到目前为止，我已尝试使用“setParseAction”来获取匹配标记的位置，但它有时无法像我预期的那样工作。以此代码为例:
>>> from pyparsing import *
>>>
>>> Z = Literal('0')
>>> POINT = Literal('.')
>>> BIN_DIGITS = Word('01')
>>> OCT_DIGITS = Word('01234567')
>>> DEC_DIGITS = Word('0123456789')
>>> HEX_DIGITS = Word('0123456789abcdefABCDEF')
>>> DEC_INT = DEC_DIGITS.setParseAction(lambda t: int(t[0]))
>>> BIN_INT = Combine(Z + ((Literal('b') | 'B')) + BIN_DIGITS).\
... setParseAction(lambda t: int(t[0], 2))
>>> OCT_INT = Combine(Z + ((Literal('o') | 'O')) + OCT_DIGITS).\
... setParseAction(lambda t: int(t[0], 8))
>>> HEX_INT = Combine(Z + ((Literal('x') | 'X')) + HEX_DIGITS).\
... setParseAction(lambda t: int(t[0], 16))
>>> INTEGER = HEX_INT | OCT_INT | BIN_INT | DEC_INT
>>> EXP = Combine(CaselessLiteral('E') + Optional(Literal('+') | '-') + DEC_INT)
>>> POINT_FLOAT = Combine(Optional(DEC_INT) + POINT + DEC_INT) | \
... Combine(DEC_INT + POINT)
>>> EXP_FLOAT = Combine(DEC_INT + EXP) | Combine(POINT_FLOAT + EXP)
>>> FLOAT = (EXP_FLOAT | POINT_FLOAT).setParseAction(lambda t: float(t[0]))
>>>
>>>
>>> def p(s, l, t):
... print 'Location of %s: %s' % (t[0], l,)
...
>>>
>>> NUMBER = (FLOAT | INTEGER).setParseAction(p)
>>> NUMBER.parseString(' 12345')
Location of 12345: 0
([12345], {})
>>> NUMBER.parseString(' 12345')
Location of 12345: 0
([12345], {})
>>> NUMBER.parseString('12345')
Location of 12345: 0
([12345], {})
无论我将数字“12345”放在字符串中的什么位置，位置始终为 0。但是，如果我尝试:
>>> LITERAL = Literal('someword').setParseAction(p)
>>> LITERAL.parseString(' someword')
Location of someword: 4
(['someword'], {})
>>> LITERAL.parseString(' someword')
Location of someword: 1
(['someword'], {})
>>> LITERAL.parseString('someword')
Location of someword: 0
(['someword'], {})
它按预期工作。我在第一个示例中做错了什么？
请您参考如下方法:
好的，多亏了 Paul 的提示，我通过将“Or”表达式与压缩的空白表达式相结合，并使用它来解析字符串，设法解决了这个问题。这是最终结果:
>>> from pyparsing import *
>>>
>>> def p(s,l,t):
... print 'Location of %s: %s' % (s, l,)
...
>>> Z = Literal('0')
>>> POINT = Literal('.')
>>> BIN_DIGITS = Word('01')
>>> OCT_DIGITS = Word('01234567')
>>> DEC_DIGITS = Word('0123456789')
>>> HEX_DIGITS = Word('0123456789abcdefABCDEF')
>>> DEC_INT = DEC_DIGITS.copy().setParseAction(lambda t: int(t[0]))
>>> BIN_INT = Combine(Z + ((Literal('b') | 'B')) + BIN_DIGITS).\
... setParseAction(lambda t: int(t[0], 2))
>>> OCT_INT = Combine(Z + ((Literal('o') | 'O')) + OCT_DIGITS).\
... setParseAction(lambda t: int(t[0], 8))
>>> HEX_INT = Combine(Z + ((Literal('x') | 'X')) + HEX_DIGITS).\
... setParseAction(lambda t: int(t[0], 16))
>>> INTEGER = HEX_INT | OCT_INT | BIN_INT | DEC_INT
>>> EXP = Combine(CaselessLiteral('E') + Optional(Literal('+') | Literal('-')) + DEC_DIGITS)
>>> POINT_FLOAT = Combine(Optional(DEC_DIGITS) + POINT + DEC_DIGITS) | \
... Combine(DEC_DIGITS + POINT)
>>> EXP_FLOAT = Combine(DEC_DIGITS + EXP) | Combine(POINT_FLOAT + EXP)
>>> FLOAT = (EXP_FLOAT | POINT_FLOAT).setParseAction(lambda t: float(t[0]))
>>> NUMBER = (FLOAT | INTEGER).setParseAction(p)
>>> NUMBER2 = Combine(ZeroOrMore(White(exact=1)).suppress() + NUMBER)
>>>
>>> NUMBER2.parseString(' 12345')
Location of 12345: 4
(['12345'], {})
