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Array<A> final ​

final class Array<A>

A fixed-size, nullable array used as a low-level building block.

Unlike Dart's List, Array deliberately allows null values regardless of the element type A. This makes it straightforward to port algorithms that treat unused slots as null (e.g. the IVector trie). Prefer higher-level collections for application code — here be dragons.

Construct with Array.ofDim, Array.fill, Array.from, Array.fromDart, Array.range, or Array.tabulate. For incremental construction use Array.builder.

Properties ​

hashCode no setter inherited ​

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation
dart
external int get hashCode;

isEmpty no setter ​

bool get isEmpty

Whether this array has no elements.

Implementation
dart
bool get isEmpty => _list.isEmpty;

isNotEmpty no setter ​

bool get isNotEmpty

Whether this array has at least one element.

Implementation
dart
bool get isNotEmpty => _list.isNotEmpty;

iterator no setter ​

RIterator<A?> get iterator

Returns an iterator over all elements, including null slots.

Implementation
dart
RIterator<A?> get iterator => RIterator.fromDart(_list.iterator);

length no setter ​

int get length

The number of elements in this array.

Implementation
dart
int get length => _list.length;

nonEmpty no setter ​

bool get nonEmpty

Whether this array has at least one element.

Implementation
dart
bool get nonEmpty => _list.isNotEmpty;

runtimeType no setter inherited ​

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation
dart
external Type get runtimeType;

Methods ​

clone() ​

Array<A> clone()

Returns a copy of this array with the same length.

Implementation
dart
Array<A> clone() => copyOf(this, length);

collect() ​

Array<B> collect<B>(Option<B> Function(A) f)

Returns a new array containing only the elements for which f returns Some, in their original order.

Implementation
dart
Array<B> collect<B>(Function1<A, Option<B>> f) {
  final b = ArrayBuilder<B>();

  var i = 0;
  while (i < _list.length) {
    f(_list[i] as A).foreach(b.addOne);
    i += 1;
  }

  return b.result();
}

filled() ​

void filled(A? elem)

Fills every slot of this array with elem.

Implementation
dart
void filled(A? elem) => _list.fillRange(0, length, elem);

foreach() ​

void foreach<U>(U Function(A?) f)

Applies f to each element in order.

Implementation
dart
void foreach<U>(Function1<A?, U> f) => _list.forEach(f);

map() ​

Array<B> map<B>(B Function(A) f)

Returns a new array produced by applying f to each element.

Implementation
dart
Array<B> map<B>(Function1<A, B> f) => Array.tabulate(length, (idx) => f(this[idx] as A));

noSuchMethod() inherited ​

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dart
dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

dart
class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation
dart
@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

slice() ​

Array<A> slice(int from, int until)

Returns a sub-array from index from (inclusive) to until (exclusive).

Out-of-bound indices are clamped to [0, length].

Implementation
dart
Array<A> slice(int from, int until) {
  final lo = max(from, 0);
  final hi = min(until, length);

  if (hi > lo) {
    return copyOfRange(this, lo, hi);
  } else {
    return Array.empty();
  }
}

toList() ​

List<A?> toList()

Returns a copy of the underlying list, preserving null slots.

Implementation
dart
List<A?> toList() => List.of(_list);

toString() inherited ​

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation
dart
external String toString();

update() ​

Array<A> update(int idx, A? value)

Sets the element at idx to value and returns this.

Implementation
dart
Array<A> update(int idx, A? value) {
  this[idx] = value;
  return this;
}

Operators ​

operator ==() inherited ​

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

  • Total: It must return a boolean for all arguments. It should never throw.

  • Reflexive: For all objects o, o == o must be true.

  • Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

  • Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation
dart
external bool operator ==(Object other);

operator ​

A? operator [](int idx)

Returns the element at idx, which may be null.

Implementation
dart
A? operator [](int idx) => _list[idx];

operator []=() ​

void operator []=(int index, A? value)

Sets the element at index to value.

