PHP算法陣列的改變「命令」

Question

方案：

1）I有一個菜單包括菜單項，每一個與一個order_index（範圍從0到n），其識別在所述菜單項的位置菜單。
2）我想插入一個新的菜單項在一個特定的位置或改變現有元素的位置。
3）假設如果它是一個新項目，我已經用order_index = null將新項目保存在我的數據庫中。
4）因此，當編輯/創建的菜單項，比order_index其他所有相關信息獲取，保存，然後下面的函數被調用：

function reOrderItems(MenuItem $item, Integer $orderIndex) 
{ 
    /* 
    Step 1: Retrieve all the MenuItems, ordered by order_index. This means that 
      If it was a new item, the item's order_index is null and would be the 
      first item in the array of retrieved items. 

    Step 2: Take the item ($item) and remove it from its current location in the 
      array and place it at its new position, $orderIndex. 

    Step 3: "Reorder" the array indexing so that it runs from 0 to 
      (array.length - 1) in the order that the Menu Items are now. 

    Step 4: Update all items in the database with their new order_index, ranging 
      from 0 to n according to the array index. 
    */ 
} 

實施例1：移動物品在位置[0]至位[3]。 [1] => [0]，[2] => [1]，[3] => [2]，[0] => [3]並且所有其他元素保持相同。

示例2：將位置[6]中的項目移動到位置[3]。 位置[0]，[1]和[2]中的項目保持不變。 [3] => [4]，[4] => [5]，[5] => [6]，[6] => [3]，所有其他元素保持不變。

我將不勝感激任何幫助一個算法，將能夠爲我做的步驟2 & 3。請記住，真正的天才在於簡單。實現這一點的算法越簡單越好。

Answer 1

您可以使用內置的PHP函數array_merge()和array_splice()。我認爲它可以回答你的問題，但表格的索引可能會通過使用這些函數來重建，但我不確定它會對你造成什麼問題。

<?php 

$menu = array(
    0 => 'Item 1', 
    1 => 'Item 2', 
    2 => 'Item 3', 
    3 => 'Item 4', 
    4 => 'Item 5' 
); 

echo('Default menu:'.PHP_EOL); 
print_r($menu); 

$menuNewEntry = array(
    0 => 'Item 0 (new)' 
); 

##### add a menu entry at the beginning ##### 
$menu = array_merge($menuNewEntry, $menu); 

echo('Default menu with new entry:'.PHP_EOL); 
print_r($menu); 

##### remove a menu entry ##### 
array_splice($menu, 2, 1); 

echo('Default menu without entry at index 2:'.PHP_EOL); 
print_r($menu); 

##### move a menu entry ##### 
# remove an element from the array and keep the result (the removed element) 
$menuRemovedEntry = array_splice($menu, 0, 1); 

# insert this element in the array (the removed element) 
array_splice($menu, 2, 0, $menuRemovedEntry); 

echo('Default menu with entry 0 moved at index 2:'.PHP_EOL); 
print_r($menu); 

下面是結果：

Default menu: 
Array 
(
    [0] => Item 1 
    [1] => Item 2 
    [2] => Item 3 
    [3] => Item 4 
    [4] => Item 5 
) 
Default menu with new entry: 
Array 
(
    [0] => Item 0 (new) 
    [1] => Item 1 
    [2] => Item 2 
    [3] => Item 3 
    [4] => Item 4 
    [5] => Item 5 
) 
Default menu without entry at index 2: 
Array 
(
    [0] => Item 0 (new) 
    [1] => Item 1 
    [2] => Item 3 
    [3] => Item 4 
    [4] => Item 5 
) 
Default menu with entry 0 moved at index 2: 
Array 
(
    [0] => Item 1 
    [1] => Item 3 
    [2] => Item 0 (new) 
    [3] => Item 4 
    [4] => Item 5 
) 

Answer 2

檢查原則sortable行爲（即用型解決方案！）或參見source code的一些想法。

Answer 3

看一看reorder功能從Nspl：

use function nspl\a\reorder; 

$menu = array(
    0 => 'Item 0', 
    1 => 'Item 1', 
    2 => 'Item 2', 
    3 => 'Item 3', 
    4 => 'Item 4', 
    5 => 'Item 5', 
    6 => 'Item 6', 
); 

echo "Example 1\n"; 
print_r(reorder($menu, 0, 3)); 

echo "\nExample 2\n"; 
print_r(reorder($menu, 6, 3)); 

輸出：

Example 1 
Array 
(
    [0] => Item 1 
    [1] => Item 2 
    [2] => Item 3 
    [3] => Item 0 
    [4] => Item 4 
    [5] => Item 5 
    [6] => Item 6 
) 

Example 2 
Array 
(
    [0] => Item 0 
    [1] => Item 1 
    [2] => Item 2 
    [3] => Item 6 
    [4] => Item 3 
    [5] => Item 4 
    [6] => Item 5 
)