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 583.

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 583 fineTuning
629fineTuning:
630    environments:
631      name: [a-zA-Z@\*0-9_\\]+
632    ifElseFi:
633      name: (?!@?if[a-zA-Z@]*?\{)@?if[a-zA-Z@]*?
634    commands:
635      name: [+a-zA-Z@\*0-9_\:]+?
636    items:
637      canBeFollowedBy: (?:\[[^]]*?\])|(?:<[^>]*?>)
638    keyEqualsValuesBracesBrackets:
639      name: [a-zA-Z@\*0-9_\/.:\#-]+[a-zA-Z@\*0-9_\/.\h\{\}:\#-]*?
640      follow: (?:(?<!\\)\{)|,|(?:(?<!\\)\[)
641    namedGroupingBracesBrackets:
642      name: [0-9\.a-zA-Z@\*><]+?
643      follow: \h|\R|\{|\[|\$|\)|\(
644    UnNamedGroupingBracesBrackets:
645      follow: \{|\[|,|&|\)|\(|\$
646    arguments:
647      before: (?:#\d\h*;?,?\/?)+|\<.*?\>
648      between: _|\^|\*
649    trailingComments:
650      notPreceededBy: (?<!\\)
651    modifyLineBreaks:
652      doubleBackSlash: \\\\(?:\h*\[\h*\d+\h*[a-zA-Z]+\h*\])?
653      comma: ','
654      betterFullStop: |-
655        (?x)                                # ignore spaces in the below
656        (?:                                 #
657          \.\)                              # .) 
658          (?!\h*[a-z])                      # not *followed by* a-z
659        )                                   #
660        |                                   # OR
661        (?:                                 #
662          (?<!                              # not *preceded by*
663            (?:                             #
664              (?:[eE]\.[gG])                # e.g OR E.g OR e.G OR E.G
665              |                             #
666              (?:[iI]\.[eE])                # i.e OR I.e OR i.E OR I.E
667              |                             #
668              (?:etc)                       # etc
669            )                               #
670          )                                 #
671        )                                   # 
672        \.                                  # .
673        (?!                                 # not *followed by*
674          (?:                               #
675            [a-zA-Z0-9-~,]                  #
676            |                               #
677            \),                             # ),
678            |                               #
679            \)\.                            # ).
680          )                                 #
681        )                                   #

The fields given in Listing 583 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 583:

  1. 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.

  2. 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’

  3. 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 \

  4. 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 <...>

  5. 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 583, 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 160

As a demonstration, consider the file given in Listing 584, together with its default output using the command

latexindent.pl finetuning1.tex

is given in Listing 585.

Listing 584 finetuning1.tex
\mycommand{
    \rule{G -> +H[-G]CL}
    \rule{H -> -G[+H]CL}
    \rule{g -> +h[-g]cL}
    \rule{h -> -g[+h]cL}
}
Listing 585 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 585 that the indentation scheme has not worked as expected. We can fine tune the indentation scheme by employing the settings given in Listing 587 and running the command

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

and the associated (desired) output is given in Listing 586.

Listing 586 finetuning1.tex using Listing 587
\mycommand{
	\rule{G -> +H[-G]CL}
	\rule{H -> -G[+H]CL}
	\rule{g -> +h[-g]cL}
	\rule{h -> -g[+h]cL}
}
Listing 587 finetuning1.yaml
fineTuning:
    arguments:
      between: '_|\^|\*|\->|\-|\+|h|H|g|G'
Example 161

Let’s have another demonstration; consider the file given in Listing 588, together with its default output using the command

latexindent.pl finetuning2.tex

is given in Listing 589.

Listing 588 finetuning2.tex
@misc{ wikilatex,
author = "{Wikipedia contributors}",
title = "LaTeX --- {Wikipedia}{,}",
note = "[Online; accessed 3-March-2020]"
}
Listing 589 finetuning2.tex default
@misc{ wikilatex,
author = "{Wikipedia contributors}",
title = "LaTeX --- {Wikipedia}{,}",
note = "[Online; accessed 3-March-2020]"
}

It’s clear from Listing 589 that the indentation scheme has not worked as expected. We can fine tune the indentation scheme by employing the settings given in Listing 591 and running the command

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

and the associated (desired) output is given in Listing 590.

Listing 590 finetuning2.tex using Listing 591
@misc{ wikilatex,
	author = "{Wikipedia contributors}",
	title = "LaTeX --- {Wikipedia}{,}",
	note = "[Online; accessed 3-March-2020]"
}
Listing 591 finetuning2.yaml
fineTuning:
    NamedGroupingBracesBrackets:
      follow: '\h|\R|\{|\[|\$|\)|\(|"'
    UnNamedGroupingBracesBrackets: 
      follow: '\{|\[|,|&|\)|\(|\$|"'
    arguments:
      between: '_|\^|\*|---'

In particular, note that the settings in Listing 591 specify that NamedGroupingBracesBrackets and UnNamedGroupingBracesBrackets can follow " and that we allow --- between arguments.

Example 162

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 592 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 593.

Listing 592 finetuning3.tex
We go; you see: this sentence \cite{tex:stackexchange} finishes here.
Listing 593 finetuning3.tex using -y switch
We go;
you see:
this sentence \cite{tex:stackexchange} finishes here.
Example 163

We can tweak the fineTuning for how trailing comments are classified. For motivation, let’s consider the code given in Listing 594

Listing 594 finetuning4.tex
some before text
 \href{Handbook%20for%30Spoken%40document.pdf}{my document}
some after text

We will compare the settings given in Listing 595 and Listing 596.

Listing 595 href1.yaml
modifyLineBreaks:
    textWrapOptions:
        columns: -1
        blocksEndBefore:
           verbatim: 0
        blocksFollow:
           verbatim: 0

removeTrailingWhitespace:
    beforeProcessing: 1
Listing 596 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 597 and Listing 598.

Listing 597 finetuning4.tex using Listing 595
some before text \href{Handbooksome after text%20for%30Spoken%40document.pdf}{my document}
Listing 598 finetuning4.tex using Listing 596
some before text \href{Handbook%20for%30Spoken%40document.pdf}{my document} some after text

We note that in:

  • Listing 597 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 598 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 164

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 599 and running the command

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

then we receive the same output given in Listing 598.

Listing 599 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 599, 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 165

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

Starting with the file in Listing 600 and running the command

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

gives the output in Listing 601.

Listing 600 bib1.bib
@online{paulo,
title="arararule,indent.yaml",
author="PauloCereda",
date={2013-05-23},
urldate={2021-03-19},
keywords={contributor},}
Listing 601 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 603 and running the command

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

gives the output in Listing 602.

Listing 602 bib1.bib using Listing 603
@online{paulo,
	title    = "arararule,indent.yaml",
	author   = "PauloCereda",
	date     = {2013-05-23},
	urldate  = {2021-03-19},
	keywords = {contributor},}
Listing 603 bibsettings1.yaml
lookForAlignDelims:
   online: 
      delimiterRegEx: '(=)'

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

Some notes about Listing 603:

  • 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 166

We can build upon Listing 603 for slightly more complicated bibliography files.

Starting with the file in Listing 604 and running the command

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

gives the output in Listing 605.

Listing 604 bib2.bib
@online{cmh:videodemo,
title="Videodemonstrationofpl.latexindentonyoutube",
url="https://www.youtube.com/watch?v=wo38aaH2F4E&spfreload=10",
urldate={2017-02-21},
}
Listing 605 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 605 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 606.

Listing 606 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 607.

Listing 607 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 606 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.

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