<?php
/**
* CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
* Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
*
* Licensed under The MIT License
* For full copyright and license information, please see the LICENSE.txt
* Redistributions of files must retain the above copyright notice.
*
* @copyright Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
* @link https://cakephp.org CakePHP(tm) Project
* @since 3.0.0
* @license https://opensource.org/licenses/mit-license.php MIT License
*/
namespace Cake\Collection;
use Iterator;
use JsonSerializable;
/**
* Describes the methods a Collection should implement. A collection is an immutable
* list of elements exposing a number of traversing and extracting method for
* generating other collections.
*
* @method \Cake\Collection\CollectionInterface cartesianProduct(callable $operation = null, callable $filter = null)
*/
interface CollectionInterface extends Iterator, JsonSerializable
{
/**
* Executes the passed callable for each of the elements in this collection
* and passes both the value and key for them on each step.
* Returns the same collection for chaining.
*
* ### Example:
*
* ```
* $collection = (new Collection($items))->each(function ($value, $key) {
* echo "Element $key: $value";
* });
* ```
*
* @param callable $c callable function that will receive each of the elements
* in this collection
* @return \Cake\Collection\CollectionInterface
*/
public function each(callable $c);
/**
* Looks through each value in the collection, and returns another collection with
* all the values that pass a truth test. Only the values for which the callback
* returns true will be present in the resulting collection.
*
* Each time the callback is executed it will receive the value of the element
* in the current iteration, the key of the element and this collection as
* arguments, in that order.
*
* ### Example:
*
* Filtering odd numbers in an array, at the end only the value 2 will
* be present in the resulting collection:
*
* ```
* $collection = (new Collection([1, 2, 3]))->filter(function ($value, $key) {
* return $value % 2 === 0;
* });
* ```
*
* @param callable|null $c the method that will receive each of the elements and
* returns true whether or not they should be in the resulting collection.
* If left null, a callback that filters out falsey values will be used.
* @return \Cake\Collection\CollectionInterface
*/
public function filter(callable $c = null);
/**
* Looks through each value in the collection, and returns another collection with
* all the values that do not pass a truth test. This is the opposite of `filter`.
*
* Each time the callback is executed it will receive the value of the element
* in the current iteration, the key of the element and this collection as
* arguments, in that order.
*
* ### Example:
*
* Filtering even numbers in an array, at the end only values 1 and 3 will
* be present in the resulting collection:
*
* ```
* $collection = (new Collection([1, 2, 3]))->reject(function ($value, $key) {
* return $value % 2 === 0;
* });
* ```
*
* @param callable $c the method that will receive each of the elements and
* returns true whether or not they should be out of the resulting collection.
* @return \Cake\Collection\CollectionInterface
*/
public function reject(callable $c);
/**
* Returns true if all values in this collection pass the truth test provided
* in the callback.
*
* Each time the callback is executed it will receive the value of the element
* in the current iteration and the key of the element as arguments, in that
* order.
*
* ### Example:
*
* ```
* $overTwentyOne = (new Collection([24, 45, 60, 15]))->every(function ($value, $key) {
* return $value > 21;
* });
* ```
*
* Empty collections always return true because it is a vacuous truth.
*
* @param callable $c a callback function
* @return bool true if for all elements in this collection the provided
* callback returns true, false otherwise.
*/
public function every(callable $c);
/**
* Returns true if any of the values in this collection pass the truth test
* provided in the callback.
*
* Each time the callback is executed it will receive the value of the element
* in the current iteration and the key of the element as arguments, in that
* order.
*
* ### Example:
*
* ```
* $hasYoungPeople = (new Collection([24, 45, 15]))->every(function ($value, $key) {
* return $value < 21;
* });
* ```
*
* @param callable $c a callback function
* @return bool true if the provided callback returns true for any element in this
* collection, false otherwise
*/
public function some(callable $c);
/**
* Returns true if $value is present in this collection. Comparisons are made
* both by value and type.
