正则表达式用一种模式替换递归

Question

$array[key][key]...[key] replace to $array['key']['key']...['key']

I managed only to add quotes to the first keyword of the array.

\\$([a-zA-Z0-9]+)\\[([a-zA-Z_-]+[0-9]*)\\] replace to \\$\\1\\[\\'\\2\\3\\'\\]

Answer 1

You may use a regex that does not perform a recursive , but consecutive matching:

$re = '/(\$\w+|(?!^)\G)\[([^]]*)\]/'; 
$str = "\$array[key][key][key]";
$subst = "$1['$2']"; 
$result = preg_replace($re, $subst, $str);
echo $result;

See IDEONE demo

The regex (\\$\\w+|(?!^)\\G)\\[([^]]*)\\] matches all square parenthetical substrings (capturing their contents into Group 2) (with \\[([^]]*)\\] ) that either are right after a '$'+alphanumerics substring (due to the \\$\\w+ part) or that follow one another consecutively (thanks to (?!^)\\G ).

Answer 2

Shouldn't need anything fancy, just get the stuff you need then
replace in a callback.

Untested:

$new_input = preg_replace_callback('/(?i)\$[a-z]+\K(?:\[[^\[\]]*\])+/',
        function( $matches ){
             return preg_replace( '/(\[)|(\])/', "$1'$2", $matches[0]);
        },
        $input );