CachingIterable<E> class

A lazy caching version of Iterable.

This iterable is efficient in the following ways:

  • It will not walk the given iterator more than you ask for.

  • If you use it twice (e.g. you check isNotEmpty, then use single), it will only walk the given iterator once. This caching will even work efficiently if you are running two side-by-side iterators on the same iterable.

  • toList uses its EfficientLength variant to create its list quickly.

It is inefficient in the following ways:

  • The first iteration through has caching overhead.

  • It requires more memory than a non-caching iterator.

  • The length and toList properties immediately pre-cache the entire list. Using these fields therefore loses the laziness of the iterable. However, it still gets cached.

The caching behavior is propagated to the iterators that are created by map, where, expand, take, takeWhile, skip, and skipWhile, and is used by the built-in methods that use an iterator like isNotEmpty and single.

Because a CachingIterable only walks the underlying data once, it cannot be used multiple times with the underlying data changing between each use. You must create a new iterable each time. This also applies to any iterables derived from this one, e.g. as returned by where.

Inheritance
Available extensions

Constructors

CachingIterable.new(Iterator<E> _prefillIterator)
Creates a CachingIterable using the given Iterator as the source of data. The iterator must be non-null and must not throw exceptions.

Properties

first → E
The first element.
no setterinherited
firstOrNull → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The first element of this iterator, or null if the iterable is empty.
no setter
hashCode → int
The hash code for this object.
no setterinherited
indexed → Iterable<(int, T)>

Available on Iterable<T>, provided by the IterableExtensions extension

Pairs of elements of the indices and elements of this iterable.
no setter
isEmpty → bool
Whether this collection has no elements.
no setterinherited
isNotEmpty → bool
Whether this collection has at least one element.
no setterinherited
iterator → Iterator<E>
A new Iterator that allows iterating the elements of this Iterable.
no setteroverride
last → E
The last element.
no setterinherited
lastOrNull → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The last element of this iterable, or null if the iterable is empty.
no setter
length → int
The number of elements in this Iterable.
no setteroverride
nonNulls → Iterable<T>

Available on Iterable<T?>, provided by the NullableIterableExtensions extension

The non-null elements of this iterable.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
single → E
Checks that this iterable has only one element, and returns that element.
no setterinherited
singleOrNull → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The single element of this iterator, or null.
no setter
wait → Future<List<T>>

Available on Iterable<Future<T>>, provided by the FutureIterable extension

Waits for futures in parallel.
no setter

Methods

any(bool test(E element)) → bool
Checks whether any element of this iterable satisfies test.
inherited
asNameMap() → Map<String, T>

Available on Iterable<T>, provided by the EnumByName extension

Creates a map from the names of enum values to the values.
byName(String name) → T

Available on Iterable<T>, provided by the EnumByName extension

Finds the enum value in this list with name name.
cast<R>() → Iterable<R>
A view of this iterable as an iterable of R instances.
inherited
contains(Object? element) → bool
Whether the collection contains an element equal to element.
inherited
elementAt(int index) → E
Returns the indexth element.
inherited
elementAtOrNull(int index) → T?

Available on Iterable<T>, provided by the IterableExtensions extension

The element at position index of this iterable, or null.
every(bool test(E element)) → bool
Checks whether every element of this iterable satisfies test.
inherited
expand<T>(Iterable<T> toElements(E element)) → Iterable<T>
Expands each element of this Iterable into zero or more elements.
override
firstWhere(bool test(E element), {E orElse()?}) → E
The first element that satisfies the given predicate test.
inherited
fold<T>(T initialValue, T combine(T previousValue, E element)) → T
Reduces a collection to a single value by iteratively combining each element of the collection with an existing value
inherited
followedBy(Iterable<E> other) → Iterable<E>
Creates the lazy concatenation of this iterable and other.
inherited
forEach(void action(E element)) → void
Invokes action on each element of this iterable in iteration order.
inherited
join([String separator = ""]) → String
Converts each element to a String and concatenates the strings.
inherited
lastWhere(bool test(E element), {E orElse()?}) → E
The last element that satisfies the given predicate test.
inherited
map<T>(T toElement(E e)) → Iterable<T>
The current elements of this iterable modified by toElement.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
reduce(E combine(E value, E element)) → E
Reduces a collection to a single value by iteratively combining elements of the collection using the provided function.
inherited
render() → String

Available on Iterable<StyleRule>, provided by the StyleRulesRender extension

Renders a list of style rules into raw css.
singleWhere(bool test(E element), {E orElse()?}) → E
The single element that satisfies test.
inherited
skip(int count) → Iterable<E>
Creates an Iterable that provides all but the first count elements.
override
skipWhile(bool test(E value)) → Iterable<E>
Creates an Iterable that skips leading elements while test is satisfied.
override
take(int count) → Iterable<E>
Creates a lazy iterable of the count first elements of this iterable.
override
takeWhile(bool test(E value)) → Iterable<E>
Creates a lazy iterable of the leading elements satisfying test.
override
toList({bool growable = true}) → List<E>
Creates a List containing the elements of this Iterable.
override
toSet() → Set<E>
Creates a Set containing the same elements as this iterable.
inherited
toString() → String
Returns a string representation of (some of) the elements of this.
inherited
where(bool test(E element)) → Iterable<E>
Creates a new lazy Iterable with all elements that satisfy the predicate test.
override
whereType<T>() → Iterable<T>
Creates a new lazy Iterable with all elements that have type T.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited