helios::utils::FilterAdapter< Iter, Pred > Class Template Reference

Iterator adapter that filters elements based on a predicate function. More...

#include <functional_adapters.hpp>

Inheritance diagram for helios::utils::FilterAdapter< Iter, Pred >:

Public Types
using	iterator_concept = details::adapter_iterator_concept_t<Iter>
using	iterator_category = details::adapter_iterator_category_t<Iter>
using	value_type = std::iter_value_t<Iter>
using	reference = value_type
using	pointer = void
using	difference_type = std::iter_difference_t<Iter>

Public Member Functions
constexpr	FilterAdapter (Iter begin, Iter end, Pred predicate) noexcept(std::is_nothrow_copy_constructible_v< Iter > &&std::is_nothrow_move_constructible_v< Iter > &&std::is_nothrow_move_constructible_v< Pred > &&noexcept(AdvanceToValid()))
	Constructs a filter adapter with the given iterator range and predicate.
template<ExternalRange R> requires FilterAdapterRequirements<std::ranges::iterator_t<R>, Pred>
constexpr	FilterAdapter (R &range, Pred predicate) noexcept(noexcept(FilterAdapter(std::ranges::begin(range), std::ranges::end(range), std::move(predicate))))
	Constructs a filter adapter from a range.
template<ExternalRange R> requires FilterAdapterRequirements<std::ranges::iterator_t<const R>, Pred>
constexpr	FilterAdapter (const R &range, Pred predicate) noexcept(noexcept(FilterAdapter(std::ranges::cbegin(range), std::ranges::cend(range), std::move(predicate))))
	Constructs a filter adapter from a const range.
constexpr	FilterAdapter (const FilterAdapter &) noexcept(std::is_nothrow_copy_constructible_v< Iter > &&std::is_nothrow_copy_constructible_v< Pred >)=default
constexpr	FilterAdapter (FilterAdapter &&) noexcept(std::is_nothrow_move_constructible_v< Iter > &&std::is_nothrow_move_constructible_v< Pred >)=default
constexpr	~FilterAdapter () noexcept(std::is_nothrow_destructible_v< Iter > &&std::is_nothrow_destructible_v< Pred >)=default
constexpr FilterAdapter &	operator= (const FilterAdapter &) noexcept(std::is_nothrow_copy_assignable_v< Iter > &&std::is_nothrow_copy_assignable_v< Pred >)=default
constexpr FilterAdapter &	operator= (FilterAdapter &&) noexcept(std::is_nothrow_move_assignable_v< Iter > &&std::is_nothrow_move_assignable_v< Pred >)=default
constexpr FilterAdapter &	operator++ () noexcept(noexcept(++std::declval< Iter & >()) &&noexcept(AdvanceToValid()))
constexpr FilterAdapter	operator++ (int) noexcept(std::is_nothrow_copy_constructible_v< FilterAdapter > &&noexcept(++std::declval< FilterAdapter & >()))
constexpr reference	operator* () const noexcept(noexcept(*std::declval< const Iter & >()))
pointer	operator-> () const =delete
constexpr bool	operator== (const FilterAdapter &other) const noexcept(noexcept(std::declval< const Iter & >()==std::declval< const Iter & >()))
constexpr bool	operator!= (const FilterAdapter &other) const noexcept(noexcept(std::declval< const FilterAdapter & >()==std::declval< const FilterAdapter & >()))
constexpr bool	IsAtEnd () const noexcept(noexcept(std::declval< const Iter & >()==std::declval< const Iter & >()))
	Checks if the iterator has reached the end.
constexpr FilterAdapter	begin () const noexcept(std::is_nothrow_copy_constructible_v< FilterAdapter >)
constexpr FilterAdapter	end () const noexcept(std::is_nothrow_constructible_v< FilterAdapter, const Iter &, const Iter &, const Pred & >)
Public Member Functions inherited from helios::utils::FunctionalAdapterBase< FilterAdapter< Iter, Pred > >
constexpr auto	Filter (Pred predicate) const noexcept(noexcept(FilterAdapter< Derived, Pred >(GetDerived().begin(), GetDerived().end(), std::move(predicate))))
	Chains another filter operation on top of this iterator.
constexpr auto	Map (Func transform) const noexcept(noexcept(MapAdapter< FilterAdapter< Iter, Pred >, Func >(GetDerived().begin(), GetDerived().end(), std::move(transform))))
	Transforms each element using the given function.
constexpr auto	Take (size_t count) const noexcept(noexcept(TakeAdapter< FilterAdapter< Iter, Pred > >(GetDerived().begin(), GetDerived().end(), count)))
	Limits the number of elements to at most count.
constexpr auto	Skip (size_t count) const noexcept(noexcept(SkipAdapter< FilterAdapter< Iter, Pred > >(GetDerived().begin(), GetDerived().end(), count)))
