moduleceylon.language1.3.3
Source Code
ceylon.language
classArray<Element>
extends Basic
satisfies SearchableList<Element> & Ranged<Integer,Element,Array<Element>> & IndexedCorrespondenceMutator<Element>
OverviewPackageConstructorsAttributesMethods
Collections

A fixed-sized array of mutable elements. An empty array is an array of size 0. An array may be created with a list of initial elements, or, via the constructor ofSize(), with a size and single initial value for all elements.

value array = Array { "hello", "world" };
value ints = Array.ofSize(1k, 0);

Arrays are mutable. Any element of an array may be set to a new value.

value array = Array { "hello", "world" };
array[0] = "goodbye";

Arrays are lists and support all operations inherited from List, along with certain additional operations for efficient mutation of the array: set(), swap(), move(), sortInPlace(), reverseInPlace(), and copyTo().

This class is provided primarily to ease interoperation with Java, and for some performance-critical low-level programming tasks.

On the JVM, for “primitive” element types Integer, Float, Byte, Character, and Boolean, Array is easily the most efficient sort of List in Ceylon. However, certain optimizations made by the compiler are impossible if the Array is assigned to a more generic type such as Iterable. Peak efficiency is obtained for algorithms coded to the static type Array.

Furthermore, Array is itself a compromise between raw performance, polymorphism, and portability. An instance of the Java primitive array type java.lang.LongArray (written long[] in Java) exhibits superior micro-level performance to an Array<Integer>, but:

  • is not a List, and
  • is not available except when compiling for the JVM.

Fortunately, given a Java primitive array, it's easy to obtain an Array backed by the primitive array:

//unportable JVM-specific code 
LongArray longArray = LongArray(size);
Array<Integer> array = longArray.integerArray;

no subtypes hierarchy

Constructors
ArraySource Codeshared Array({Element*} elements)

Create an array with the given elements.

ofSizeSource Codeshared ofSize(Integer size, Element element)

Create an array of the specified size, populating every index with the given element. The specified size must be no larger than runtime.maxArraySize. If size<=0, the new array will have no elements.

Parameters:
  • size

    The size of the resulting array. If the size is non-positive, an empty array will be created.

  • element

    The element value with which to populate the array. All elements of the resulting array will have the same value.

Throws
See also runtime.maxArraySize
Since 1.2.0
Attributes
coalescedSource Codeshared actual {Element&Object*} coalesced

The non-null elements of this stream, in the order in which they occur in this stream. For null elements of the original stream, there is no entry in the resulting stream.

For example, the expression

{ "123", "abc", "456"}.map(parseInteger).coalesced

results in the stream { 123, 456 }.

Refines Iterable.coalesced
emptySource Codeshared actual Boolean empty

Determines if the stream is empty, that is to say, if the iterator returns no elements.

Refines Collection.empty ultimately refines Iterable.empty
firstSource Codeshared actual Element? first

The first element returned by the iterator, if any, or null if this stream is empty. For a stream with an unstable iteration order, a different value might be produced each time first is evaluated.

Refines List.first ultimately refines Iterable.first
hashSource Codeshared actual Integer hash

The hash value of the value, which allows the value to be an element of a hash-based set or key of a hash-based map. Implementations must respect the constraint that:

  • if x==y then x.hash==y.hash.

Therefore, a class which refines Object.equals() must also refine hash.

In general, hash values vary between platforms and between executions of the same program.

Note that when executing on a Java Virtual Machine, the 64-bit Integer value returned by an implementation of hash is truncated to a 32-bit integer value by taking the exclusive disjunction of the 32 lowest-order bits with the 32 highest-order bits, before returning the value to the caller.

Refines Identifiable.hash ultimately refines Object.hash
lastSource Codeshared actual Element? last

The last element returned by the iterator, if any, or null if this stream is empty. In the case of an infinite stream, this operation never terminates; furthermore, this default implementation iterates all elements, which might be very expensive.

Refines List.last ultimately refines Iterable.last
lastIndexSource Codeshared actual Integer? lastIndex

The index of the last element of the list, or null if the list is empty. Always size>0 then size-1.

Refines List.lastIndex
lengthSee size
sizeSource Codeshared actual Integer size

The immutable number of elements of this array.

Refines List.size ultimately refines Iterable.size
Aliases: length
stringSource Codeshared actual String string

A developer-friendly string representing the instance. Concatenates the name of the concrete class of the instance with the hash of the instance. Subclasses are encouraged to refine this implementation to produce a more meaningful representation.

