今さらながらJSONPath。(PHP)

なぜ今さらながらJSONPathかっていうと、どうにもいい感じにつかえるやつがなかったのです。
http://goessner.net/articles/JsonPath/
LastUpdateが2007年だけど^^;^^;
で、テストコードを書いてみると、ちょっとイイ感じです。
何がイイかって、resultTypeに"PATH"なるものが設定できるところで、この先頭の$を削除してObjectの変数名をつっこみ、
"黒魔術"のevalで、参照したり設定したり。
※javascriptの方も同様にできました。
●テストコード

 require_once "pear/Var_Dump.php";
 require_once "./jsonpath-0.8.1.php";

 $jstr = file_get_contents('samplejson.txt');
 $json = json_decode($jstr,true);

 $match1 = jsonPath($json, "$..author");
 $match2 = jsonPath($json, "$..author", array("resultType" => "PATH"));

 $res1 = Var_Dump::display($match1,true);
 $res2 = Var_Dump::display($match2,true);

 header( "Content-Type:text/html; charset=utf-8");

 $idxstr = $match2[1];
 $idxstr = "\x24json" . substr($idxstr,1);

 eval("\x24aa=" . $idxstr . ";");
 echo "->  {$aa} 
";

 $idxstr .= "='A123456789';";

 @eval($idxstr); // 失敗してもtry-catchで拾えません^^;

 $res3 = Var_Dump::display($json,true);

 echo "-> " . $idxstr . "
";

 echo $res1;
 echo $res2;
 echo $res3;
 exit;

/*
samplejson.txtの中身。

{ "store": {
    "book": [ 
      { "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      { "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      },
      { "category": "fiction",
        "author": "Herman Melville",
        "title": "Moby Dick",
        "isbn": "0-553-21311-3",
        "price": 8.99
      },
      { "category": "fiction",
        "author": "J. R. R. Tolkien",
        "title": "The Lord of the Rings",
        "isbn": "0-395-19395-8",
        "price": 22.99
      }
    ],
    "bicycle": {
      "color": "red",
      "price": 19.95
    }
  }
}
*/

?>

●表示結果

-> Evelyn Waugh 
-> $json['store']['book'][1]['author']='A123456789';
array(4) {
  0 => string(10) Nigel Rees
  1 => string(12) Evelyn Waugh
  2 => string(15) Herman Melville
  3 => string(16) J. R. R. Tolkien
}
array(4) {
  0 => string(31) $['store']['book'][0]['author']
  1 => string(31) $['store']['book'][1]['author']
  2 => string(31) $['store']['book'][2]['author']
  3 => string(31) $['store']['book'][3]['author']
}
array(1) {
  store => array(2) {
    book => array(4) {
      0 => array(4) {
        category => string(9) reference
        author => string(10) Nigel Rees
        title => string(22) Sayings of the Century
        price => float 8.95
      }
      1 => array(4) {
        category => string(7) fiction
        author => string(10) A123456789
...略...