interface AsyncStream<T>
A possibly infinite asynchronous sequence of elements of type T. See the Stream documentation and the AsyncStream API documentation
Companion namespace: AsyncStream
Extends: AsyncStreamable<T>
, AsyncFastIterable<T>
Implemented by: AsyncStream.NonEmpty<T>
, AsyncStreamBase<T>
Type parameters
Name | Description |
---|---|
T | the element type |
const s1 = AsyncStream.empty<number>()
const s2 = AsyncStream.of(1, 3, 2)
const s3 = AsyncStream.from(Stream.range({ start: 10, amount: 15 }))
Methods
[Symbol.asyncIterator]
undocumented
[Symbol.asyncIterator]
append
Returns the current stream succeeded by the given value
append
value
Definition
append(value: AsyncOptLazy<T>):
AsyncStream.NonEmpty
<T>;
Parameters
Name | Type | Description |
---|---|---|
value | AsyncOptLazy<T> | the value to append |
await AsyncStream.of(1, 2, 3).append(4).toArray()
// => [1, 2, 3, 4]
O(1)
assumeNonEmpty
Returns the stream as a non-empty instance.
assumeNonEmpty
Definition
assumeNonEmpty():
AsyncStream.NonEmpty
<T>;
RimbuError.EmptyCollectionAssumedNonEmptyError if the stream is known to be empty.
AsyncStream.from(Stream.range({ amount: 100 })).assumeNonEmpty()
// => type: AsyncStream.NonEmpty<number>
the function does not actually check if the stream is empty, so treat with extra care @note O(1)
asyncStream
Returns an async stream of elements of type T.
asyncStream
collect
Returns an AsyncStream containing the resulting elements from applying the given collectFun
to each element in this Stream.
collect
collectFun
to each element in this Stream.Definition
collect<R>(collectFun: AsyncCollectFun<T, R>):
AsyncStream
<R>;
Type parameters
Name | Description |
---|---|
R | the resulting element type |
Parameters
Name | Type | Description |
---|---|---|
collectFun | AsyncCollectFun<T, R> | a potentially asynchronous function taking the parameters below and returning a new element or a skip token - value: the next element - index: the element index - skip: an element that can be returned if the current element should be skipped - halt: a function that, if called, ensures that no new elements are passed |
await AsyncStream.of(1, 2, 3).collect(async (v, i, skip, halt) => {
if (i === 0) return skip;
if (i === 1) halt();
return String(v)
}).toArray();
// => ['1']
O(1)
concat
Returns an AsyncStream containing the elements of this stream followed by all elements produced by the others
array of AsyncStreamSources.
concat
others
array of AsyncStreamSources.Definitions
concat<T2 = T>(...others: ArrayNonEmpty<
AsyncStreamSource.NonEmpty
<T2>>):
AsyncStream.NonEmpty
<T
|
T2>;
concat<T2 = T>(...others: ArrayNonEmpty<
AsyncStreamSource
<T2>>):
AsyncStream
<T
|
T2>;
Type parameters
Name | Default | Description |
---|---|---|
T2 | T | the element type of the stream to concatenate |
Parameters
Name | Type | Description |
---|---|---|
others | ArrayNonEmpty< AsyncStreamSource.NonEmpty <T2>> | a series of AsyncStreamSources to concatenate. |
await AsyncStream.of(1, 2, 3).concat([4, 5], () => [6, 7]).toArray()
// [1, 2, 3, 4, 5, 6, 7]
O(1)
contains
Returns true if the AsyncStream contains given amount
instances of given value
, using given eq
function.
contains
amount
instances of given value
, using given eq
function.Definition
contains(value: T, amount?: number, eq?: Eq<T>): Promise<boolean>;
Parameters
Name | Type | Description |
---|---|---|
value | T | the value to search for |
amount | number | (default: 1) the amount of values the Stream should contain |
eq | Eq<T> | (optional) the equality function to use |
const source = Stream.from('marmot')
await source.contains('m') // => true
await source.contains('m', 2) // => true
await source.contains('m', 3) // => false
await source.contains('q') // => false
O(N)
containsSlice
Returns true if this stream contains the same sequence of elements as the given source
, false otherwise.
containsSlice
source
, false otherwise.Definition
containsSlice(source:
AsyncStreamSource.NonEmpty
<T>, eq?: Eq<T>): Promise<boolean>;
Parameters
Name | Type | Description |
---|---|---|
source | AsyncStreamSource.NonEmpty <T> | a non-empty async stream source containing the element sequence to find |
eq | Eq<T> | (default: Eq.objectIs ) the function to use to test element equality |
await AsyncStream.of(1, 2, 3, 4, 5).containsSlice([2, 3, 4])
// => true
await AsyncStream.of(1, 2, 3, 4, 5).containsSlice([4, 3, 2])
// => false
count
Returns the amount of elements in the AsyncStream.