*
* @param mixed $value The value to check for
* @return bool true if $value is present in this collection
*/
public function contains($value);
/**
* Returns another collection after modifying each of the values in this one using
* the provided callable.
*
* Each time the callback is executed it will receive the value of the element
* in the current iteration, the key of the element and this collection as
* arguments, in that order.
*
* ### Example:
*
* Getting a collection of booleans where true indicates if a person is female:
*
* ```
* $collection = (new Collection($people))->map(function ($person, $key) {
* return $person->gender === 'female';
* });
* ```
*
* @param callable $c the method that will receive each of the elements and
* returns the new value for the key that is being iterated
* @return \Cake\Collection\CollectionInterface
*/
public function map(callable $c);
/**
* Folds the values in this collection to a single value, as the result of
* applying the callback function to all elements. $zero is the initial state
* of the reduction, and each successive step of it should be returned
* by the callback function.
* If $zero is omitted the first value of the collection will be used in its place
* and reduction will start from the second item.
*
* @param callable $c The callback function to be called
* @param mixed $zero The state of reduction
* @return mixed
*/
public function reduce(callable $c, $zero = null);
/**
* Returns a new collection containing the column or property value found in each
* of the elements, as requested in the $matcher param.
*
* The matcher can be a string with a property name to extract or a dot separated
* path of properties that should be followed to get the last one in the path.
*
* If a column or property could not be found for a particular element in the
* collection, that position is filled with null.
*
* ### Example:
*
* Extract the user name for all comments in the array:
*
* ```
* $items = [
* ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark']],
* ['comment' => ['body' => 'very cool', 'user' => ['name' => 'Renan']]
* ];
* $extracted = (new Collection($items))->extract('comment.user.name');
*
* // Result will look like this when converted to array
* ['Mark', 'Renan']
* ```
*
* It is also possible to extract a flattened collection out of nested properties
*
* ```
* $items = [
* ['comment' => ['votes' => [['value' => 1], ['value' => 2], ['value' => 3]]],
* ['comment' => ['votes' => [['value' => 4]]
* ];
* $extracted = (new Collection($items))->extract('comment.votes.{*}.value');
*
* // Result will contain
* [1, 2, 3, 4]
* ```
*
* @param string $matcher a dot separated string symbolizing the path to follow
* inside the hierarchy of each value so that the column can be extracted.
* @return \Cake\Collection\CollectionInterface
*/
public function extract($matcher);
/**
* Returns the top element in this collection after being sorted by a property.
* Check the sortBy method for information on the callback and $type parameters
*
* ### Examples:
*
* ```
* // For a collection of employees
* $max = $collection->max('age');
* $max = $collection->max('user.salary');
* $max = $collection->max(function ($e) {
* return $e->get('user')->get('salary');
* });
*
* // Display employee name
* echo $max->name;
* ```
*
* @param callable|string $callback the callback or column name to use for sorting
* @param int $type the type of comparison to perform, either SORT_STRING
* SORT_NUMERIC or SORT_NATURAL
* @see \Cake\Collection\CollectionIterface::sortBy()
* @return mixed The value of the top element in the collection
*/
public function max($callback, $type = \SORT_NUMERIC);
/**
* Returns the bottom element in this collection after being sorted by a property.
* Check the sortBy method for information on the callback and $type parameters
*
* ### Examples:
*
* ```
* // For a collection of employees
* $min = $collection->min('age');
* $min = $collection->min('user.salary');
* $min = $collection->min(function ($e) {
* return $e->get('user')->get('salary');
* });
*
* // Display employee name
* echo $min->name;
* ```
*
* @param callable|string $callback the callback or column name to use for sorting
* @param int $type the type of comparison to perform, either SORT_STRING
* SORT_NUMERIC or SORT_NATURAL
* @see \Cake\Collection\CollectionInterface::sortBy()
* @return mixed The value of the bottom element in the collection
*/
public function min($callback, $type = \SORT_NUMERIC);
/**
* Returns the average of all the values extracted with $matcher
* or of this collection.