Refines Iterable.string ultimately refines Object.string
Inherited Attributes
Attributes inherited from: Object
hash, string
Attributes inherited from: Collection<Element>
empty, permutations, string
Attributes inherited from: Correspondence<Key,Item>
keys
Attributes inherited from: Iterable<Element,Absent>
coalesced, cycled, distinct, empty, exceptLast, first, indexed, last, paired, rest, size, string
Attributes inherited from: List<Element>
first, hash, keys, last, lastIndex, rest, reversed, size
Methods
anySource Codeshared actual Boolean any(Boolean selecting(Element element))

Determines if there is at least one element of this stream that satisfies the given predicate function. If the stream is empty, returns false. For an infinite stream, this operation might not terminate.

Refines Iterable.any
bySource Codeshared actual {Element*} by(Integer step)

Produces a stream containing every stepth element of this stream. If the step size is 1, the resulting stream contains the same elements as this stream.

For example, the expression

(0..10).by(3)

results in the stream { 0, 3, 6, 9 }.

The step size must be greater than zero.

Refines Iterable.by
cloneSource Codeshared actual Array<Element> clone()

A new array with the same elements as this array.

Refines List.clone ultimately refines Collection.clone
containsSource Codeshared actual Boolean contains(Object element)

Returns true if the given value belongs to this Category, that is, if it is an element of this Category, or false otherwise.

For any instance c of Category, c.contains(element) may be written using the in operator:

element in c

For most Categorys, the following relationship is satisfied by every pair of elements x and y:

  • if x==y, then x in category == y in category

However, it is possible to form a useful Category consistent with some other equivalence relation, for example ===. Therefore implementations of contains() which do not satisfy this relationship are tolerated.

Refines List.contains ultimately refines Category.contains
copyToSource Codeshared void copyTo(Array<in Element> destination, Integer sourcePosition = 0, Integer destinationPosition = 0, Integer length = ...)

Efficiently copy the elements in the measure sourcePosition:length of this array to the measure destinationPosition:length of the given array, which may be this array.

The given sourcePosition and destinationPosition must be non-negative and, together with the given length, must identify meaningful ranges within the two arrays, satisfying:

  • size >= sourcePosition+length, and
  • destination.size >= destinationPosition+length.

If the given length is not strictly positive, no elements are copied.

Parameters:
  • destination

    The array into which to copy the elements, which may be this array.

  • sourcePosition = 0

    The index of the first element in this array to copy.

  • destinationPosition = 0

    The index in the given array into which to copy the first element.

  • length = smallest(size - sourcePosition, destination.size - destinationPosition)

    The number of elements to copy.

Throws
  • AssertionError

    if the arguments do not identify meaningful ranges within the two arrays:

countSource Codeshared actual Integer count(Boolean selecting(Element element))

Produces the number of elements in this stream that satisfy the given predicate function. For an infinite stream, this method never terminates.

Refines Iterable.count
definesSource Codeshared actual Boolean defines(Integer index)

Determines if there is a value defined for the given key.

Refines List.defines ultimately refines Correspondence.defines
eachSource Codeshared actual void each(void step(Element element))

Call the given function for each element of this stream, passing the elements in the order they occur in this stream.

For example:

words.each((word) {
    print(word.lowercased);
    print(word.uppercased);
});

Has the same effect as the following for loop:

for (word in words) {
    print(word.lowercased);
    print(word.uppercased);
}

For certain streams this method is highly efficient, surpassing the performance of for loops on the JVM. Thus, each() is sometimes preferred in highly performance-critical low-level code.

Refines Iterable.each
equalsSource Codeshared actual Boolean equals(Object that)

Determine if two values are equal.

For any two non-null objects x and y, x.equals(y) may be written as:

x == y

Implementations should respect the constraints that:

  • if x===y then x==y (reflexivity),
  • if x==y then y==x (symmetry),
  • if x==y and y==z then x==z (transitivity).

Furthermore it is recommended that implementations ensure that if x==y then x and y have the same concrete class.

A class which explicitly refines equals() is said to support value equality, and the equality operator == is considered much more meaningful for such classes than for a class which simply inherits the default implementation of identity equality from Identifiable.

Note that an implementation of equals() that always returns false does satisfy the constraints given above, as long as the class does not inherit Identifiable. Therefore, in very rare cases where there is no reasonable definition of value equality for a class, for example, function references, it is acceptable for equals() to be defined to return false for every argument.

