Dynamically create 'n' depth array with values

Question

I'm trying to create a class by which i should be able to create array having any depth of arrays/values. But i cannot get find the way to do it. Any suggestions/hints/helps would be great.

Here is the codes

    class CreateArray{
        public function __construct() {

        }

        private $array = [];
        public function add_value($value){
            $this->array[] = $value;
            return $this;
        }

        public function sub_array_start() {
            // What to do here?!
            return $this;
        }

        public function sub_array_end() {
            // What to do here?!
            return $this;
        }

        public function get() {
            return $this->array;
        }
    }

    $d_array = new CreateArray();
    $d_array = $d_array
                    ->add_value([1, 2, 3])
                    ->sub_array_start()
                        ->add_value([3, 2, 8])
                        ->add_value([4, 2, 5])

                        ->sub_array_start()
                            ->add_value([4, 2, 5])
                            ->add_value([3, 2, 8])
                        ->sub_array_end()

                        ->add_value([4, 2, 5])
                    ->sub_array_end()

                    ->add_value([1, 2, 3])
                    ->add_value([1, 2, 3])

                    ->sub_array_start()
                        ->add_value([3, 2, 8])
                        ->add_value([4, 2, 5])

                        ->sub_array_start()
                            ->sub_array_start()
                                ->add_value([3, 2, 8])
                                ->add_value([4, 2, 5])

                                ->sub_array_start()
                                    ->add_value([3, 2, 8])
                                    ->add_value([4, 2, 5])
                                ->sub_array_end()

                            ->sub_array_end()

                            ->add_value([3, 2, 8])
                            ->add_value([4, 2, 5])
                        ->sub_array_end()
                    ->sub_array_end();
                    ->get();
    print_r($d_array);

Above codes should create an array like this -

This doesn't help with the construction of a class but may help you figure it out: https://stackoverflow.com/questions/27929875/how-to-access-and-manipulate-multi-dimensional-array-by-key-names-path — AbraCadaver, Jul 05 '18 at 18:52
I fear the concept `sub_array_start` and `sub_array_end` really does not fit with how arrays work — RiggsFolly, Jul 05 '18 at 19:00
@RiggsFolly, there must be a way to do it! I'm not very good at PHP, so cannot think further :( — Xahed Kamal, Jul 05 '18 at 19:02
Here is a hint, you have to track the current index (or at least call end() ) and the nesting level of the array pointer. ie. you have to maintain the state of where you are in the array — ArtisticPhoenix, Jul 05 '18 at 19:22
I thought of that. but dont understand how to implement it :( — Xahed Kamal, Jul 05 '18 at 19:25

score 2 · Accepted Answer · answered Jul 05 '18 at 21:14

I think the easiest (but certainly not an efficient) way is to keep a simple simple list of the current keys inside your array. Then you can traverse down and add your values/sub-arrays in the right place (if the =& is unfamiliar, check the PHP manual for references). In code:

class CreateArray{
    private $array = [];
    private $keys = [];
    public function __construct() {
    }

    public function add_value($value){
        $tmp =& $this->array;
        foreach ($this->keys as $key) {
            $tmp =& $tmp[$key];
        }
        $tmp[] = $value;
        return $this;
    }

    public function sub_array_start() {
        $tmp =& $this->array;
        foreach ($this->keys as $key) {
            $tmp =& $tmp[$key];
        }
        $tmp[] = [];
        end($tmp);
        $this->keys[] = key($tmp);
        reset($tmp);
        return $this;
    }

    public function sub_array_end() {
        array_pop($this->keys);
        return $this;
    }

    public function get() {
        return $this->array;
    }
}

Note: You have an extra ; after your last sub_array_end(), but otherwise the example code works (unless I overlooked something while quickly comparing the print_r's;)

score 0 · Answer 2 · answered Jul 05 '18 at 21:48

0

I was bored so I started this. My brain is tired now but maybe this will help you or someone else in the proper direction:

class CreateArray{

    private $array;
    private $previous;
    private $current;

    public function __construct(){
        $this->current =& $this->array;
    }

    public function add_value($value){
        $this->current[] = $value;
        return $this;
    }

    public function sub_array_start() {
        $this->previous =& $this->current;
        $this->current =& $this->array[];
        return $this;
    }

    public function sub_array_end() {
        $this->array =& $this->previous;
        $this->current =& $this->array;
        return $this;
    }

    public function get() {
        return $this->array;
    }
}

answered Jul 05 '18 at 21:48

AbraCadaver

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This will not work on two or more consecutive sub_array_end() calls. You need to store and restore all previous nodes. That was the reason I half-assed my answer. – jh1711 Jul 05 '18 at 22:12
Yes, this is not complete and I don't expect any upvotes. Maybe you have an idea using this approach? Should be able to store a reference to the deepest level somehow. – AbraCadaver Jul 05 '18 at 22:24
Imho your idea is spot on for a clean implementation. You just need to use sth. like a stack for previous nodes. After that, there's just a little busy work left. E.g. `$this->current =& $this->array[];` needs to be replaced by 'add a new empty array to current, and make current point to it'. I'm too lazy to do it, but maybe somebody else will; or I get really bored. – jh1711 Jul 05 '18 at 22:43

score 0 · Answer 3 · answered Jul 06 '18 at 13:41

I found a way to do it. Though i'm not sure if its perfect or not. But here is my own solution -

class CreateArray{
    public function __construct() {

    }

    private $json_string = '';

    public function add_value($value){
        $value = json_encode($value, true);
        $this->json_string .= $value . ',';
        return $this;
    }

    public function sub_array_start() {
        $this->json_string .= '[';
        return $this;
    }

    public function sub_array_end() {
        $this->json_string = substr($this->json_string, 0, -1);
        $this->json_string .= '],';
        return $this;
    }

    public function get() {
        $value = '[' . $this->json_string . ']';
        $value = str_replace('],]', ']]', $value);
        $value = str_replace('},]', '}]', $value);
        $value = json_decode($value);
        return $value;
    }
}

Dynamically create 'n' depth array with values

3 Answers3