icollection.hpp File Reference

#include "ienumerable.hpp"
#include "extensions/collection_common.hpp"
#include "../../internal/__array_definition.hpp"
#include "../../object.hpp"
#include "../../size.hpp"

Definition

Contains xtd::collections::generic::icollection <type_t> interface.

Copyright

Copyright (c) 2026 Gammasoft. All rights reserved.

Go to the source code of this file.

Namespaces
namespace	xtd
	The xtd namespace contains all fundamental classes to access Hardware, Os, System, and more.
namespace	xtd::collections
	The xtd::collections namespace contains interfaces and classes that define various collections of objects, such as lists, queues, bit arrays, hash tables and dictionaries.
namespace	xtd::collections::generic
	The xtd::collections::generic namespace contains interfaces and classes that define generic collections, which allow users to create strongly typed collections that provide better type safety and performance than non-generic strongly typed collections.

Public Aliases
Defines methods to manipulate generic collections. Definition template<class type_t> class icollection : public xtd::collections::generic::ienumerable<type_t>, public xtd::collections::generic::extensions::collection_common<type_t, icollection<type_t>>; Header #include <xtd/collections/generic/icollection> Namespace xtd::collections::generic Library xtd.core Examples The following example implements the xtd::collections::generic::icollection <type_t> interface to create a collection of custom box objects named box_collection. Each box has height, length, and width properties, which are used to define equality. Equality can be defined as all dimensions being the same or the volume being the same. The box class implements the xtd::iequatable <type_t> interface to define the default equality as the dimensions being the same. The box_collection class implements the xtd::collections::generic::icollection::contains method to use the default equality to determine whether a box is in the collection. This method is used by the xtd::collections::generic::icollection::add method so that each box added to the collection has a unique set of dimensions. The box_collection class also provides an overload of the xtd::collections::generic::icollection::contains method that takes a specified xtd::collections::generic::iequality_comparer <type_t> interface, such as box_same_dimensions and box_same_volume` classes in the example. This example also implements an xtd::collections::generic::ienumerator <type_t> interface for the box_collection class so that the collection can be enumerated. #include <xtd/xtd> class program { public: static auto main() -> void { auto boxes = box_collection {}; boxes.add(program::box {10, 4, 6}); boxes.add(program::box {4, 6, 10}); boxes.add(program::box {6, 10, 4}); boxes.add(program::box {12, 8, 10}); // Same dimensions. Cannot be added: boxes.add(program::box {10, 4, 6}); // Test the Remove method. display(boxes); console::write_line("Removing 6x10x4"); boxes.remove(program::box {6, 10, 4}); display(boxes); // Test the Contains method. auto box_check = program::box {8, 12, 10}; console::write_line("Contains {}x{}x{} by dimensions: {}", box_check.height, box_check.length, box_check.width, boxes.contains(box_check)); // Test the Contains method overload with a specified equality comparer. console::write_line("Contains {}x{}x{} by volume: {}", box_check.height, box_check.length, box_check.width, boxes.contains(box_check, box_same_volume {})); } struct box : public object, public iequatable<program::box> { // Public Constructors : box() = default; box(int h, int l, int w) : height {h}, length{l}, width {w} {} // Public Properties : int height = 0; int length = 0; int width = 0; // Public Methods : bool equals(const object& o) const noexcept override {return is<program::box>(o) && equals(as<program::box>(o));} bool equals(const program::box& o) const noexcept override {return box_same_dimensions {}.equals(*this, o);} }; class box_collection : public icollection<program::box> { public: // Public Constructors : box_collection(const std::initializer_list<program::box>& boxes) : boxes_(boxes) {} // Public Properties : xtd::size count() const noexcept override {return boxes_.count();} bool is_read_only() const noexcept override {return false;} bool is_synchronized() const noexcept override {return false;} const object& sync_root() const noexcept override {return sync_root_;} // Public Methods : void add(const program::box& item) override { if (!contains(item)) boxes_.add(item); else console::write_line("A box with {}x{}x{} dimensions was already added to the collection.", item.height, item.length, item.width); } void clear() override {boxes_.clear();} bool contains(const program::box& item) const noexcept override {return boxes_.contains(item);} bool contains(const program::box& item, const iequality_comparer<program::box>& comparer) const noexcept { for (auto box : boxes_) if (comparer.equals(box, item)) return true; return false; } void copy_to(array<program::box>& array, xtd::size array_index) const override {boxes_.copy_to(array, array_index);} enumerator<program::box> get_enumerator() const override {return {new_ptr<box_enumerator>(boxes_)};} bool remove(const program::box& item) override {return boxes_.remove(item);} private: list<program::box> boxes_; object sync_root_; }; class box_enumerator : public ienumerator<program::box> { public: // Public Constructors : explicit box_enumerator(const list<program::box>& items) : items_(items) {} // Public Properties : const program::box& current() const override {return items_[index_];} // Public Methods : bool move_next() override {return ++index_ < items_.count();} void reset() override {index_ = size_object::max_value;} protected: const list<program::box>& items_; size index_ = size_object::max_value; }; // Defines two boxes as equal if they have the same dimensions. class box_same_dimensions : public iequality_comparer<program::box> { public: // Public Methods : bool equals(const program::box& b1, const program::box& b2) const noexcept override {return b1.height == b2.height && b1.length == b2.length && b1.width == b2.width;} size get_hash_code(const program::box& box) const noexcept override {return hash_code::combine(box.height, box.length, box.width);} }; // Defines two boxes as equal if they have the same volume. class box_same_volume : public iequality_comparer<program::box> { public: // Public Methods : bool equals(const program::box& b1, const program::box& b2) const noexcept override {return b1.height * b1.length * b1.width == b2.height * b2.length * b2.width;} size get_hash_code(const program::box& box) const noexcept override { auto hash_code = hash_code::combine(box.height, box.length, box.width); console::write_line("HC: {}", hash_code); return hash_code; } }; static void display(const box_collection& boxes) { console::write_line("\nheight length width hash code"); for (auto box : boxes) console::write_line("{,-6} {,-6} {,-6} {}", box.height, box.length, box.width, box.get_hash_code()); // Results by manipulating the enumerator directly: //auto enumerator = boxes.get_enumerator(); //console::write_line("\nheight length width hash code"); //while (enumerator.move_next()) { // auto b = enumerator.current(); // console::write_line("{,-6} {,-6} {,-6} {}", b.height, b.length, b.width, b.get_hash_code()); //} console::write_line(); } }; startup_(program::main); // This code can produce the following output : // // A box with 10x4x6 dimensions was already added to the collection. // // height length width hash code // 10 4 6 215240349697 // 4 6 10 215240349697 // 6 10 4 215240349697 // 12 8 10 215240349697 // // Removing 6x10x4 // // height length width hash code // 10 4 6 215240349697 // 4 6 10 215240349697 // 12 8 10 215240349697 // // Contains 8x12x10 by dimensions: false // Contains 8x12x10 by volume: true Remarks The xtd::collections::generic::icollection <type_t> interface is the base interface for classes in the xtd::collections::generic namespace. The xtd::collections::generic::icollection <type_t> interface extends xtd::collections::generic::ienumerable <type_t>; xtd::collections::generic::idictionary <key_t, value_t> and xtd::collections::generic::ilist <type_t> are more specialized interfaces that extend xtd::collections::generic::icollection <type_t>. A xtd::collections::generic::idictionary <key_t, value_t> implementation is a collection of key/value pairs, like the xtd::collections::generic::dictoinary <key_t, value_t> class. A xtd::collections::generic::ilist <type_t> implementation is a collection of values, and its members can be accessed by index, like the xtd::collections::generic::list <type_t> class. If neither the xtd::collections::generic::idictionary <key_t, value_t> interface nor the xtd::collections::generic::ilist <type_t> interface meet the requirements of the required collection, derive the new collection class from the xtd::collections::generic::icollection <type_t> interface instead for more flexibility. */ template<class type_t> class icollection : public xtd::collections::generic::ienumerable<type_t>, public xtd::collections::generic::extensions::collection_common<type_t, icollection<type_t >> { public: / /** Represents the xtd::collections::generic::icollection value type.
using	xtd::collections::generic::value_type

