Inheritance diagram for xtd::collections::generic::icollection< type_t >:

Definition

template<typename type_t>
class xtd::collections::generic::icollection< type_t >

Defines methods to manipulate generic collections.

Definition: template<typename type_t>

class icollection : public xtd::collections::generic::ienumerable<type_t>, public xtd::collections::generic::extensions::collection_common<type_t, icollection<type_t>>;

xtd::collections::generic::extensions::collection_common
Internal collection common definition.
Definition collection_common.hpp:32

xtd::collections::generic::icollection
Defines methods to manipulate generic collections.
Definition icollection.hpp:45

xtd::collections::generic::ienumerable
Exposes the enumerator, which supports a simple iteration over a collection of a specified type.
Definition ienumerable.hpp:40

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 :
    usize 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, usize 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_ = usize_object::max_value;}
    
  protected:
    const list<program::box>& items_;
    usize index_ = usize_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;}
    
    usize 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;}
    
    usize 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.

Public Aliases
using	value_type
	Represents the xtd::collections::generic::icollection value type.

Public Properties
virtual auto	count () const noexcept -> xtd::usize=0
	Gets the number of elements contained in the xtd::collections::generic::icollection <type_t>.
virtual auto	is_read_only () const noexcept -> bool=0
	Gets a value indicating whether the xtd::collections::generic::icollection <type_t> is read-only.
virtual auto	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	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	add (const type_t &item) -> void=0
	Adds an item to the xtd::collections::generic::icollection <type_t>.
virtual auto	clear () -> void=0
	Removes all items from the xtd::collections::generic::icollection <type_t>.
virtual auto	contains (const type_t &item) const noexcept -> bool=0
	Determines whether the xtd::collections::generic::icollection <type_t> contains a specific value.
virtual auto	copy_to (xtd::array< type_t > &array, xtd::usize 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	get_enumerator () const -> xtd::collections::generic::enumerator< type_t >=0
	Returns an enumerator that iterates through a collection.
virtual auto	remove (const type_t &item) -> bool=0
	Removes the first occurrence of a specific object from the xtd::collections::generic::icollection <type_t>.

Additional Inherited Members
using	value_type
	Represents the xtd::collections::generic::ienumerable value type.
using	iterator
	Represents the iterator of xtd::collections::generic::ienumerable value type.
using	const_iterator
	Represents the const iterator of xtd::collections::generic::ienumerable value type.
using	iterator
	Represents the iterator of enumerable value type.
using	const_iterator
	Represents the const iterator of enumerable value type.
using	enumerable_type
	Represents the ienumerable enumerable type.
using	source_type
	Represents the ienumerable source type.
using	ienumerable
	Represents the ienumerable value type.
using	list
	Represents the list value type.
virtual auto	begin () const -> const_iterator
	Returns an iterator to the first element of the enumerable.
virtual auto	cbegin () const -> const_iterator
	Returns an iterator to the first element of the enumerable.
virtual auto	cend () const -> const_iterator
	Returns an iterator to the element following the last element of the enumerable.
virtual auto	end () const -> const_iterator
	Returns an iterator to the element following the last element of the enumerable.
auto	aggregate (const std::function< type_t(const type_t &, const type_t &)> &funcfunc) const -> type_t
	Applies an accumulator function over a sequence.
auto	all (const std::function< bool(const type_t &)> &predicatepredicate) const -> bool
	Determines whether all elements of a sequence satisfy a condition.
auto	any () const noexcept -> bool
	Determines whether a sequence contains any elements.
auto	append (const type_t &element) const noexcept
	Appends a value to the end of the sequence.
auto	as_enumerable () const noexcept
	Returns the input typed as xtd::collections::generic::ienumerable <type_t>.
auto	average () const noexcept
	Computes the average of a sequence of source_t values.
auto	cast () const noexcept
	Casts the elements of an xtd::collections::generic::ienumerable to the specified type.
auto	chunk (xtd::usize size) const
	Splits the elements of a sequence into chunks of size at most size.
auto	concat (const ienumerable< type_t > &second) const noexcept
	Concatenates two sequences.
auto	contains (const type_t &value) const noexcept -> bool
	Determines whether a sequence contains a specified element by using the default equality comparer.
auto	count () const noexcept -> xtd::usize
	Returns the number of elements in current sequence.
auto	count_by (const std::function< key_t(const type_t &)> &key_selector) const noexcept
	Returns the count of elements in the current sequence grouped by key.
auto	default_if_empty () const noexcept
	Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the current sequence is empty.
auto	distinct () const noexcept
	Returns distinct elements from a sequence by using the default equality comparer to compare values.
auto	first_or_default (const std::function< bool(const type_t &)> &predicatepredicate, const type_t &default_value) const noexcept -> type_t
	Returns the first element of the sequence that satisfies a condition, or a specified default value if no such element is found.
auto	order () const
	Sorts the elements of a sequence in ascending order.
auto	order_by (const std::function< type_t(const type_t &)> &key_selector) const
	Sorts the elements of a sequence in ascending order according to a key.
auto	order_by_descending (const std::function< key_t(const type_t &)> &key_selector) const
	Sorts the elements of a sequence in descending order according to a key.
auto	select (auto &&selector) const
	Projects each element of a sequence into a new form.
auto	to_array () const noexcept -> xtd::array< type_t >
	Creates a xtd::array <type_t> from an xtd::collections::generic::ienumerable <type_t>.
auto	to_list () const noexcept -> xtd::collections::generic::list< type_t >
	Creates a xtd::collections::generic::list <type_t> from an xtd::collections::generic::ienumerable <type_t>.
auto	where (auto &&predicatepredicate) const
	Filters a sequence of values based on a predicate.
virtual auto	empty () const noexcept -> bool
	Checks whether the container is empty.
virtual auto	size () const noexcept -> xtd::usize
	Gets the number of elements contained in the xtd::collections::generic::icollection <type_t>.
virtual auto	operator<< (const type_t &item) -> icollection< type_t > &
	The shift left operator adds an item to the xtd::collections::generic::icollection <type_t>.
virtual auto	operator>> (const type_t &item) -> icollection< type_t > &
	The shift right operator removes the first occurrence of a specific object from the xtd::collections::generic::icollection <type_t>.
static auto	to_const_iterator (typename source_collection_t::const_iterator &value, const source_collection_t &source_collection, const target_collection_t &target_collection) noexcept -> typename target_collection_t::const_iterator
	Converts source iterator to target iterator.
static auto	to_iterator (typename source_collection_t::const_iterator &value, const source_collection_t &source_collection, const target_collection_t &target_collection) noexcept -> typename target_collection_t::const_iterator
	Converts source iterator to target iterator.

