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 precache 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
- Object
- Iterable<
E> - IterableBase<
E> - CachingIterable
Constructors
-
CachingIterable(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
-
iterator
→ Iterator<
E> -
Returns a new
Iterator
that allows iterating the elements of thisIterable
. [...]read-only, override - length → int
-
Returns the number of elements in this. [...]
read-only, override
- first → E
-
Returns the first element. [...]
read-only, inherited
- hashCode → int
-
The hash code for this object. [...]
read-only, inherited
- isEmpty → bool
-
Returns
true
if there are no elements in this collection. [...]read-only, inherited - isNotEmpty → bool
-
Returns true if there is at least one element in this collection. [...]
read-only, inherited
- last → E
-
Returns the last element. [...]
read-only, inherited
- runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
- single → E
-
Checks that this iterable has only one element, and returns that element. [...]
read-only, inherited
Methods
-
expand<
T>( Iterable< T> f(E element)) → Iterable< T> -
Expands each element of this Iterable into zero or more elements. [...]
override
-
map<
T>( T f(E e)) → Iterable< T> -
Returns a new lazy Iterable with elements that are created by
calling
f
on each element of thisIterable
in iteration order. [...]override -
skip(
int count) → Iterable< E> -
Returns an Iterable that provides all but the first
count
elements. [...]override -
skipWhile(
bool test(E value)) → Iterable< E> -
Returns an
Iterable
that skips leading elements whiletest
is satisfied. [...]override -
take(
int count) → Iterable< E> -
Returns a lazy iterable of the
count
first elements of this iterable. [...]override -
takeWhile(
bool test(E value)) → Iterable< E> -
Returns 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
-
where(
bool test(E element)) → Iterable< E> -
Returns a new lazy Iterable with all elements that satisfy the
predicate
test
. [...]override -
any(
bool test(E element)) → bool -
Checks whether any element of this iterable satisfies
test
. [...]inherited -
cast<
R>( ) → Iterable< R> -
Provides a view of this iterable as an iterable of
R
instances. [...]inherited -
contains(
Object element) → bool -
Returns true if the collection contains an element equal to
element
. [...]inherited -
elementAt(
int index) → E -
Returns the
index
th element. [...]inherited -
every(
bool test(E element)) → bool -
Checks whether every element of this iterable satisfies
test
. [...]inherited -
firstWhere(
bool test(E element), { E orElse() }) → E -
Returns 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> -
Returns the lazy concatentation of this iterable and
other
. [...]inherited -
forEach(
void f(E element)) → void -
Applies the function
f
to each element of this collection 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 -
Returns the last element that satisfies the given predicate
test
. [...]inherited -
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent 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
-
singleWhere(
bool test(E element), { E orElse() }) → E -
Returns the single element that satisfies
test
. [...]inherited -
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 -
whereType<
T>( ) → Iterable< T> -
Returns a new lazy Iterable with all elements that have type
T
. [...]inherited
Operators
-
operator ==(
dynamic other) → bool -
The equality operator. [...]
inherited