Implementation
dart
void operator []=(int index, A? value) => _list[index] = value;

Static Methods ​

arraycopy() ​

void arraycopy<A>(
  Array<A> src,
  int srcPos,
  Array<A> dest,
  int destPos,
  int length,
)

Copies length elements from src starting at srcPos into dest starting at destPos.

Implementation
dart
static void arraycopy<A>(
  Array<A> src,
  int srcPos,
  Array<A> dest,
  int destPos,
  int length,
) => dest._list.setRange(
  destPos,
  destPos + length,
  src._list.getRange(srcPos, srcPos + length),
);

builder() ​

ArrayBuilder<A> builder<A>()

Returns a mutable builder for incrementally constructing an Array.

Implementation
dart
static ArrayBuilder<A> builder<A>() => ArrayBuilder();

copyOf() ​

Array<A> copyOf<A>(Array<A> original, int newLength)

Returns a new array of length newLength containing the elements of original, truncating or padding with null as needed.

Implementation
dart
static Array<A> copyOf<A>(Array<A> original, int newLength) {
  final dest = Array.ofDim<A>(newLength);
  arraycopy(original, 0, dest, 0, min(original.length, newLength));
  return dest;
}

copyOfRange() ​

Array<A> copyOfRange<A>(Array<A> original, int from, int to)

Returns a new array containing elements of original in the range [from, to).

Implementation
dart
static Array<A> copyOfRange<A>(Array<A> original, int from, int to) =>
    Array.fromDart(original._list.getRange(from, to));

empty() ​

Array<A> empty<A>()

Returns an empty Array of length zero.

Implementation
dart
static Array<A> empty<A>() => Array.ofDim(0);

equals() ​

bool equals<A>(Array<A> a, Array<A> b)

Returns true if a and b have the same length and equal elements at every index.

Implementation
dart
static bool equals<A>(Array<A> a, Array<A> b) {
  if (identical(a, b)) return true;
  if (a.length != b.length) return false;

  for (int idx = 0; idx < a.length; idx++) {
    if (a[idx] != b[idx]) return false;
  }

  return true;
}

fill() ​

Array<A> fill<A>(int len, A? elem)

Returns an Array of length len where every slot holds elem.

Implementation
dart
static Array<A> fill<A>(int len, A? elem) => Array._(List.filled(len, elem));

from() ​

Array<A> from<A>(RIterableOnce<A?> elems)

Creates an Array from a RIterableOnce.

Implementation
dart
static Array<A> from<A>(RIterableOnce<A?> elems) => fromDart(elems.toList(growable: false));

fromDart() ​

Array<A> fromDart<A>(Iterable<A?> elems)

Creates an Array from a Dart Iterable.

Implementation
dart
static Array<A> fromDart<A>(Iterable<A?> elems) {
  return Array._(elems.toList(growable: false));
}

ofDim() ​

Array<A> ofDim<A>(int len)

Returns an Array of length len with all slots initialised to null.

Implementation
dart
static Array<A> ofDim<A>(int len) => Array._(List.filled(len, null));

range() ​

Array<int> range(int start, int end, [int step = 1])

Returns an Array containing the integers from start (inclusive) to end (exclusive), incremented by step.

Throws ArgumentError if step is zero.

Implementation
dart
static Array<int> range(int start, int end, [int step = 1]) {
  if (step == 0) throw ArgumentError('zero step');

  final array = Array.ofDim<int>(Range.elementCount(start, end, step));

  var n = 0;
  var i = start;
  while (step < 0 ? end < i : i < end) {
    array[n] = i;
    i += step;
    n += 1;
  }

  return array;
}

tabulate() ​

Array<A> tabulate<A>(int n, A? Function(int) f)

Returns an Array of length n where element i is f(i).

Implementation
dart
static Array<A> tabulate<A>(int n, Function1<int, A?> f) => Array._(List.generate(n, f));