PHP Ds\Set Functions

A set is a collection of unique values. The Ds\Set in PHP works like Ds\Map and uses a hash table. In Ds\Set, the values act as keys, and the mapped values are not used.

Requirements

To use Ds\Set, you need:

• PHP 7 or later
• The compatibility polyfill

Installation

The easiest way to install Ds\Set is by using the PECL extension. Run the following command:

pecl install ds

Syntax

The syntax for using functions in Ds\Set is:

public Ds\Set::functionName()

Example

Here is an example of using the Ds\Set::count() function:

<?php

// Declare a new Set
$set = new \Ds\Set([10, 15, 21]);

// Display the Set elements
var_dump($set);

// Display the count of elements in the Set
echo "Count is: ";
print_r($set->count());

?>

Output

The output of the above code will be:

object(Ds\Set)#1 (3) {
  [0]=>
  int(10)
  [1]=>
  int(15)
  [2]=>
  int(21)
}
Count is: 3

This simple guide should help you understand and use Ds\Set in your PHP projects.

Complete list of data structure DS\Set:

Ds\Set Functions	Description
add(value)	Add a new value to the set. The value must be unique, and attempting to add duplicate values will have no effect.
allocate(capacity)	Allocate enough memory for the set to hold a specific number of elements (`capacity`). This pre-allocates space to potentially avoid performance overhead during insertions.
capacity()	Return the current maximum number of elements the set can hold without needing reallocation.
clear()	Remove all elements from the set.
__construct([iterable])	**Optional:** Create a new set instance. You can optionally provide an iterable object (like an array) to populate the set initially.
contains(value)	Check whether the set contains a specific value.
copy()	Create a new set that is a shallow copy of the original set. Changes to the original set will not be reflected in the copy, and vice versa.
count()	Return the number of elements currently in the set.
diff(otherSet)	Create a new set containing only the elements that are present in the first set but not in the `otherSet`.
filter(callback)	Create a new set containing only the elements that pass a test defined by the callback function.
first()	Return the first element (in insertion order) from the set. If the set is empty, it may return an error or null value.
get(value)	**Not applicable:** Sets don't use keys for retrieval. Use `contains` to check if a value exists.
intersect(otherSet)	Create a new set containing only the elements that are present in both the current set and the `otherSet`.
isEmpty()	Check whether the set is empty (contains no elements).
join(separator)	Join all values in the set into a string, separated by the provided delimiter (separator).
last()	Return the last element added to the set (if the insertion order is maintained). If the set is empty, it may return an error or null value.
merge(iterable)	Add all the elements from the provided iterable (like an array) to the set. Duplicate values will be ignored.
reduce(callback, initial_value)	Reduce the set to a single value by applying a callback function to each element sequentially. The callback function takes the accumulated result and the current element as arguments and returns a new accumulated value.
remove(value)	Remove a specific value from the set. If the value is not found, no error is raised.
reverse()	**Not applicable:** Sets don't have a defined order. Use `toArray` and reverse the resulting array if needed.
reversed()	**Not applicable:** Similar to `reverse`, creating a copy with a reversed order isn't efficient for sets.
slice(offset, length)	**Not applicable:** Slicing a set doesn't make sense as sets don't maintain a specific order.
sort([comparison_function])	Sort the elements in-place by value. You can optionally provide a comparison function to define the sorting order. Sorting a set might not be very efficient due to the underlying hashing mechanism.
sorted([comparison_function])	Create a new set containing a copy of the elements sorted by value. You can optionally provide a comparison function to define the sorting order. Sorting a set might not be very efficient due to the underlying hashing mechanism.
sum()	**Not applicable:** Sets typically don't contain numerical values that can be summed. If you need to perform mathematical operations, consider converting the set to a more suitable data structure like an array.
toArray()	Convert the set to a regular PHP array. The order of elements in the resulting array may not reflect the insertion order in the set.
union(otherSet)	Create a new set containing all the elements that are present in either the current set or the `otherSet`, or both.
xor(otherSet)	Create a new set containing the elements that are present in exactly one of the current set and the `otherSet`. Elements that are in both sets will be excluded.