TrieMap
final class TrieMap[K, V] extends AbstractMap[K, V] with Map[K, V] with MapOps[K, V, [K, V] =>> TrieMap[K, V], TrieMap[K, V]] with MapFactoryDefaults[K, V, [K, V] =>> TrieMap[K, V], Iterable] with DefaultSerializable
A concurrent hash-trie or TrieMap is a concurrent thread-safe lock-free
implementation of a hash array mapped trie. It is used to implement the
concurrent map abstraction. It has particularly scalable concurrent insert
and remove operations and is memory-efficient. It supports O(1), atomic,
lock-free snapshots which are used to implement linearizable lock-free size,
iterator and clear operations. The cost of evaluating the (lazy) snapshot is
distributed across subsequent updates, thus making snapshot evaluation horizontally scalable.
For details, see: http://lampwww.epfl.ch/~prokopec/ctries-snapshot.pdf
trait DefaultSerializable
trait Serializable
trait Shrinkable[K]
trait Clearable
trait Cloneable
trait Equals
class Object
trait Matchable
class Any
Value members
Methods
Returns a snapshot of this TrieMap.
This operation is lock-free and linearizable.
The snapshot is lazily updated - the first time some branch
in the snapshot or this TrieMap are accessed, they are rewritten.
This means that the work of rebuilding both the snapshot and this
TrieMap is distributed across all the threads doing updates or accesses
subsequent to the snapshot creation.
- Source
- (source)
Returns a read-only snapshot of this TrieMap.
This operation is lock-free and linearizable.
The snapshot is lazily updated - the first time some branch
of this TrieMap are accessed, it is rewritten. The work of creating
the snapshot is thus distributed across subsequent updates
and accesses on this TrieMap by all threads.
Note that the snapshot itself is never rewritten unlike when calling
the
snapshot
method, but the obtained snapshot cannot be modified.This method is used by other methods such as
size
and iterator
.
- Source
- (source)
If the specified key is not already in the map, computes its value using
the given thunk
op
and enters it into the map.If the specified mapping function throws an exception,
that exception is rethrown.
Note: This method will invoke op at most once.
However,
op
may be invoked without the result being added to the map if
a concurrent process is also trying to add a value corresponding to the
same key k
.
- Value Params
- k
-
the key to modify
- op
-
the expression that computes the value
- Returns
-
the newly added value
- Definition Classes
- Source
- (source)
@deprecated("Use .view.filterKeys(f). A future version will include a strict version of this method (for now, .view.filterKeys(p).toMap).", "2.13.0")
@deprecated("Use .view.mapValues(f). A future version will include a strict version of this method (for now, .view.mapValues(f).toMap).", "2.13.0")
Inherited methods
Optionally applies a binary operator to all elements of this collection, going
right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the
underlying collection type is ordered or the operator is associative
and commutative.
- Type Params
- B
-
the result type of the binary operator.
- Value Params
- op
-
the binary operator.
- Returns
-
an option value containing the result of
reduceRight(op)
if this collection is nonempty,None
otherwise. - Inhertied from
- IterableOnceOps
- Source
- (source)
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
The last element of this iterable collection.
- Throws
- NoSuchElementException
- NoSuchElementException
- Inhertied from
- IterableOps
- Source
- (source)
Composes this partial function with an action function which
gets applied to results of this partial function.
The action function is invoked only for its side effects; its result is ignored.
Note that expression
pf.runWith(action)(x)
is equivalent toif(pf isDefinedAt x) { action(pf(x)); true } else false
except that
runWith
is implemented via applyOrElse
and thus potentially more efficient.
Using runWith
avoids double evaluation of pattern matchers and guards for partial function literals.- Value Params
- action
-
the action function
- Returns
-
a function which maps arguments
x
toisDefinedAt(x)
. The resulting function runsaction(this(x))
wherethis
is defined. - See also
applyOrElse
.- Inhertied from
- PartialFunction
- Source
- (source)
@throws(scala.throws.$lessinit$greater$default$1[scala.NoSuchElementException])
Defines the default value computation for the map,
returned when a key is not found
The method implemented here throws an exception,
but it might be overridden in subclasses.
- Value Params
- key
-
the given key value for which a binding is missing.
- Throws
- NoSuchElementException
- NoSuchElementException
- Inhertied from
- MapOps
- Source
- (source)
Update a mapping for the specified key and its current optionally-mapped value
(
Some
if there is current mapping, None
if not).If the remapping function returns
Some(v)
, the mapping is updated with the new value v
.
If the remapping function returns None
, the mapping is removed (or remains absent if initially absent).
If the function itself throws an exception, the exception is rethrown, and the current mapping is left unchanged.If the map is updated by another concurrent access, the remapping function will be retried until successfully updated.
Builds a new collection by applying a partial function to all elements of this map
on which the function is defined.
