Does anybody understand why this doesn't compile?

Question

I'm attempting to parse an svg path W3C SVG Paths, with this pattern. EDIT: Ok I've changed my pattern and have a sample with a new problem. See I got some things to work with a new pattern. I'm now working on the line_to regex, and the svg specification demands that values be able to support one point like: L100,200 to many points like: L100,200 100,400 0,100 I can't seem to get it to work. I'm parsing inkscape_path2 and recive output like this.

We're only looking at the first tuple of output:

This is what I'm getting:

('L 6,82 ','L ','6','82')

This is what I'm trying to get:

('L 6,82 6,14 6,12 ','L ','6','82','6','14','6','12')

Actual Code:

from PyQt4.QtGui import QPainterPath
import string,re

inkscape_path1 = "M 12,6 C 8.676,6 6,8.676 6,12 l 0,2 0,68 0,2 c 0,0.334721 0.04135,0.6507 0.09375,0.96875 0.0487,0.295596 0.09704,0.596915 0.1875,0.875 0.00988,0.03038 0.020892,0.0636 0.03125,0.09375 0.098865,0.287771 0.2348802,0.547452 0.375,0.8125 0.1445918,0.273507 0.3156161,0.535615 0.5,0.78125 0.1843839,0.245635 0.3737765,0.473472 0.59375,0.6875 0.439947,0.428056 0.94291,0.814526 1.5,1.09375 0.278545,0.139612 0.5734731,0.246947 0.875,0.34375 -0.2562018,-0.100222 -0.4867109,-0.236272 -0.71875,-0.375 -0.00741,-0.0044 -0.023866,0.0045 -0.03125,0 -0.031933,-0.0193 -0.062293,-0.04251 -0.09375,-0.0625 -0.120395,-0.0767 -0.2310226,-0.163513 -0.34375,-0.25 -0.1061728,-0.0808 -0.2132809,-0.161112 -0.3125,-0.25 C 8.4783201,88.557317 8.3087904,88.373362 8.15625,88.1875 8.0486711,88.057245 7.9378561,87.922215 7.84375,87.78125 7.818661,87.74287 7.805304,87.69538 7.78125,87.65625 7.716487,87.553218 7.6510225,87.451733 7.59375,87.34375 7.4927417,87.149044 7.3880752,86.928049 7.3125,86.71875 7.30454,86.69694 7.288911,86.6782 7.28125,86.65625 7.2494249,86.5643 7.2454455,86.469419 7.21875,86.375 7.1884177,86.268382 7.1483606,86.171969 7.125,86.0625 7.0521214,85.720988 7,85.364295 7,85 L 7,83 7,15 7,13 C 7,10.218152 9.2181517,8 12,8 l 2,0 68,0 2,0 c 2.781848,0 5,2.218152 5,5 l 0,2 0,68 0,2 c 0,0.364295 -0.05212,0.720988 -0.125,1.0625 -0.04415,0.206893 -0.08838,0.397658 -0.15625,0.59375 -0.0077,0.02195 -0.0233,0.04069 -0.03125,0.0625 -0.06274,0.173739 -0.138383,0.367449 -0.21875,0.53125 -0.04158,0.0828 -0.07904,0.169954 -0.125,0.25 -0.0546,0.09721 -0.126774,0.18835 -0.1875,0.28125 -0.09411,0.140965 -0.204921,0.275995 -0.3125,0.40625 -0.143174,0.17445 -0.303141,0.346998 -0.46875,0.5 -0.01117,0.0102 -0.01998,0.02115 -0.03125,0.03125 -0.138386,0.125556 -0.285091,0.234436 -0.4375,0.34375 -0.102571,0.07315 -0.204318,0.153364 -0.3125,0.21875 -0.0074,0.0045 -0.02384,-0.0044 -0.03125,0 -0.232039,0.138728 -0.462548,0.274778 -0.71875,0.375 0.301527,-0.0968 0.596455,-0.204138 0.875,-0.34375 0.55709,-0.279224 1.060053,-0.665694 1.5,-1.09375 0.219973,-0.214028 0.409366,-0.441865 0.59375,-0.6875 0.184384,-0.245635 0.355408,-0.507743 0.5,-0.78125 0.14012,-0.265048 0.276135,-0.524729 0.375,-0.8125 0.01041,-0.03078 0.02133,-0.06274 0.03125,-0.09375 0.09046,-0.278085 0.1388,-0.579404 0.1875,-0.875 C 89.95865,84.6507 90,84.334721 90,84 l 0,-2 0,-68 0,-2 C 90,8.676 87.324,6 84,6 L 12,6 z"

