Converting regex from ruby to PHP
php, regex, ruby
Solution
The problem lies with your backslashes.
I managed to get it to compile after removing all backslashes.
Then, I replaced all double slashes with 4 of them, and `preg_match_all()` was able to compile the regex too.
const PAIR = '/("[^"\\\\]*(?:\\\\.[^"\\\\]*)*"|[^\s=,][^\s=,\\\\]*(?:\\\\.[^\s=,\\\\]*|=[^,>])*)\s*=>\s*("[^"\\\\]*(?:\\\\.[^"\\\\]*)*"|[^\s=,][^\s=,\\\\]*(?:\\\\.[^\s=,\\\\]*|=[^,>])*)/';
You might have to edit it to get the exact regex you want. You had the compilation error because `\\` was fed to the regex engine as `\`, which escaped the immediate square brackets. To encode a literal backslash, you need to use `\\\\` - once for the string, and once for the regex engine.
string '\\\\' --becomes--> regex \\ --becomes--> literal \
Ruby doesn't have this problem because its regex syntax is separate from its string syntax.
(Related question: preg_match(): Compilation failed: unmatched parentheses.)
Problem
I have been trying to convert a regular expression from ruby to PHP, however I have had little luck. This is the ruby regular expression: ``` QUOTED_LITERAL = /"[^"\\]*(?:\\.[^"\\]*)*"/ UNQUOTED_LITERAL = /[^\s=,][^\s=,\\]*(?:\\.[^\s=,\\]*|=[^,>])*/ LITERAL = /(#{QUOTED_LITERAL}|#{UNQUOTED_LITERAL})/ PAIR = /#{LITERAL}\s*=>\s*#{LITERAL}/ ``` And this is my go in PHP: ``` const PAIR = '/("[^"\\]*(?:\\.[^"\\]*)*"|[^\s=,][^\s=,\\]*(?:\\.[^\s=,\\]*|=[^,>])*)\s*=>\s*("[^"\\]*(?:\\.[^"\\]*)*"|[^\s=,][^\s=,\\]*(?:\\.[^\s=,\\]*|=[^,>])*)/'; ``` However when I run ``` $result = preg_match_all(self::PAIR, $input, $matches); ``` I get the error: `preg_match_all(): Compilation failed: unmatched parentheses at offset 62` However when run it through, http://www.phpliveregex.com/ with the test data: ``` "foo" => "bar", "foo" => bar, foo => "bar" ``` it seems to work fine. Not sure whats going on.