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

Properties

average → double

Available on Iterable<num>, provided by the IterableNumberExtension extension

The arithmetic mean of the elements of a non-empty iterable.
no setter
average → double

Available on Iterable<int>, provided by the IterableIntegerExtension extension

The arithmetic mean of the elements of a non-empty iterable.
no setter
first → E
The first element.
no setterinherited
firstOrNull → T?

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

The first element, or null if the iterable is empty.
no setter
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
flattened → Iterable<T>

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

The sequential elements of each iterable in this iterable.
no setter
flattenedToList → List<T>

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

The sequential elements of each iterable in this iterable.
no setter
flattenedToSet → Set<T>

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

The unique sequential elements of each iterable in this iterable.
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
lastOrNull → T?

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

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

Available on Iterable<int>, provided by the IterableIntegerExtension extension

A maximal element of the iterable.
no setter
max → double

Available on Iterable<double>, provided by the IterableDoubleExtension extension

A maximal element of the iterable.
no setter
max → num

Available on Iterable<num>, provided by the IterableNumberExtension extension

A maximal element of the iterable.
no setter
max → T

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

A maximal element of the iterable.
no setter
maxOrNull → double?

Available on Iterable<double>, provided by the IterableDoubleExtension extension

A maximal element of the iterable, or null if the iterable is empty.
no setter
maxOrNull → int?

Available on Iterable<int>, provided by the IterableIntegerExtension extension

A maximal element of the iterable, or null if the iterable is empty.
no setter
maxOrNull → T?

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

A maximal element of the iterable, or null if the iterable is empty.
no setter
maxOrNull → num?

Available on Iterable<num>, provided by the IterableNumberExtension extension

A maximal element of the iterable, or null if the iterable is empty.
no setter
min → double

Available on Iterable<double>, provided by the IterableDoubleExtension extension

A minimal element of the iterable.
no setter
min → T

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

A minimal element of the iterable.
no setter
min → int

Available on Iterable<int>, provided by the IterableIntegerExtension extension

A minimal element of the iterable.
no setter
min → num

Available on Iterable<num>, provided by the IterableNumberExtension extension

A minimal element of the iterable.
no setter
minOrNull → double?

Available on Iterable<double>, provided by the IterableDoubleExtension extension

A minimal element of the iterable, or null it the iterable is empty.
no setter
minOrNull → int?

Available on Iterable<int>, provided by the IterableIntegerExtension extension

A minimal element of the iterable, or null it the iterable is empty.
no setter
minOrNull → T?

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

A minimal element of the iterable, or null it the iterable is empty.
no setter
minOrNull → num?

Available on Iterable<num>, provided by the IterableNumberExtension extension

A minimal element of the iterable, or null it the iterable is empty.
no setter
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 IterableExtension extension

The single element of the iterable, or null.
no setter
singleOrNull → T?

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

The single element of this iterator, or null.
no setter
sum → int

Available on Iterable<int>, provided by the IterableIntegerExtension extension

The sum of the elements.
no setter
sum → num

Available on Iterable<num>, provided by the IterableNumberExtension extension

The sum of the elements.
no setter
sum → double

Available on Iterable<double>, provided by the IterableDoubleExtension extension

The sum of the elements.
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.
elementAtOrNull(int index) → T?

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

The indexth element, or null if there is no such element.
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
expandIndexed<R>(Iterable<R> expand(int index, T element)) → Iterable<R>

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

Expands each element and index to a number of elements in a new iterable.
firstWhere(bool test(E element), {E orElse()?}) → E
The first element that satisfies the given predicate test.
inherited
firstWhereIndexedOrNull(bool test(int index, T element)) → T?

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

The first element whose value and index satisfies test.
firstWhereOrNull(bool test(T element)) → T?