- Type Params
- K2
-
the key type of the returned map.
- V2
-
the value type of the returned map.
- Value Params
- pf
-
the partial function which filters and maps the map.
- Returns
-
a new map resulting from applying the given partial function
pf
to each element on which it is defined and collecting the results. The order of the elements is preserved. - Inhertied from
- MapOps
- Source
- (source)
@deprecated("Use foldLeft instead of /:", "2.13.0") @inline
- Inhertied from
- IterableOnceOps
- Source
- (source)
Finds the first element of the collection for which the given partial
function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Value Params
- pf
-
the partial function
- Returns
-
an option value containing pf applied to the first value for which it is defined, or
None
if none exists. - Example
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
- Inhertied from
- IterableOnceOps
- Source
- (source)
Partitions this iterable collection into a map of iterable collections according to a discriminator function
key
.
Each element in a group is transformed into a value of type B
using the value
function.It is equivalent to
groupBy(key).mapValues(_.map(f))
, but more efficient.case class User(name: String, age: Int)
def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
users.groupMap(_.age)(_.name)
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Type Params
- B
-
the type of values returned by the transformation function
- K
-
the type of keys returned by the discriminator function
- Value Params
- f
-
the element transformation function
- key
-
the discriminator function
- Inhertied from
- IterableOps
- Source
- (source)
Returns a iterable collection formed from this iterable collection and another iterable collection
by combining corresponding elements in pairs.
If one of the two collections is longer than the other, its remaining elements are ignored.
- Type Params
- B
-
the type of the second half of the returned pairs
- Value Params
- that
-
The iterable providing the second half of each result pair
- Returns
-
a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and
that
. The length of the returned collection is the minimum of the lengths of this iterable collection andthat
. - Inhertied from
- IterableOps
- Source
- (source)
The same map with a given default function.
Note: The default is only used for
apply
. Other methods like get
, contains
, iterator
, keys
, etc.
are not affected by withDefaultValue
.@nowarn("msg=will most likely never compare equal")
Removes all elements produced by an iterator from this shrinkable collection.
- Value Params
- xs
-
the iterator producing the elements to remove.
- Returns
-
the shrinkable collection itself
- Inhertied from
- Shrinkable
- Source
- (source)
Applies a function
f
to each element of the iterable collection and returns a pair of iterable collections: the first one
made of those values returned by f
that were wrapped in scala.util.Left, and the second
one made of those wrapped in scala.util.Right.Example:
val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap {
case i: Int => Left(i)
case s: String => Right(s)
}
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three))
- Type Params
- A1
-
the element type of the first resulting collection
- A2
-
the element type of the second resulting collection
- Value Params
- f
-
the 'split function' mapping the elements of this iterable collection to an scala.util.Either
- Returns
-
a pair of iterable collections: the first one made of those values returned by
f
that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right. - Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use .to(LazyList) instead of .toStream", "2.13.0") @inline
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use -- or removeAll on an immutable Map", "2.13.0")
@deprecated("Use - or remove on an immutable Map", "2.13.0")
@deprecated("Consider requiring an immutable Map.", "2.13.0") @inline
Apply
f
to each element for its side effects
Note: [U] parameter needed to help scalac's type inference.
- Inhertied from
- IterableOnceOps
- Source
- (source)
Sums up the elements of this collection.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
the result type of the
+
operator.
- Value Params
- num
-
an implicit parameter defining a set of numeric operations which includes the
+
operator to be used in forming the sum.
- Returns
-
the sum of all elements of this collection with respect to the
+
operator innum
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Builds a new map by applying a function to all elements of this map
and using the elements of the resulting collections.
@deprecated("Use mapValuesInPlace instead", "2.13.0") @inline
Produces a collection containing cumulative results of applying the operator going right to left.
The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
- Type Params
- B
-
the type of the elements in the resulting collection
- Value Params
- op
-
the binary operator applied to the intermediate result and the element
- z
-
the initial value
- Returns
-
collection with intermediate results
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use `--=` aka `subtractAll` instead of varargs `-=`; infix operations with an operand of multiple args will be deprecated", "2.13.3")
Removes two or more elements from this shrinkable collection.
- Value Params
- elem1
-
the first element to remove.
- elem2
-
the second element to remove.
- elems
-
the remaining elements to remove.
- Returns
-
the shrinkable collection itself
- Inhertied from
- Shrinkable
- Source
- (source)
Alias for
subtractOne
- Inhertied from
- Shrinkable
- Source
- (source)
Tests whether every element of this collection's iterator relates to the
corresponding element of another collection by satisfying a test predicate.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
the type of the elements of
that
- Value Params
- p
-
the test predicate, which relates elements from both collections
- that
-
the other collection
- Returns
-
true
if both collections have the same length andp(x, y)
istrue
for all corresponding elementsx
of this iterator andy
ofthat
, otherwisefalse
- Inhertied from
- IterableOnceOps
- Source
- (source)
Folds the elements of this collection using the specified associative binary operator.