Public Properties
virtual auto	xtd::collections::generic::count () const noexcept -> xtd::size=0
	Gets the number of elements contained in the xtd::collections::generic::icollection <type_t>.
virtual auto	xtd::collections::generic::is_read_only () const noexcept -> bool=0
	Gets a value indicating whether the xtd::collections::generic::icollection <type_t> is read-only.
virtual auto	xtd::collections::generic::is_synchronized () const noexcept -> bool=0
	Gets a value indicating whether access to the xtd::collections::generic::icollection <type_t> is synchronized (thread safe).
virtual auto	xtd::collections::generic::sync_root () const noexcept -> const xtd::object &=0
	Gets an object that can be used to synchronize access to the the xtd::collections::generic::icollection <type_t>.

Public Methods
virtual auto	xtd::collections::generic::add (const type_t &item) -> void=0
	Adds an item to the xtd::collections::generic::icollection <type_t>.
virtual auto	xtd::collections::generic::clear () -> void=0
	Removes all items from the xtd::collections::generic::icollection <type_t>.
virtual auto	xtd::collections::generic::contains (const type_t &item) const noexcept -> bool=0
	Determines whether the xtd::collections::generic::icollection <type_t> contains a specific value.
virtual auto	xtd::collections::generic::copy_to (xtd::array< type_t > &array, xtd::size array_index) const -> void=0
	Copies the elements of the xtd::collections::generic::icollection <type_t> to an xtd::array, starting at a particular xtd::array index.
virtual auto	xtd::collections::generic::remove (const type_t &item) -> bool=0
	Removes the first occurrence of a specific object from the xtd::collections::generic::icollection <type_t>.