如何通过键名/路径访问和操作多维数组? [英] How to access and manipulate multi-dimensional array by key names / path?

问题描述

我必须在PHP中实现一个 setter ，它允许我指定数组(目标)的键或子键，并将名称作为点分隔键传递值.

I've to implement a setter in PHP, that allows me to specify the key, or sub key, of an array (the target), passing the name as a dot-separated-keys value.

给出以下代码:

$arr = array('a' => 1,
             'b' => array(
                 'y' => 2,
                 'x' => array('z' => 5, 'w' => 'abc')
             ),
             'c' => null);

$key = 'b.x.z';
$path = explode('.', $key);

我要从$key的值达到$arr['b']['x']['z']的 5 值.

现在，给定变量值$key和不同的$arr值(深度不同).

Now, given a variable value of $key and a different $arr value (with different deepness).

对于 getter get()，我编写了以下代码:

For the getter get() I wrote this code:

public static function get($name, $default = null)
{
    $setting_path = explode('.', $name);
    $val = $this->settings;

    foreach ($setting_path as $key) {
        if(array_key_exists($key, $val)) {
            $val = $val[$key];
        } else {
            $val = $default;
            break;
        }
    }
    return $val;
}

写一个 setter 更加困难，因为我成功地到达了正确的元素(来自$key)，但是我无法在原始数组中设置该值，所以我没有这样做.不知道如何一次指定所有按键.

To write a setter is more difficult because I succeed in reaching the right element (from the $key), but I am not able to set the value in the original array and I don't know how to specify the keys all at once.

我应该使用某种回溯吗?还是可以避免?

Should I use some kind of backtracking? Or can I avoid it?

推荐答案

假定$path已经是通过explode组成的数组(或添加到函数中)，则可以使用引用.您需要添加一些错误检查，以防$path等无效(请考虑isset):

Assuming $path is already an array via explode (or add to the function), then you can use references. You need to add in some error checking in case of invalid $path etc. (think isset):

$key = 'b.x.z';
$path = explode('.', $key);

Getter

function get($path, $array) {
    //$path = explode('.', $path); //if needed
    $temp =& $array;

    foreach($path as $key) {
        $temp =& $temp[$key];
    }
    return $temp;
}

$value = get($path, $arr); //returns NULL if the path doesn't exist

设置者/创建者

如果您传递的数组尚未定义，则此组合将在现有数组中设置一个值或创建该数组.确保定义$array以通过引用&$array传递:

Setter / Creator

This combination will set a value in an existing array or create the array if you pass one that has not yet been defined. Make sure to define $array to be passed by reference &$array:

function set($path, &$array=array(), $value=null) {
    //$path = explode('.', $path); //if needed
    $temp =& $array;

    foreach($path as $key) {
        $temp =& $temp[$key];
    }
    $temp = $value;
}

set($path, $arr);
//or
set($path, $arr, 'some value');

取消设置

这将unset路径中的最终键:

Unsetter

This will unset the final key in the path:

function unsetter($path, &$array) {
    //$path = explode('.', $path); //if needed
    $temp =& $array;

    foreach($path as $key) {
        if(!is_array($temp[$key])) {
            unset($temp[$key]);
        } else {
            $temp =& $temp[$key];
        }
    }
}
unsetter($path, $arr);

*如果原始答案对某人有用，我将保留一些有限的功能:

设置

确保定义$array以通过引用&$array传递:

Make sure to define $array to be passed by reference &$array:

function set(&$array, $path, $value) {
    //$path = explode('.', $path); //if needed
    $temp =& $array;

    foreach($path as $key) {
        $temp =& $temp[$key];
    }
    $temp = $value;
}

set($arr, $path, 'some value');

或者如果您想返回更新的数组(因为我很无聊):

Or if you want to return the updated array (because I'm bored):

function set($array, $path, $value) {
    //$path = explode('.', $path); //if needed
    $temp =& $array;

    foreach($path as $key) {
        $temp =& $temp[$key];
    }
    $temp = $value;

    return $array;
}

$arr = set($arr, $path, 'some value');

创作者

如果您不想创建数组并选择设置值:

If you wan't to create the array and optionally set the value:

function create($path, $value=null) {
    //$path = explode('.', $path); //if needed
    foreach(array_reverse($path) as $key) {
        $value = array($key => $value);
    }
    return $value;
}    

$arr = create($path);    
//or
$arr = create($path, 'some value');

为了娱乐

在给定字符串b.x.z的情况下，构造并评估类似$array['b']['x']['z']的内容:

Constructs and evaluates something like $array['b']['x']['z'] given a string b.x.z:

function get($array, $path) {
    //$path = explode('.', $path); //if needed
    $path = "['" . implode("']['", $path) . "']";
    eval("\$result = \$array{$path};");

    return $result;
}

设置类似$array['b']['x']['z'] = 'some value';的内容:

function set(&$array, $path, $value) {
    //$path = explode('.', $path); //if needed
    $path = "['" . implode("']['", $path) . "']";
    eval("\$array{$path} = $value;");
}

取消类似$array['b']['x']['z']的设置:

function unsetter(&$array, $path) {
    //$path = explode('.', $path); //if needed
    $path = "['" . implode("']['", $path) . "']";
    eval("unset(\$array{$path});");
}

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