Member Typedef Documentation

◆ value_type

template<typename type_t>

using xtd::collections::generic::icollection< type_t >::value_type

Represents the xtd::collections::generic::icollection value type.

Member Function Documentation

◆ count()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::count ( ) const -> xtd::usize

nodiscardpure virtualnoexcept

Gets the number of elements contained in the xtd::collections::generic::icollection <type_t>.

Returns: The number of elements contained in the xtd::collections::generic::icollection <type_t>.

◆ is_read_only()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::is_read_only ( ) const -> bool

nodiscardpure virtualnoexcept

Gets a value indicating whether the xtd::collections::generic::icollection <type_t> is read-only.

Returns: true if the xtd::collections::generic::icollection <type_t> is read-only; otherwise, false.

Remarks: A collection that is read-only does not allow the addition or removal of elements after the collection is created. Note that read-only in this context does not indicate whether individual elements of the collection can be modified, since the xtd::collections::generic::icollection <type_t> interface only supports addition and removal operations. For example, the xtd::collections::generic::icollection::is_read_only property of an array that is cast or converted to an xtd::collections::generic::icollection <type_t> object returns true, even though individual array elements can be modified.

◆ is_synchronized()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::is_synchronized ( ) const -> bool

nodiscardpure virtualnoexcept

Gets a value indicating whether access to the xtd::collections::generic::icollection <type_t> is synchronized (thread safe).

Returns: true if access to the xtd::collections::generic::icollection <type_t> is synchronized (thread safe); otherwise, false.

Remarks: xtd::collections::generic::icollection::sync_root returns an object, which can be used to synchronize access to the xtd::collections::generic::icollection <type_t>.; Most collection classes in the xtd::collections namespace also implement a synchronized method, which provides a synchronized wrapper around the underlying collection.; Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.; The following code example shows how to lock the collection using the xtd::collections::generic::icollection::sync_root property during the entire enumeration.
icollection& my_collection = some_collection;

lock_(my_collection.sync_root()) {

for (const auto& item : my_collection) {

// Insert your code here.

}

}

xtd::collections::generic::icollection::sync_root
virtual auto sync_root() const noexcept -> const xtd::object &=0
Gets an object that can be used to synchronize access to the the xtd::collections::generic::icollecti...

lock_
#define lock_(object)
The lock_ keyword marks a statement block as a critical section by obtaining the mutual-exclusion loc...
Definition lock.hpp:68

◆ sync_root()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::sync_root ( ) const -> const xtd::object &

nodiscardpure virtualnoexcept

Gets an object that can be used to synchronize access to the the xtd::collections::generic::icollection <type_t>.

Returns: An object that can be used to synchronize access to the the xtd::collections::generic::icollection <type_t>.

Remarks: For collections whose underlying store is not publicly available, the expected implementation is to return the current instance. Note that the pointer to the current instance might not be sufficient for collections that wrap other collections; those should return the underlying collection's sync_root property.; Most collection classes in the xts::.collections namespace also implement a synchronized method, which provides a synchronized wrapper around the underlying collection. However, derived classes can provide their own synchronized version of the collection using the xtd::collections::generic::icollection::sync_root property. The synchronizing code must perform operations on the xtd::collections::generic::icollection::sync_root property of the collection, not directly on the collection. This ensures proper operation of collections that are derived from other objects. Specifically, it maintains proper synchronization with other threads that might be simultaneously modifying the collection instance.; In the absence of a synchronized method on a collection, the expected usage for the xtd::collections::generic::icollection::sync_root looks as follows:
icollection& my_collection = some_collection;

lock_(my_collection.sync_root()) {

// Some operation on the collection, which is now thread safe.

