scala.collection.parallel.immutable
Parallel ranges.
This is a base trait for Scala parallel collections. It defines behaviour
common to all parallel collections. Concrete parallel collections should
inherit this trait and ParIterable if they want to define specific combiner
factories.
Parallel operations are implemented with divide and conquer style algorithms that parallelize well. The basic idea is to split the collection into smaller parts until they are small enough to be operated on sequentially.
All of the parallel operations are implemented as tasks within this trait. Tasks rely on the concept of splitters, which extend iterators. Every parallel collection defines:
def parallelIterator: ParIterableIterator[T]
which returns an instance of ParIterableIterator[T], which is a subtype of Splitter[T].
Parallel iterators have a method remaining to check the remaining number of elements,
and method split which is defined by splitters. Method split divides the splitters
iterate over into disjunct subsets:
def split: Seq[Splitter]
which splits the splitter into a sequence of disjunct subsplitters. This is typically a very fast operation which simply creates wrappers around the receiver collection. This can be repeated recursively.
Method newCombiner produces a new combiner. Combiners are an extension of builders.
They provide a method combine which combines two combiners and returns a combiner
containing elements of both combiners.
This method can be implemented by aggressively copying all the elements into the new combiner
or by lazily binding their results. It is recommended to avoid copying all of
the elements for performance reasons, although that cost might be negligible depending on
the use case. Standard parallel collection combiners avoid copying when merging results,
relying either on a two-step lazy construction or specific data-structure properties.
Methods:
def seq: Sequential
def par: Repr
produce the sequential or parallel implementation of the collection, respectively.
Method par just returns a reference to this parallel collection.
Method seq is efficient - it will not copy the elements. Instead,
it will create a sequential version of the collection using the same underlying data structure.
Note that this is not the case for sequential collections in general - they may copy the elements
and produce a different underlying data structure.
The combination of methods toMap, toSeq or toSet along with par and seq is a flexible
way to change between different collection types.
The method:
def threshold(sz: Int, p: Int): Int
provides an estimate on the minimum number of elements the collection has before the splitting stops and depends on the number of elements in the collection. A rule of the thumb is the number of elements divided by 8 times the parallelism level. This method may be overridden in concrete implementations if necessary.
Since this trait extends the Iterable trait, methods like size must also
be implemented in concrete collections, while iterator forwards to parallelIterator by
default.
Each parallel collection is bound to a specific fork/join pool, on which dormant worker
threads are kept. The fork/join pool contains other information such as the parallelism
level, that is, the number of processors used. When a collection is created, it is assigned the
default fork/join pool found in the scala.parallel package object.
Parallel collections are not necessarily ordered in terms of the foreach
operation (see Traversable). Parallel sequences have a well defined order for iterators - creating
an iterator and traversing the elements linearly will always yield the same order.
However, bulk operations such as foreach, map or filter always occur in undefined orders for all
parallel collections.
Existing parallel collection implementations provide strict parallel iterators. Strict parallel iterators are aware
of the number of elements they have yet to traverse. It's also possible to provide non-strict parallel iterators,
which do not know the number of elements remaining. To do this, the new collection implementation must override
isStrictSplitterCollection to false. This will make some operations unavailable.
To create a new parallel collection, extend the ParIterable trait, and implement size, parallelIterator,
newCombiner and seq. Having an implicit combiner factory requires extending this trait in addition, as
well as providing a companion object, as with regular collections.
Method size is implemented as a constant time operation for parallel collections, and parallel collection
operations rely on this assumption.
2.9
the sequential range this parallel range was obtained from
Standard accessor task that iterates over the elements of the collection.
Used to iterate elements using indices
Performs two tasks in parallel, and waits for both to finish.
An iterator that can be split into arbitrary subsets of iterators.
The type implementing this traversable
Sequentially performs one task after another.
A stackable modification that ensures signal contexts get passed along the iterators.
A class supporting filtered operations.
o != arg0 is the same as !(o == (arg0)).
o != arg0 is the same as !(o == (arg0)).
the object to compare against this object for dis-equality.
false if the receiver object is equivalent to the argument; true otherwise.
[use case] Concatenates this immutable parallel range with the elements of a traversable collection.
Concatenates this immutable parallel range with the elements of a traversable collection.
the element type of the returned collection.
the traversable to append.
a new immutable parallel range which contains all elements of this immutable parallel range
followed by all elements of that.
Concatenates this immutable parallel range with the elements of a traversable collection.
Concatenates this immutable parallel range with the elements of a traversable collection.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the traversable to append.
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That which contains all elements
of this immutable parallel range followed by all elements of that.
This overload exists because: for the implementation of ++: we should reuse that of ++ because many collections override it with more efficient versions.
This overload exists because: for the implementation of ++: we should reuse that of ++ because many collections override it with more efficient versions. Since TraversableOnce has no '++' method, we have to implement that directly, but Traversable and down can use the overload.
[use case] Concatenates this immutable parallel range with the elements of a traversable collection.
Concatenates this immutable parallel range with the elements of a traversable collection. It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one.
the element type of the returned collection.
the traversable to append.
a new immutable parallel range which contains all elements of this immutable parallel range
followed by all elements of that.
Concatenates this immutable parallel range with the elements of a traversable collection.
