Question: How can you implement a queue in GameMaker?

Answer

GameMaker Language (GML) does not have a built-in queue data type, but it is possible to implement a queue using arrays or lists. Below is an example of how you could implement a queue with an array.

// Create a new queue
var queue = [];

// Function to add elements to the end of the queue
function queue_enqueue(element) {
    array_push(queue, element);
}

// Function to remove and return the element at the start of the queue
function queue_dequeue() {
    if (array_length_1d(queue) > 0) {
        var element = queue[0];
        queue = array_delete(queue, 0, 1);
        return element;
    }
    return undefined; // Return undefined if the queue is empty
}

// Function to get the element at the start of the queue without removing it
function queue_peek() {
    if (array_length_1d(queue) > 0) {
        return queue[0];
    }
    return undefined; // Return undefined if the queue is empty
}

Alternatively, you can use the ds_list data structure as a queue in GameMaker, as it has functions that closely match queue operations: ds_list_add for enqueue, and ds_list_delete for dequeue. Here's an implementation using ds_list:

// Create a new queue
var queue = ds_list_create();

// Function to add elements to the end of the queue
function queue_enqueue(element) {
    ds_list_add(queue, element);
}

// Function to remove and return the element at the start of the queue
function queue_dequeue() {
    if (!ds_list_empty(queue)) {
        var element = ds_list_find_value(queue, 0);
        ds_list_delete(queue, 0);
        return element;
    }
    return undefined; // Return undefined if the queue is empty
}

// Function to get the element at the start of the queue without removing it
function queue_peek() {
    if (!ds_list_empty(queue)) {
        return ds_list_find_value(queue, 0);
    }
    return undefined; // Return undefined if the queue is empty
}

Remember to destroy your ds_list when you're done with it to prevent memory leaks:

ds_list_destroy(queue);

In both examples, queue_enqueue adds an element to the end of the queue, queue_dequeue removes and returns the element from the beginning of the queue, and queue_peek gets the element at the front of the queue without removing it.

Choose arrays if you're looking for a faster performance for smaller queues, and ds_list if you require more complex data operations or expect the queue to become quite large.