PHP cdata 处理(详细介绍)

 // States:
        //
        //     'out'
        //     '<'
        //     '<!'
        //     '<!['
        //     '<![C'
        //     '<![CD'
        //     '<![CDAT'
        //     '<![CDATA'
        //     'in'
        //     ']'
        //     ']]'
        //
        // (Yes, the states a represented by strings.)
        //
        $state = 'out';
        $a = str_split($xml);
        $new_xml = '';
        foreach ($a AS $k => $v) {
            // Deal with "state".
            switch ( $state ) {
                case 'out':
                    if ( '<' == $v ) {
                        $state = $v;
                    } else {
                        $new_xml .= $v;
                    }
                break;
                case '<':
                    if ( '!' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                 case '<!':
                    if ( '[' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                case '<![':
                    if ( 'C' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                case '<![C':
                    if ( 'D' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                case '<![CD':
                    if ( 'A' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                case '<![CDA':
                    if ( 'T' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                case '<![CDAT':
                    if ( 'A' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                case '<![CDATA':
                    if ( '[' == $v  ) {
                        $cdata = '';
                        $state = 'in';
                    } else {
                        $new_xml .= $state . $v;
                        $state = 'out';
                    }
                break;
                case 'in':
                    if ( ']' == $v ) {
                        $state = $v;
                    } else {
                        $cdata .= $v;
                    }
                break;
                case ']':
                    if (  ']' == $v  ) {
                        $state = $state . $v;
                    } else {
                        $cdata .= $state . $v;
                        $state = 'in';
                    }
                break;
                case ']]':
   if (  '>' == $v  ) {
    $new_xml .= htmlentities($cdata);
#       $new_xml.= $cdata;
//                        $new_xml .= str_replace('>','>',
  //                                  str_replace('>','<',
    //                                str_replace('"','"',
      //                              str_replace('&','&',
        //                            $cdata))));
                        $state = 'out';
                    } else {
                        $cdata .= $state . $v;
                        $state = 'in';
                    }
                break;
            } // switch
        }
        //
        // Return.
        //
            return $new_xml;