count
Definition
count(): Promise<number>;
await AsyncStream.of(1, 2, 3).count() // => 3
O(N) for most types of Stream @note be careful not to use on infinite streams
countElement
Returns the amount of elements that are equal according to the given eq
to the given value
in the AsyncStream.
countElement
eq
to the given value
in the AsyncStream.countNotElement
Returns the amount of elements that are not equal according to the given eq
to the given value
in the AsyncStream.
countNotElement
eq
to the given value
in the AsyncStream.Definition
countNotElement(value: T, eq?: Eq<T>): Promise<number>;
Parameters
Name | Type | Description |
---|---|---|
value | T | the value to compare to |
eq | Eq<T> | (optional) the Eq instance to use to test equality |
await AsyncStream.of(1, 2, 3).countNotElement(2) // => 2
O(N) @note be careful not to use on infinite streams
distinctPrevious
Returns an AsyncStream containing non-repetitive elements of the source stream, where repetitive elements are compared using the optionally given eq
equality function.
distinctPrevious
eq
equality function.Definition
distinctPrevious(eq?: Eq<T>):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
eq | Eq<T> | (default: Eq.objectIs ) the Eq instance to use to test equality of elements |
await AsyncStream.of(1, 1, 2, 2, 3, 1).distinctPrevious().toArray()
// => [1, 2, 3, 1]
drop
Returns an AsyncStream that skips the first amount
elements of this stream and returns the rest.
drop
amount
elements of this stream and returns the rest.Definition
drop(amount: number):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
amount | number | the amount of elements to skip |
await AsyncStream.of(1, 2, 3).drop(1).toArray() // => [2, 3]
O(N)
dropWhile
Returns an AsyncStream that contains the elements of this stream starting from the first element that does not satisfy given pred
function.
dropWhile
pred
function.Definition
dropWhile(pred: (value: T, index: number) => MaybePromise<boolean>):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number) => MaybePromise<boolean> | a potentially asynchronous predicate function taking an element and its index |
await AsyncStream.of(1, 2, 3).dropWhile(async v => v < 2).toArray()
// => [2, 3]
O(N)
elementAt
Returns the element in the AsyncStream at the given index, or a fallback value (default undefined) otherwise.
elementAt
Definitions
elementAt(index: number): Promise<T
|
undefined>;
elementAt<O>(index: number, otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
Parameters
Name | Type | Description |
---|---|---|
index | number | the index of the element to retrieve |
await AsyncStream.of(1, 2, 3).elementAt(1) // => 2
await AsyncStream.of(1, 2, 3).elementAt(5) // => undefined
await AsyncStream.of(1, 2, 3).elementAt(5, 'a') // => 'a'
await AsyncStream.of(1, 2, 3).elementAt(5, async () => 'a') // => 'a'
O(N) for most types of Stream
equals
Returns true if the sequence of elements in this stream are equal to the sequence in the other
stream according to the provided eq
function.
equals
other
stream according to the provided eq
function.Definition
equals(other:
AsyncStreamSource
<T>, eq?: Eq<T>): Promise<boolean>;
Parameters
Name | Type | Description |
---|---|---|
other | AsyncStreamSource <T> | the other stream to compare |
eq | Eq<T> | (optional) the equality function |
await AsyncStream.of(1, 2, 3).equals([1, 2, 3]) // => true
await AsyncStream.of(1, 2, 3, 4).equals([1, 2, 3]) // => false
don't use on potentially infinite streams @note O(N)
every
Returns true if every element of the AsyncStream satifies given pred
function.
every
pred
function.Definition
every(pred: (value: T, index: number) => MaybePromise<boolean>): Promise<boolean>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number) => MaybePromise<boolean> | a potentially asynchronous predicate function taking an element and its index |
await AsyncStream.of(1, 2, 3).every((v, i) => v + i > 10) // => false
await AsyncStream.of(1, 2, 3).every(async (v, i) => v + i < 10) // => true
O(N)
filter
Returns an AsyncStream containing only those elements from this stream for which the given pred
function returns true.
filter
pred
function returns true.Definition
filter(pred: (value: T, index: number, halt: () => void) => MaybePromise<boolean>):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number, halt: () => void) => MaybePromise<boolean> | a potentially asynchronous function taking an element and its index, and returning true if the element should be included in the resulting stream. |
O(1)
await AsyncStream.of(1, 2, 3).filter(async (v, i) => v + i !== 3).toArray()
// => [1, 3]
filterNot
Returns an AsyncStream containing only those elements from this stream for which the given pred
function returns false.
filterNot
pred
function returns false.Definition
filterNot(pred: (value: T, index: number, halt: () => void) => MaybePromise<boolean>):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number, halt: () => void) => MaybePromise<boolean> | a potentially asynchronous function taking an element and its index, and returning false if the element should be included in the resulting stream. |
O(1)
await AsyncStream.of(1, 2, 3).filterNot(async (v, i) => v + i !== 3).toArray()
// => [2]
filterNotPure
Returns an AsyncStream containing only those elements from this stream for which the given pred
function returns false.