Refines Identifiable.equals ultimately refines Object.equals
everySource Codeshared actual Boolean every(Boolean selecting(Element element))

Determines if all elements of this stream satisfy the given predicate function. If the stream is empty, return true. For an infinite stream, this operation might not terminate.

Refines Iterable.every
filterSource Codeshared actual {Element*} filter(Boolean selecting(Element element))

Produces a stream containing the elements of this stream that satisfy the given predicate function.

For any empty stream, filter() returns an empty stream:

{}.filter(p) == {}

For any nonempty stream it, and predicate p, the result of filter() may be obtained according to this recursive definition:

it.filter(p) == { if (p(it.first)) it.first }.chain(it.rest.filter(f))

Alternatively, and in practice, filter() may be defined by this comprehension:

it.filter(p) == { for (e in it) if (p(e)) e };

For example, the expression

(1..100).filter(13.divides)

results in the stream { 13, 26, 39, 52, 65, 78, 91 }.

Refines Iterable.filter
findSource Codeshared actual Element? find(Boolean selecting(Element&Object element))

The first element of this stream which is not null and satisfies the given predicate function, if any, or null if there is no such element. For an infinite stream, this method might not terminate.

For example, the expression

(-10..10).find(Integer.positive)

evaluates to 1.

Refines List.find ultimately refines Iterable.find
findLastSource Codeshared actual Element? findLast(Boolean selecting(Element&Object element))

The last element of this stream which is not null and satisfies the given predicate function, if any, or null if there is no such element. For an infinite stream, this method will not terminate.

For example, the expression

(-10..10).findLast(3.divides)

evaluates to 9.

Refines List.findLast ultimately refines Iterable.findLast
firstIndexWhereSource Codeshared actual Integer? firstIndexWhere(Boolean selecting(Element&Object element))

The first index in this list for which the element is not null and satisfies the given predicate function.

Refines List.firstIndexWhere
firstOccurrenceSource Codeshared actual Integer? firstOccurrence(Element element, Integer from, Integer length)

The first index in this list at which the given value occurs, that falls within the segment from:length defined by the optional starting index and length.

Refines SearchableList.firstOccurrence
getFromFirstSource Codeshared actual Element? getFromFirst(Integer index)

Get the element at the specified index, or null if the index falls outside the bounds of this array.

Refines List.getFromFirst ultimately refines Iterable.getFromFirst
getFromLastSource Codeshared actual Element? getFromLast(Integer index)

Get the element at the specified index, where the array is indexed from the end of the array, or null if the index falls outside the bounds of this array.

Refines List.getFromLast
indexesWhereSource Codeshared actual {Integer*} indexesWhere(Boolean selecting(Element&Object element))

The indexes in this list for which the element is not null and satisfies the given predicate function.

Refines List.indexesWhere
iteratorSource Codeshared actual Iterator<Element> iterator()

An iterator for the elements belonging to this stream.

If this is a nonempty stream with type {Element+}, the iterator must produce at least one element.

Refines List.iterator ultimately refines Iterable.iterator
lastIndexWhereSource Codeshared actual Integer? lastIndexWhere(Boolean selecting(Element&Object element))

The last index in this list for which the element is not null and satisfies the given predicate function.

Refines List.lastIndexWhere
lastOccurrenceSource Codeshared actual Integer? lastOccurrence(Element element, Integer from, Integer length)

The last index in this list at which the given value occurs, that falls within the range size-length-from:length defined by the optional starting index, interpreted as a reverse index counting from the end of the list, and length.

Refines SearchableList.lastOccurrence
locateSource Codeshared actual <Integer->Element&Object>? locate(Boolean selecting(Element&Object element))

The first element of this stream which is not null and satisfies the given predicate function, if any, together with its position in the stream, or null if there is no such element. For an infinite stream, this method might not terminate.

For example, the expression

(-10..10).locate(Integer.positive)

evaluates to 11->1.

Refines Iterable.locate
locateLastSource Codeshared actual <Integer->Element&Object>? locateLast(Boolean selecting(Element&Object element))

The last element of this stream which is not null and satisfies the given predicate function, if any, together with its position in the stream, or null if there is no such element. For an infinite stream, this method might not terminate.

For example, the expression

(-10..10).locateLast(3.divides)

evaluates to 19->9.

