Python 查找并替换文件中的字符串，参数是字符串被引用而不是更大字符串的一部分 [英] Python find and replace strings in files with argument that the string is quoted and not part of bigger string

问题描述

我需要解决以下问题.如果在文件中找到动态字符串，我想替换动态字符串，但前提是字符串周围有引号，无论是在它旁边还是中间最多有两个空格，并且不是更大字符串的一部分(在 python 中):

i need a solution to the following problem. I want to replace a dynamic string if found in a file but only if there are quotes surrounding the string, either next to it or with max two spaces between, and not be part of bigger string (in python) :

ori = 'testing'
rep = 'posting'

file contents:

Line1 This is one line with some words for testing purposes
Line2 this is the seconds "testing" function.
Line3 that is one more " testing" line
Line4 "testing"
Line5 "  testing"
Line6 "testing  "
Line7 "  testing  "

我正在寻找以下结果，最好使用正则表达式作为简单有效的方法，而不是单独的函数.

Im looking for the following result preferably with regex as simple and efficient way instead of a separate function.

Line1 This is one line with some words for testing purposes
Line2 this is the seconds "testing" function.
Line3 that is one more " testing" line
Line4 "posting"
Line5 "  posting"
Line6 "posting  "
Line7 "  posting  "

正则表达式魔术师可能会在这方面帮助我.

regex magicians may help me at this one.

提前致谢.

推荐答案

正则表达式将是完成此类任务的好工具.
始终注意清楚地表达它们.
正则表达式很快就会变得令人费解并且难以调试.

A regular expression would be a good tool for such a task.
Always take care to express them clearly.
Regular expressions can quickly become puzzling and hard to debug.

import re

original = 'testing'
replacement = 'posting'

line1 = 'This is one line with some words for testing purposes'
line2 = 'this is the seconds "testing" function.'
line3 = 'that is one more " testing" line'
line4 = '"testing"'
line5 = '"  testing"'
line6 = '"testing  "'
line7 = '"  testing  "'

lines = [line1, line2, line3, line4, line5, line6, line7]

starts_with_parentheses = '^"'
ends_with_parentheses = '"$'
one_space = ' {1}'
two_spaces = ' {2}'
none_one_or_two_spaces = '(|{}|{})'.format(one_space, two_spaces)

query = starts_with_parentheses \
        + none_one_or_two_spaces \
        + original \
        + none_one_or_two_spaces \
        + ends_with_parentheses

for line in lines:
    match = re.search(query, line)
    if match:
        line = line.replace(original, replacement)

    print(line)

输出:

This is one line with some words for testing purposes
this is the seconds "testing" function.
that is one more " testing" line
"posting"
"  posting"
"posting  "
"  posting  "

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