filterNotPure
pred
function returns false.Definition
filterNotPure<A extends readonly unknown[]>(pred: (value: T, ...args: A) => MaybePromise<boolean>, ...args: A):
AsyncStream
<T>;
Type parameters
Name | Constraints | Description |
---|---|---|
A | readonly unknown[] | the type of the arguments to be passed to the pred function after each element |
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, ...args: A) => MaybePromise<boolean> | a potentially asynchronous function taking an element and the optionally given args , and returning false if the element should be included in the resulting stream. |
args | A | (optional) the extra arguments to pass to the given mapFun |
O(1)
await AsyncStream.of(1, 2, 3).filterNotPure(Object.is, 2).toArray()
// => [1, 3]
filterPure
Returns an AsyncStream containing only those elements from this stream for which the given pred
function returns true.
filterPure
pred
function returns true.Definition
filterPure<A extends readonly unknown[]>(pred: (value: T, ...args: A) => MaybePromise<boolean>, ...args: A):
AsyncStream
<T>;
Type parameters
Name | Constraints | Description |
---|---|---|
A | readonly unknown[] | the type of the arguments to be passed to the pred function after each element |
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, ...args: A) => MaybePromise<boolean> | a potentially asynchronous function taking an element the optionaly given args , and returning true if the element should be included in the resulting stream. |
args | A | (optional) the extra arguments to pass to the given mapFun |
O(1)
await AsyncStream.of(1, 2, 3).filterPure(Object.is, 2).toArray()
// => [2]
find
Returns the first element for which the given pred
function returns true, or a fallback value otherwise.
find
pred
function returns true, or a fallback value otherwise.Definitions
find(pred: (value: T, index: number) => MaybePromise<boolean>, occurrance?: number): Promise<T
|
undefined>;
find<O>(pred: (value: T, index: number) => MaybePromise<boolean>, occurrance: number
|
undefined, otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number) => MaybePromise<boolean> | a potentially asynchronous predicate function taking an element and its index |
occurrance | number | (default: 1) the occurrance number to look for |
const isEven = async (v: number) => v % 2 === 0
await AsyncStream.of(1, 2, 3, 4).find(isEven) // => 2
await AsyncStream.of(1, 2, 3, 4).find(isEven, 2) // => 4
await AsyncStream.of(1, 2, 3, 4).find(isEven, 3) // => undefined
await AsyncStream.of(1, 2, 3, 4).find(isEven, 3, 'a') // => 'a'
O(N)
first
Returns the first element of the AsyncStream, or a fallback value (default undefined) if the stream is empty.
first
Definitions
first(): Promise<T
|
undefined>;
first<O>(otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
await AsyncStream.of(1, 2, 3).first() // => 1
await AsyncStream.empty<number>().first() // => undefined
await AsyncStream.empty<number>().first(0) // => 0
await AsyncStream.empty<number>().first(async () => 0) // => 0
O(1)
flatMap
Returns an AsyncStream consisting of the concatenation of flatMapFun
applied to each element.
flatMap
flatMapFun
applied to each element.Definition
flatMap<T2>(flatMapFun: (value: T, index: number, halt: () => void) =>
AsyncStreamSource
<T2>):
AsyncStream
<T2>;
Type parameters
Name | Description |
---|---|
T2 | the resulting element type |
Parameters
Name | Type | Description |
---|---|---|
flatMapFun | (value: T, index: number, halt: () => void) => AsyncStreamSource <T2> | a potentially asynchronous function receiving the inputs described below and returning a StreamSource of new elements- value: the next element - index: the index of the element - halt: a function that, if called, ensures that no new elements are passed |
O(1)
await AsyncStream.of(1, 2, 3).flatMap(async (v, i, halt) => {
if (i >= 1) halt();
return [v, i, v + i]
}).toArray()
// => [1, 0, 1, 2, 1, 3]
flatZip
Returns an AsyncStream consisting of the concatenation of flatMapFun
applied to each element, zipped with the element that was provided to the function.
flatZip
flatMapFun
applied to each element, zipped with the element that was provided to the function.Definition
flatZip<T2>(flatMapFun: (value: T, index: number, halt: () => void) =>
AsyncStreamSource
<T2>):
AsyncStream
<[T, T2]>;
Type parameters
Name | Description |
---|---|
T2 | the result element type |
Parameters
Name | Type | Description |
---|---|---|
flatMapFun | (value: T, index: number, halt: () => void) => AsyncStreamSource <T2> | a function receiving the inputs described below and returning a StreamSource of new elements- value: the next element - index: the index of the element - halt: a function that, if called, ensures that no new elements are passed |
O(1)
await AsyncStream.of(1, 2, 3).flatZip((v, i, halt) => {
if (i >= 1) halt();
return [v, i, v + i]
}).toArray()
// => [[1, 1], [1, 0], [1, 1], [2, 2], [2, 1], [2, 3]]
fold
Returns the value resulting from applying the given the given next
function to a current state (initially the given init
value), and the next stream value, and returning the new state. When all elements are processed, the resulting state is returned.
