Example of monkey patching to match KiCad EDA pretty print

[FabriceSalvaire]

KiCad EDA indents sexp contextually. Thus, the prettyfier requires a Symbol stack to decide whether to break or not.

from sexpdata import loads, dumps, tosexp, Delimiters, Symbol



ROUND_2_SYMBOLS = ('at',)

@tosexp.register(float)
def _(obj, **kwds):
    if kwds['car_stack'][-1] in ROUND_2_SYMBOLS:
        _ = round(obj, 2)
        return f'{_:.2f}'
    return str(obj)



BREAK_OPENER_SYMBOLS = ('symbol', 'property', 'effects', 'pin', 'name', 'number', 'rectangle', 'stroke', 'fill')
BREAK_CLOSER_SYMBOLS = ('kicad_symbol_lib', 'symbol', 'property', 'pin', 'rectangle')
BREAK_PREFIX_SYMBOLS = ('kicad_symbol_lib',)

def dont_break(car_stack, str_car):
    return (str_car == 'effects' and car_stack[-1] in ('name', 'number'))

@tosexp.register(Delimiters)
def _(self, **kwds):
    expr_separator = ' '
    exprs_indent = ''
    break_prefix_opener = ''
    break_prefix_closer = ''
    suffix_break = ''

    car = self.I[0]
    if isinstance(car, Symbol):
        str_car = str(car)
        kwds.setdefault('car_stack', [])
        if str_car in BREAK_OPENER_SYMBOLS and not dont_break(kwds['car_stack'], str_car):
            exprs_indent = '  '
            break_prefix_opener = '\n' + exprs_indent
        if str_car in BREAK_CLOSER_SYMBOLS:
            break_prefix_closer = '\n' + exprs_indent
        kwds['car_stack'].append(str_car)
        if str_car in BREAK_PREFIX_SYMBOLS:
            suffix_break = '\n'

    exprs = expr_separator.join(tosexp(x, **kwds) for x in self.I)
    indented_exprs = '\n'.join(exprs_indent + line.rstrip() for line in exprs.splitlines(True))
    indented_exprs = indented_exprs[len(exprs_indent):]

    if kwds.get('car_stack', None):
        kwds['car_stack'].pop()

    return (
        break_prefix_opener + self.__class__.opener +
        indented_exprs +
        break_prefix_closer + self.__class__.closer + suffix_break
    )

[jd-boyd]

I'm not entirely clear on what you're suggesting. Are you suggesting that this should feel the documentation? If so I'd love to see you make a patch for that. Otherwise if you're suggesting an addition to the code, could you make it match for that and do a PR for it? Thank you very much. I do like the idea of prettier kicad stuff.

[FabriceSalvaire]

Well, I don't know if we can improve the code for such feature. I tried to write clean code, but it is a hack for KiCad conventions...
Maybe we could first add this as an example in the documentation. And see later if someone can merge this as a generic custom prettifier.