	Skips the first count elements.
constexpr auto	TakeWhile (Pred predicate) const noexcept(noexcept(TakeWhileAdapter< FilterAdapter< Iter, Pred >, Pred >(GetDerived().begin(), GetDerived().end(), std::move(predicate))))
	Takes elements while a predicate is true.
constexpr auto	SkipWhile (Pred predicate) const noexcept(noexcept(SkipWhileAdapter< FilterAdapter< Iter, Pred >, Pred >(GetDerived().begin(), GetDerived().end(), std::move(predicate))))
	Skips elements while a predicate is true.
constexpr auto	Enumerate () const noexcept(noexcept(EnumerateAdapter< FilterAdapter< Iter, Pred > >(GetDerived().begin(), GetDerived().end())))
	Adds an index to each element.
constexpr auto	Inspect (Func inspector) const noexcept(noexcept(InspectAdapter< FilterAdapter< Iter, Pred >, Func >(GetDerived().begin(), GetDerived().end(), std::move(inspector))))
	Observes each element without modifying it.
constexpr auto	StepBy (size_t step) const noexcept(noexcept(StepByAdapter< FilterAdapter< Iter, Pred > >(GetDerived().begin(), GetDerived().end(), step)))
	Takes every Nth element.
constexpr auto	Chain (OtherIter begin, OtherIter end) const noexcept(noexcept(ChainAdapter< FilterAdapter< Iter, Pred >, OtherIter >(GetDerived().begin(), GetDerived().end(), std::move(begin), std::move(end))))
	Chains another range after this one.
constexpr auto	Reverse () const noexcept(noexcept(ReverseAdapter< FilterAdapter< Iter, Pred > >(GetDerived().begin(), GetDerived().end())))
	Reverses the order of elements.
constexpr auto	Slide (size_t window_size) const noexcept(noexcept(SlideAdapter< FilterAdapter< Iter, Pred > >(GetDerived().begin(), GetDerived().end(), window_size)))
	Creates sliding windows over elements.
constexpr auto	Stride (size_t stride) const noexcept(noexcept(StrideAdapter< FilterAdapter< Iter, Pred > >(GetDerived().begin(), GetDerived().end(), stride)))
	Takes every Nth element with stride.
constexpr auto	Zip (OtherIter begin, OtherIter end) const noexcept(noexcept(ZipAdapter< FilterAdapter< Iter, Pred >, OtherIter >(GetDerived().begin(), GetDerived().end(), std::move(begin), std::move(end))))
	Zips another range with this one.
constexpr void	ForEach (const Action &action) const
	Terminal operation: applies an action to each element.
constexpr T	Fold (T init, const Folder &folder) const
	Terminal operation: reduces elements to a single value using a folder function.
constexpr auto	Find (const Pred &predicate) const
	Terminal operation: finds the first element satisfying a predicate.
constexpr size_t	CountIf (const Pred &predicate) const
	Terminal operation: counts elements satisfying a predicate.
constexpr auto	Partition (const Pred &predicate) const
	Terminal operation: partitions elements into two groups based on a predicate.
constexpr auto	PartitionWith (const Pred &predicate, Allocator allocator) const
	Terminal operation: partitions elements with a custom allocator.
constexpr auto	MaxBy (const KeyFunc &key_func) const
	Terminal operation: finds the element with the maximum value according to a key function.
constexpr auto	MinBy (const KeyFunc &key_func) const
	Terminal operation: finds the element with the minimum value according to a key function.
constexpr auto	GroupBy (const KeyFunc &key_func) const
	Terminal operation: groups elements by a key function.
constexpr auto	GroupByWith (const KeyFunc &key_func, MapAllocator map_allocator, ValueAllocator value_allocator) const
	Terminal operation: groups elements by key with custom allocators.
constexpr auto	Collect () const
	Terminal operation: collects all elements into a vector.
constexpr auto	CollectWith (Allocator allocator={}) const
	Terminal operation: collects all elements into a vector with a custom allocator.
constexpr void	Into (OutIt out) const
	Terminal operation: writes all elements into an output iterator.
constexpr bool	Any (const Pred &predicate) const
	Terminal operation: checks if any element satisfies a predicate.
constexpr bool	All (const Pred &predicate) const
	Terminal operation: checks if all elements satisfy a predicate.
constexpr bool	None (const Pred &predicate) const
	Terminal operation: checks if no elements satisfy a predicate.

