优化php脚本的内存使用，而不是增加php.ini中的php内存限制

我一直在阅读php中的gabarge collection，但现在一切似乎都有点混乱。上面的脚本comapares 2文件的差异和它的工作确定的文件小于168kb的准确。。。。。。我有一个168KB的大文件，当你试图比较这两个文件时，它会抱怨内存耗尽。试图增加php.ini中的内存，直到大约1000M，对我来说，这似乎是一段写得很糟糕的代码。。。。。。你能帮我优化它吗？

递归调用doDiff（）对内存使用来说不是特别好Hie Mark baker，我想看看我是否能将它转换成迭代代码，你能帮我在递归语句中读取doDiff吗。使用xdebugger跟踪，它肯定被doDiff（）方法卡住了

<?php

class diff {

  var $changes = array();
  var $diff = array();
  var $linepadding = null;

  function doDiff($old, $new) {
    if (!is_array($old))
      $old = file($old);
    if (!is_array($new))
      $new = file($new);

    $maxlen = 0;

    foreach ($old as $oindex => $ovalue) {
      $nkeys = array_keys($new, $ovalue);
      foreach ($nkeys as $nindex) {
        $matrix[$oindex][$nindex] = isset($matrix[$oindex - 1][$nindex - 1]) ? $matrix[$oindex - 1][$nindex - 1] + 1 : 1;
        if ($matrix[$oindex][$nindex] > $maxlen) {
          $maxlen = $matrix[$oindex][$nindex];
          $omax = $oindex + 1 - $maxlen;
          $nmax = $nindex + 1 - $maxlen;
        }
      }
    }
    if ($maxlen == 0)
      return array(array('d' => $old, 'i' => $new));

    return array_merge(
            $this->doDiff(array_slice($old, 0, $omax), array_slice($new, 0, $nmax)), array_slice($new, $nmax, $maxlen), $this->doDiff(array_slice($old, $omax + $maxlen), array_slice($new, $nmax + $maxlen)));
  }

  function diffWrap($old, $new) {
    $this->diff = $this->doDiff($old, $new);
    $this->changes = array();
    $ndiff = array();
    foreach ($this->diff as $line => $k) {
      if (is_array($k)) {
        if (isset($k['d'][0]) || isset($k['i'][0])) {
          $this->changes[] = $line;
          $ndiff[$line] = $k;
        }
      } else {
        $ndiff[$line] = $k;
      }
    }
    $this->diff = $ndiff;
    return $this->diff;
  }

  function formatcode($code) {
    $code = htmlentities($code);
    $code = str_replace(" ", '&nbsp;', $code);
    $code = str_replace("\t", '&nbsp;&nbsp;&nbsp;&nbsp;', $code);
    return $code;
  }

  function showline($line) {
    if ($this->linepadding === 0) {
      if (in_array($line, $this->changes))
        return true;
      return false;
    }
    if (is_null($this->linepadding))
      return true;

    $start = (($line - $this->linepadding) > 0) ? ($line - $this->linepadding) : 0;
    $end = ($line + $this->linepadding);
    //echo '<br />'.$line.': '.$start.': '.$end;
    $search = range($start, $end);
    //pr($search);
    foreach ($search as $k) {
      if (in_array($k, $this->changes))
        return true;
    }
    return false;
  }

  function inline($old, $new, $linepadding = null) {

// get device details by exloding device path passed over to method
    $device_a_pathArr = explode("/", $old);
    $device_b_pathArr = explode("/", $new);

// $device_a (Old) details
    $device_a_Name = $device_a_pathArr['5'];
    $device_a_Date = $device_a_pathArr['8'] . " " . $device_a_pathArr['7'] . " " . $device_a_pathArr['6'];
    $device_a_File = $device_a_pathArr['9'];

// $device_b (New) details
    $device_b_Name = $device_b_pathArr['5'];
    $device_b_Date = $device_b_pathArr['8'] . " " . $device_b_pathArr['7'] . " " . $device_b_pathArr['6'];
    $device_b_File = $device_b_pathArr['9'];

    $this->linepadding = $linepadding;

    $ret = '<pre>
            <table width="75%" border="0" cellspacing="0" cellpadding="0" class="code">';
    $ret.= '<tr>
              <td>Line</td>
              <td style="padding-left:20px;"><font size="2"><b>Device:' . $device_a_Name . '</b><font> Date:' . $device_a_Date . ' FileName:' . $device_a_File . ' </td>
              <td>Line</td>
              <td style="padding-left:20px;"><font size="2"><b>Device:' . $device_b_Name . '</b><font> Date:' . $device_b_Date . ' FileName:' . $device_b_File . ' </td>
             </tr>';
    $count_old = 1;
    $count_new = 1;

    $insert = false;
    $delete = false;
    $truncate = false;

    $diff = $this->diffWrap($old, $new);

    foreach ($diff as $line => $k) {
      if ($this->showline($line)) {
        $truncate = false;
        if (is_array($k)) {
          foreach ($k['d'] as $val) {
            $class = '';
            if (!$delete) {
              $delete = true;
              $class = 'first';
              if ($insert)
                $class = '';
              $insert = false;
            }
            $ret.= '<tr><th>' . $count_old . '</th>';
            $ret.= '<td class="del ' . $class . '">' . $this->formatcode($val) . '</td>';
            $ret.= '<th>&nbsp;</th>';
            $ret.= '<td class="truncated ' . $class . '">&nbsp;</td>';
            $ret.= '</tr>';
            $count_old++;
          }
          foreach ($k['i'] as $val) {
            $class = '';
            if (!$insert) {
              $insert = true;
              $class = 'first';
              if ($delete)
                $class = '';
              $delete = false;
            }
            $ret.= '<tr><th>&nbsp;</th>';
            $ret.= '<td class="truncated ' . $class . '">&nbsp;</td>';
            $ret.= '<th>' . $count_new . '</th>';
            $ret.= '<td class="ins ' . $class . '">' . $this->formatcode($val) . '</td>';
            $ret.= '</tr>';
            $count_new++;
          }
        } else {
          $class = ($delete) ? 'del_end' : '';
          $class = ($insert) ? 'ins_end' : $class;
          $delete = false;
          $insert = false;
          $ret.= '<tr><th>' . $count_old . '</th>';
          $ret.= '<td class="' . $class . '">' . $this->formatcode($k) . '</td>';
          $ret.= '<th>' . $count_new . '</th>';
          $ret.= '<td class="' . $class . '">' . $this->formatcode($k) . '</td>';
          $ret.= '</tr>';
          $count_old++;
          $count_new++;
        }
      } else {
        $class = ($delete) ? 'del_end' : '';
        $class = ($insert) ? 'ins_end' : $class;
        $delete = false;
        $insert = false;

        if (!$truncate) {
          $truncate = true;
          $ret.= '<tr><th>...</th>';
          $ret.= '<td class="truncated ' . $class . '">&nbsp;</td>';
          $ret.= '<th>...</th>';
          $ret.= '<td class="truncated ' . $class . '">&nbsp;</td>';
          $ret.= '</tr>';
        }
        $count_old++;
        $count_new++;
      }
    }
    $ret.= '</table></pre>';
    return $ret;
  }
}
?>