xtd::collections::generic::enumerable_generator< type_t > Class Template Reference

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

Definition

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

Represents an enumerable generator that supports deferred, lazy iteration over a collection of a specified type using C++20 coroutines.

Definition

template<typename type_t>
class enumerable_generator : public xtd::collections::generic::ienumerable<type_t>

Header

#include <xtd/collections/generic/enumerable_generator>

Namespace

xtd::collections::generic

Library

xtd.core

Examples

The following example demonstrates how to create and consume an xtd::collections::generic::enumerable_generator <type_t> using the co_yield keyword and LINQ pipeline operators.

#include <xtd/xtd>
 
[[nodiscard]] auto odd_numbers_generator(int count = 100, int min_value = 0, int max_value = 100) -> enumerable_generator<int> {
  auto rnd = xtd::random {};
  for (auto __ : range(count))
    co_yield rnd.next(min_value, max_value) | 1;
}
 
auto main() -> int {
  println("Odd numbers : ");
  for (auto number : odd_numbers_generator().where(_ % 5 == 0).distinct().order_by(_))
    println("{,4}", number);
  println("Done!");
}
 
// This code can produce the following output :
//
// Odd numbers :
//    5
//   25
//   45
//   55
//   65
//   75
//   85
//   95
// Done!

Remarks

xtd::collections::generic::enumerable_generator <type_t> acts as a stream-like, lazy-evaluated data source. It leverages the C++20 coroutine standard to suspend and resume execution on-demand whenever an element is requested by an iterator or an enumerator.

Because it wraps an ephemeral coroutine frame state, an xtd::collections::generic::enumerable_generator <type_t> is a single-pass stream. It cannot be copied, only moved. Multiple iterators active at the same time on the same generator will advance and consume the exact same underlying state stream.

Tenting to invoke the xtd::collections::generic::ienumerator::reset method on a generator's enumerator will systematically throw an xtd::not_supported_exception, as coroutine execution states cannot be rewound.

Classes
struct	promise_type
	The promise type required by the C++20 coroutine standard to manage the state and lifecycle of the enumerable_generator. More...

Public Methods
xtd::collections::generic::enumerator< type_t >	get_enumerator () const override
	Returns an enumerator that iterates through the xtd::collections::generic::enumerable_generator.
auto	to_string () const -> xtd::string override
	Returns a xtd::string that represents the current object.

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	value_type
	Represents the ienumerable value type.
using	ienumerable
	Represents the ienumerable value type.
using	list
	Represents the list value type.
	object ()=default
	Create a new instance of the ultimate base class object.
virtual auto	equals (const object &obj) const noexcept -> bool
	Determines whether the specified object is equal to the current object.
virtual auto	get_hash_code () const noexcept -> xtd::usize
	Serves as a hash function for a particular type.
virtual auto	get_type () const noexcept -> type_object
	Gets the type of the current instance.
template<typename object_t>
auto	memberwise_clone () const -> xtd::unique_ptr_object< object_t >
	Creates a shallow copy of the current object.
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 (func_t &&funcfunc) const -> type_t
	Applies an accumulator function over a sequence.
auto	all (predicate_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 (element_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 value_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 (second_t &&second) const noexcept
	Concatenates two sequences.
auto	contains (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 (key_selector_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 (predicate_t &&predicatepredicate, 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	max (selector_t &&selector) const
auto	min (auto &&selector) const
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 -> xtd::array< type_t >
	Creates a xtd::array <type_t> from an xtd::collections::generic::ienumerable <type_t>.
auto	to_list () const -> 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.
template<typename object_a_t, typename object_b_t>
static auto	equals (const object_a_t &object_a, const object_b_t &object_b) noexcept -> bool
	Determines whether the specified object instances are considered equal.
template<typename object_a_t, typename object_b_t>
static auto	reference_equals (const object_a_t &object_a, const object_b_t &object_b) noexcept -> bool
	Determines whether the specified object instances are the same instance.
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 Function Documentation

get_enumerator()

template<typename type_t>

xtd::collections::generic::enumerator< type_t > xtd::collections::generic::enumerable_generator< type_t >::get_enumerator ( ) const

inlineoverridevirtual

Returns an enumerator that iterates through the xtd::collections::generic::enumerable_generator.

Returns

An xtd::collections::generic::enumerator object that can be used to iterate through the xtd::collections::generic::enumerable_generator <type_t>.

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

to_string()

template<typename type_t>

auto xtd::collections::generic::enumerable_generator< type_t >::to_string ( ) const -> xtd::string

nodiscardoverridevirtual

Returns a xtd::string that represents the current object.

Returns

A string that represents the current object.

Reimplemented from xtd::object.

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

• xtd.core/include/xtd/collections/generic/enumerable_generator.hpp