Parsing PHP define statement with a Python regex

Question

I'd like to parse define statements in a PHP file using a Python regex. (Or in other words: I want to use Python to parse a PHP file.)

What I'd like to parse are define statements like this:

define("My_KEY", "My_Value l");
define('My_KEY', 'My_Value');
define(   'My_KEY'  ,    "My_Value"   );

So I came up with the following Python regex:

define\(\s*["']{1}(.[^'"]*)["']{1}\s*,\s*["']{1}(.[^'"]*)["']{1}\s*\)

This works great, as long as there is no use of a " or ' inside the define statement. For example something like this will not work:

define(   'My_KEY'  ,    'My\'_\'Value'   );
define(   'My_KEY'  ,    "My'_'Value"   );

Any ideas how to approach this problem?

Is regex necessary for the whole task? You could use regex to find define(..) then split the string between the parens, and trim it, etc., to get the values you need. — Andy G
– Andy G, Commented May 14, 2016 at 13:10
@AndyG yes I could, but I want to learn more about how to use regex, so that why I came up with the question. — tony994
– tony994, Commented May 14, 2016 at 13:52
@manuel fair enough (from the answers you can see why I suggested taking two stages to do this ;)) — Andy G
– Andy G, Commented May 14, 2016 at 14:09

Pedro Lobito · Accepted Answer · 2016-05-14 13:33:45Z

1

You can use something like:

import re
result = re.findall(r"""^define\(\s*['"]*(.*?)['"]*[\s,]+['"]*(.*?)['"]*\s*\)""", subject, re.IGNORECASE | re.DOTALL | re.MULTILINE)

Regex101 Demo and Explanation

Matches:

MATCH 1
1.  [8-14]  `My_KEY`
2.  [18-28] `My_Value l`
MATCH 2
1.  [40-46] `My_KEY`
2.  [50-58] `My_Value`
MATCH 3
1.  [73-79] `My_KEY`
2.  [88-96] `My_Value`
MATCH 4
1.  [114-120]   `My_KEY`
2.  [129-141]   `My\'_\'Value`
MATCH 5
1.  [159-165]   `My_KEY`
2.  [174-184]   `My'_'Value`

answered May 14, 2016 at 13:33

Pedro Lobito

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2 Comments

tony994 Over a year ago

this looks great. but how does it work? why doesn't it stop when it reaches a " or '?

Pedro Lobito Over a year ago

I don't know, where do you mention or in your question?

Jan · Accepted Answer · 2016-05-14 13:50:05Z

1

Use look arounds with this monster regex:

define\(\s*(["'])(?P<key>.+?(?=\1))\1\s*,
\s*(["'])(?P<value>.+?)(?=\3)(?<!\\)\3

See a demo on regex101.com.

answered May 14, 2016 at 13:50

Jan

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Comments

Ani Menon · Accepted Answer · 2016-05-14 13:50:57Z

0

In python,

str="define(   'My_KEY'  ,    'My\'_\'Value'   )";
import re
re.sub(r"""^define\(\s*['"]*(.*?)['"]*[\s,]+['"]*(.*?)['"]*\s*\)""",r'\2 ; \1', str)

Output :

"My'_'Value ; My_KEY"

edited May 14, 2016 at 13:50

answered May 14, 2016 at 13:20

Ani Menon

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Comments

Ro Yo Mi · Accepted Answer · 2016-05-14 14:34:21Z

Description

This regex will do the following:

match all lines that start with define and have a key and value set inside parentheses
capture the key and value strings, without including the wrapping quotes
all key and value to be wrapped in single or double quotes
correctly handle escaped quotes
avoid difficult edge cases like:
- define( 'file path', "C:\\windows\\temp\\" ); where an escaped slash may exist before a closing quote

The Regex

Note: using the following flags: case-insensitive, global, multiline

^define\(\s*(['"])((?:\\\1|(?:(?!\1).))*)\1\s*,\s*(['"])((?:\\\3|(?:(?!\3).))*)\3\s*\);