fold
next
function to a current state (initially the given init
value), and the next stream value, and returning the new state. When all elements are processed, the resulting state is returned.Definition
fold<R>(init: AsyncOptLazy<R>, next: (current: R, value: T, index: number, halt: () => void) => MaybePromise<R>): Promise<R>;
Type parameters
Name | Description |
---|---|
R | the resulting type |
Parameters
Name | Type | Description |
---|---|---|
init | AsyncOptLazy<R> | the initial result/state value |
next | (current: R, value: T, index: number, halt: () => void) => MaybePromise<R> | a potentially asynchronous function taking the parameters below and returning the new result/state value - current: the current result/state value, initially init .- value: the next Stream value - index: the index of the given value - halt: a function that, if called, ensures that no new elements are passed |
console.log(await AsyncStream.empty<number>().fold(5, async (current, value) => current + value))
// => 5
console.log(await AsyncStream.of(1, 2, 3).fold(() => 5, (current, value) => current + value))
// => 11 (= 5 + 1 + 2 + 3)
foldStream
Returns an AsyncStream containing the values resulting from applying the given the given next
function to a current state (initially the given init
value), and the next stream value, and returning the new state.
foldStream
next
function to a current state (initially the given init
value), and the next stream value, and returning the new state.Definition
foldStream<R>(init: AsyncOptLazy<R>, next: (current: R, value: T, index: number, halt: () => void) => MaybePromise<R>):
AsyncStream
<R>;
Type parameters
Name | Description |
---|---|
R | the resulting element type |
Parameters
Name | Type | Description |
---|---|---|
init | AsyncOptLazy<R> | the initial result/state value |
next | (current: R, value: T, index: number, halt: () => void) => MaybePromise<R> | a function taking the parameters below and returning the new result/state value - current: the current result/state value, initially init .- value: the next Stream value - index: the index of the given value - halt: a function that, if called, ensures that no new elements are passed |
console.log(
await AsyncStream.empty<number>()
.foldStream(5, async (current, value) => current + value)
.toArray()
)
// => []
console.log(
await AsyncStream.of(1, 2, 3)
.foldStream(() => 5, (current, value) => current + value)
.toArray()
)
// => [6, 8, 11]
forEach
Performs given function f
for each element of the Stream, using given state
as initial traversal state.
forEach
f
for each element of the Stream, using given state
as initial traversal state.Definition
forEach(f: (value: T, index: number, halt: () => void) => MaybePromise<void>, state?: TraverseState): Promise<void>;
Parameters
Name | Type | Description |
---|---|---|
f | (value: T, index: number, halt: () => void) => MaybePromise<void> | the potentially asynchronous function to perform for each element, receiving: - value: the next element - index: the index of the element - halt: a function that, if called, ensures that no new elements are passed |
state | TraverseState | (optional) the traverse state |
if f is an async function, each call will be awaited consecutively
await AsyncStream.of(1, 2, 3).forEach(async (v, i, halt) => {
console.log(v);
if (i >= 1) halt();
})
// => 1, 2
O(N)
forEachPure
Performs given function f
for each element of the Stream, with the optionally given args
as extra arguments.
forEachPure
f
for each element of the Stream, with the optionally given args
as extra arguments.Definition
forEachPure<A extends readonly unknown[]>(f: (value: T, ...args: A) => MaybePromise<void>, ...args: A): Promise<void>;
Type parameters
Name | Constraints | Description |
---|---|---|
A | readonly unknown[] | the type of the arguments to be passed to the f function after each element |
Parameters
Name | Type | Description |
---|---|---|
f | (value: T, ...args: A) => MaybePromise<void> | the potentially asynchronous function to perform for each element, optionally receiving given extra args . |
args | A | (optional) a list of extra arguments to pass to given f for each element |
if f is an async function, each call will be awaited consecutively
await AsyncStream.of(1, 2, 3).forEachPure(console.log, 'sheep')
// => logs:
// 1 sheep
// 2 sheep
// 3 sheep
O(N)
indexed
Returns an AsyncStream where each element in this stream is paired with its index
indexed
Definition
indexed(startIndex?: number):
AsyncStream
<[number, T]>;
Parameters
Name | Type | Description |
---|---|---|
startIndex | number | (optional) an alternative start index to use |
await AsyncStream.of(1, 2, 3).indexed().toArray()
// => [[0, 1], [1, 2], [2, 3]]
O(1)
indexOf
Returns the index of the occurrance
instance of given searchValue
in the AsyncStream, using given eq
function, or undefined if no such value is found.
indexOf
occurrance
instance of given searchValue
in the AsyncStream, using given eq
function, or undefined if no such value is found.Definition
indexOf(searchValue: T, occurrance?: number, eq?: Eq<T>): Promise<number
|
undefined>;
Parameters
Name | Type | Description |
---|---|---|
searchValue | T | the element to search for |
occurrance | number | (default: 1) the occurrance to search for |
eq | Eq<T> | (optional) the equality function to use |
const source = AsyncStream.from('marmot')
await source.indexOf('m') // => 0
await source.indexOf('m', 2) // => 3
await source.indexOf('m', 3) // => undefined
await source.indexOf('q') // => undefined
O(N)
indexWhere
Returns the index of the given occurrance
instance of the element in the AsyncStream that satisfies given pred
function, or undefined if no such instance is found.
