PyParsing：shell 样式 space 使用反斜杠转义

Question

我需要解析 space 形式的分隔键值对文本

<key>=<value> <key>=<value> ...

这对于 pyparsing 来说非常简单。除非值可以包含 spaces 例如

dog=blue cat="orange tangerine" mouse=a\ small\ grey\ mouse

最后一对的 pyparsing 语法是什么样的 pyparsing 在 spaces 上贪婪.. 看起来像

的跨行文本使它变得更加复杂

dog=blue cat="orange tangerine" mouse=a\ small\ grey\ mouse \
   lion=nonexistent

我在 http://pyparsing.wikispaces.com/share/view/7002417 看了几个例子和 Python/Pyparsing - Multiline quotes 这对多行文本有帮助，但对反斜杠转义没有帮助-space

Answer 1

假设您的输入字符串位于名为 "input.py" 的文件中，以下适用于您的示例：

import pyparsing
from pyparsing import ZeroOrMore, Group


OP_EQ   = pyparsing.Literal('=').suppress()
DQUOTE  = pyparsing.Literal('"').suppress()
ESPACE  = pyparsing.Literal('\ ').suppress().leaveWhitespace()
BSLASH  = pyparsing.Literal('\')

S       = pyparsing.Word(" \t\r\n").suppress().leaveWhitespace()

DELIM   = ZeroOrMore(S ^ BSLASH).suppress()

KEY     = pyparsing.Word(pyparsing.alphanums)("KEY")

VALTOK  = pyparsing.Word(pyparsing.printables, excludeChars='="\')

QVALUE  = ( DQUOTE +
            Group(VALTOK + ZeroOrMore(S + VALTOK)) +
            DQUOTE
            )
NQVALUE = Group(VALTOK + ZeroOrMore(ESPACE + VALTOK))
VALUE   = (NQVALUE ^ QVALUE)("VALUE")

PAIR    = Group(KEY + OP_EQ + VALUE)("PAIR")

PAIRS   = (PAIR + ZeroOrMore(DELIM + PAIR))

with open('input.txt') as f:
    lines = f.read()

res = PAIRS.parseString(lines, parseAll=True)

for (k,v) in res:
    print('{} = "{}"'.format(k, ' '.join(v)))

输出：

dog = "blue"
cat = "orange tangerine"
mouse = "a small grey mouse"
dog = "blue"
cat = "orange tangerine"
mouse = "a small grey mouse"
lion = "nonexistent"

和XML一样，供参考：

<PAIRS>
  <PAIR>
    <KEY>dog</KEY>
    <VALUE>
      <ITEM>blue</ITEM>
    </VALUE>
  </PAIR>
  <PAIR>
    <KEY>cat</KEY>
    <VALUE>
      <ITEM>orange</ITEM>
      <ITEM>tangerine</ITEM>
    </VALUE>
  </PAIR>
  <PAIR>
    <KEY>mouse</KEY>
    <VALUE>
      <ITEM>a</ITEM>
      <ITEM>small</ITEM>
      <ITEM>grey</ITEM>
      <ITEM>mouse</ITEM>
    </VALUE>
  </PAIR>
  <PAIR>
    <KEY>dog</KEY>
    <VALUE>
      <ITEM>blue</ITEM>
    </VALUE>
  </PAIR>
  <PAIR>
    <KEY>cat</KEY>
    <VALUE>
      <ITEM>orange</ITEM>
      <ITEM>tangerine</ITEM>
    </VALUE>
  </PAIR>
  <PAIR>
    <KEY>mouse</KEY>
    <VALUE>
      <ITEM>a</ITEM>
      <ITEM>small</ITEM>
      <ITEM>grey</ITEM>
      <ITEM>mouse</ITEM>
    </VALUE>
  </PAIR>
  <PAIR>
    <KEY>lion</KEY>
    <VALUE>
      <ITEM>nonexistent</ITEM>
    </VALUE>
  </PAIR>
</PAIRS>

编辑：FWIW，你可以在正则表达式中这样做：

import re

with open('input.txt') as f:
    lines = f.read()

mat = re.sub(r'=([^"]\w*(?:(?:\ )\w*)*)', r'=""', lines)  # Quote unquoted values
mat = mat.replace("\ "," ").replace("\\n","")              # Replace escaped spaces
mat = re.findall(r'(\w*)="(.*?)"', mat)                      # Extract pairs
for (k,v) in mat:                                            # Print pairs
    print('{} = "{}"'.format(k, v))

输出：

dog = "blue"
cat = "orange tangerine"
mouse = "a small grey mouse"
dog = "blue"
cat = "orange tangerine"
mouse = "a small grey mouse"
lion = "nonexistent"

PyParsing：shell 样式 space 使用反斜杠转义

PyParsing: shell style space escape using backslash

python

escaping

backslash

pyparsing