php json encode decode

对于老的php版本是没有json_encode 和json_decode函数的，但是又想使用这个功能。下边就是一个用php代码写的json encode 和decode 的函数。

 

 

function fromJSON ( $json, $assoc = false ) {

 

  /* by default we don't tolerate ' as string delimiters

     if you need this, then simply change the comments on

     the following lines: */

 

   $matchString = '/(".*?(?<!\\\\)"|\'.*?(?<!\\\\)\')/';

  //$matchString = '/".*?(?<!\\\\)"/';

  

  // safety / validity test

  $t = preg_replace( $matchString, '', $json );

  $t = preg_replace( '/[,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]/', '', $t );

  if ($t != '') { return null; }

 

  // build to/from hashes for all strings in the structure

  $s2m = array();

  $m2s = array();

  preg_match_all( $matchString, $json, $m );

  foreach ($m[0] as $s) {

    $hash       = '"' . md5( $s ) . '"';

    $s2m[$s]    = $hash;

    $m2s[$hash] = str_replace( '$', '\$', $s );  // prevent $ magic

  }

  

  // hide the strings

  $json = strtr( $json, $s2m );

  

  // convert JS notation to PHP notation

  $a = ($assoc) ? '' : '(object) ';

  $json = strtr( $json, 

    array(

      ':' => '=>', 

      '[' => 'array(', 

      '{' => "{$a}array(", 

      ']' => ')', 

      '}' => ')'

    ) 

  );

  

  // remove leading zeros to prevent incorrect type casting

  $json = preg_replace( '~([\s\(,>])(-?)0~', '$1$2', $json );

  

  // return the strings

  $json = strtr( $json, $m2s );

 

  /* "eval" string and return results. 

     As there is no try statement in PHP4, the trick here 

     is to suppress any parser errors while a function is 

     built and then run the function if it got made. */

  $f = @create_function( '', "return {$json};" );

  $r = ($f) ? $f() : null;

 

  // free mem (shouldn't really be needed, but it's polite)

  unset( $s2m ); unset( $m2s ); unset( $f );

 

  return $r;

}

 

/**

 * Encodes a PHP variable into a JSON string.

 * @param mixed $value A PHP variable to be encoded.

 */

function toJSON ( $value ) {

 

  if ($value === null) { return 'null'; };  // gettype fails on null?

 

  $out = '';

  $esc = "\"\\/\n\r\t" . chr( 8 ) . chr( 12 );  // escaped chars

  $l   = '.';  // decimal point

  

  switch ( gettype( $value ) ) 

  {

    case 'boolean':

      $out .= $value ? 'true' : 'false';

      break;

      

    case 'float':

    case 'double':

      // PHP uses the decimal point of the current locale but JSON expects %x2E

      $l = localeconv();

      $l = $l['decimal_point'];

      // fallthrough...

 

    case 'integer':

      $out .= str_replace( $l, '.', $value );  // what, no getlocale?

      break;

 

    case 'array':

      // if array only has numeric keys, and is sequential... ?

      for ($i = 0; ($i < count( $value ) && isset( $value[$i]) ); $i++);

      if ($i === count($value)) {

        // it's a "true" array... or close enough

        $out .= '[' . implode(',', array_map('toJSON', $value)) . ']';

        break;

      }

      // fallthrough to object for associative arrays... 

 

    case 'object':

      $arr = is_object($value) ? get_object_vars($value) : $value;

      $b = array();

      foreach ($arr as $k => $v) {

        $b[] = '"' . addcslashes($k, $esc) . '":' . toJSON($v);

      }

      $out .= '{' . implode( ',', $b ) . '}';

      break;

 

    default:  // anything else is treated as a string

      return '"' . addcslashes($value, $esc) . '"';

      break;

  }

  return $out;

  

}