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"""
Parser for various kinds of CSS values as per CSS2 spec section 4.3
"""
from pyparsing import Word, Combine, Optional, Literal, oneOf, CaselessLiteral, StringEnd, OneOrMore
def asInt(s,l,t):
return int(t[0])
def asFloat(s,l,t):
return float(t[0])
def asFloatOrInt(s,l,t):
""" Return an int if possible, otherwise a float"""
v = t[0]
try:
return int(v)
except ValueError:
return float(v)
integer = Word("0123456789").setParseAction(asInt)
number = Combine(
Optional(Word("0123456789")) + Literal(".") + Word("01234567890")
| integer
)
number.setName('number')
sign = oneOf("+ -")
signedNumber = Combine(Optional(sign) + number).setParseAction(asFloat)
lengthValue = Combine(Optional(sign) + number).setParseAction(asFloatOrInt)
lengthValue.setName('lengthValue')
lengthUnit = oneOf(['em', 'ex', 'px', 'pt', 'in', 'cm', 'mm', 'pc', '%'], caseless=True)
#the spec says that the unit is only optional for a 0 length, but
#there are just too many places where a default is permitted.
#TODO: Maybe should use a ctor like optional to let clients declare it?
length = lengthValue + Optional(lengthUnit, default=None) + StringEnd()
length.leaveWhitespace()
#set the parse action aftward so it doesn't "infect" the parsers that build on it
number.setParseAction(asFloat)
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