The default implementation in
IterableOnce
is equivalent to foldLeft
but may be
overridden for more efficient traversal orders. The order in which operations are performed on elements is unspecified
and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
- Type Params
- A1
-
a type parameter for the binary operator, a supertype of
A
.
- Value Params
- op
-
a binary operator that must be associative.
- z
-
a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g.,
Nil
for list concatenation, 0 for addition, or 1 for multiplication).
- Returns
-
the result of applying the fold operator
op
between all the elements andz
, orz
if this collection is empty. - Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Iterable.seq always returns the iterable itself", "2.13.0")
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The result type of the function f.
- Value Params
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
- Returns
-
an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering
cmp
. - Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use `++=` aka `addAll` instead of varargs `+=`; infix operations with an operand of multiple args will be deprecated", "2.13.0") @inline
Convert collection to array.
Implementation note: DO NOT call Array.from from this method.
- Inhertied from
- IterableOnceOps
- Source
- (source)
Iterates over the inits of this iterable collection. The first value will be this
iterable collection and the final one will be an empty iterable collection, with the intervening
values the results of successive applications of
init
. Note: Even when applied to a view or a lazy collection it will always force the elements.
- Returns
-
an iterator over all the inits of this iterable collection
- Example
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
- Inhertied from
- IterableOps
- Source
- (source)
Tries to extract a
B
from an A
in a pattern matching expression.- Inhertied from
- PartialFunction
- Source
- (source)
Groups elements in fixed size blocks by passing a "sliding window"
over them (as opposed to partitioning them, as is done in grouped.)
The returned iterator will be empty when called on an empty collection.
The last element the iterator produces may be smaller than the window
size when the original collection isn't exhausted by the window before
it and its last element isn't skipped by the step before it.
- Value Params
- size
-
the number of elements per group
- step
-
the distance between the first elements of successive groups
- Returns
-
An iterator producing iterable collections of size
size
, except the last element (which may be the only element) will be smaller if there are fewer thansize
elements remaining to be grouped. - See also
- scala.collection.Iterator, method
sliding
- Example
List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))
List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))
- Inhertied from
- IterableOps
- Source
- (source)
Groups elements in fixed size blocks by passing a "sliding window"
over them (as opposed to partitioning them, as is done in
grouped
.)An empty collection returns an empty iterator, and a non-empty
collection containing fewer elements than the window size returns
an iterator that will produce the original collection as its only
element.
- Value Params
- size
-
the number of elements per group
- Returns
-
An iterator producing iterable collections of size
size
, except for a non-empty collection with less thansize
elements, which returns an iterator that produces the source collection itself as its only element. - See also
- scala.collection.Iterator, method
sliding
- Example
List().sliding(2) = empty iterator
List(1).sliding(2) = Iterator(List(1))
List(1, 2).sliding(2) = Iterator(List(1, 2))
List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("`aggregate` is not relevant for sequential collections. Use `foldLeft(z)(seqop)` instead.", "2.13.0")
- Inhertied from
- IterableOnceOps
- Source
- (source)
Transposes this iterable collection of iterable collections into
a iterable collection of iterable collections.
The resulting collection's type will be guided by the
static type of iterable collection. For example:
val xs = List(
Set(1, 2, 3),
Set(4, 5, 6)).transpose
// xs == List(
// List(1, 4),
// List(2, 5),
// List(3, 6))
val ys = Vector(
List(1, 2, 3),
List(4, 5, 6)).transpose
// ys == Vector(
// Vector(1, 4),
// Vector(2, 5),
// Vector(3, 6))
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Type Params
- B
-
the type of the elements of each iterable collection.
- Value Params
- asIterable
-
an implicit conversion which asserts that the element type of this iterable collection is an
Iterable
.
- Returns
-
a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.
- Throws
- IllegalArgumentException
- IllegalArgumentException
- Inhertied from
- IterableOps
- Source
- (source)
Applies a binary operator to a start value and all elements of this collection,
going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the
underlying collection type is ordered or the operator is associative
and commutative.
- Type Params
- B
-
the result type of the binary operator.
- Value Params
- op
-
the binary operator.
- z
-
the start value.
- Returns
-
the result of inserting
op
between consecutive elements of this collection, going left to right with the start valuez
on the left:op(...op(z, x1), x2, ..., xn)
wherex1, ..., xn
are the elements of this collection. Returnsz
if this collection is empty. - Inhertied from
- IterableOnceOps
- Source
- (source)
Appends all elements of this collection to a string builder.
The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this collection without any separator string.Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> val h = a.addString(b)
h: StringBuilder = 1234
- Value Params
- b
-
the string builder to which elements are appended.