indexWhere
occurrance
instance of the element in the AsyncStream that satisfies given pred
function, or undefined if no such instance is found.Definition
indexWhere(pred: (value: T, index: number) => MaybePromise<boolean>, occurrance?: number): Promise<number
|
undefined>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number) => MaybePromise<boolean> | a potentially asynchronous predicate function taking an element and its index |
occurrance | number | (default: 1) the occurrance to search for |
await AsyncStream.of(1, 2, 3).indexWhere((v, i) => v + i > 2) // => 1
await AsyncStream.of(1, 2, 3).indexWhere(async (v, i) => v + i > 2, 2) // => 2
O(N)
indicesOf
Returns an AsyncStream containing the indicies of the occurrance of the given searchValue
, according to given eq
function.
indicesOf
searchValue
, according to given eq
function.Definition
indicesOf(searchValue: T, eq?: Eq<T>):
AsyncStream
<number>;
Parameters
Name | Type | Description |
---|---|---|
searchValue | T | the value to search for |
eq | Eq<T> | (optional) the equality function to use |
await AsyncStream.from('marmot').indicesOf('m').toArray()
// => [0, 3]
O(N)
indicesWhere
Returns an AsyncStream containing the indices of the elements for which the given pred
function returns true.
indicesWhere
pred
function returns true.Definition
indicesWhere(pred: (value: T) => MaybePromise<boolean>):
AsyncStream
<number>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T) => MaybePromise<boolean> | a potentially asynchronous predicate function taking an element |
await AsyncStream.of(1, 2, 3).indicesWhere((v, i) => v + i !== 3).toArray()
// => [0, 2]
O(N)
intersperse
Returns an AsyncStream with all elements from the given sep
AsyncStreamSource between two elements of this stream.
intersperse
sep
AsyncStreamSource between two elements of this stream.Definition
intersperse(sep:
AsyncStreamSource
<T>):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
sep | AsyncStreamSource <T> | the AsyncStreamSource to insert between each element of this Stream |
await AsyncStream.of(1, 2, 3).intersperse("ab").toArray()
// => [1, 'a', 'b', 2, 'a', 'b', 3]
O(1)
join
Returns a string resulting from converting each element to string with options.valueToString
, interspersed with options.sep
, starting with options.start
and ending with options.end
.
join
options.valueToString
, interspersed with options.sep
, starting with options.start
and ending with options.end
.Definition
join(options?: {
sep?: string
|
undefined;
start?: string
|
undefined;
end?: string
|
undefined;
valueToString?: ((value: T) => MaybePromise<string>)
|
undefined;
ifEmpty?: string
|
undefined;
}): Promise<string>;
Parameters
Name | Type | Description |
---|---|---|
options | { sep?: string | undefined; start?: string | undefined; end?: string | undefined; valueToString?: ((value: T) => MaybePromise<string>) | undefined; ifEmpty?: string | undefined; } | (optional) object specifying the following properties - sep: (optional) a seperator to insert between each Stream element - start: (optional) a start string to prepend at the start - end: (optional) an end string to append at the end - valueToString: (default: String) a potentially asynchronous function converting a Stream element to a string - ifEmpty: (optional) a string to return instead of the start and end tag if the stream is empty |
await AsyncStream.of(1, 2, 3).join({ start: '<', sep: ', ', end: '>' })
// => '<1, 2, 3>'
O(N)
last
Returns the last element of the AsyncStream, or a fallback value (default undefined) if the stream is empty.
last
Definitions
last(): Promise<T
|
undefined>;
last<O>(otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
await AsyncStream.of(1, 2, 3).last() // => 3
await AsyncStream.empty<number>().last() // => undefined
await AsyncStream.empty<number>().last(0) // => 0
await AsyncStream.empty<number>().last(async () => 0) // => 0
O(N)
map
Returns an AsyncStream where mapFun
is applied to each element.
map
mapFun
is applied to each element.Definition
map<T2>(mapFun: (value: T, index: number) => MaybePromise<T2>):
AsyncStream
<T2>;
Type parameters
Name | Description |
---|---|
T2 | the resulting element type |
Parameters
Name | Type | Description |
---|---|---|
mapFun | (value: T, index: number) => MaybePromise<T2> | a potentially asynchronous function taking an element and its index, and returning some new element |
await AsyncStream.of(1, 2, 3).map(async (v, i) => `[${i}]: ${v}`).toArray()
// => ['[0]: 1', '[1]: 2', '[2]: 3']
O(1)
mapPure
Returns an AsyncStream where the given mapFun
is applied to each value in the stream, with optionally as extra arguments the given args
.