*
* ### Example:
*
* ```
* $items = [
* ['invoice' => ['total' => 100]],
* ['invoice' => ['total' => 200]]
* ];
*
* $total = (new Collection($items))->avg('invoice.total');
*
* // Total: 150
*
* $total = (new Collection([1, 2, 3]))->avg();
* // Total: 2
* ```
*
* @param string|callable|null $matcher The property name to sum or a function
* If no value is passed, an identity function will be used.
* that will return the value of the property to sum.
* @return float|int|null
*/
public function avg($matcher = null);
/**
* Returns the median of all the values extracted with $matcher
* or of this collection.
*
* ### Example:
*
* ```
* $items = [
* ['invoice' => ['total' => 400]],
* ['invoice' => ['total' => 500]]
* ['invoice' => ['total' => 100]]
* ['invoice' => ['total' => 333]]
* ['invoice' => ['total' => 200]]
* ];
*
* $total = (new Collection($items))->median('invoice.total');
*
* // Total: 333
*
* $total = (new Collection([1, 2, 3, 4]))->median();
* // Total: 2.5
* ```
*
* @param string|callable|null $matcher The property name to sum or a function
* If no value is passed, an identity function will be used.
* that will return the value of the property to sum.
* @return float|int|null
*/
public function median($matcher = null);
/**
* Returns a sorted iterator out of the elements in this collection,
* ranked in ascending order by the results of running each value through a
* callback. $callback can also be a string representing the column or property
* name.
*
* The callback will receive as its first argument each of the elements in $items,
* the value returned by the callback will be used as the value for sorting such
* element. Please note that the callback function could be called more than once
* per element.
*
* ### Example:
*
* ```
* $items = $collection->sortBy(function ($user) {
* return $user->age;
* });
*
* // alternatively
* $items = $collection->sortBy('age');
*
* // or use a property path
* $items = $collection->sortBy('department.name');
*
* // output all user name order by their age in descending order
* foreach ($items as $user) {
* echo $user->name;
* }
* ```
*
* @param callable|string $callback the callback or column name to use for sorting
* @param int $dir either SORT_DESC or SORT_ASC
* @param int $type the type of comparison to perform, either SORT_STRING
* SORT_NUMERIC or SORT_NATURAL
* @return \Cake\Collection\CollectionInterface
*/
public function sortBy($callback, $dir = SORT_DESC, $type = \SORT_NUMERIC);
/**
* Splits a collection into sets, grouped by the result of running each value
* through the callback. If $callback is a string instead of a callable,
* groups by the property named by $callback on each of the values.
*
* When $callback is a string it should be a property name to extract or
* a dot separated path of properties that should be followed to get the last
* one in the path.
*
* ### Example:
*
* ```
* $items = [
* ['id' => 1, 'name' => 'foo', 'parent_id' => 10],
* ['id' => 2, 'name' => 'bar', 'parent_id' => 11],
* ['id' => 3, 'name' => 'baz', 'parent_id' => 10],
* ];
*
* $group = (new Collection($items))->groupBy('parent_id');
*
* // Or
* $group = (new Collection($items))->groupBy(function ($e) {
* return $e['parent_id'];
* });
*
* // Result will look like this when converted to array
* [
* 10 => [
* ['id' => 1, 'name' => 'foo', 'parent_id' => 10],
* ['id' => 3, 'name' => 'baz', 'parent_id' => 10],
* ],
* 11 => [
* ['id' => 2, 'name' => 'bar', 'parent_id' => 11],
* ]
* ];
* ```
*
* @param callable|string $callback the callback or column name to use for grouping
* or a function returning the grouping key out of the provided element
* @return \Cake\Collection\CollectionInterface
*/
public function groupBy($callback);
/**
* Given a list and a callback function that returns a key for each element
* in the list (or a property name), returns an object with an index of each item.
* Just like groupBy, but for when you know your keys are unique.
*
* When $callback is a string it should be a property name to extract or
* a dot separated path of properties that should be followed to get the last
* one in the path.