Refines Iterable.locateLast
locationsSource Codeshared actual {<Integer->Element&Object>*} locations(Boolean selecting(Element&Object element))

A stream producing all elements of this stream which are not null and which satisfy the given predicate function, together with their positions in the stream.

For example, the expression

(-5..5).locations(3.divides)

evaluates to the stream { 2->-3, 5->0, 8->3 }.

Note that this method is more efficient than the alternative of applying Iterable.filter() to an Iterable.indexed stream.

Refines Iterable.locations
measureSource Codeshared actual Array<Element> measure(Integer from, Integer length)

Obtain a measure containing the mapped values starting from the given starting index, with the given length. If length<=0, the resulting measure is empty.

For any ranged stream r, r.measure(from, length) may be written using the measure operator:

r[from:length]

The measure should contain the given number of elements of this stream, starting from the element at the given starting index, in the same order as they are produced by the Iterable.iterator() of the stream. In the case where the iterator would be exhausted before length elements are produced, the resulting measure contains only those elements which were produced before the iterator was exhausted, and the length of the measure is less then the given length.

When the given index does not belong to this ranged object, the behavior is implementation dependent.

Refines List.measure ultimately refines Ranged.measure
moveSource Codeshared void move(Integer from, Integer to)

Efficiently move the element of this array at the given source index to the given destination index, shifting every element falling between the two given indices by one position to accommodate the change of position. If the source index is larger than the destination index, elements are shifted toward the end of the array. If the source index is smaller than the destination index, elements are shifted toward the start of the array. If the given indices are identical, no change is made to the array. The array always contains the same elements before and after this operation.

Parameters:
  • from

    The source index of the element to move.

  • to

    The destination index to which the element is moved.

Throws
Since 1.2.0
occurrencesSource Codeshared actual {Integer*} occurrences(Element element, Integer from, Integer length)

The indexes in this list at which the given value occurs.

Refines SearchableList.occurrences
occursSource Codeshared actual Boolean occurs(Element element, Integer from, Integer length)

Determines if the given value occurs as an element of this list, at any index that falls within the segment from:length defined by the optional starting index and length.

Refines SearchableList.occurs
occursAtSource Codeshared actual Boolean occursAt(Integer index, Element element)

Determines if the given value occurs at the given index in this list.

Refines SearchableList.occursAt
reduceSource Codeshared actual Result|Element|Null reduce<Result>(Result accumulating(Result|Element partial, Element element))

Beginning with the Iterable.first element of this stream, apply the given combining function to each element of this stream in turn, progressively accumulating a single result.

For an empty stream, reduce() always returns null.

For a stream with one element, reduce() returns that element:

{ first }.reduce(f) == first

For a given stream it with more than one element, and combining function f, the result of reduce() is obtained according to the following recursive definition:

it.reduce(f) == f(it.exceptLast.reduce(f), it.last)

For example, the expression

(1..100).reduce(plus)

results in the integer 5050.

Refines Iterable.reduce
reverseInPlaceSource Codeshared void reverseInPlace()

Reverses the order of the current elements in this array. This operation works by side-effect, modifying the array. The array always contains the same elements before and after this operation.

Since 1.1.0
sequenceSource Codeshared actual [Element+]|[] sequence()

A sequence containing all the elements of this stream, in the same order they occur in this stream. This operation eagerly evaluates and collects every element of the stream.

If this stream is known to be nonempty, that is, if it is an instance of {Anything+}, then this operation has a nonempty return type, that is, a subtype of [Anything+]. For example:

[String+] bits = "hello world".split().sequence();
Refines Iterable.sequence
setSource Codeshared actual void set(Integer index, Element element)

Replace the existing element at the specified index with the given element.

Parameters:
  • index

    The index of the element to replace.

  • element

    The new element.

Throws
  • AssertionError

    if the given index is out of bounds, that is, if index<0 or if index>lastIndex

Refines IndexedCorrespondenceMutator.set
skipSource Codeshared actual {Element*} skip(Integer skipping)

Produces a stream containing the elements of this stream, after skipping the first skipping elements produced by its iterator.

If this stream does not contain more elements than the specified number of elements to skip, the resulting stream has no elements. If the specified number of elements to skip is zero or fewer, the resulting stream contains the same elements as this stream.

Refines Iterable.skip
sortSource Codeshared actual [Element+]|[] sort(Comparison comparing(Element x, Element y))

Sorts the elements in this array according to the order induced by the given comparison function, returning a new sequence. This operation has no side-effect, and does not modify the array.