- Returns
-
the string builder
b
to which elements were appended. - Inhertied from
- IterableOnceOps
- Source
- (source)
Appends all elements of this collection to a string builder using a separator string.
The written text consists of the string representations (w.r.t. the method
toString
)
of all elements of this collection, separated by the string sep
.Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4
- Value Params
- b
-
the string builder to which elements are appended.
- sep
-
the separator string.
- Returns
-
the string builder
b
to which elements were appended. - Inhertied from
- IterableOnceOps
- Source
- (source)
Turns this partial function into a plain function returning an
Option
result.- Returns
-
a function that takes an argument
x
toSome(this(x))
ifthis
is defined forx
, and toNone
otherwise. - See also
- Function.unlift
- Inhertied from
- PartialFunction
- Source
- (source)
@deprecated("Use toIterable instead", "2.13.0")
Converts this iterable collection to an unspecified Iterable. Will return
the same collection if this instance is already Iterable.
- Returns
-
An Iterable containing all elements of this iterable collection.
- Inhertied from
- IterableOps
- Source
- (source)
Applies a binary operator to all elements of this collection and a start value,
going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the
underlying collection type is ordered or the operator is associative
and commutative.
- Type Params
- B
-
the result type of the binary operator.
- Value Params
- op
-
the binary operator.
- z
-
the start value.
- Returns
-
the result of inserting
op
between consecutive elements of this collection, going right to left with the start valuez
on the right:op(x1, op(x2, ... op(xn, z)...))
wherex1, ..., xn
are the elements of this collection. Returnsz
if this collection is empty. - Inhertied from
- IterableOnceOps
- Source
- (source)
- Returns
-
This collection as a
Seq[A]
. This is equivalent toto(Seq)
but might be faster. - Inhertied from
- IterableOnceOps
- Source
- (source)
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The result type of the function f.
- Value Params
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
- Returns
-
the first element of this collection with the smallest value measured by function f with respect to the ordering
cmp
. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)", "2.13.0")
Tests whether this collection is known to have a finite size.
All strict collections are known to have finite size. For a non-strict
collection such as
Stream
, the predicate returns true
if all
elements have been computed. It returns false
if the stream is
not yet evaluated to the end. Non-empty Iterators usually return
false
even if they were created from a collection with a known
finite size.Note: many collection methods will not work on collections of infinite sizes.
The typical failure mode is an infinite loop. These methods always attempt a
traversal without checking first that
hasDefiniteSize
returns true
.
However, checking hasDefiniteSize
can provide an assurance that size is
well-defined and non-termination is not a concern.
- Returns
-
true
if this collection is known to have finite size,false
otherwise. - See also
- method
knownSize
for a more useful alternative - Inhertied from
- IterableOnceOps
- Source
- (source)
A pair of, first, all elements that satisfy predicate
p
and, second,
all elements that do not. Interesting because it splits a collection in two.The default implementation provided here needs to traverse the collection twice.
Strict collections have an overridden version of
partition
in StrictOptimizedIterableOps
,
which requires only a single traversal.
- Inhertied from
- IterableOps
- Source
- (source)
@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0")
Tests whether the collection is not empty.
- Returns
-
true
if the collection contains at least one element,false
otherwise. - Inhertied from
- IterableOnceOps
- Source
- (source)
Composes another partial function
k
with this partial function so that this
partial function gets applied to results of k
.Note that calling isDefinedAt on the resulting partial function may apply the first
partial function and execute its side effect. It is highly recommended to call applyOrElse
instead of isDefinedAt / apply for efficiency.
- Type Params
- R
-
the parameter type of the transformation function.
- Value Params
- k
-
the transformation function
- Returns
-
a partial function with the domain of other partial function narrowed by this partial function, which maps arguments
x
tothis(k(x))
. - Inhertied from
- PartialFunction
- Source
- (source)
@deprecated("Use ++ with an explicit collection argument instead of + with varargs", "2.13.0")
@deprecated("Consider requiring an immutable Map or fall back to Map.concat.", "2.13.0")
Compares the size of this iterable collection to the size of another
Iterable
.
- Value Params
- that
-
the
Iterable
whose size is compared with this iterable collection's size.
- Returns
-
A value
x
wherex < 0 if this.size < that.size x == 0 if this.size == that.size x > 0 if this.size > that.size
The method as implemented here does not callsize
directly; its running time isO(this.size min that.size)
instead ofO(this.size + that.size)
. The method should be overridden if computingsize
is cheap andknownSize
returns-1
. - Inhertied from
- IterableOps
- Source
- (source)
Compares the size of this iterable collection to a test value.
- Value Params
- otherSize
-
the test value that gets compared with the size.
