使用字符串来访问（可能很大）多维数组 [英] use strings to access (potentially large) multidimensional arrays

问题描述

我无法找出一种方法来简单解析字符串输入，并找到一个多维数组中的正确位置。

I am having trouble figuring out a way to simply parse a string input and find the correct location within a multidimensional array.

我希望一个或两行要做到这一点，因为我已经看到了解决方案依赖于长期（10-20线）循环。

I am hoping for one or two lines to do this, as the solutions I have seen rely on long (10-20 line) loops.

（注意嵌套的可以，理论上是任意深度的）：

Given the following code (note that the nesting could, in theory, be of any arbitrary depth):

function get($string)
{
    $vars = array(
        'one' => array(
            'one-one' => "hello",
            'one-two' => "goodbye"
        ),
        'two' => array(
            'two-one' => "foo",
            'two-two' => "bar"
        )
    );

    return $vars[$string]; //this syntax isn't required, just here to give an idea
}

get("two['two-two']");  //desired output: "bar".  Actual output: null

有一个简单的使用内置函数或别的东西，很容易将重建我的期望的输出？

Is there a simple use of built-in functions or something else easy that would recreate my desired output?

推荐答案

考虑 $瓦尔为您的变量，你想获得单['一对一'] 或双['两进两出'] ['更多'] 从（的演示）：

Considering $vars being your variables you would like to get one['one-one'] or two['two-two']['more'] from (Demo):

$vars = function($str) use ($vars)
{
    $c = function($v, $w) {return $w ? $v[$w] : $v;};
    return array_reduce(preg_split('~\[\'|\'\]~', $str), $c, $vars);
};
echo $vars("one['one-one']"); # hello
echo $vars("two['two-two']['more']"); # tea-time!

这是乐星串入的键的标记，然后遍历上的键控的值，而 $瓦尔阵列在 $瓦尔阵列已经变成了一个功能。

This is lexing the string into key tokens and then traverse the $vars array on the keyed values while the $vars array has been turned into a function.

的旧的东西：的

重载阵列功能，只是EVAL的：

Overload the array with a function that just eval's:

$vars = array(
    'one' => array(
        'one-one' => "hello",
        'one-two' => "goodbye"
    ),
    'two' => array(
        'two-one' => "foo",
        'two-two' => "bar"
    )
);

$vars = function($str) use ($vars)
{
    return eval('return $vars'.$str.';');
};

echo $vars("['one']['one-two']"); # goodbye

如果你不是EVAL的粉丝，改变实现：

If you're not a fan of eval, change the implementation:

$vars = function($str) use ($vars)
{
    $r = preg_match_all('~\[\'([a-z-]+)\']~', $str, $keys);
    $var = $vars;
    foreach($keys[1] as $key)
        $var = $var[$key];
    return $var;
};
echo $vars("['one']['one-two']"); # goodbye

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