PHP 7 - 在回调中迭代填充多级数组

Question

I need to build complex multilevel array in callback only, one atomic update per call.

The reason for it: callback is called many times from iterative parser. Finally it should build deserialized PHP-array of binary format being parsed.

Here is runnable code:

const ACTION_VALUE = 1;
const ACTION_ENTER = 2;
const ACTION_LEAVE = 3;

function callback($action, $value, &$param)
{
   switch ($action) 
   {
    case ACTION_ENTER:
        $param['parent'][] = &$param['current'];
        $param['current'][] = [];

        end($param['current']);                
        $param['current'] = &$param['current'][key($param['current'])];
    break;

    case ACTION_LEAVE:
        unset($param['current']);
        $param['current'] = array_pop($param['parent']);
        end($param['current']);
    break;

    case ACTION_VALUE:
        $param['current'][] = $value;
    break;
   }
}

// prepare container
$arr = [];
$arr['data'] = [];
$arr['current'] = &$arr['data'];
$arr['parent'] = [];

// callback invocations
callback(ACTION_VALUE, 1, $arr);
callback(ACTION_VALUE, 2, $arr);
callback(ACTION_ENTER, 0, $arr);
callback(ACTION_VALUE, 10, $arr);
callback(ACTION_VALUE, 11, $arr);
callback(ACTION_LEAVE, 0, $arr);
callback(ACTION_VALUE, 3, $arr);
callback(ACTION_VALUE, 4, $arr);

// now see result
var_dump(json_encode($arr['data']));

Try it here

Above example prints:

[1,2,[10,11]], but should [1,2,[10,11],3,4].

Update: Multilevel means arbitrary arrays of random depth.

Update: The problem was with array_pop(), see below accepted answer for fixed version.

Answer 1

I think the problem is array_pop which doesn't return actual reference to the last element. This one works:

<?php

const ACTION_VALUE = 1;
const ACTION_ENTER = 2;
const ACTION_LEAVE = 3;

function callback($action, $value, &$param)
{
    switch ($action) {
        case ACTION_ENTER:
            $param['parent'][] = &$param['current'];
            $param['current'][] = [];

            end($param['current']);
            $param['current'] = &$param['current'][key($param['current'])];
            break;

        case ACTION_LEAVE:
            unset($param['current']);
            end($param['parent']);
            $param['current'] = &$param['parent'][key($param['parent'])];
            unset($param['parent'][key($param['parent'])]);
            end($param['current']);
            break;

        case ACTION_VALUE:
            $param['current'][] = $value;
            break;
    }
}

// prepare container
$arr = [];
$arr['data'] = [];
$arr['current'] = &$arr['data'];
$arr['parent'] = [];

// callback invocations
callback(ACTION_VALUE, 1, $arr);
callback(ACTION_VALUE, 2, $arr);
callback(ACTION_ENTER, 0, $arr);
callback(ACTION_VALUE, 10, $arr);
callback(ACTION_VALUE, 11, $arr);
callback(ACTION_ENTER, 0, $arr);
callback(ACTION_VALUE, 40, $arr);
callback(ACTION_VALUE, 41, $arr);
callback(ACTION_LEAVE, 0, $arr);
callback(ACTION_LEAVE, 0, $arr);
callback(ACTION_VALUE, 3, $arr);
callback(ACTION_VALUE, 4, $arr);

// now see result
var_dump(json_encode($arr['data']));