and 456 are still treated as trailing comments.

Friedl, Jeffrey E. F. n.d. Mastering Regular Expressions.