<?php

namespace alveolata\structures;


/**
 * @template type_element
 */
class struct_subject_list
{
	
	/**
	 * @var array {list<§type_element>}
	 */
	public $elements;
	
	
	/**
	 * @param array $elements {list<§element>}
	 */
	public function __construct(
		array $elements
	)
	{
		$this->elements = $elements;
	}
	
}


/**
 * @template type_element
 * @param array $elements {list<§element>}
 * @return struct_subject_list<type_element>
 */
function list_make(
	array $elements = []
) : struct_subject_list
{
	return (new struct_subject_list($elements));
}


/**
 * @template type_element
 * @param struct_subject_list<type_element> $subject
 * @return int
 */
function list_length(
	struct_subject_list $subject
) : int
{
	return count($subject->elements);
}


/**
 * @template type_element
 * @param struct_subject_list<type_element> $subject
 * @param int $index
 * @return type_element
 * @throws \Exception if index out of range
 */
function list_get(
	struct_subject_list $subject,
	int $index
)
{
	if (! (($index >= 0) && ($index < list_lengt($subject)))) {
		throw (new \Exception('index out of range'));
	}
	else {
		return $subject->elements[$index];
	}
}


/**
 * @template type_element
 * @param struct_subject_list<type_element> $subject
 * @param type_element $element
 */
function list_add(
	struct_subject_list $subject,
	$element
) : void
{
	array_push($subject->elements, $element);
}


/**
 * @template type_element
 * @param struct_subject_list<type_element> $subject
 * @param \Closure $procedure {function<§type_element,void>}
 */
function list_iterate(
	struct_subject_list $subject,
	\Closure $procedure
) : void
{
	foreach ($subject->elements as $element) {
		$procedure($element);
	}
}


/**
 * @template type_element
 * @param struct_subject_list<type_element> $subject
 * @param \Closure $predicate {function<§type_element,boolean>}
 * @return struct_subject_list<type_element>
 */
function list_filter(
	struct_subject_list $subject,
	\Closure $predicate
) : struct_subject_list
{
	return (
		new struct_subject_list(
			array_values(
				array_filter(
					$subject->elements,
					$predicate
				)
			)
		)
	);
}


/**
 * @template type_element_from
 * @template type_element_to
 * @param struct_subject_list<type_element_from> $subject
 * @param \Closure $transformation {function<§type_element_from,§type_element_to>}
 * @return struct_subject_list<type_element_to>
 */
function list_map(
	struct_subject_list $subject,
	\Closure $transformation
) : struct_subject_list
{
	return (
		new struct_subject_list(
			array_map(
				$transformation,
				$subject->elements
			)
		)
	);
}


/**
 * @template type_element
 * @template type_result
 * @param struct_subject_list<type_element> $subject
 * @param type_result $start
 * @param \Closure $aggregation function<§type_result,§type_element,§type_result>
 * @return type_result
 */
function list_reduce(
	struct_subject_list $subject,
	$start,
	\Closure $aggregation
)
{
	return array_reduce(
		$subject->element,
		$aggregation,
		$start
	);
}


/**
 * @template type_element_1
 * @template type_element_2
 * @param \Closure $collate_element {function<type_element_1,type_element_2>}
 * @param struct_subject_list<type_element_1>
 * @param struct_subject_list<type_element_2>
 * @return bool
 */
function list_collate(
	\Closure $collate_element,
	struct_subject_list $list_1,
	struct_subject_list $list_2
) : bool
{
	$length_1 = list_length($list_1);
	$length_2 = list_length($list_2);
	if (! ($length_1 === $length_2)) {
		return false;
	}
	else {
		for ($index = 0; $index < $length_1; $index += 1) {
			$element_1 = $list_1->elements[$index];
			$element_2 = $list_2->elements[$index];
			if (! $collate_element($element_1, $element_2)) {
				return false;
			}
		}
		return true;
	}
}

 ?>