}

@encode

@remarks Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

@remarks The following code example shows how to lock the collection using the xtd::collections::generic::icollection::sync_root property during the entire enumeration.

@code

icollection& my_collection = some_collection;

lock_(my_collection.sync_root()) {

for (const auto& item : my_collection) {

// Insert your code here.

}

}

xtd::exception
Defines the base class for predefined exceptions in the xtd namespace.
Definition exception.hpp:29

xtd::enumeration
Definition enumeration.hpp:12

xtd::is
auto is(xtd::any value) -> bool
Checks if the result of an expression is compatible with a given type.
Definition is.hpp:485

xtd::platform_id::other
@ other
The operating system is other.
Definition platform_id.hpp:60

xtd::console_key::a
@ a
The A key.
Definition console_key.hpp:88

xtd::collections::generic::enumerator
Supports a simple iteration over a generic collection.
Definition enumerator.hpp:39

◆ add()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::add ( const type_t & item ) -> void

pure virtual

Adds an item to the xtd::collections::generic::icollection <type_t>.

Parameters

item	The object to add to the xtd::collections::generic::icollection <type_t>.

Exceptions

xtd::not_supported_exception The xtd::collections::generic::icollection <type_t> is read-only.

◆ clear()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::clear ( ) -> void

pure virtual

Removes all items from the xtd::collections::generic::icollection <type_t>.

Exceptions

xtd::not_supported_exception The xtd::collections::generic::icollection <type_t> is read-only.

Remarks: xtd::collections::generic::icollection::count must be set to 0, and references to other objects from elements of the collection must be released.

◆ contains()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::contains ( const type_t & item ) const -> bool

nodiscardpure virtualnoexcept

Determines whether the xtd::collections::generic::icollection <type_t> contains a specific value.

Parameters

item	The object to locate in the xtd::collections::generic::icollection <type_t>.

Returns: true if item is found in the xtd::collections::generic::icollection <type_t>; otherwise, false.

Remarks: Implementations can vary in how they determine equality of objects; for example, xtd::collections::generic::list <type_t> uses xtd::collections::generic::compoarer <type_t>::default_comparer, whereas xtd::collections::generic::dictionary <key_t, value_t> allows the user to specify the xtd::collections::generic::icompoarer <type_t> implementation to use for comparing keys.

◆ copy_to()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::copy_to	(	xtd::array< type_t > &	array,
		xtd::usize	array_index ) const -> void

pure virtual

Copies the elements of the xtd::collections::generic::icollection <type_t> to an xtd::array, starting at a particular xtd::array index.

Parameters

array	The one-dimensional xtd::array that is the destination of the elements copied from xtd::collections::generic::icollection <type_t>. The xtd::array must have zero-based indexing.
array_index	The zero-based index in array at which copying begins.

Exceptions

xtd::argument_exception The number of elements in the source xtd::collections::generic::icollection <type_t> is greater than the available space from `array_index` to the end of the destination `array`.

◆ get_enumerator()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::get_enumerator ( ) const -> xtd::collections::generic::enumerator< type_t >

nodiscardpure virtual

Returns an enumerator that iterates through a collection.

Returns: An xtd::collections::generic::enumerator object that can be used to iterate through the collection.

Implements xtd::collections::generic::ienumerable< type_t >.

◆ remove()

template<typename type_t>

virtual auto xtd::collections::generic::icollection< type_t >::remove ( const type_t & item ) -> bool

pure virtual

Removes the first occurrence of a specific object from the xtd::collections::generic::icollection <type_t>.

Parameters

item	The object to remove from the xtd::collections::generic::icollection <type_t>.

Returns: true if item was successfully removed from the xtd::collections::generic::icollection <type_t>; otherwise, false. This method also returns false if item is not found in the original xtd::collections::generic::icollection <type_t>.

Exceptions

xtd::not_supported_exception The xtd::collections::generic::icollection <type_t> is read-only.

Remarks: Implementations can vary in how they determine equality of objects; for example, xtd::collections::generic::list <type_t> uses xtd::collections::generic::compoarer <type_t>::default_comparer, whereas, xtd::collections::generic::dictionary <key_t, value_t> allows the user to specify the xtd::collections::generic::icompoarer <type_t> implementation to use for comparing keys.; In collections of contiguous elements, such as lists, the elements that follow the removed element move up to occupy the vacated spot. If the collection is indexed, the indexes of the elements that are moved are also updated. This behavior does not apply to collections where elements are conceptually grouped into buckets, such as a hash table.

The documentation for this class was generated from the following file:

xtd.core/include/xtd/collections/generic/icollection.hpp

Definition

Public Aliases

Public Properties

Public Methods

Additional Inherited Members

Member Typedef Documentation

◆ value_type

Member Function Documentation

◆ count()

◆ is_read_only()

◆ is_synchronized()

◆ sync_root()

◆ add()

◆ clear()

◆ contains()

◆ copy_to()

◆ get_enumerator()

◆ remove()