Could latexindent.pl provide appropriate spaces and text wraps before or after math operators? (sounds like many formatters doing for Python or C language)

[Saltsmart]

Please provide the following when posting an issue:

original .tex code

$a=1$  % one space before and one space after general binary operators
\((a ,b)=(1 ,2)\)  % one space between the comma and the following variable
\[( a+b ) * c = d\]  % no space between parentheses and variables
\[a + b\times  c = d\]  % \times is also an operator 
% Suppose if I want to have line break after = operator
\begin{equation}
a^2+b^2=c^2
\end{equation}

yaml settings

I have searched the documentation on CTAN, but found no yaml setting that could be used for this aim.

actual/given output

Just the same as original .tex code. Nothing changes.

desired or expected output

$a = 1$  % one space before and one space after general binary operators
\((a, b) = (1, 2)\)  % one space between the comma and the following variable
\[(a + b) * c = d\]  % no space between parentheses and variables
\[a + b \times c = d\]  % \times is also an operator 
% Suppose if I want to have line break after = operator
\begin{equation}
    a ^ 2 + b ^ 2 =
    c ^ 2
\end{equation}

anything else

If you are familiar with Python, here is a nice discussion for whitespaces in PEP 8: Does PEP 8 require whitespace around operators?

The BLACK formatting style is also strongly recommended for your reference: Line breaks & binary operators

[cmhughes]

Thanks for this, it's interesting.

Starting with

% \( ... \)
\((a ,b)=(1 ,2)\)  % one space between the comma and the following variable
\(( a+b ) * c = d(a ,b)\)  % no space between parentheses and variables
% $ ... $
$( a+b ) * c = d(a ,b)$    % no space between parentheses and variables
$a=1$  % one space before and one space after general binary operators
% \[ ... \]
\[( a+b ) * c = d\]  % no space between parentheses and variables
\[a + b\times  c = d\]  % \times is also an operator 
\[( a+b ) * c = d(a ,b)\]  % no space between parentheses and variables
% Suppose if I want to have line break after = operator
\begin{equation}
a^2+b^2=c^2
\end{equation}

and using the following, say issue-524.yaml

replacements:
  - 
    substitution: |-
      s@(
         (?:
          \\\(                     # \(
          .*?
          \\\)                     # \)
         )
         |
         (?:
           (?<!\$)(?<!\\)\$(?!\$)  # $
           [^\$]*?
           (?<!\\)\$(?!\$)         # $
          )
         |
         (?:
          \\\[                     # \[
          .*?
          \\\]                     # \]
         )
         |
         (?:
          \\begin\{                # \begin{equation|align|fleqn, etc}
            (
            equation|align|fleqn   # populate as necessary
            )
            \}
          .*?
          \\end\{\2\}              # \end{equation|align|fleqn, etc}
         )
        )
        @
      # store the middle
      my $middle = $1;
      # store the beginning
      $middle =~s/^(\\\(|\$|\\\[|\\begin\{[^}]+?\})//s;
      my $begin =  $1;
      # store the end
      $middle =~s/(\\\)|\$|\\\]|\\end\{[^}]+?\})$//s;
      my $end    = $1;
      #
      # perform the operations
      #
      # comma space unification
      $middle =~ s|([a-zA-Z0-9])\h*,\h*([a-zA-Z0-9])|$1, $2|sg;
      # <(> <space> <variable> into <(><variable>
      $middle =~ s|\(\h*([a-zA-Z0-9])|($1|sg;
      # <variable> <space> <)> into <variable><)>
      $middle =~ s|([a-zA-Z0-9])\h*\)|$1)|sg;
      # <variable-1>=<variable-2> into <variable-1> = <variable-2>
      $middle =~ s/([a-zA-Z0-9])\h*(=|\*|\+|\-)\h*([a-zA-Z0-9])/$1 $2 $3/sg;
      $middle =~ s/([a-zA-Z0-9])\h*(\\times)\h*([a-zA-Z0-9])/$1 $2 $3/sg;
      $begin.$middle.$end;@sgxe

and calling

latexindent.pl -r -l issue-524.yaml myfile.tex

gives

% \( ... \)
\((a, b)=(1, 2)\)  % one space between the comma and the following variable
\((a + b) * c = d(a, b)\)  % no space between parentheses and variables
% $ ... $
$(a + b) * c = d(a, b)$    % no space between parentheses and variables
$a = 1$  % one space before and one space after general binary operators
% \[ ... \]
\[(a + b) * c = d\]  % no space between parentheses and variables
\[a + b \times c = d\]  % \times is also an operator 
\[(a + b) * c = d(a, b)\]  % no space between parentheses and variables
% Suppose if I want to have line break after = operator
\begin{equation}
    a^2 + b^2 = c^2
\end{equation}

I hope this helps.

[cmhughes]

Let me know if you need anything else on this.

[PiotrSokol]

@cmhughes Any way to make this work with trailing comments?

Currently, with issue-524.yaml and input

\begin{equation}
 x=2 % a^2+b^2=c^2
a^2+b^2=c^2
x=2 % a^2+b^2=c^2
\end{equation}

one gets

\begin{equation}
  x = 2 %latexindenttrailingcomment6 - END
  a^2 + b^2 = c^2
  x = 2 %latexindenttrailingcomment7 - END
\end{equation}