- Returns
-
A value
x
wherex < 0 if this.size < otherSize x == 0 if this.size == otherSize x > 0 if this.size > otherSize
The method as implemented here does not callsize
directly; its running time isO(size min otherSize)
instead ofO(size)
. The method should be overridden if computingsize
is cheap andknownSize
returns-1
. - See also
- Inhertied from
- IterableOps
- Source
- (source)
Analogous to
zip
except that the elements in each collection are not consumed until a strict operation is
invoked on the returned LazyZip2
decorator.Calls to
lazyZip
can be chained to support higher arities (up to 4) without incurring the expense of
constructing and deconstructing intermediary tuples.val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)
- Type Params
- B
-
the type of the second element in each eventual pair
- Value Params
- that
-
the iterable providing the second element of each eventual pair
- Returns
-
a decorator
LazyZip2
that allows strict operations to be performed on the lazily evaluated pairs or chained calls tolazyZip
. Implicit conversion toIterable[(A, B)]
is also supported. - Inhertied from
- Iterable
- Source
- (source)
Applies a binary operator to all elements of this collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the
underlying collection type is ordered or the operator is associative
and commutative.
- Type Params
- B
-
the result type of the binary operator.
- Value Params
- op
-
the binary operator.
- Returns
-
the result of inserting
op
between consecutive elements of this collection, going right to left:op(x1, op(x2, ..., op(xn-1, xn)...))
wherex1, ..., xn
are the elements of this collection. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
The same map with a given default value.
Note: The default is only used for
apply
. Other methods like get
, contains
, iterator
, keys
, etc.
are not affected by withDefaultValue
.Finds the smallest element.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The type over which the ordering is defined.
- Value Params
- ord
-
An ordering to be used for comparing elements.
- Returns
-
the smallest element of this collection with respect to the ordering
ord
. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use `dest ++= coll` instead", "2.13.0") @inline
- Inhertied from
- IterableOnceOps
- Source
- (source)
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The result type of the function f.
- Value Params
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
- Returns
-
an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering
cmp
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Type Params
- K
-
the type of keys returned by the discriminator function.
- Value Params
- f
-
the discriminator function.
- Returns
-
A map from keys to iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
That is, every keyk
is bound to a iterable collection of those elementsx
for whichf(x)
equalsk
. - Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use .iterator instead of .toIterator", "2.13.0") @inline
- Inhertied from
- IterableOnceOps
- Source
- (source)
Gives a hint that one expects the
result
of this builder
to have the same size as the given collection, plus some delta. This will
provide a hint only if the collection has a known size
Some builder classes
will optimize their representation based on the hint. However,
builder implementations are still required to work correctly even if the hint is
wrong, i.e. a different number of elements is added.
Gives a hint how many elements are expected to be added
when the next
result
is called. Some builder classes
will optimize their representation based on the hint. However,
builder implementations are still required to work correctly even if the hint is
wrong, i.e. a different number of elements is added.
Finds the first element of the collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Value Params
- p
-
the predicate used to test elements.
- Returns
-
an option value containing the first element in the collection that satisfies
p
, orNone
if none exists. - Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecated("Use iterableFactory instead", "2.13.0") @deprecatedOverriding("Use iterableFactory instead", "2.13.0") @inline
- Inhertied from
- IterableOps
- Source
- (source)
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The result type of the function f.
- Value Params
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
- Returns
-
the first element of this collection with the largest value measured by function f with respect to the ordering
cmp
. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Composes this partial function with another partial function that
gets applied to results of this partial function.
Note that calling isDefinedAt on the resulting partial function may apply the first
partial function and execute its side effect. It is highly recommended to call applyOrElse
instead of isDefinedAt / apply for efficiency.
- Type Params
- C
-
the result type of the transformation function.
- Value Params
- k
-
the transformation function
- Returns
-
a partial function with the domain of this partial function narrowed by other partial function, which maps arguments
x
tok(this(x))
. - Inhertied from
- PartialFunction
- Source
- (source)
Composes this partial function with a transformation function that
gets applied to results of this partial function.
If the runtime type of the function is a
PartialFunction
then the
other andThen
method is used (note its cautions).
- Type Params
- C
-
the result type of the transformation function.
- Value Params
- k
-
the transformation function
- Returns
-
a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments
x
tok(this(x))
. - Definition Classes
- Inhertied from
- PartialFunction
- Source
- (source)
Selects the last n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Value Params
- n
-
the number of elements to take from this iterable collection.
- Returns
-
a iterable collection consisting only of the last
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements. Ifn
is negative, returns an empty iterable collection. - Inhertied from
- IterableOps
- Source
- (source)
Converts this iterable collection of pairs into two collections of the first and second
half of each pair.
val xs = Iterable(
(1, "one"),
(2, "two"),
(3, "three")).unzip
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three))
- Type Params
- A1
-
the type of the first half of the element pairs
- A2
-
the type of the second half of the element pairs
- Value Params
- asPair
-
an implicit conversion which asserts that the element type of this iterable collection is a pair.