Parameters:
  • comparing

    A comparison function that compares pairs of elements of this array.

Refines Iterable.sort
sortInPlaceSource Codeshared void sortInPlace(Comparison comparing(Element x, Element y))

Sorts the elements in this array according to the order induced by the given comparison function. This operation works by side-effect, modifying the array. The array always contains the same elements before and after this operation.

Parameters:
  • comparing

    A comparison function that compares pairs of elements of this array.

Since 1.1.0
spanSource Codeshared actual Array<Element> span(Integer from, Integer to)

Obtain a span containing the elements between the two given indices.

For any ranged stream r, r.span(from, to) may be written using the span operator:

r[from..to]

The span should contain elements of this stream, starting from the element at the given starting index, and ending with the element at the given ending index, in the same order as they are produced by the Iterable.iterator() of the stream, except when the ending index occurs earlier than the starting index, in which case they occur in the opposite order.

When one or both of the given indices does not belong to this ranged stream, the behavior is implementation dependent.

Refines List.span ultimately refines Ranged.span
spanFromSource Codeshared actual Array<Element> spanFrom(Integer from)

Obtain a span containing the elements between the given starting index and the last index of this ranged object.

For any ranged stream r, r.spanFrom(from) may be written using the span operator:

r[from...]

The span should contain elements of this stream, starting from the element at the given starting index, in the same order as they are produced by the Iterable.iterator() of the stream.

When the given index does not belong to this ranged stream, the behavior is implementation dependent.

Refines List.spanFrom ultimately refines Ranged.spanFrom
spanToSource Codeshared actual Array<Element> spanTo(Integer to)

Obtain a span containing the elements between the first index of this ranged stream and given end index.

For any ranged stream r, r.spanTo(to) may be written using the span operator:

r[...to]

The span should contain elements of this stream, up to the element at the given ending index, in the same order as they are produced by the Iterable.iterator() of the stream.

When the given index does not belong to this ranged stream, the behavior is implementation dependent.

Refines List.spanTo ultimately refines Ranged.spanTo
swapSource Codeshared void swap(Integer i, Integer j)

Given two indices within this array, efficiently swap the positions of the elements at these indices. If the two given indices are identical, no change is made to the array. The array always contains the same elements before and after this operation.

Parameters:
  • i

    The index of the first element.

  • j

    The index of the second element.

Throws
Since 1.2.0
takeSource Codeshared actual {Element*} take(Integer taking)

Produces a stream containing the first taking elements of this stream.

If the specified number of elements to take is larger than the number of elements of this stream, the resulting stream contains the same elements as this stream. If the specified number of elements to take is fewer than one, the resulting stream has no elements.

Refines Iterable.take
Inherited Methods
Methods inherited from: Object
equals()
Methods inherited from: Category<Element>
contains(), containsAny(), containsEvery()
Methods inherited from: Collection<Element>
clone(), combinations(), contains()
Methods inherited from: Correspondence<Key,Item>
defines(), definesAny(), definesEvery(), get(), getAll()
Methods inherited from: IndexedCorrespondenceMutator<Element>
set()
Methods inherited from: Iterable<Element,Absent>
any(), by(), chain(), collect(), contains(), count(), defaultNullElements(), each(), every(), filter(), find(), findLast(), flatMap(), fold(), follow(), frequencies(), getFromFirst(), group(), indexes(), interpose(), iterator(), locate(), locateLast(), locations(), longerThan(), map(), max(), narrow(), partition(), product(), reduce(), repeat(), scan(), select(), sequence(), shorterThan(), skip(), skipWhile(), sort(), spread(), summarize(), tabulate(), take(), takeWhile()
Methods inherited from: List<Element>
clone(), collect(), contains(), defines(), endsWith(), equals(), find(), findLast(), firstIndexWhere(), get(), getFromFirst(), getFromLast(), indexesWhere(), initial(), iterator(), lastIndexWhere(), longerThan(), mapElements(), measure(), patch(), repeat(), shorterThan(), slice(), span(), spanFrom(), spanTo(), startsWith(), sublist(), sublistFrom(), sublistTo(), terminal(), trim(), trimLeading(), trimTrailing()
Methods inherited from: Ranged<Index,Element,Subrange>
measure(), span(), spanFrom(), spanTo()
Methods inherited from: SearchableList<Element>
firstInclusion(), firstOccurrence(), includes(), includesAt(), inclusions(), lastInclusion(), lastOccurrence(), occurrences(), occurs(), occursAt()