Concatenates this immutable parallel range with the elements of a traversable collection. It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one.
the element type of the returned collection.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the traversable to append.
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That which contains all elements
of this immutable parallel range followed by all elements of that.
[use case] Prepends an element to this immutable parallel range
Prepends an element to this immutable parallel range
the prepended element
a new immutable parallel range consisting of elem followed
by all elements of this immutable parallel range.
Prepends an element to this immutable parallel range
Prepends an element to this immutable parallel range
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the prepended element
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That consisting of elem followed
by all elements of this immutable parallel range.
Applies a binary operator to a start value and all elements of this immutable parallel range, going left to right.
Applies a binary operator to a start value and all elements of this immutable parallel range, going left to right.
Note: /: is alternate syntax for foldLeft; z /: xs is the same as
xs foldLeft z.
Note: will not terminate for infinite-sized collections.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this immutable parallel range,
going left to right with the start value z on the left:
op(...op(op(z, x,,1,,), x,,2,,), ..., x,,n,,)
where x,,1,,, ..., x,,n,, are the elements of this immutable parallel range.
[use case] Appends an element to this immutable parallel range
Appends an element to this immutable parallel range
Note: will not terminate for infinite-sized collections.
the appended element
a new immutable parallel range consisting of
all elements of this immutable parallel range followed by elem.
Appends an element to this immutable parallel range
Appends an element to this immutable parallel range
Note: will not terminate for infinite-sized collections.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the appended element
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That consisting of
all elements of this immutable parallel range followed by elem.
Applies a binary operator to all elements of this immutable parallel range and a start value, going right to left.
Applies a binary operator to all elements of this immutable parallel range and a start value, going right to left.
Note: :\ is alternate syntax for foldRight; xs :\ z is the same as
xs foldRight z.
Note: will not terminate for infinite-sized collections.
the result type of the binary operator.
the start value
the binary operator
the result of inserting op between consecutive elements of this immutable parallel range,
going right to left with the start value z on the right:
op(x,,1,,, op(x,,2,,, ... op(x,,n,,, z)...))
where x,,1,,, ..., x,,n,, are the elements of this immutable parallel range.
o == arg0 is the same as if (o eq null) arg0 eq null else o.equals(arg0).
o == arg0 is the same as if (o eq null) arg0 eq null else o.equals(arg0).
the object to compare against this object for equality.
true if the receiver object is equivalent to the argument; false otherwise.
o == arg0 is the same as o.equals(arg0).
o == arg0 is the same as o.equals(arg0).
the object to compare against this object for equality.
true if the receiver object is equivalent to the argument; false otherwise.
Appends all elements of this immutable parallel range to a string builder.
Appends all elements of this immutable parallel range to a string builder.
The written text consists of the string representations (w.r.t. the method
toString) of all elements of this immutable parallel range without any separator string.
the string builder to which elements are appended.
the string builder b to which elements were appended.
Appends all elements of this immutable parallel range to a string builder using a separator string.
Appends all elements of this immutable parallel range 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 immutable parallel range, separated by the
string sep.
the string builder to which elements are appended.
the separator string.
the string builder b to which elements were appended.
Appends all elements of this immutable parallel range to a string builder using start, end, and separator strings.
Appends all elements of this immutable parallel range to a string builder using start, end,
and separator strings.
The written text begins with the string start and ends with the string
end. Inside, the string representations (w.r.t. the method toString)
of all elements of this immutable parallel range are separated by the string sep.
the string builder to which elements are appended.
the starting string.
the separator string.
the ending string.
the string builder b to which elements were appended.
Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
This is a more general form of fold and reduce. It has similar semantics, but does
not require the result to be a supertype of the element type. It traverses the elements in
different partitions sequentially, using seqop to update the result, and then
applies combop to results from different partitions. The implementation of this
operation may operate on an arbitrary number of collection partitions, so combop
may be invoked arbitrary number of times.
For example, one might want to process some elements and then produce a Set. In this
case, seqop would process an element and append it to the list, while combop
would concatenate two lists from different partitions together. The initial value
z would be an empty set.
pc.aggregate(Set[Int]())(_ += process(_), _ ++ _)
Another example is calculating geometric mean from a collection of doubles (one would typically require big doubles for this).
the type of accumulated results
the initial value for the accumulated result of the partition - this
will typically be the neutral element for the seqop operator (e.g.
Nil for list concatenation or 0 for summation)
an operator used to accumulate results within a partition
an associative operator used to combine results from different partitions
Composes this partial function with a transformation function that gets applied to results of this partial function.
Composes this partial function with a transformation function that gets applied to results of this partial function.
the result type of the transformation function.
the transformation function
a partial function with the same domain as this partial function, which maps
arguments x to k(this(x)).
Selects an element by its index in the immutable parallel range.
This method is used to cast the receiver object to be of type T0.
This method is used to cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression
1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression
List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as
part of compilation it is not possible to check whether the contents of the list are of the requested typed.
the receiver object.
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
The object with which this immutable parallel range should be compared
true, if this immutable parallel range can possibly equal that, false otherwise. The test
takes into consideration only the run-time types of objects but ignores their elements.
This method creates and returns a copy of the receiver object.
[use case] Builds a new collection by applying a partial function to all elements of this immutable parallel range on which the function is defined.