mapPure
mapFun
is applied to each value in the stream, with optionally as extra arguments the given args
.Definition
mapPure<T2, A extends readonly unknown[]>(mapFun: (value: T, ...args: A) => MaybePromise<T2>, ...args: A):
AsyncStream
<T2>;
Type parameters
Name | Constraints | Description |
---|---|---|
T2 | the result value type | |
A | readonly unknown[] | the type of arguments to be supplied to the mapFun after each element |
Parameters
Name | Type | Description |
---|---|---|
mapFun | (value: T, ...args: A) => MaybePromise<T2> | a potentially asynchronous function taking an element and the given args, and returning the resulting stream value |
args | A | (optional) the extra arguments to pass to the given mapFun |
is mostly aimed to increase performance so that an extra function is not required @note can be used on function that really expect 1 argument, since the normal map will also pass more arguments
const s = AsyncStream.of({ a: 1 }, { a: 2, c: { d: true } })
const s2 = s.mapPure(JSON.stringify, ['a'], 5)
// when stream is evaluated, will call JSON.stringify on each stream element with the given extra arguments
console.log(await s2.toArray())
// => ["{\n \"a\": 1\n}", "{\n \"a\": 2\n}"]
max
Returns the maximum element of the AsyncStream according to a default compare function, or the provided otherwise
fallback value if the stream is empty.
max
otherwise
fallback value if the stream is empty.Definitions
max(): Promise<T
|
undefined>;
max<O>(otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
await AsyncStream.of(5, 1, 3).max() // => 1
await AsyncStream.empty<number>().max() // => undefined
await AsyncStream.empty<number>().max('a') // => 'a'
O(N)
maxBy
Returns the maximum element of the AsyncStream according to the provided compare
function, or the provided otherwise
fallback value if the stream is empty.
maxBy
compare
function, or the provided otherwise
fallback value if the stream is empty.Definitions
maxBy(compare: (v1: T, v2: T) => number): Promise<T
|
undefined>;
maxBy<O>(compare: (v1: T, v2: T) => number, otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
Parameters
Name | Type | Description |
---|---|---|
compare | (v1: T, v2: T) => number |
function compareLength(a: string, b: string): number { return b.length - a.length };
await AsyncStream.of('abc', 'a', 'ab').maxBy(compareLength) // => 'abc'
await AsyncStream.empty<string>().maxBy(compareLength) // => undefined
await AsyncStream.empty<string>().maxBy(compareLength, 'a') // => 'a'
O(N)
min
Returns the mimimum element of the AsyncStream according to a default compare function, or the provided otherwise
fallback value if the stream is empty.
min
otherwise
fallback value if the stream is empty.Definitions
min(): Promise<T
|
undefined>;
min<O>(otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
await AsyncStream.of(5, 1, 3).min() // => 1
await AsyncStream.empty<number>().min() // => undefined
await AsyncStream.empty<number>().min('a') // => 'a'
await AsyncStream.empty<number>().min(async () => 'a') // => 'a'
O(N)
minBy
Returns the mimimum element of the AsyncStream according to the provided compare
function, or the provided otherwise
fallback value if the stream is empty.
minBy
compare
function, or the provided otherwise
fallback value if the stream is empty.Definitions
minBy(compare: (v1: T, v2: T) => number): Promise<T
|
undefined>;
minBy<O>(compare: (v1: T, v2: T) => number, otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
Parameters
Name | Type | Description |
---|---|---|
compare | (v1: T, v2: T) => number |
function compareLength(a: string, b: string): number { return b.length - a.length };
await AsyncStream.of('abc', 'a', 'ab').minBy(compareLength) // => 'a'
await AsyncStream.empty<string>().minBy(compareLength) // => undefined
await AsyncStream.empty<string>().minBy(compareLength, 'a') // => 'a'
O(N)
mkGroup
Returns an AsyncStream starting with options.sep
, then returning the elements of this Stream interspersed with options.sep
, and ending with options.end
.
mkGroup
options.sep
, then returning the elements of this Stream interspersed with options.sep
, and ending with options.end
.Definition
mkGroup(options: {
sep?:
AsyncStreamSource
<T>;
start?:
AsyncStreamSource
<T>;
end?:
AsyncStreamSource
<T>;
}):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
options | { sep?: AsyncStreamSource <T>; start?: AsyncStreamSource <T>; end?: AsyncStreamSource <T>; } | object specifying the following properties - sep: (optional) a seperator StreamSource to insert between each Stream element - start: (optional) a start StreamSource to prepend - end: (optional) an end StreamSource to append |
await AsyncStream.of(1, 2, 3).mkGroup({ start: '<<', sep: '-', end: '>>' }).toArray()
// => ['<', '<', 1, '-', 2, '-', 3, '>', '>']
O(N)
prepend
Returns the current stream preceded by the given value
prepend
value
Definition
prepend(value: AsyncOptLazy<T>):
AsyncStream.NonEmpty
<T>;
Parameters
Name | Type | Description |
---|---|---|
value | AsyncOptLazy<T> | the value to prepend |
await AsyncStream.of(1, 2, 3).prepend(0).toArray()
// => [0, 1, 2, 3]
O(1)
reduce
Applies the given (Async)Reducer
to each element in the AsyncStream, and returns the final result.