Additional Inherited Members
Protected Member Functions inherited from helios::utils::FunctionalAdapterBase< FilterAdapter< Iter, Pred > >
constexpr FilterAdapter< Iter, Pred > &	GetDerived () noexcept
	Gets reference to derived class instance.

Detailed Description

template<typename Iter, typename Pred>
requires FilterAdapterRequirements<Iter, Pred>
class helios::utils::FilterAdapter< Iter, Pred >

Iterator adapter that filters elements based on a predicate function.

This adapter provides lazy filtering of iterator values. The filtering happens during iteration, not upfront, making it memory efficient for large sequences.

Supports chaining with other adapters for complex data transformations.

Note

This adapter maintains forward iterator semantics.

The adapter is constexpr-compatible for compile-time evaluation.

Template Parameters

Iter	Underlying iterator type that satisfies IteratorLike concept
Pred	Predicate function type

auto enemies = query.Filter([](const Health& h) {
  return h.points > 0;
});

Definition at line 475 of file functional_adapters.hpp.

Member Typedef Documentation

difference_type

template<typename Iter, typename Pred>

using helios::utils::FilterAdapter< Iter, Pred >::difference_type = std::iter_difference_t<Iter>

Definition at line 483 of file functional_adapters.hpp.

iterator_category

template<typename Iter, typename Pred>

using helios::utils::FilterAdapter< Iter, Pred >::iterator_category = details::adapter_iterator_category_t<Iter>

Definition at line 479 of file functional_adapters.hpp.

iterator_concept

template<typename Iter, typename Pred>

using helios::utils::FilterAdapter< Iter, Pred >::iterator_concept = details::adapter_iterator_concept_t<Iter>

Definition at line 478 of file functional_adapters.hpp.

pointer

template<typename Iter, typename Pred>

using helios::utils::FilterAdapter< Iter, Pred >::pointer = void

Definition at line 482 of file functional_adapters.hpp.

reference

template<typename Iter, typename Pred>

using helios::utils::FilterAdapter< Iter, Pred >::reference = value_type

Definition at line 481 of file functional_adapters.hpp.

value_type

template<typename Iter, typename Pred>

using helios::utils::FilterAdapter< Iter, Pred >::value_type = std::iter_value_t<Iter>

Definition at line 480 of file functional_adapters.hpp.

Constructor & Destructor Documentation

FilterAdapter() [1/5]

template<typename Iter, typename Pred>

helios::utils::FilterAdapter< Iter, Pred >::FilterAdapter ( Iter begin, Iter end, Pred predicate )

inlineconstexprnoexcept

Constructs a filter adapter with the given iterator range and predicate.

Parameters

begin	Start of the iterator range
end	End of the iterator range
predicate	Function to filter elements

Definition at line 492 of file functional_adapters.hpp.

FilterAdapter() [2/5]

template<typename Iter, typename Pred>

template<ExternalRange R>
requires FilterAdapterRequirements<std::ranges::iterator_t<R>, Pred>

helios::utils::FilterAdapter< Iter, Pred >::FilterAdapter ( R & range, Pred predicate )

inlineconstexprnoexcept

Constructs a filter adapter from a range.

