Re: Formatter for Bison Input Files

[Simon Richter]

Hi,

On 9/29/23 15:37, Julian Hapke wrote:

> having gotten used to using clang-format in C and C++ as well as black 
> in Python, I would like to try and write a file formatter for a 
> different language.

There will be a lot of personal preferences involved in this, plus you 
will need to contend with "inside {} is a different language which has 
its own formatting rules."

My preferred style these days is

    rule:
        "keyword" IDENTIFIER '{' members '}'
            {
                multi();
                line();
                action();
            }
    |   "keyword" IDENTIFIER ';'
            { short_action(); }

because it gives minimal diffs for adding alternatives and for adding 
actions after the grammar accepts the example set of inputs, and it also 
allows code coverage analysis to give sensible results with tools that 
report on a line-by-line basis.

I am fairly sure that there will be a plethora of different styles out 
there, all with their own rationale, and there are a few degrees of 
freedom inside the Bison syntax that a good formatter will need to 
either replicate or make consistent, such as whether rules need to have 
a trailing semicolon.

I don't know of any existing tool, but I haven't looked too hard either.

   Simon