inkscape_path2 = "M 12,90 C 8.676,90 6,87.324 6,84 L 6,82 6,14 6,12 c 0,-0.334721 0.04135,-0.6507 0.09375,-0.96875 0.0487,-0.295596 0.09704,-0.596915 0.1875,-0.875 C 6.29113,10.12587 6.302142,10.09265 6.3125,10.0625 6.411365,9.774729 6.5473802,9.515048 6.6875,9.25 6.8320918,8.976493 7.0031161,8.714385 7.1875,8.46875 7.3718839,8.223115 7.5612765,7.995278 7.78125,7.78125 8.221197,7.353194 8.72416,6.966724 9.28125,6.6875 9.559795,6.547888 9.8547231,6.440553 10.15625,6.34375 9.9000482,6.443972 9.6695391,6.580022 9.4375,6.71875 c -0.00741,0.0044 -0.023866,-0.0045 -0.03125,0 -0.031933,0.0193 -0.062293,0.04251 -0.09375,0.0625 -0.120395,0.0767 -0.2310226,0.163513 -0.34375,0.25 -0.1061728,0.0808 -0.2132809,0.161112 -0.3125,0.25 C 8.4783201,7.442683 8.3087904,7.626638 8.15625,7.8125 8.0486711,7.942755 7.9378561,8.077785 7.84375,8.21875 7.818661,8.25713 7.805304,8.30462 7.78125,8.34375 7.716487,8.446782 7.6510225,8.548267 7.59375,8.65625 7.4927417,8.850956 7.3880752,9.071951 7.3125,9.28125 7.30454,9.30306 7.288911,9.3218 7.28125,9.34375 7.2494249,9.4357 7.2454455,9.530581 7.21875,9.625 7.1884177,9.731618 7.1483606,9.828031 7.125,9.9375 7.0521214,10.279012 7,10.635705 7,11 l 0,2 0,68 0,2 c 0,2.781848 2.2181517,5 5,5 l 2,0 68,0 2,0 c 2.781848,0 5,-2.218152 5,-5 l 0,-2 0,-68 0,-2 C 89,10.635705 88.94788,10.279012 88.875,9.9375 88.83085,9.730607 88.78662,9.539842 88.71875,9.34375 88.71105,9.3218 88.69545,9.30306 88.6875,9.28125 88.62476,9.107511 88.549117,8.913801 88.46875,8.75 88.42717,8.6672 88.38971,8.580046 88.34375,8.5 88.28915,8.40279 88.216976,8.31165 88.15625,8.21875 88.06214,8.077785 87.951329,7.942755 87.84375,7.8125 87.700576,7.63805 87.540609,7.465502 87.375,7.3125 87.36383,7.3023 87.35502,7.29135 87.34375,7.28125 87.205364,7.155694 87.058659,7.046814 86.90625,6.9375 86.803679,6.86435 86.701932,6.784136 86.59375,6.71875 c -0.0074,-0.0045 -0.02384,0.0044 -0.03125,0 -0.232039,-0.138728 -0.462548,-0.274778 -0.71875,-0.375 0.301527,0.0968 0.596455,0.204138 0.875,0.34375 0.55709,0.279224 1.060053,0.665694 1.5,1.09375 0.219973,0.214028 0.409366,0.441865 0.59375,0.6875 0.184384,0.245635 0.355408,0.507743 0.5,0.78125 0.14012,0.265048 0.276135,0.524729 0.375,0.8125 0.01041,0.03078 0.02133,0.06274 0.03125,0.09375 0.09046,0.278085 0.1388,0.579404 0.1875,0.875 C 89.95865,11.3493 90,11.665279 90,12 l 0,2 0,68 0,2 c 0,3.324 -2.676,6 -6,6 l -72,0 z"
w3c_path1 = "M100,200 C100,100 250,100 250,200 S400,300 400,200"
w3c_path2 = '''
           M600,350 l 50,-25 \n
           a25,25 -30 0,1 50,-25 l 50,-25 \n
           a25,50 -30 0,1 50,-25 l 50,-25 \n
           a25,75 -30 0,1 50,-25 l 50,-25 \n
           a25,100 -30 0,1 50,-25 l 50,-25 \n
           '''

  if __name__ == '__main__':
    data = inkscape_path2
    assert re.match('M', data)
    integer = r'-\d+|\d+' # A negative or positive set of digits of unknown length
    float = r'-\d+\.\d+|\d+\.\d+' # The same as above but looks for a decimal
    number = r'({}|{})'.format(integer, float) 
    point = r'{},{}'.format(number, number)
    move_to = r'([Mm]\s*){}'.format(point)
    line_to = r'(([Ll]\s*){}+\s)'.format(point)
    curve_to = r'(([Cc]\s*){}\s{}\s{})'.format(point, point, point)
    t = re.findall(line_to, data)
    for token in t: # we're only testing line_to right now move_to some what works.
        print(token)
    print(data)
    print(line_to)

Answer 1

You haven't provided any code, actual error messages, sample input, or anything else. So I'm just going to guess:

I don't believe you can use the ?P<label> syntax outside of a match group. So when you have this:

?P<point>(\d[(,)|\s]\d)

You actually need these:

(?P<point>(\d[(,)|\s]\d))

Notice the extra parentheses enclosing the entire expression. Taking just this example:

>>> re.compile('''?P<point>(\d[(,)|\s]\d)''')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python2.7/re.py", line 190, in compile
    return _compile(pattern, flags)
  File "/usr/lib64/python2.7/re.py", line 244, in _compile
    raise error, v # invalid expression
sre_constants.error: nothing to repeat

Vs:

>>> re.compile('''(?P<point>(\d[(,)|\s]\d))''')
<_sre.SRE_Pattern object at 0x7f8b14a3fa80>