Template Parameters

R	Range type

Parameters

range	Range to filter
predicate	Function to filter elements

Definition at line 511 of file functional_adapters.hpp.

FilterAdapter() [3/5]

template<typename Iter, typename Pred>

template<ExternalRange R>
requires FilterAdapterRequirements<std::ranges::iterator_t<const R>, Pred>

helios::utils::FilterAdapter< Iter, Pred >::FilterAdapter ( const R & range, Pred predicate )

inlineconstexprnoexcept

Constructs a filter adapter from a const range.

Template Parameters

R	Range type

Parameters

range	Range to filter
predicate	Function to filter elements

Definition at line 525 of file functional_adapters.hpp.

FilterAdapter() [4/5]

template<typename Iter, typename Pred>

helios::utils::FilterAdapter< Iter, Pred >::FilterAdapter ( const FilterAdapter< Iter, Pred > & ) const &&

constexprdefaultnoexcept

FilterAdapter() [5/5]

template<typename Iter, typename Pred>

helios::utils::FilterAdapter< Iter, Pred >::FilterAdapter ( FilterAdapter< Iter, Pred > && ) const &&

constexprdefaultnoexcept

~FilterAdapter()

template<typename Iter, typename Pred>

helios::utils::FilterAdapter< Iter, Pred >::~FilterAdapter ( ) &&

constexprdefaultnoexcept

Member Function Documentation

begin()

template<typename Iter, typename Pred>

FilterAdapter helios::utils::FilterAdapter< Iter, Pred >::begin ( ) const

inlinenodiscardconstexprnoexcept

Definition at line 583 of file functional_adapters.hpp.

end()

template<typename Iter, typename Pred>

FilterAdapter helios::utils::FilterAdapter< Iter, Pred >::end ( ) const

inlinenodiscardconstexprnoexcept

Definition at line 588 of file functional_adapters.hpp.

IsAtEnd()

template<typename Iter, typename Pred>

bool helios::utils::FilterAdapter< Iter, Pred >::IsAtEnd ( ) const

inlinenodiscardconstexprnoexcept

Checks if the iterator has reached the end.

Returns

True if at end, false otherwise

Definition at line 577 of file functional_adapters.hpp.

operator!=()

template<typename Iter, typename Pred>

bool helios::utils::FilterAdapter< Iter, Pred >::operator!= ( const FilterAdapter< Iter, Pred > & other ) const

inlinenodiscardconstexprnoexcept

Definition at line 567 of file functional_adapters.hpp.

operator*()

template<typename Iter, typename Pred>

reference helios::utils::FilterAdapter< Iter, Pred >::operator* ( ) const

inlinenodiscardconstexprnoexcept

Definition at line 554 of file functional_adapters.hpp.

operator++() [1/2]

template<typename Iter, typename Pred>
requires FilterAdapterRequirements<Iter, Pred>

auto helios::utils::FilterAdapter< Iter, Pred >::operator++ ( )

constexprnoexcept

Definition at line 615 of file functional_adapters.hpp.

operator++() [2/2]

template<typename Iter, typename Pred>
requires FilterAdapterRequirements<Iter, Pred>

auto helios::utils::FilterAdapter< Iter, Pred >::operator++ ( int )

nodiscardconstexprnoexcept

Definition at line 625 of file functional_adapters.hpp.

operator->()

template<typename Iter, typename Pred>

pointer helios::utils::FilterAdapter< Iter, Pred >::operator-> ( ) const

delete

operator=() [1/2]

template<typename Iter, typename Pred>

FilterAdapter & helios::utils::FilterAdapter< Iter, Pred >::operator= ( const FilterAdapter< Iter, Pred > & ) &&

constexprdefaultnoexcept

operator=() [2/2]

template<typename Iter, typename Pred>

FilterAdapter & helios::utils::FilterAdapter< Iter, Pred >::operator= ( FilterAdapter< Iter, Pred > && ) &&

constexprdefaultnoexcept

operator==()

template<typename Iter, typename Pred>

bool helios::utils::FilterAdapter< Iter, Pred >::operator== ( const FilterAdapter< Iter, Pred > & other ) const

inlinenodiscardconstexprnoexcept

Definition at line 561 of file functional_adapters.hpp.