*
* ### Example:
*
* ```
* $items = [
* ['id' => 1, 'name' => 'foo'],
* ['id' => 2, 'name' => 'bar'],
* ['id' => 3, 'name' => 'baz'],
* ];
*
* $indexed = (new Collection($items))->indexBy('id');
*
* // Or
* $indexed = (new Collection($items))->indexBy(function ($e) {
* return $e['id'];
* });
*
* // Result will look like this when converted to array
* [
* 1 => ['id' => 1, 'name' => 'foo'],
* 3 => ['id' => 3, 'name' => 'baz'],
* 2 => ['id' => 2, 'name' => 'bar'],
* ];
* ```
*
* @param callable|string $callback the callback or column name to use for indexing
* or a function returning the indexing key out of the provided element
* @return \Cake\Collection\CollectionInterface
*/
public function indexBy($callback);
/**
* Sorts a list into groups and returns a count for the number of elements
* in each group. Similar to groupBy, but instead of returning a list of values,
* returns a count for the number of values in that group.
*
* When $callback is a string it should be a property name to extract or
* a dot separated path of properties that should be followed to get the last
* one in the path.
*
* ### Example:
*
* ```
* $items = [
* ['id' => 1, 'name' => 'foo', 'parent_id' => 10],
* ['id' => 2, 'name' => 'bar', 'parent_id' => 11],
* ['id' => 3, 'name' => 'baz', 'parent_id' => 10],
* ];
*
* $group = (new Collection($items))->countBy('parent_id');
*
* // Or
* $group = (new Collection($items))->countBy(function ($e) {
* return $e['parent_id'];
* });
*
* // Result will look like this when converted to array
* [
* 10 => 2,
* 11 => 1
* ];
* ```
*
* @param callable|string $callback the callback or column name to use for indexing
* or a function returning the indexing key out of the provided element
* @return \Cake\Collection\CollectionInterface
*/
public function countBy($callback);
/**
* Returns the total sum of all the values extracted with $matcher
* or of this collection.
*
* ### Example:
*
* ```
* $items = [
* ['invoice' => ['total' => 100]],
* ['invoice' => ['total' => 200]]
* ];
*
* $total = (new Collection($items))->sumOf('invoice.total');
*
* // Total: 300
*
* $total = (new Collection([1, 2, 3]))->sumOf();
* // Total: 6
* ```
*
* @param string|callable|null $matcher The property name to sum or a function
* If no value is passed, an identity function will be used.
* that will return the value of the property to sum.
* @return float|int
*/
public function sumOf($matcher = null);
/**
* Returns a new collection with the elements placed in a random order,
* this function does not preserve the original keys in the collection.
*
* @return \Cake\Collection\CollectionInterface
*/
public function shuffle();
/**
* Returns a new collection with maximum $size random elements
* from this collection
*
* @param int $size the maximum number of elements to randomly
* take from this collection
* @return \Cake\Collection\CollectionInterface
*/
public function sample($size = 10);
/**
* Returns a new collection with maximum $size elements in the internal
* order this collection was created. If a second parameter is passed, it
* will determine from what position to start taking elements.
*
* @param int $size the maximum number of elements to take from
* this collection
* @param int $from A positional offset from where to take the elements
* @return \Cake\Collection\CollectionInterface
*/
public function take($size = 1, $from = 0);
/**
* Returns the last N elements of a collection
*
* ### Example:
*
* ```
* $items = [1, 2, 3, 4, 5];
*
* $last = (new Collection($items))->takeLast(3);
*
* // Result will look like this when converted to array
* [3, 4, 5];
* ```
*
* @param int $howMany The number of elements at the end of the collection
* @return \Cake\Collection\CollectionInterface
*/
public function takeLast($howMany);
/**
* Returns a new collection that will skip the specified amount of elements
* at the beginning of the iteration.
*
* @param int $howMany The number of elements to skip.
* @return \Cake\Collection\CollectionInterface
*/
public function skip($howMany);
/**
* Looks through each value in the list, returning a Collection of all the
* values that contain all of the key-value pairs listed in $conditions.