reduce
(Async)Reducer
to each element in the AsyncStream, and returns the final result.Definition
reduce<R>(reducer: AsyncReducer<T, R>): Promise<R>;
Type parameters
Name | Description |
---|---|
R | the resulting type |
Parameters
Name | Type | Description |
---|---|---|
reducer | AsyncReducer<T, R> | the (Async)Reducer instance to use to apply to all stream elements. |
console.log(await AsyncStream.of(1, 2, 4).reduce(Reducer.sum))
// => 7
console.log(await AsyncStream.of(1, 2, 4).reduce(Reducer.product))
// => 8
reduceAll
Returns a tuple where each tuple element corresponds to result of applying all AsyncStream elements to the corresponding (Async)Reducer
instance of the given reducers
.
reduceAll
(Async)Reducer
instance of the given reducers
.Definition
reduceAll<R extends [unknown, unknown, ...unknown[]]>(...reducers: {
[K in keyof R]: AsyncReducer<T, R[K]>;
}): Promise<R>;
Type parameters
Name | Constraints | Description |
---|---|---|
R | [unknown, unknown, ...unknown[]] | the resulting tuple type |
Parameters
Name | Type | Description |
---|---|---|
reducers | { [K in keyof R]: AsyncReducer<T, R[K]>; } | a non-empty array of (Async)Reducer instances to use to apply to all stream elements. |
all reducers are processed in parallel, thus only one traversal is needed
console.log(await AsyncStream.of(1, 2, 4).reduceAll(Reducer.sum, Reducer.product))
// => [7, 8]
reduceAllStream
Returns an AsyncStream of tuples where each tuple element corresponds to result of applying all stream elements to the corresponding (Async)Reducer
instance of the given reducers
. Returns one element per input stream element.
reduceAllStream
(Async)Reducer
instance of the given reducers
. Returns one element per input stream element.Definition
reduceAllStream<R extends [unknown, unknown, ...unknown[]]>(...reducers: {
[K in keyof R]: AsyncReducer<T, R[K]>;
}):
AsyncStream
<R>;
Type parameters
Name | Constraints | Description |
---|---|---|
R | [unknown, unknown, ...unknown[]] | the resulting tuple element type |
Parameters
Name | Type | Description |
---|---|---|
reducers | { [K in keyof R]: AsyncReducer<T, R[K]>; } | a non-empty array of (Async)Reducer instances to use to apply to all stream elements. |
all reducers are processed in parallel, thus only one traversal is needed
console.log(
await ASyncStream.of(1, 2, 4)
.reduceAllStream(Reducer.sum, Reducer.product)
.toArray()
)
// => [[1, 1], [3, 2], [7, 8]]
reduceStream
Returns an AsyncStream where the given (Async)Reducer
is applied to each element in the stream.
reduceStream
(Async)Reducer
is applied to each element in the stream.Definition
reduceStream<R>(reducer: AsyncReducer<T, R>):
AsyncStream
<R>;
Type parameters
Name | Description |
---|---|
R | the resulting element type |
Parameters
Name | Type | Description |
---|---|---|
reducer | AsyncReducer<T, R> | the (Async)Reducer instance to use to apply to all stream elements. |
console.log(
await AsyncStream.of(1, 2, 4)
.reduceStream(Reducer.sum)
.toArray()
)
// => [1, 3, 7]
console.log(
await AsyncStream.of(1, 2, 4)
.reduce(Reducer.product)
.toArray()
)
// => [1, 2, 8]
repeat
Returns an AsyncStream that returns the elements from this stream given amount
of times.
repeat
amount
of times.Definition
repeat(amount?: number):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
amount | number | (default: undefined) the amount of times to return this Stream |
const source = AsyncStream.of(1, 2, 3)
source.repeat() // => AsyncStream(1, 2, 3, 1, 2, 3, 1, 2, ...)
await source.repeat(1).toArray() // => [1, 2, 3]
await source.repeat(3).toArray() // => [1, 2, 3, 1, 2, 3, 1, 2, 3]
await source.repeat(-3).toArray() // => [1, 2, 3]
amount = undefined means that the AsyncStream is repeated indefintely @note amount = 1 means that the Stream is not repeated @note amount < 1 will be normalized to amount = 1 @note O(1)
single
Returns the first element of the Stream if it only has one element, or a fallback value if the Stream does not have exactly one value.
single
Definitions
single(): Promise<T
|
undefined>;
single<O>(otherwise: AsyncOptLazy<O>): Promise<T
|
O>;
await AsyncStream.empty<number>().single() // => undefined
await AsyncStream.of(1, 2, 3).single() // => undefined
await AsyncStream.of(1).single() // => 1
await AsyncStream.of(1, 2, 3).single(0) // => 0
some
Returns true if any element of the AsyncStream satifies given pred
function.