Builds a new collection by applying a partial function to all elements of this immutable parallel range on which the function is defined.
the element type of the returned collection.
the partial function which filters and maps the immutable parallel range.
a new immutable parallel range 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.
Builds a new collection by applying a partial function to all elements of this immutable parallel range on which the function is defined.
Builds a new collection by applying a partial function to all elements of this immutable parallel range on which the function is defined.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the partial function which filters and maps the immutable parallel range.
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That resulting from applying the partial function
pf to each element on which it is defined and collecting the results.
The order of the elements is preserved.
Finds the first element of the immutable parallel range for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the immutable parallel range for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
the partial function
an option value containing pf applied to the first
value for which it is defined, or None if none exists.
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Iterates over combinations.
Iterates over combinations.
An Iterator which traverses the possible n-element combinations of this immutable parallel range.
"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)
The factory companion object that builds instances of class immutable.
The factory companion object that builds instances of class immutable.ParRange.
(or its Iterable superclass where class immutable.ParRange is not a Seq.)
Composes two instances of Function1 in a new Function1, with this function applied last.
Composes two instances of Function1 in a new Function1, with this function applied last.
the type to which function g can be applied
a function A => T1
a new function f such that f(x) == apply(g(x))
Tests whether this immutable parallel range contains a given value as an element.
Tests whether this immutable parallel range contains a given value as an element.
Note: may not terminate for infinite-sized collections.
the element to test.
true if this immutable parallel range has an element that is
is equal (wrt ==) to elem, false otherwise.
Tests whether this immutable parallel range contains a given sequence as a slice.
Tests whether this immutable parallel range contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
the sequence to test
true if this immutable parallel range contains a slice with the same elements
as that, otherwise false.
[use case] Copies elements of this immutable parallel range to an array.
Copies elements of this immutable parallel range to an array.
Fills the given array xs with at most len elements of
this immutable parallel range, starting at position start.
Copying will stop once either the end of the current immutable parallel range is reached,
or the end of the array is reached, or len elements have been copied.
the array to fill.
the starting index.
the maximal number of elements to copy.
Copies elements of this immutable parallel range to an array.
Copies elements of this immutable parallel range to an array.
Fills the given array xs with at most len elements of
this immutable parallel range, starting at position start.
Copying will stop once either the end of the current immutable parallel range is reached,
or the end of the array is reached, or len elements have been copied.
Note: will not terminate for infinite-sized collections.
the array to fill.
the starting index.
the maximal number of elements to copy.
[use case] Copies values of this immutable parallel range to an array.
Copies values of this immutable parallel range to an array.
Fills the given array xs with values of this immutable parallel range.
Copying will stop once either the end of the current immutable parallel range is reached,
or the end of the array is reached.
the array to fill.
Copies values of this immutable parallel range to an array.
Copies values of this immutable parallel range to an array.
Fills the given array xs with values of this immutable parallel range.
Copying will stop once either the end of the current immutable parallel range is reached,
or the end of the array is reached.
Note: will not terminate for infinite-sized collections.
the type of the elements of the array.
the array to fill.
[use case] Copies values of this immutable parallel range to an array.
Copies values of this immutable parallel range to an array.
Fills the given array xs with values of this immutable parallel range, after skipping start values.
Copying will stop once either the end of the current immutable parallel range is reached,
or the end of the array is reached.
the array to fill.
the starting index.
Copies values of this immutable parallel range to an array.
Copies values of this immutable parallel range to an array.
Fills the given array xs with values of this immutable parallel range, after skipping start values.
Copying will stop once either the end of the current immutable parallel range is reached,
or the end of the array is reached.
Note: will not terminate for infinite-sized collections.
the type of the elements of the array.
the array to fill.
the starting index.
Copies all elements of this immutable parallel range to a buffer.
Copies all elements of this immutable parallel range to a buffer.
Note: will not terminate for infinite-sized collections.
The buffer to which elements are copied.
Tests whether every element of this immutable parallel range relates to the corresponding element of another parallel sequence by satisfying a test predicate.
Tests whether every element of this immutable parallel range relates to the corresponding element of another parallel sequence by satisfying a test predicate.
This method will use abort signalling capabilities. This means
that splitters may send and read abort signals.
the type of the elements of that
the other parallel sequence
the test predicate, which relates elements from both sequences
true if both parallel sequences have the same length and
p(x, y) is true for all corresponding elements x of this immutable parallel range
and y of that, otherwise false
Counts the number of elements in the immutable parallel range which satisfy a predicate.
Counts the number of elements in the immutable parallel range which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p.
[use case] Computes the multiset difference between this immutable parallel range and another sequence.
Computes the multiset difference between this immutable parallel range and another sequence.
Note: will not terminate for infinite-sized collections.
the sequence of elements to remove
a new immutable parallel range which contains all elements of this immutable parallel range
except some of occurrences of elements that also appear in that.
If an element value x appears
n times in that, then the first n occurrences of x will not form
part of the result, but any following occurrences will.
Computes the multiset difference between this immutable parallel range and another sequence.
Computes the multiset difference between this immutable parallel range and another sequence.
Note: will not terminate for infinite-sized collections.
the element type of the returned immutable parallel range.
the sequence of elements to remove
a new collection of type That which contains all elements of this immutable parallel range
except some of occurrences of elements that also appear in that.
