Python取消注释正确的行

Question

我有一个文件，内容如下：

line 1: _____
   ...
# for AAA
#export CONFIG = AAA_defconfig

# for BBB, BbB, Bbb, BBb3
#export CONFIG = BBB_defconfig

# for CCC, CcC, Ccc, Ccc1
#export CONFIG = CCC_defconfig
   ...
other lines

我想对这个文件进行处理，根据给定的字符串，导出正确的“CONFIG”，并把其他的注释掉。比如，如果我得到了“CcC”，那么文件会被处理成：

line 1: _____
    ...
# for AAA
#export CONFIG = AAA_defconfig

# for BBB, BbB, Bbb, BBb3
#export CONFIG = BBB_defconfig

# for CCC, CcC, Ccc, Ccc1
export CONFIG = CCC_defconfig
    ...
other lines

在Python中有什么好的方法来做到这一点吗？

提前谢谢大家！！

Answer 1

首先，创建一个生成器函数：

import re
def uncomment(seq, prev_pattern, curr_pattern):
    """Remove comment from any string in seq matching curr_pattern if the previous line matches prev_pattern"""
    prev = ""
    for curr in seq:
        if re.match(curr_pattern, curr) and re.match(prev_pattern, prev):
            yield curr[1:]
    else:
       yield curr
    prev = curr

现在来测试一下这个函数：

>>> lines = ["leave this alone", "#fix next line", "#fix this line", "leave this alone"]
>>> print "\n".join(uncomment(lines, "^#fix next", "^#fix this"))
leave this alone
#fix next line
fix this line
leave this alone

接下来，用这个函数来修复你的文件：

with open(input_filename, 'r') as f_in:
    with open(output_filename, 'w') as f_out:
        for line in uncomment(f_in, "^#for AAA", "^#export CONFIG"):
            f_out.write(line)

Answer 2

我觉得这样写会更干净、更容易读懂。

（对了，要修改文件中的一行，你必须把整个文件都覆盖重写一遍。）

#!/usr/bin/env python2.7
import re

def find_and_modify(config_file, given_string):

    with open(config_file) as f:
        lines = f.readlines()

    given_string_re = re.compile(r'# for .*{}'.format(given_string))

    # line #'s that start with either "export" or "#export"
    export_line_numbers = []
    # the line # containing the given_string we're searching for
    uncomment_line_number = None

    for i,line in enumerate(lines):
        if re.match(r'#?export', line):
            export_line_numbers.append(i)
            prev_line = lines[i-1]
            if given_string_re.match(prev_line):
                uncomment_line_number = i

    for i in export_line_numbers:
        if i == uncomment_line_number:
            lines[i] = re.sub(r'^#*', '', lines[i])
        else:
            lines[i] = re.sub(r'^#*', '#', lines[i])

    with open(config_file, 'w') as f:
        f.writelines(lines)

find_and_modify('some_file', 'AAA')
find_and_modify('some_file', 'CcC')

Answer 3

那么为什么不这样做呢

line = 'xxxx'
CONFIG = default_deconfig

if line == 'AAA':
    CONFIG =  AAA_defconfig
elif line == 'CCC':
    CONFIG =  CCC_defconfig
...

除非这不是一个Python文件，而且你想对它进行一些操作。看起来是这样的。

在这种情况下，可以创建一个配置生成器，它会根据行变量生成一个配置文件。

[编辑：根据评论]

你可能需要做一些调整，但这个方法应该可以用。

# Simple , crude solution

f = open('file1', 'r')
manipulated_lines = []
readFirstLine = False
config = ''
configComma = ''
uncommentLine = 0
for line in f:
    tokens = line.split()

    if uncommentLine == 1:
        # this is comment line
        if tokens[0] == '#export':
            manipulated_lines.append(line[1:])
            uncommentLine = uncommentLine + 1
            continue
    elif uncommentLine > 1:
        manipulated_lines.append(line)
        continue

    if not readFirstLine: 
        config = line.rstrip('\n')
        configComma = config + ','
        readFirstLine = True

    # Process additional lines 
    manipulated_lines.append(line)

    if len(tokens) > 0 and tokens[0] == '#':
        if tokens[1] == 'for':
            if config in tokens or configComma in tokens:
                uncommentLine = uncommentLine + 1
                continue

print manipulated_lines
f.close()
fw = open('file2', 'w')
fw.writelines(manipulated_lines)
fw.close()

输入：file1

CCC
# for AAA
#export CONFIG = AAA_defconfig

# for BBB, BbB, Bbb, BBb3
#export CONFIG = BBB_defconfig

# for CCC, CcC, Ccc, Ccc1
#export CONFIG = CCC_defconfig
   ...

输出：file2

CCC
# for AAA
#export CONFIG = AAA_defconfig

# for BBB, BbB, Bbb, BBb3
#export CONFIG = BBB_defconfig

# for CCC, CcC, Ccc, Ccc1
export CONFIG = CCC_defconfig
   ...