- Returns
-
a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
- Inhertied from
- IterableOps
- Source
- (source)
Partitions elements in fixed size iterable collections.
- Value Params
- size
-
the number of elements per group
- Returns
-
An iterator producing iterable collections of size
size
, except the last will be less than sizesize
if the elements don't divide evenly. - See also
- scala.collection.Iterator, method
grouped
- Inhertied from
- IterableOps
- Source
- (source)
Finds the largest element.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The type over which the ordering is defined.
- Value Params
- ord
-
An ordering to be used for comparing elements.
- Returns
-
an option value containing the largest element of this collection with respect to the ordering
ord
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Multiplies up the elements of this collection.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
the result type of the
*
operator.
- Value Params
- num
-
an implicit parameter defining a set of numeric operations which includes the
*
operator to be used in forming the product.
- Returns
-
the product of all elements of this collection with respect to the
*
operator innum
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Composes this partial function with a fallback partial function which
gets applied where this partial function is not defined.
- Type Params
- A1
-
the argument type of the fallback function
- B1
-
the result type of the fallback function
- Value Params
- that
-
the fallback function
- Returns
-
a partial function which has as domain the union of the domains of this partial function and
that
. The resulting partial function takesx
tothis(x)
wherethis
is defined, and tothat(x)
where it is not. - Inhertied from
- PartialFunction
- Source
- (source)
Given a collection factory
factory
, convert this collection to the appropriate
representation for the current element type A
. Example uses: xs.to(List)
xs.to(ArrayBuffer)
xs.to(BitSet) // for xs: Iterable[Int]
- Inhertied from
- IterableOnceOps
- Source
- (source)
@nowarn("msg=will most likely never compare equal")
Computes a prefix scan of the elements of the collection.
Note: The neutral element
z
may be applied more than once.
- Type Params
- B
-
element type of the resulting collection
- Value Params
- op
-
the associative operator for the scan
- z
-
neutral element for the operator
op
- Returns
-
a new iterable collection containing the prefix scan of the elements in this iterable collection
- Inhertied from
- IterableOps
- Source
- (source)
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
the first element of this iterable collection if it is nonempty,
None
if it is empty. - Inhertied from
- IterableOps
- Source
- (source)
Tests whether a predicate holds for all elements of this collection.
Note: may not terminate for infinite-sized collections.
- Value Params
- p
-
the predicate used to test elements.
- Returns
-
true
if this collection is empty or the given predicatep
holds for all elements of this collection, otherwisefalse
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Returns the value associated with a key, or a default value if the key is not contained in the map.
- Type Params
- V1
-
the result type of the default computation.
- Value Params
- default
-
a computation that yields a default value in case no binding for
key
is found in the map. - key
-
the key.
- Returns
-
the value associated with
key
if it exists, otherwise the result of thedefault
computation. - Inhertied from
- MapOps
- Source
- (source)
@deprecated("Use foldRight instead of :\\", "2.13.0") @inline
- Inhertied from
- IterableOnceOps
- Source
- (source)
Alias for
concat
- Inhertied from
- IterableOps
- Source
- (source)
Copy elements to an array, returning the number of elements written.
Fills the given array
xs
starting at index start
with at most len
elements of this collection.Copying will stop once either all the elements of this collection have been copied,
or the end of the array is reached, or
len
elements have been copied.
- Type Params
- B
-
the type of the elements of the array.
- Value Params
- len
-
the maximal number of elements to copy.
- start
-
the starting index of xs.
- xs
-
the array to fill.
- Returns
-
the number of elements written to the array
- Note
- Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
Copy elements to an array, returning the number of elements written.
Fills the given array
xs
starting at index start
with values of this collection.Copying will stop once either all the elements of this collection have been copied,
or the end of the array is reached.
- Type Params
- B
-
the type of the elements of the array.
- Value Params
- start
-
the starting index of xs.
- xs
-
the array to fill.
- Returns
-
the number of elements written to the array
- Note
- Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
- Inhertied from
- IterableOnceOps
- Source
- (source)
@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")
Copy elements to an array, returning the number of elements written.
Fills the given array
xs
starting at index start
with values of this collection.Copying will stop once either all the elements of this collection have been copied,
or the end of the array is reached.
- Type Params
- B
-
the type of the elements of the array.
- Value Params
- xs
-
the array to fill.
- Returns
-
the number of elements written to the array
- Note
- Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
- Inhertied from
- IterableOnceOps
- Source
- (source)
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The type over which the ordering is defined.
- Value Params
- ord
-
An ordering to be used for comparing elements.
- Returns
-
an option value containing the smallest element of this collection with respect to the ordering
ord
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Displays all elements of this collection in a string.
Delegates to addString, which can be overridden.
- Returns
-
a string representation of this collection. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this collection follow each other without any separator string. - Inhertied from
- IterableOnceOps
- Source
- (source)
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
- Value Params
- sep
-
the separator string.