*
* ### Example:
*
* ```
* $items = [
* ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark']],
* ['comment' => ['body' => 'very cool', 'user' => ['name' => 'Renan']]
* ];
*
* $extracted = (new Collection($items))->match(['user.name' => 'Renan']);
*
* // Result will look like this when converted to array
* [
* ['comment' => ['body' => 'very cool', 'user' => ['name' => 'Renan']]
* ]
* ```
*
* @param array $conditions a key-value list of conditions where
* the key is a property path as accepted by `Collection::extract,
* and the value the condition against with each element will be matched
* @return \Cake\Collection\CollectionInterface
*/
public function match(array $conditions);
/**
* Returns the first result matching all of the key-value pairs listed in
* conditions.
*
* @param array $conditions a key-value list of conditions where the key is
* a property path as accepted by `Collection::extract`, and the value the
* condition against with each element will be matched
* @see \Cake\Collection\CollectionInterface::match()
* @return mixed
*/
public function firstMatch(array $conditions);
/**
* Returns the first result in this collection
*
* @return mixed The first value in the collection will be returned.
*/
public function first();
/**
* Returns the last result in this collection
*
* @return mixed The last value in the collection will be returned.
*/
public function last();
/**
* Returns a new collection as the result of concatenating the list of elements
* in this collection with the passed list of elements
*
* @param array|\Traversable $items Items list.
* @return \Cake\Collection\CollectionInterface
*/
public function append($items);
/**
* Returns a new collection where the values extracted based on a value path
* and then indexed by a key path. Optionally this method can produce parent
* groups based on a group property path.
*
* ### Examples:
*
* ```
* $items = [
* ['id' => 1, 'name' => 'foo', 'parent' => 'a'],
* ['id' => 2, 'name' => 'bar', 'parent' => 'b'],
* ['id' => 3, 'name' => 'baz', 'parent' => 'a'],
* ];
*
* $combined = (new Collection($items))->combine('id', 'name');
*
* // Result will look like this when converted to array
* [
* 1 => 'foo',
* 2 => 'bar',
* 3 => 'baz',
* ];
*
* $combined = (new Collection($items))->combine('id', 'name', 'parent');
*
* // Result will look like this when converted to array
* [
* 'a' => [1 => 'foo', 3 => 'baz'],
* 'b' => [2 => 'bar']
* ];
* ```
*
* @param callable|string $keyPath the column name path to use for indexing
* or a function returning the indexing key out of the provided element
* @param callable|string $valuePath the column name path to use as the array value
* or a function returning the value out of the provided element
* @param callable|string|null $groupPath the column name path to use as the parent
* grouping key or a function returning the key out of the provided element
* @return \Cake\Collection\CollectionInterface
*/
public function combine($keyPath, $valuePath, $groupPath = null);
/**
* Returns a new collection where the values are nested in a tree-like structure
* based on an id property path and a parent id property path.
*
* @param callable|string $idPath the column name path to use for determining
* whether an element is parent of another
* @param callable|string $parentPath the column name path to use for determining
* whether an element is child of another
* @param string $nestingKey The key name under which children are nested
* @return \Cake\Collection\CollectionInterface
*/
public function nest($idPath, $parentPath, $nestingKey = 'children');
/**
* Returns a new collection containing each of the elements found in `$values` as
* a property inside the corresponding elements in this collection. The property
* where the values will be inserted is described by the `$path` parameter.
*
* The $path can be a string with a property name or a dot separated path of
* properties that should be followed to get the last one in the path.
*
* If a column or property could not be found for a particular element in the
* collection as part of the path, the element will be kept unchanged.
