返回字符串的所有可能替换的数组的函数或类

Question

I am looking for a function or class that substitutes given string and returns array of all possible replacements. In other words I am seeking for a magic_function:

function magic_function( $str, $find, $replace )
{
     $arr = array();

     // some magic stuff

     return $arr;
}

var_dump( magic_function( 'aaa', 'a', 'b' ) );

/*
    should return:

    Array(
          'aab',
          'aba',
          'baa',
          'bba',
          'bab',
          'abb',
          'bbb'
    );
*/

I am thinking of using explode and then somehow looping through that array, but maybe there is a simpler way? Maybe with regex? Any ideas? :)

Thank you in advance!

Answer 1

explode and loop seems fairly simple.

<?php

function magic_function ($str, $find, $replace) {
   $parts = explode($find, $str);
   $n = count($parts)-1;
   $p = 1<<$n;

   for ($i=1; $i<$p; $i++) {
      for ($perm="", $seps=$i, $j=0; $j<$n; $seps>>=1, $j++) {
         $perm .= $parts[$j] . ($seps&1 ? $replace : $find);
      }
      $res[] = $perm . $parts[$n];
   }

   return $res;
}

Start from $i=0 to include the no-replacement case.