If an element value x appears
n times in that, then the first n occurrences of x will not form
part of the result, but any following occurrences will.
Builds a new immutable parallel range from this immutable parallel range without any duplicate elements.
Builds a new immutable parallel range from this immutable parallel range without any duplicate elements.
Note: will not terminate for infinite-sized collections.
A new immutable parallel range which contains the first occurrence of every element of this immutable parallel range.
Selects all elements except first n ones.
Selects all elements except first n ones.
the number of elements to drop from this immutable parallel range.
a immutable parallel range consisting of all elements of this immutable parallel range except the first n ones, or else the
empty immutable parallel range, if this immutable parallel range has less than n elements.
Selects all elements except last n ones.
Selects all elements except last n ones.
The number of elements to take
a immutable parallel range consisting of all elements of this immutable parallel range except the last n ones, or else the
empty immutable parallel range, if this immutable parallel range has less than n elements.
Drops all elements in the longest prefix of elements that satisfy the predicate, and returns a collection composed of the remaining elements.
Drops all elements in the longest prefix of elements that satisfy the predicate, and returns a collection composed of the remaining elements.
This method will use indexFlag signalling capabilities. This means
that splitters may set and read the indexFlag state.
The index flag is initially set to maximum integer value.
the predicate used to test the elements
a collection composed of all the elements after the longest prefix of elements
in this immutable parallel range that satisfy the predicate pred
use iterator' instead
Tests whether this immutable parallel range ends with the given parallel sequence
Tests whether this immutable parallel range ends with the given parallel sequence
This method will use abort signalling capabilities. This means
that splitters may send and read abort signals.
the type of the elements of that sequence
the sequence to test
true if this immutable parallel range has that as a suffix, false otherwise
This method is used to test whether the argument (arg0) is a reference to the
receiver object (this).
This method is used to test whether the argument (arg0) is a reference to the
receiver object (this).
The eq method implements an [http://en.wikipedia.org/wiki/Equivalence_relation equivalence relation] on
non-null instances of AnyRef:
* It is reflexive: for any non-null instance x of type AnyRef, x.eq(x) returns true.
* It is symmetric: for any non-null instances x and y of type AnyRef, x.eq(y) returns true if and
only if y.eq(x) returns true.
* It is transitive: for any non-null instances x, y, and z of type AnyRef if x.eq(y) returns true
and y.eq(z) returns true, then x.eq(z) returns true.
Additionally, the eq method has three other properties.
* It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of
x.eq(y) consistently returns true or consistently returns false.
* For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
* null.eq(null) returns true.
When overriding the equals or hashCode methods, it is important to ensure that their behavior is
consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they
should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
the object to compare against this object for reference equality.
true if the argument is a reference to the receiver object; false otherwise.
The equals method for arbitrary sequences.
Tests whether every element of this immutable parallel range relates to the corresponding element of another sequence by satisfying a test predicate.
Tests whether every element of this immutable parallel range relates to the corresponding element of another sequence by satisfying a test predicate.
the type of the elements of that
the other sequence
true if both sequences have the same length and
p(x, y) is true for all corresponding elements x of this immutable parallel range
and y of that, otherwise false.
use corresponds instead
Tests whether a predicate holds for some element of this immutable parallel range.
Tests whether a predicate holds for some element of this immutable parallel range.
This method will use abort signalling capabilities. This means
that splitters may send and read abort signals.
true if p holds for some element, false otherwise
Selects all elements of this immutable parallel range which satisfy a predicate.
Selects all elements of this immutable parallel range which satisfy a predicate.
a new immutable parallel range consisting of all elements of this immutable parallel range that satisfy the given
predicate p. The order of the elements is preserved.
Selects all elements of this immutable parallel range which do not satisfy a predicate.
Selects all elements of this immutable parallel range which do not satisfy a predicate.
a new immutable parallel range consisting of all elements of this immutable parallel range that do not satisfy the given
predicate p. The order of the elements is preserved.
This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.
This method is called by the garbage collector on the receiver object when garbage collection determines that there are no more references to the object.
The details of when and if the finalize method are invoked, as well as the interaction between finalize
and non-local returns and exceptions, are all platform dependent.
Finds some element in the collection for which the predicate holds, if such an element exists.
Finds some element in the collection for which the predicate holds, if such an element exists. The element may not necessarily be the first such element in the iteration order.
If there are multiple elements obeying the predicate, the choice is nondeterministic.
This method will use abort signalling capabilities. This means
that splitters may send and read abort signals.
an option value with the element if such an element exists, or None otherwise
Returns index of the first element satisfying a predicate, or -1.
Returns index of the first element satisfying a predicate, or -1.
Returns index of the last element satisfying a predicate, or -1.
Returns index of the last element satisfying a predicate, or -1.
use lastIndexWhere instead
use head' instead
None if iterable is empty.
None if iterable is empty.
use headOption' instead
[use case] Builds a new collection by applying a function to all elements of this immutable parallel range and concatenating the results.
Builds a new collection by applying a function to all elements of this immutable parallel range and concatenating the results.
the element type of the returned collection.
the function to apply to each element.
a new immutable parallel range resulting from applying the given collection-valued function
f to each element of this immutable parallel range and concatenating the results.
