markov chain

class dissociatedpress {
 
 public static function dissociate ($str, $randomstart = true, $groupsize = 4, $max = 128) {
  if ($groupsize < 2) {
   $groupsize = 2;
  }
  // Capitalize the first word
  $capital = true;
 
  //Remove from corpus, they just make the result confusing
  $str = str_replace(array("(",")","[","]","{","}", "|"), array(),$str);
 
  //Break up tokens
  $tokens = preg_split("/[ \r\n\t]/", $str);
 
  //Clean up token array
  for ($i = 0; $i < sizeof($tokens); $i++){
   if ($tokens[$i] == ""){
    unset($tokens[$i]);
   }
  }
 
  $tokens = array_values($tokens);
 
  //Init variables
  $return = "";
  $lastmatch = array();
 
   // if we start at the beginning, start there
  if (!$randomstart) {
   for ($n = 0; $n < $groupsize; $n++){
    array_push($lastmatch,$tokens[$n]);
    $res = dissociatedpress::cleanToken($tokens[$n],$capital);
    $return .= $res[0];
    $capital = $res[1];
   }
  }
 
   //Loop until we have enough output
  $i = 0;
  while ($i < $max + 32){
    // Try and end on a full sentence
   if ($i > $max - 8 and $capital){
    break;
   }
 
    //If the lastmatch group isn't good enough, start randomly
   if (sizeof($lastmatch) < $groupsize){
    $loc = rand(0,sizeof($tokens)-$groupsize);
    $lastmatch = array();
    for ($n = 0; $n < $groupsize; $n++){
     array_push($lastmatch,$tokens[$loc+$n]);
     $res = dissociatedpress::cleanToken($tokens[$loc+$n],$capital);
     $return .= $res[0];
     $capital = $res[1];
    }
   } else {
    $chains = dissociatedpress::findChains($tokens, $lastmatch);
    $lastmatch = array();
 
     // If there aren't enough chains, start randomly next time (avoid getting caught in loops)
    if (sizeof($chains) > 2) {
     $loc = $chains[rand(0, sizeof($chains)-1)];
     for ($n = 0; $n < $groupsize; $n++){
      array_push($lastmatch,$tokens[$loc+$n]);
       $res = dissociatedpress::cleanToken($tokens[$loc+$n],$capital);
      $return .= $res[0];
      $capital = $res[1];
     }
    }
   }
   $i++;
  }
 
  return $return;
 }
 
 /**
  * Join the tokens with proper typography
  */
 
 public static function cleanToken($token,$capital) {
  if ($capital){
   $token = ucfirst($token);
   $capital = false;
  }
 
  if (substr($token,-1,1) == '.'){
   $capital = true;
   return array($token . " ",$capital);
  } else {
   return array($token . " ",$capital);
  }
 }
 
 /**
  * Naively find possible Markov Chains
  */
 
 public static function findChains($haystack, $needle) {
  $return = array();
  for ($i = 0; $i < sizeof($haystack) - sizeof($needle); $i++){
   if ($haystack[$i] == $needle[0]){
    $matches = true;
    for ($j = 1; $j < sizeof($needle); $j++){
     if ($haystack[$i+$j] != $needle[$j]){
      $matches = false;
      break;
     }
    }
    if ($matches == true){
     array_push($return, $i + sizeof($needle));
    }
   }
  }
  return $return;
 }
 
}