some
pred
function.Definition
some(pred: (value: T, index: number) => MaybePromise<boolean>): Promise<boolean>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number) => MaybePromise<boolean> | a potentially asynchonous predicate function taking an element and its index |
await AsyncStream.of(1, 2, 3).some((v, i) => v + i > 10) // => false
await AsyncStream.of(1, 2, 3).some(async (v, i) => v + i > 1) // => true
O(N)
splitOn
Returns an AsyncStream of arrays of stream elements, where each array is filled with elements of this stream up to the next element that equals given sepElem
according to the given eq
function.
splitOn
sepElem
according to the given eq
function.Definition
splitOn(sepElem: T, eq?: Eq<T>):
AsyncStream
<T[]>;
Parameters
Name | Type | Description |
---|---|---|
sepElem | T | the separator element to look for |
eq | Eq<T> | (optional) the equality function to use |
await AsyncStream.from('marmot').splitOn('m').toArray() // => [[], ['a', 'r'], ['o', 't']]
O(1)
splitWhere
Returns an AsyncStream of arrays of stream elements, where each array is filled with elements of this stream up to the next element that satisfies give function pred
.
splitWhere
pred
.Definition
splitWhere(pred: (value: T, index: number) => MaybePromise<boolean>):
AsyncStream
<T[]>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number) => MaybePromise<boolean> | a potentially asynchronous predicate function taking an element and its index |
await AsyncStream.of(1, 2, 3, 4).splitWhere(async v => v == 3).toArray()
// => [[1, 2], [4]]
O(1)
take
Returns an AsyncStream that contains the elements of this stream up to a maximum of amount
elements.
take
amount
elements.Definition
take(amount: number):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
amount | number | the maximum amount of elements to return from the resulting Stream |
await AsyncStream.of(1, 2, 3).take(2).toArray() // => [1, 2]
O(N)
takeWhile
Returns an AsyncStream that contains the elements of this stream up to the first element that does not satisfy given pred
function.
takeWhile
pred
function.Definition
takeWhile(pred: (value: T, index: number) => MaybePromise<boolean>):
AsyncStream
<T>;
Parameters
Name | Type | Description |
---|---|---|
pred | (value: T, index: number) => MaybePromise<boolean> | a potentially asynchronous predicate function taking an element and its index |
await AsyncStream.of(1, 2, 3).takeWhile(async v => v < 3).toArray()
// => [1, 2]
O(N)
toArray
Returns an Array containing all elements in the AsyncStream.
toArray
toJSON
Returns a JSON representation of the AsyncStream.
toJSON
Definition
toJSON(): Promise<ToJSON<T[], 'AsyncStream'>>;
take care not to call on infinite Streams
await AsyncStream.of(1, 2, 3).toJSON() // => { dataType: 'AsyncStream', value: [1, 2, 3] }
toString
Returns a string representation of the AsyncStream.
toString
Definition
toString(): string;
to avoid issues with potentially infinite stream, this method does not list the stream elements. To do this, use join
.
AsyncStream.of(1, 2, 3).toString() // => 'AsyncStream(...<potentially empty>)'
transform
Returns an AsyncStream consisting of the concatenation of AsyncStreamSource elements resulting from applying the given reducer
to each element.
transform
reducer
to each element.Definition
transform<R>(transformer: AsyncTransformer<T, R>):
AsyncStream
<R>;
Type parameters
Name | Description |
---|---|
R | the resulting element type |
Parameters
Name | Type | Description |
---|---|---|
transformer | AsyncTransformer<T, R> | an async reducer taking elements ot type T as input, and returing an AsyncStreamSource of element type R |
O(1)
await AsyncStream.of(1, 2, 3, 4, 5, 6).transform(AsyncTransformer.window(3)).toArray()
// => [[1, 2, 3], [4, 5, 6]]
window
Returns an AsyncStream containing windows
of windowSize
consecutive elements of the source stream, with each window starting skipAmount
elements after the previous one.
window
windows
of windowSize
consecutive elements of the source stream, with each window starting skipAmount
elements after the previous one.Definitions
window(windowSize: number, skipAmount?: number):
AsyncStream
<T[]>;
window<R>(windowSize: number, skipAmount?: number, collector?: AsyncReducer<T, R>):
AsyncStream
<R>;
Parameters
Name | Type | Description |
---|---|---|
windowSize | number | the size in elements of the windows |
skipAmount | number | (default: windowSize ) the amount of elements to skip to start the next window |
await Stream.of(1, 2, 3, 4, 5, 6, 7).window(3).toArray()
// => [[1, 2, 3], [4, 5, 6]]
await Stream.of(1, 2, 3, 4, 5).window(3, 1).toArray()
// => [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
await Stream.of(1, 2, 3, 4).window(2, 2, AsyncReducer.toJSSet()).toArray()
// => [Set(1, 2), Set(3, 4)]