Builds a new collection by applying a function to all elements of this immutable parallel range and concatenating the results.
Builds a new collection by applying a function to all elements of this immutable parallel range and concatenating the results.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the function to apply to each element.
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That resulting from applying the given collection-valued function
f to each element of this immutable parallel range and concatenating the results.
[use case] Converts this immutable parallel range of traversable collections into a immutable parallel range in which all element collections are concatenated.
Converts this immutable parallel range of traversable collections into a immutable parallel range in which all element collections are concatenated.
the type of the elements of each traversable collection.
a new immutable parallel range resulting from concatenating all element immutable parallel ranges.
Converts this immutable parallel range of traversable collections into a immutable parallel range in which all element collections are concatenated.
Converts this immutable parallel range of traversable collections into a immutable parallel range in which all element collections are concatenated.
the type of the elements of each traversable collection.
an implicit conversion which asserts that the element
type of this immutable parallel range is a Traversable.
a new immutable parallel range resulting from concatenating all element immutable parallel ranges.
Folds the elements of this sequence using the specified associative binary operator.
Folds the elements of this sequence using the specified associative binary operator. The order in which the elements are reduced is unspecified and may be nondeterministic.
Note this method has a different signature than the foldLeft
and foldRight methods of the trait Traversable.
The result of folding may only be a supertype of this parallel collection's
type parameter T.
a type parameter for the binary operator, a supertype of T.
a neutral element for the fold operation, it may be added to the result
an arbitrary number of times, not changing the result (e.g. Nil for list concatenation,
0 for addition, or 1 for multiplication)
a binary operator that must be associative
the result of applying fold operator op between all the elements and z
Applies a binary operator to a start value and all elements of this immutable parallel range, going left to right.
Applies a binary operator to a start value and all elements of this immutable parallel range, going left to right.
Note: will not terminate for infinite-sized collections.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this immutable parallel range,
going left to right with the start value z on the left:
op(...op(z, x,,1,,), x,,2,,, ..., x,,n,,)
where x,,1,,, ..., x,,n,, are the elements of this immutable parallel range.
Applies a binary operator to all elements of this immutable parallel range and a start value, going right to left.
Applies a binary operator to all elements of this immutable parallel range and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this immutable parallel range,
going right to left with the start value z on the right:
op(x,,1,,, op(x,,2,,, ... op(x,,n,,, z)...))
where x,,1,,, ..., x,,n,, are the elements of this immutable parallel range.
Tests whether a predicate holds for all elements of this immutable parallel range.
Tests whether a predicate holds for all elements of this immutable parallel range.
This method will use abort signalling capabilities. This means
that splitters may send and read abort signals.
true if p holds for all elements, false otherwise
Applies a function f to all the elements of immutable parallel range in a sequential order.
Applies a function f to all the elements of immutable parallel range in a sequential order.
the result type of the function applied to each element, which is always discarded
function applied to each element
The generic builder that builds instances of immutable.
The generic builder that builds instances of immutable.ParRange at arbitrary element types.
Returns a representation that corresponds to the dynamic class of the receiver object.
Returns a representation that corresponds to the dynamic class of the receiver object.
The nature of the representation is platform dependent.
a representation that corresponds to the dynamic class of the receiver object.
Partitions this immutable parallel range into a map of immutable parallel ranges according to some discriminator function.
Partitions this immutable parallel range into a map of immutable parallel ranges according to some discriminator function.
Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new immutable parallel range.
the type of keys returned by the discriminator function.
the discriminator function.
A map from keys to immutable parallel ranges such that the following invariant holds:
(xs partition f)(k) = xs filter (x => f(x) == k)
That is, every key k is bound to a immutable parallel range of those elements x
for which f(x) equals k.
Partitions elements in fixed size immutable parallel ranges.
Partitions elements in fixed size immutable parallel ranges.
the number of elements per group
An iterator producing immutable parallel ranges of size size, except the
last will be truncated if the elements don't divide evenly.
Iterator#grouped
Tests whether this immutable parallel range is known to have a finite size.
Tests whether this immutable parallel range 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.
Note: many collection methods will not work on collections of infinite sizes.
true if this collection is known to have finite size, false otherwise.
Hashcodes for immutable.
Hashcodes for immutable.ParRange produce a value from the hashcodes of all the elements of the immutable parallel range.@return the hash code value for the object. */
Selects the first element of this immutable parallel range.
Selects the first element of this immutable parallel range.
the first element of this immutable parallel range.
Optionally selects the first element.
Optionally selects the first element.
the first element of this immutable parallel range if it is nonempty, None if it is empty.
[use case] Finds index of first occurrence of some value in this immutable parallel range after or at some start index.
Finds index of first occurrence of some value in this immutable parallel range after or at some start index.
the element value to search for.
the start index
the index >= from of the first element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
Finds index of first occurrence of some value in this immutable parallel range after or at some start index.
Finds index of first occurrence of some value in this immutable parallel range after or at some start index.
Note: may not terminate for infinite-sized collections.
the element value to search for.
the start index
the index >= from of the first element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
[use case] Finds index of first occurrence of some value in this immutable parallel range.