- Returns
-
a string representation of this collection. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this collection are separated by the stringsep
. - Example
List(1, 2, 3).mkString("|") = "1|2|3"
- Inhertied from
- IterableOnceOps
- Source
- (source)
Displays all elements of this collection in a string using start, end, and
separator strings.
Delegates to addString, which can be overridden.
- Value Params
- end
-
the ending string.
- sep
-
the separator string.
- start
-
the starting string.
- Returns
-
a string representation of this collection. The resulting string begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this collection are separated by the stringsep
. - Example
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
- Inhertied from
- IterableOnceOps
- Source
- (source)
Returns a scala.collection.Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, see
scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be
used as an iterator which doesn't box the elements.
The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the
element type of this collection.
-
For collections of
Long
a scala.collection.LongStepper is returned -
For any other element type, an scala.collection.AnyStepper is returned
Note that this method is overridden in subclasses and the return type is refined to
S with EfficientSplit
, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with
scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters
allow creating parallel streams, whereas bare Steppers can be converted only to sequential
streams.
- Inhertied from
- IterableOnce
- Source
- (source)
@deprecated("Use m.clone().addOne((k,v)) instead of m.updated(k, v)", "2.13.0")
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
the first element of this iterable collection.
- Throws
- NoSuchElementException
- NoSuchElementException
- Inhertied from
- IterableOps
- Source
- (source)
Reduces the elements of this collection, if any, using the specified
associative binary operator.
The order in which operations are performed on elements is unspecified
and may be nondeterministic.
- Type Params
- B
-
A type parameter for the binary operator, a supertype of
A
.
- Value Params
- op
-
A binary operator that must be associative.
- Returns
-
An option value containing result of applying reduce operator
op
between all the elements if the collection is nonempty, andNone
otherwise. - Inhertied from
- IterableOnceOps
- Source
- (source)
Partitions this iterable collection into a map according to a discriminator function
key
. All the values that
have the same discriminator are then transformed by the f
function and then reduced into a
single value with the reduce
function.It is equivalent to
groupBy(key).mapValues(_.map(f).reduce(reduce))
, but more efficient.def occurrences[A](as: Seq[A]): Map[A, Int] =
as.groupMapReduce(identity)(_ => 1)(_ + _)
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Inhertied from
- IterableOps
- Source
- (source)
Counts the number of elements in the collection which satisfy a predicate.
Note: will not terminate for infinite-sized collections.
- Value Params
- p
-
the predicate used to test elements.
- Returns
-
the number of elements satisfying the predicate
p
. - Inhertied from
- IterableOnceOps
- Source
- (source)
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the
right hand operand. The element type of the iterable collection is the most specific superclass encompassing
the element types of the two operands.
- Type Params
- B
-
the element type of the returned collection.
- Value Params
- suffix
-
the traversable to append.
- Returns
-
a new iterable collection which contains all elements of this iterable collection followed by all elements of
suffix
. - Inhertied from
- IterableOps
- Source
- (source)
Returns a new map containing the elements from the left hand operand followed by the elements from the
right hand operand. The element type of the map is the most specific superclass encompassing
the element types of the two operands.
Alias for
subtractAll
- Inhertied from
- Shrinkable
- Source
- (source)
@deprecated("Use filterInPlace instead", "2.13.0") @inline
The initial part of the collection without its last element.
Note: Even when applied to a view or a lazy collection it will always force the elements.
- Inhertied from
- IterableOps
- Source
- (source)
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
These operations are implemented in terms of
sizeCompare(Int)
, and
allow the following more readable usages:this.sizeIs < size // this.sizeCompare(size) < 0
this.sizeIs <= size // this.sizeCompare(size) <= 0
this.sizeIs == size // this.sizeCompare(size) == 0
this.sizeIs != size // this.sizeCompare(size) != 0
this.sizeIs >= size // this.sizeCompare(size) >= 0
this.sizeIs > size // this.sizeCompare(size) > 0
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use coll instead of repr in a collection implementation, use the collection value itself from the outside", "2.13.0")
- Inhertied from
- IterableOps
- Source
- (source)
Applies a binary operator to all elements of this collection,
going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the
underlying collection type is ordered or the operator is associative
and commutative.
- Type Params
- B
-
the result type of the binary operator.
- Value Params
- op
-
the binary operator.
- Returns
-
the result of inserting
op
between consecutive elements of this collection, going left to right:op( op( ... op(x1, x2) ..., xn-1), xn)
wherex1, ..., xn
are the elements of this collection. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Tests whether a predicate holds for at least one element of this collection.
Note: may not terminate for infinite-sized collections.
- Value Params
- p
-
the predicate used to test elements.