*
* ### Example:
*
* Insert ages into a collection containing users:
*
* ```
* $items = [
* ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark']],
* ['comment' => ['body' => 'awesome', 'user' => ['name' => 'Renan']]
* ];
* $ages = [25, 28];
* $inserted = (new Collection($items))->insert('comment.user.age', $ages);
*
* // Result will look like this when converted to array
* [
* ['comment' => ['body' => 'cool', 'user' => ['name' => 'Mark', 'age' => 25]],
* ['comment' => ['body' => 'awesome', 'user' => ['name' => 'Renan', 'age' => 28]]
* ];
* ```
*
* @param string $path a dot separated string symbolizing the path to follow
* inside the hierarchy of each value so that the value can be inserted
* @param mixed $values The values to be inserted at the specified path,
* values are matched with the elements in this collection by its positional index.
* @return \Cake\Collection\CollectionInterface
*/
public function insert($path, $values);
/**
* Returns an array representation of the results
*
* @param bool $preserveKeys whether to use the keys returned by this
* collection as the array keys. Keep in mind that it is valid for iterators
* to return the same key for different elements, setting this value to false
* can help getting all items if keys are not important in the result.
* @return array
*/
public function toArray($preserveKeys = true);
/**
* Returns an numerically-indexed array representation of the results.
* This is equivalent to calling `toArray(false)`
*
* @return array
*/
public function toList();
/**
* Convert a result set into JSON.
*
* Part of JsonSerializable interface.
*
* @return array The data to convert to JSON
*/
public function jsonSerialize();
/**
* Iterates once all elements in this collection and executes all stacked
* operations of them, finally it returns a new collection with the result.
* This is useful for converting non-rewindable internal iterators into
* a collection that can be rewound and used multiple times.
*
* A common use case is to re-use the same variable for calculating different
* data. In those cases it may be helpful and more performant to first compile
* a collection and then apply more operations to it.
*
* ### Example:
*
* ```
* $collection->map($mapper)->sortBy('age')->extract('name');
* $compiled = $collection->compile();
* $isJohnHere = $compiled->some($johnMatcher);
* $allButJohn = $compiled->filter($johnMatcher);
* ```
*
* In the above example, had the collection not been compiled before, the
* iterations for `map`, `sortBy` and `extract` would've been executed twice:
* once for getting `$isJohnHere` and once for `$allButJohn`
*
* You can think of this method as a way to create save points for complex
* calculations in a collection.
*
* @param bool $preserveKeys whether to use the keys returned by this
* collection as the array keys. Keep in mind that it is valid for iterators
* to return the same key for different elements, setting this value to false
* can help getting all items if keys are not important in the result.
* @return \Cake\Collection\CollectionInterface
*/
public function compile($preserveKeys = true);
/**
* Returns a new collection where any operations chained after it are guaranteed
* to be run lazily. That is, elements will be yieleded one at a time.
*
* A lazy collection can only be iterated once. A second attempt results in an error.
*
* @return \Cake\Collection\CollectionInterface
*/
public function lazy();
/**
* Returns a new collection where the operations performed by this collection.
* No matter how many times the new collection is iterated, those operations will
* only be performed once.
*
* This can also be used to make any non-rewindable iterator rewindable.
*
* @return \Cake\Collection\CollectionInterface
*/
public function buffered();
/**
* Returns a new collection with each of the elements of this collection
* after flattening the tree structure. The tree structure is defined
* by nesting elements under a key with a known name. It is possible
* to specify such name by using the '$nestingKey' parameter.
*
* By default all elements in the tree following a Depth First Search
* will be returned, that is, elements from the top parent to the leaves
* for each branch.
*
* It is possible to return all elements from bottom to top using a Breadth First
* Search approach by passing the '$dir' parameter with 'asc'. That is, it will
* return all elements for the same tree depth first and from bottom to top.
*
* Finally, you can specify to only get a collection with the leaf nodes in the
* tree structure. You do so by passing 'leaves' in the first argument.