Finds index of first occurrence of some value in this immutable parallel range.
the element value to search for.
the index of the first element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
Finds index of first occurrence of some value in this immutable parallel range.
Finds index of first occurrence of some value in this immutable parallel range.
Note: may not terminate for infinite-sized collections.
the element value to search for.
the index of the first element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
Finds first index after or at a start index where this immutable parallel range contains a given sequence as a slice.
Finds first index after or at a start index where this immutable parallel range contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
the sequence to test
the start index
the first index >= from such that the elements of this immutable parallel range starting at this index
match the elements of sequence that, or -1 of no such subsequence exists.
Finds first index where this immutable parallel range contains a given sequence as a slice.
Finds first index where this immutable parallel range contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
the sequence to test
the first index such that the elements of this immutable parallel range starting at this index
match the elements of sequence that, or -1 of no such subsequence exists.
Finds index of first element satisfying some predicate.
Finds index of first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
the index of the first element of this immutable parallel range that satisfies the predicate p,
or -1, if none exists.
Finds the first element satisfying some predicate.
Finds the first element satisfying some predicate.
This method will use indexFlag signalling capabilities. This means
that splitters may set and read the indexFlag state.
The index flag is initially set to maximum integer value.
the predicate used to test the elements
the starting offset for the search
the index >= from of the first element of this immutable parallel range that satisfies the predicate p,
or -1, if none exists
Produces the range of all indices of this sequence.
Produces the range of all indices of this sequence.
a Range value from 0 to one less than the length of this immutable parallel range.
Selects all elements except the last.
Selects all elements except the last.
a immutable parallel range consisting of all elements of this immutable parallel range except the last one.
Iterates over the inits of this immutable parallel range.
Iterates over the inits of this immutable parallel range. The first value will be this
immutable parallel range and the final one will be an empty immutable parallel range, with the intervening
values the results of successive applications of init.
an iterator over all the inits of this immutable parallel range
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
[use case] Computes the multiset intersection between this immutable parallel range and another sequence.
Computes the multiset intersection between this immutable parallel range and another sequence.
Note: may not terminate for infinite-sized collections.
the sequence of elements to intersect with.
a new immutable parallel range which contains all elements of this immutable parallel range
which also appear in that.
If an element value x appears
n times in that, then the first n occurrences of x will be retained
in the result, but any following occurrences will be omitted.
Computes the multiset intersection between this immutable parallel range and another sequence.
Computes the multiset intersection between this immutable parallel range and another sequence.
Note: may not terminate for infinite-sized collections.
the element type of the returned immutable parallel range.
the sequence of elements to intersect with.
a new collection of type That which contains all elements of this immutable parallel range
which also appear in that.
If an element value x appears
n times in that, then the first n occurrences of x will be retained
in the result, but any following occurrences will be omitted.
Tests whether this immutable parallel range contains given index.
Tests whether this immutable parallel range contains given index.
The implementations of methods apply and isDefinedAt turn a Seq[A] into
a PartialFunction[Int, A].
the index to test
true if this immutable parallel range contains an element at position idx, false otherwise.
Tests whether this immutable parallel range is empty.
Tests whether this immutable parallel range is empty.
true if the immutable parallel range contain no elements, false otherwise.
This method is used to test whether the dynamic type of the receiver object is T0.
This method is used to test whether the dynamic type of the receiver object is T0.
Note that the test result of the test is modulo Scala's erasure semantics. Therefore the expression
1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will
return true. In the latter example, because the type argument is erased as part of compilation it is not
possible to check whether the contents of the list are of the requested typed.
true if the receiver object is an instance of erasure of type T0; false otherwise.
Denotes whether this parallel collection has strict splitters.
Denotes whether this parallel collection has strict splitters.
This is true in general, and specific collection instances may choose to
override this method. Such collections will fail to execute methods
which rely on splitters being strict, i.e. returning a correct value
in the remaining method.
This method helps ensure that such failures occur on method invocations, rather than later on and in unpredictable ways.
Tests whether this immutable parallel range can be repeatedly traversed.
Tests whether this immutable parallel range can be repeatedly traversed.
true
Creates a new split iterator used to traverse the elements of this collection.
Creates a new split iterator used to traverse the elements of this collection.
By default, this method is implemented in terms of the protected parallelIterator method.
a split iterator
Selects the last element.
Selects the last element.
The last element of this immutable parallel range.
[use case] Finds index of last occurrence of some value in this immutable parallel range before or at a given end index.
Finds index of last occurrence of some value in this immutable parallel range before or at a given end index.
the element value to search for.
the end index.
the index <= end of the last element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
Finds index of last occurrence of some value in this immutable parallel range before or at a given end index.
Finds index of last occurrence of some value in this immutable parallel range before or at a given end index.
the type of the element elem.
the element value to search for.
the end index.
the index <= end of the last element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
[use case] Finds index of last occurrence of some value in this immutable parallel range.
Finds index of last occurrence of some value in this immutable parallel range.
the element value to search for.
the index of the last element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
Finds index of last occurrence of some value in this immutable parallel range.
Finds index of last occurrence of some value in this immutable parallel range.
Note: will not terminate for infinite-sized collections.
the type of the element elem.
the element value to search for.
the index of the last element of this immutable parallel range that is equal (wrt ==)
to elem, or -1, if none exists.
