如何在pyparsing中为此编写语法:匹配一组单词但不包含给定模式

Question

我是Python和pyparsing的新手.我需要完成以下任务.

我的示例文本行是这样的:

12 items - Ironing Service    11 Mar 2009 to 10 Apr 2009
Washing service (3 Shirt)  23 Mar 2009

我需要提取项目描述,期间

tok_date_in_ddmmmyyyy = Combine(Word(nums,min=1,max=2)+ " " + Word(alphas, exact=3) + " " + Word(nums,exact=4))
tok_period = Combine((tok_date_in_ddmmmyyyy + " to " + tok_date_in_ddmmmyyyy)|tok_date_in_ddmmmyyyy)

tok_desc =  Word(alphanums+"-()") but stop before tok_period

这该怎么做？

Answer 1

我建议将SkipTo视为最合适的pyparsing类,因为你对不需要的文本有一个很好的定义,但在此之前会接受很多东西.以下是使用SkipTo的几种方法:

text = """\
12 items - Ironing Service    11 Mar 2009 to 10 Apr 2009
Washing service (3 Shirt)  23 Mar 2009"""

# using tok_period as defined in the OP

# parse each line separately
for tx in text.splitlines():
    print SkipTo(tok_period).parseString(tx)[0]

# or have pyparsing search through the whole input string using searchString
for [[td,_]] in SkipTo(tok_period,include=True).searchString(text):
    print td

两个for循环都打印以下内容:

12 items - Ironing Service    
Washing service (3 Shirt)