- Returns
-
true
if the given predicatep
is satisfied by at least one element of this collection, otherwisefalse
- Inhertied from
- IterableOnceOps
- Source
- (source)
Selects all elements except last n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Value Params
- n
-
the number of elements to drop from this iterable collection.
- Returns
-
a iterable collection consisting of all elements of this iterable collection except the last
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements. Ifn
is negative, don't drop any elements. - Inhertied from
- IterableOps
- Source
- (source)
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Value Params
- p
-
The predicate used to test elements.
- Returns
-
the longest prefix of this iterable collection whose elements all satisfy the predicate
p
. - Inhertied from
- IterableOps
- Source
- (source)
def unzip3[A1, A2, A3](asTriple: (K, V) => (A1, A2, A3)): (Iterable[A1], Iterable[A2], Iterable[A3])
Converts this iterable collection of triples into three collections of the first, second,
and third element of each triple.
val xs = Iterable(
(1, "one", '1'),
(2, "two", '2'),
(3, "three", '3')).unzip3
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three),
// Iterable(1, 2, 3))
- Type Params
- A1
-
the type of the first member of the element triples
- A2
-
the type of the second member of the element triples
- A3
-
the type of the third member of the element triples
- Value Params
- asTriple
-
an implicit conversion which asserts that the element type of this iterable collection is a triple.
- Returns
-
a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
- Inhertied from
- IterableOps
- Source
- (source)
Returns a iterable collection formed from this iterable collection and another iterable collection
by combining corresponding elements in pairs.
If one of the two collections is shorter than the other,
placeholder elements are used to extend the shorter collection to the length of the longer.
- Value Params
- that
-
the iterable providing the second half of each result pair
- thatElem
-
the element to be used to fill up the result if
that
is shorter than this iterable collection. - thisElem
-
the element to be used to fill up the result if this iterable collection is shorter than
that
.
- Returns
-
a new collection of type
That
containing pairs consisting of corresponding elements of this iterable collection andthat
. The length of the returned collection is the maximum of the lengths of this iterable collection andthat
. If this iterable collection is shorter thanthat
,thisElem
values are used to pad the result. Ifthat
is shorter than this iterable collection,thatElem
values are used to pad the result. - Inhertied from
- IterableOps
- Source
- (source)
Returns an extractor object with a
unapplySeq
method, which extracts each element of a sequence data.
- Example
val firstChar: String => Option[Char] = _.headOption Seq("foo", "bar", "baz") match { case firstChar.unlift.elementWise(c0, c1, c2) => println(s"$c0, $c1, $c2") // Output: f, b, b }
- Inhertied from
- PartialFunction
- Source
- (source)
Finds the largest element.
Note: will not terminate for infinite-sized collections.
- Type Params
- B
-
The type over which the ordering is defined.
- Value Params
- ord
-
An ordering to be used for comparing elements.
- Returns
-
the largest element of this collection with respect to the ordering
ord
. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Gives a hint how many elements are expected to be added
when the next
result
is called, together with an upper bound
given by the size of some other collection. Some builder classes
will optimize their representation based on the hint. However,
builder implementations are still required to work correctly even if the hint is
wrong, i.e. a different number of elements is added.
@deprecated("Use ++ instead of ++: for collections of type Iterable", "2.13.0")
- Inhertied from
- IterableOps
- Source
- (source)
@deprecated("Use ++ instead of ++: for collections of type Iterable", "2.13.0")
@deprecated("Use .view.slice(from, until) instead of .view(from, until)", "2.13.0")
A view over a slice of the elements of this collection.
- Inhertied from
- IterableOps
- Source
- (source)
Optionally applies a binary operator to all elements of this collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the
underlying collection type is ordered or the operator is associative
and commutative.
- Type Params
- B
-
the result type of the binary operator.
- Value Params
- op
-
the binary operator.
- Returns
-
an option value containing the result of
reduceLeft(op)
if this collection is nonempty,None
otherwise. - Inhertied from
- IterableOnceOps
- Source
- (source)
Iterates over the tails of this iterable collection. The first value will be this
iterable collection and the final one will be an empty iterable collection, with the intervening
values the results of successive applications of
tail
.
- Returns
-
an iterator over all the tails of this iterable collection
- Example
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
- Inhertied from
- IterableOps
- Source
- (source)
Reduces the elements of this collection using the specified associative binary operator.
The order in which operations are performed on elements is unspecified
and may be nondeterministic.
- Type Params
- B
-
A type parameter for the binary operator, a supertype of
A
.
- Value Params
- op
-
A binary operator that must be associative.
- Returns
-
The result of applying reduce operator
op
between all the elements if the collection is nonempty. - Throws
- UnsupportedOperationException
- UnsupportedOperationException
- Inhertied from
- IterableOnceOps
- Source
- (source)
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- Returns
-
the last element of this iterable collection$ if it is nonempty,
None
if it is empty. - Inhertied from
- IterableOps
- Source
- (source)