Finds last index before or at a given end index where this immutable parallel range contains a given sequence as a slice.
Finds last index before or at a given end index where this immutable parallel range contains a given sequence as a slice.
the sequence to test
the end index
the last index <= end such that the elements of this immutable parallel range starting at this index
match the elements of sequence that, or -1 of no such subsequence exists.
Finds last index where this immutable parallel range contains a given sequence as a slice.
Finds last index where this immutable parallel range contains a given sequence as a slice.
Note: will not terminate for infinite-sized collections.
the sequence to test
the last index such that the elements of this immutable parallel range starting a this index
match the elements of sequence that, or -1 of no such subsequence exists.
Finds the last element satisfying some predicate.
Finds the last element satisfying some predicate.
This method will use indexFlag signalling capabilities. This means
that splitters may set and read the indexFlag state.
The index flag is initially set to minimum integer value.
the predicate used to test the elements
the maximum offset for the search
the index <= end of the first element of this immutable parallel range that satisfies the predicate p,
or -1, if none exists
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
the predicate used to test elements.
the index of the last element of this immutable parallel range that satisfies the predicate p,
or -1, if none exists.
Optionally selects the last element.
Optionally selects the last element.
the last element of this immutable parallel range$ if it is nonempty, None if it is empty.
The length of the immutable parallel range.
Compares the length of this immutable parallel range to a test value.
Compares the length of this immutable parallel range to a test value.
the test value that gets compared with the length.
A value x where
x < 0 if this.length < len
x == 0 if this.length == len
x > 0 if this.length > len
The method as implemented here does not call length directly; its running time
is O(length min len) instead of O(length). The method should be overwritten
if computing length is cheap.
Turns this partial function into an plain function returning an Option result.
Turns this partial function into an plain function returning an Option result.
a function that takes an argument x to Some(this(x)) if this
is defined for x, and to None otherwise.
Function.unlift
[use case] Builds a new collection by applying a function to all elements of this immutable parallel range.
Builds a new collection by applying a function to all elements of this immutable parallel range.
the element type of the returned collection.
the function to apply to each element.
a new immutable parallel range resulting from applying the given function
f to each element of this immutable parallel range and collecting the results.
Builds a new collection by applying a function to all elements of this immutable parallel range.
Builds a new collection by applying a function to all elements of this immutable parallel range.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the function to apply to each element.
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That resulting from applying the given function
f to each element of this immutable parallel range and collecting the results.
[use case] Finds the largest element.
Finds the largest element.
the largest element of this immutable parallel range.
Finds the largest element.
Finds the largest element.
the largest element of this immutable parallel range with respect to the ordering cmp.
[use case] Finds the smallest element.
Finds the smallest element.
the smallest element of this immutable parallel range
Finds the smallest element.
Finds the smallest element.
the smallest element of this immutable parallel range with respect to the ordering cmp.
Displays all elements of this immutable parallel range in a string.
Displays all elements of this immutable parallel range in a string.
a string representation of this immutable parallel range. In the resulting string
the string representations (w.r.t. the method toString)
of all elements of this immutable parallel range follow each other without any
separator string.
Displays all elements of this immutable parallel range in a string using a separator string.
Displays all elements of this immutable parallel range in a string using a separator string.
the separator string.
a string representation of this immutable parallel range. In the resulting string
the string representations (w.r.t. the method toString)
of all elements of this immutable parallel range are separated by the string sep.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this immutable parallel range in a string using start, end, and separator strings.
Displays all elements of this immutable parallel range in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
a string representation of this immutable parallel range. The resulting string
begins with the string start and ends with the string
end. Inside, the string representations (w.r.t. the method
toString) of all elements of this immutable parallel range are separated by
the string sep.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
o.ne(arg0) is the same as !(o.eq(arg0)).
o.ne(arg0) is the same as !(o.eq(arg0)).
the object to compare against this object for reference dis-equality.
false if the argument is not a reference to the receiver object; true otherwise.
The newBuilder operation returns a parallel builder assigned to this collection's fork/join pool.
The newBuilder operation returns a parallel builder assigned to this collection's fork/join pool.
This method forwards the call to newCombiner.
Tests whether the immutable parallel range is not empty.
Tests whether the immutable parallel range is not empty.
true if the immutable parallel range contains at least one element, false otherwise.
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
the argument type of the fallback function
the result type of the fallback function
the fallback function
a partial function which has as domain the union of the domains
of this partial function and that. The resulting partial function
takes x to this(x) where this is defined, and to that(x) where it is not.
[use case] Appends an element value to this immutable parallel range until a given target length is reached.
Appends an element value to this immutable parallel range until a given target length is reached.
the target length
the padding value
a new immutable parallel range consisting of
all elements of this immutable parallel range followed by the minimal number of occurrences of elem so
that the resulting immutable parallel range has a length of at least len.
Appends an element value to this immutable parallel range until a given target length is reached.
Appends an element value to this immutable parallel range until a given target length is reached.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the target length
the padding value
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That consisting of
all elements of this immutable parallel range followed by the minimal number of occurrences of elem so
that the resulting collection has a length of at least len.
Returns a parallel implementation of this collection.
Returns a parallel implementation of this collection.