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

The first element satisfying test, or null if there are none.
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
foldIndexed<R>(R initialValue, R combine(int index, R previous, T element)) → R

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

Combine the elements with a value and the current index.
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
forEachIndexed(void action(int index, T element)) → void

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

Takes an action for each element.
forEachIndexedWhile(bool action(int index, T element)) → void

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

Takes an action for each element and index as long as desired.
forEachWhile(bool action(T element)) → void

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

Takes an action for each element as long as desired.
groupFoldBy<K, G>(K keyOf(T element), G combine(G? previous, T element)) → Map<K, G>

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

Groups elements by keyOf then folds the elements in each group.
groupListsBy<K>(K keyOf(T element)) → Map<K, List<T>>

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

Groups elements into lists by keyOf.
groupSetsBy<K>(K keyOf(T element)) → Map<K, Set<T>>

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

Groups elements into sets by keyOf.
isSorted(Comparator<T> compare) → bool

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

Whether the elements are sorted by the compare ordering.
isSorted([Comparator<T>? compare]) → bool

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

Whether the elements are sorted by the compare ordering.
isSortedBy<K extends Comparable<K>>(K keyOf(T element)) → bool

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

Whether the elements are sorted by their keyOf property.
isSortedByCompare<K>(K keyOf(T element), Comparator<K> compare) → bool

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

Whether the elements are compare-sorted by their keyOf property.
join([String separator = ""]) → String
Converts each element to a String and concatenates the strings.
inherited
lastBy<K>(K key(T)) → Map<K, T>

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

Associates the elements in this by the value returned by key.
lastWhere(bool test(E element), {E orElse()?}) → E
The last element that satisfies the given predicate test.
inherited
lastWhereIndexedOrNull(bool test(int index, T element)) → T?

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

The last element whose index and value satisfies test.
lastWhereOrNull(bool test(T element)) → T?

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

The last element satisfying test, or null if there are none.
map<T>(T toElement(E e)) → Iterable<T>
The current elements of this iterable modified by toElement.
override
mapIndexed<R>(R convert(int index, T element)) → Iterable<R>

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

Maps each element and its index to a new value.
none(bool test(T)) → bool

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

Whether no element satisfies test.
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
reduceIndexed(T combine(int index, T previous, T element)) → T

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

Combine the elements with each other and the current index.
sample(int count, [Random? random]) → List<T>

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

Selects count elements at random from this iterable.
shuffled([Random? random]) → List<T>

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

Creates a shuffled list of the elements of the iterable.
singleWhere(bool test(E element), {E orElse()?}) → E
The single element that satisfies test.
inherited
singleWhereIndexedOrNull(bool test(int index, T element)) → T?

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

The single element satisfying test.
singleWhereOrNull(bool test(T element)) → T?

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

The single element satisfying test.
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
slices(int length) → Iterable<List<T>>

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

Contiguous slices of this with the given length.
sorted([Comparator<T>? compare]) → List<T>

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

Creates a sorted list of the elements of the iterable.
sorted(Comparator<T> compare) → List<T>

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

Creates a sorted list of the elements of the iterable.
sortedBy<K extends Comparable<K>>(K keyOf(T element)) → List<T>

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

Creates a sorted list of the elements of the iterable.
sortedByCompare<K>(K keyOf(T element), Comparator<K> compare) → List<T>

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

Creates a sorted list of the elements of the iterable.
splitAfter(bool test(T element)) → Iterable<List<T>>

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

Splits the elements into chunks after some elements.
splitAfterIndexed(bool test(int index, T element)) → Iterable<List<T>>

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

Splits the elements into chunks after some elements and indices.
splitBefore(bool test(T element)) → Iterable<List<T>>

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

Splits the elements into chunks before some elements.
splitBeforeIndexed(bool test(int index, T element)) → Iterable<List<T>>

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

Splits the elements into chunks before some elements and indices.
splitBetween(bool test(T first, T second)) → Iterable<List<T>>

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

Splits the elements into chunks between some elements.
splitBetweenIndexed(bool test(int index, T first, T second)) → Iterable<List<T>>

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

Splits the elements into chunks between some elements and indices.
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
whereIndexed(bool test(int index, T element)) → Iterable<T>

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

The elements whose value and index satisfies test.
whereNot(bool test(T element)) → Iterable<T>

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

The elements that do not satisfy test.
whereNotIndexed(bool test(int index, T element)) → Iterable<T>

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

The elements whose value and index do not satisfy test.
whereNotNull() → Iterable<T>

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

The non-null elements of this Iterable.
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