*
* The possible values for the first argument are aliases for the following
* constants and it is valid to pass those instead of the alias:
*
* - desc: TreeIterator::SELF_FIRST
* - asc: TreeIterator::CHILD_FIRST
* - leaves: TreeIterator::LEAVES_ONLY
*
* ### Example:
*
* ```
* $collection = new Collection([
* ['id' => 1, 'children' => [['id' => 2, 'children' => [['id' => 3]]]]],
* ['id' => 4, 'children' => [['id' => 5]]]
* ]);
* $flattenedIds = $collection->listNested()->extract('id'); // Yields [1, 2, 3, 4, 5]
* ```
*
* @param string|int $dir The direction in which to return the elements
* @param string|callable $nestingKey The key name under which children are nested
* or a callable function that will return the children list
* @return \Cake\Collection\CollectionInterface
*/
public function listNested($dir = 'desc', $nestingKey = 'children');
/**
* Creates a new collection that when iterated will stop yielding results if
* the provided condition evaluates to true.
*
* This is handy for dealing with infinite iterators or any generator that
* could start returning invalid elements at a certain point. For example,
* when reading lines from a file stream you may want to stop the iteration
* after a certain value is reached.
*
* ### Example:
*
* Get an array of lines in a CSV file until the timestamp column is less than a date
*
* ```
* $lines = (new Collection($fileLines))->stopWhen(function ($value, $key) {
* return (new DateTime($value))->format('Y') < 2012;
* })
* ->toArray();
* ```
*
* Get elements until the first unapproved message is found:
*
* ```
* $comments = (new Collection($comments))->stopWhen(['is_approved' => false]);
* ```
*
* @param callable $condition the method that will receive each of the elements and
* returns true when the iteration should be stopped.
* If an array, it will be interpreted as a key-value list of conditions where
* the key is a property path as accepted by `Collection::extract`,
* and the value the condition against with each element will be matched.
* @return \Cake\Collection\CollectionInterface
*/
public function stopWhen($condition);
/**
* Creates a new collection where the items are the
* concatenation of the lists of items generated by the transformer function
* applied to each item in the original collection.
*
* The transformer function will receive the value and the key for each of the
* items in the collection, in that order, and it must return an array or a
* Traversable object that can be concatenated to the final result.
*
* If no transformer function is passed, an "identity" function will be used.
* This is useful when each of the elements in the source collection are
* lists of items to be appended one after another.
*
* ### Example:
*
* ```
* $items [[1, 2, 3], [4, 5]];
* $unfold = (new Collection($items))->unfold(); // Returns [1, 2, 3, 4, 5]
* ```
*
* Using a transformer
*
* ```
* $items [1, 2, 3];
* $allItems = (new Collection($items))->unfold(function ($page) {
* return $service->fetchPage($page)->toArray();
* });
* ```
*
* @param callable|null $transformer A callable function that will receive each of
* the items in the collection and should return an array or Traversable object
* @return \Cake\Collection\CollectionInterface
*/
public function unfold(callable $transformer = null);
/**
* Passes this collection through a callable as its first argument.
* This is useful for decorating the full collection with another object.
*
* ### Example:
*
* ```
* $items = [1, 2, 3];
* $decorated = (new Collection($items))->through(function ($collection) {
* return new MyCustomCollection($collection);
* });
* ```
*
* @param callable $handler A callable function that will receive
* this collection as first argument.
* @return \Cake\Collection\CollectionInterface
*/
public function through(callable $handler);
/**
* Combines the elements of this collection with each of the elements of the
* passed iterables, using their positional index as a reference.
*
* ### Example:
*
* ```
* $collection = new Collection([1, 2]);
* $collection->zip([3, 4], [5, 6])->toList(); // returns [[1, 3, 5], [2, 4, 6]]
* ```
*
* @param array|\Traversable ...$items The collections to zip.
* @return \Cake\Collection\CollectionInterface
*/
public function zip($items);
/**
* Combines the elements of this collection with each of the elements of the
* passed iterables, using their positional index as a reference.
*
* The resulting element will be the return value of the $callable function.
*
* ### Example:
*
* ```
* $collection = new Collection([1, 2]);
* $zipped = $collection->zipWith([3, 4], [5, 6], function (...$args) {
* return array_sum($args);
* });
* $zipped->toList(); // returns [9, 12]; [(1 + 3 + 5), (2 + 4 + 6)]
* ```
*
* @param array|\Traversable ...$items The collections to zip.
