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