Regular expression visualization

Capture groups

capture group 0 gets the entire string
capture group 1 gets the quote type surrounding the key
capture group 2 gets the key string inside the quotes
capture group 3 gets the quote type surrounding the value
capture group 4 gets the value string inside the quotes

Examples

Live Demo

https://regex101.com/r/oP4sV0/1

Sample Text

define("0 My_KEY", "0 My_Value l");
define('1 My_KEY', '1 My_Value');
define(   '2 My_KEY'  ,    "2 My_Value"   );
define(   '3 My_KEY\\'  ,    '3 My\'_\'Value'   );
define(   '4 My_KEY'  ,    "4 My'_'Value\\"   );

Sample Matches

[0][0] = define("0 My_KEY", "0 My_Value l");
[0][1] = "
[0][2] = 0 My_KEY
[0][3] = "
[0][4] = 0 My_Value l

[1][0] = define('1 My_KEY', '1 My_Value');
[1][1] = '
[1][2] = 1 My_KEY
[1][3] = '
[1][4] = 1 My_Value

[2][0] = define(   '2 My_KEY'  ,    "2 My_Value"   );
[2][1] = '
[2][2] = 2 My_KEY
[2][3] = "
[2][4] = 2 My_Value

[3][0] = define(   '3 My_KEY'  ,    '3 My\'_\'Value'   );
[3][1] = '
[3][2] = 3 My_KEY\\
[3][3] = '
[3][4] = 3 My\'_\'Value

[4][0] = define(   '4 My_KEY'  ,    "4 My'_'Value"   );
[4][1] = '
[4][2] = 4 My_KEY
[4][3] = "
[4][4] = 4 My'_'Value\\

Explanation

NODE                     EXPLANATION
----------------------------------------------------------------------
  ^                        the beginning of a "line"
----------------------------------------------------------------------
  define                   'define'
----------------------------------------------------------------------
  \(                       '('
----------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    ['"]                     any character of: ''', '"'
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
  (                        group and capture to \2:
----------------------------------------------------------------------
    (?:                      group, but do not capture (0 or more
                             times (matching the most amount
                             possible)):
----------------------------------------------------------------------
      \\                       '\'
----------------------------------------------------------------------
      \1                       what was matched by capture \1
----------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------
      (?:                      group, but do not capture:
----------------------------------------------------------------------
        (?!                      look ahead to see if there is not:
----------------------------------------------------------------------
          \1                       what was matched by capture \1
----------------------------------------------------------------------
        )                        end of look-ahead
----------------------------------------------------------------------
        .                        any character except \n
----------------------------------------------------------------------
      )                        end of grouping
----------------------------------------------------------------------
    )*                       end of grouping
----------------------------------------------------------------------
  )                        end of \2
----------------------------------------------------------------------
  \1                       what was matched by capture \1
----------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
----------------------------------------------------------------------
  ,                        ','
----------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
----------------------------------------------------------------------
  (                        group and capture to \3:
----------------------------------------------------------------------
    ['"]                     any character of: ''', '"'
----------------------------------------------------------------------
  )                        end of \3
----------------------------------------------------------------------
  (                        group and capture to \4:
----------------------------------------------------------------------
    (?:                      group, but do not capture (0 or more
                             times (matching the most amount
                             possible)):
----------------------------------------------------------------------
      \\                       '\'
----------------------------------------------------------------------
      \3                       what was matched by capture \3
----------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------
      (?:                      group, but do not capture:
----------------------------------------------------------------------
        (?!                      look ahead to see if there is not:
----------------------------------------------------------------------
          \3                       what was matched by capture \3
----------------------------------------------------------------------
        )                        end of look-ahead
----------------------------------------------------------------------
        .                        any character except \n
----------------------------------------------------------------------
      )                        end of grouping
----------------------------------------------------------------------
    )*                       end of grouping
----------------------------------------------------------------------
  )                        end of \4
----------------------------------------------------------------------
  \3                       what was matched by capture \3
----------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
----------------------------------------------------------------------
  \)                       ')'
----------------------------------------------------------------------
  ;                        ';'

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