* @param callable $callable The function to use for zipping the elements together.
* @return \Cake\Collection\CollectionInterface
*/
public function zipWith($items, $callable);
/**
* Breaks the collection into smaller arrays of the given size.
*
* ### Example:
*
* ```
* $items [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
* $chunked = (new Collection($items))->chunk(3)->toList();
* // Returns [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11]]
* ```
*
* @param int $chunkSize The maximum size for each chunk
* @return \Cake\Collection\CollectionInterface
*/
public function chunk($chunkSize);
/**
* Breaks the collection into smaller arrays of the given size.
*
* ### Example:
*
* ```
* $items ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' => 6];
* $chunked = (new Collection($items))->chunkWithKeys(3)->toList();
* // Returns [['a' => 1, 'b' => 2, 'c' => 3], ['d' => 4, 'e' => 5, 'f' => 6]]
* ```
*
* @param int $chunkSize The maximum size for each chunk
* @param bool $preserveKeys If the keys of the array should be preserved
* @return \Cake\Collection\CollectionInterface
*/
public function chunkWithKeys($chunkSize, $preserveKeys = true);
/**
* Returns whether or not there are elements in this collection
*
* ### Example:
*
* ```
* $items [1, 2, 3];
* (new Collection($items))->isEmpty(); // false
* ```
*
* ```
* (new Collection([]))->isEmpty(); // true
* ```
*
* @return bool
*/
public function isEmpty();
/**
* Returns the closest nested iterator that can be safely traversed without
* losing any possible transformations. This is used mainly to remove empty
* IteratorIterator wrappers that can only slowdown the iteration process.
*
* @return \Traversable
*/
public function unwrap();
/**
* Transpose rows and columns into columns and rows
*
* ### Example:
*
* ```
* $items = [
* ['Products', '2012', '2013', '2014'],
* ['Product A', '200', '100', '50'],
* ['Product B', '300', '200', '100'],
* ['Product C', '400', '300', '200'],
* ]
*
* $transpose = (new Collection($items))->transpose()->toList();
*
* // Returns
* // [
* // ['Products', 'Product A', 'Product B', 'Product C'],
* // ['2012', '200', '300', '400'],
* // ['2013', '100', '200', '300'],
* // ['2014', '50', '100', '200'],
* // ]
* ```
*
* @return \Cake\Collection\CollectionInterface
*/
public function transpose();
/**
* Returns the amount of elements in the collection.
*
* ## WARNINGS:
*
* ### Consumes all elements for NoRewindIterator collections:
*
* On certain type of collections, calling this method may render unusable afterwards.
* That is, you may not be able to get elements out of it, or to iterate on it anymore.
*
* Specifically any collection wrapping a Generator (a function with a yield statement)
* or a unbuffered database cursor will not accept any other function calls after calling
* `count()` on it.
*
* Create a new collection with `buffered()` method to overcome this problem.
*
* ### Can report more elements than unique keys:
*
* Any collection constructed by appending collections together, or by having internal iterators
* returning duplicate keys, will report a larger amount of elements using this functions than
* the final amount of elements when converting the collections to a keyed array. This is because
* duplicate keys will be collapsed into a single one in the final array, whereas this count method
* is only concerned by the amount of elements after converting it to a plain list.
*
* If you need the count of elements after taking the keys in consideration
* (the count of unique keys), you can call `countKeys()`
*
* ### Will change the current position of the iterator:
*
* Calling this method at the same time that you are iterating this collections, for example in
* a foreach, will result in undefined behavior. Avoid doing this.
*
*
* @return int
*/
public function count();
/**
* Returns the number of unique keys in this iterator. This is, the number of
* elements the collection will contain after calling `toArray()`
*
* This method comes with a number of caveats. Please refer to `CollectionInterface::count()`
* for details.
*
* @see \Cake\Collection\CollectionInterface::count()
* @return int
*/
public function countKeys();
}