For most collection types, this method creates a new parallel collection by copying
all the elements. For these collection, par takes linear time. Mutable collections
in this category do not produce a mutable parallel collection that has the same
underlying dataset, so changes in one collection will not be reflected in the other one.
Specific collections (e.g. ParArray or mutable.ParHashMap) override this default
behaviour by creating a parallel collection which shares the same underlying dataset.
For these collections, par takes constant or sublinear time.
All parallel collections return a reference to themselves.
a parallel implementation of this collection
The default par implementation uses the combiner provided by this method
to create a new parallel collection.
The default par implementation uses the combiner provided by this method
to create a new parallel collection.
a combiner for the parallel collection of type ParRepr
A more refined version of the iterator found in the ParallelIterable trait,
this iterator can be split into arbitrary subsets of iterators.
A more refined version of the iterator found in the ParallelIterable trait,
this iterator can be split into arbitrary subsets of iterators.
an iterator that can be split into subsets of precise size
Partitions this immutable parallel range in two immutable parallel ranges according to a predicate.
Partitions this immutable parallel range in two immutable parallel ranges according to a predicate.
a pair of immutable parallel ranges: the first immutable parallel range consists of all elements that
satisfy the predicate p and the second immutable parallel range consists of all elements
that don't. The relative order of the elements in the resulting immutable parallel ranges
is the same as in the original immutable parallel range.
[use case] Produces a new immutable parallel range where a slice of elements in this immutable parallel range is replaced by another sequence.
Produces a new immutable parallel range where a slice of elements in this immutable parallel range is replaced by another sequence.
the index of the first replaced element
the number of elements to drop in the original immutable parallel range
a new immutable parallel range consisting of all elements of this immutable parallel range
except that replaced elements starting from from are replaced
by patch.
Produces a new immutable parallel range where a slice of elements in this immutable parallel range is replaced by another sequence.
Produces a new immutable parallel range where a slice of elements in this immutable parallel range is replaced by another sequence.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the index of the first replaced element
the replacement sequence
the number of elements to drop in the original immutable parallel range
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new immutable parallel range consisting of all elements of this immutable parallel range
except that replaced elements starting from from are replaced
by patch.
Iterates over distinct permutations.
Iterates over distinct permutations.
An Iterator which traverses the distinct permutations of this immutable parallel range.
"abb".permutations = Iterator(abb, bab, bba)
Returns the length of the longest prefix whose elements all satisfy some predicate.
Returns the length of the longest prefix whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
the length of the longest prefix of this immutable parallel range
such that every element of the segment satisfies the predicate p.
[use case] Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
the product of all elements in this immutable parallel range of numbers of type Int.
Instead of Int, any other type T with an implicit Numeric[T] implementation
can be used as element type of the immutable parallel range and as result type of product.
Examples of such types are: Long, Float, Double, BigInt.
Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
an implicit parameter defining a set of numeric operations
which includes the * operator to be used in forming the product.
the product of all elements of this immutable parallel range with respect to the * operator in num.
returns a projection that can be used to call non-strict filter,
map, and flatMap methods that build projections
of the collection.
returns a projection that can be used to call non-strict filter,
map, and flatMap methods that build projections
of the collection.
use view' instead
the sequential range this parallel range was obtained from
the sequential range this parallel range was obtained from
Reduces the elements of this sequence using the specified associative binary operator.
Reduces the elements of this sequence using the specified associative binary operator.
The order in which the operations on elements are performed is unspecified and may be nondeterministic.
Note this method has a different signature than the reduceLeft
and reduceRight methods of the trait Traversable.
The result of reducing may only be a supertype of this parallel collection's
type parameter T.
A type parameter for the binary operator, a supertype of T.
A binary operator that must be associative.
The result of applying reduce operator op between all the elements if the collection is nonempty.
Applies a binary operator to all elements of this immutable parallel range, going left to right.
Applies a binary operator to all elements of this immutable parallel range, going left to right.
Note: will not terminate for infinite-sized collections.
the binary operator.
the result of inserting op between consecutive elements of this immutable parallel range,
going left to right:
op(...(op(x,,1,,, x,,2,,), ... ) , x,,n,,)
where x,,1,,, ..., x,,n,, are the elements of this immutable parallel range.
Optionally applies a binary operator to all elements of this immutable parallel range, going left to right.
Optionally applies a binary operator to all elements of this immutable parallel range, going left to right.
Note: will not terminate for infinite-sized collections.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceLeft(op) is this immutable parallel range is nonempty,
None otherwise.
Optionally reduces the elements of this sequence using the specified associative binary operator.
Optionally reduces the elements of this sequence using the specified associative binary operator.
The order in which the operations on elements are performed is unspecified and may be nondeterministic.
Note this method has a different signature than the reduceLeftOption
and reduceRightOption methods of the trait Traversable.
The result of reducing may only be a supertype of this parallel collection's
type parameter T.
A type parameter for the binary operator, a supertype of T.
A binary operator that must be associative.
An option value containing result of applying reduce operator op between all
the elements if the collection is nonempty, and None otherwise.
Applies a binary operator to all elements of this immutable parallel range, going right to left.
Applies a binary operator to all elements of this immutable parallel range, going right to left.
Note: will not terminate for infinite-sized collections.
the binary operator.
the result of inserting op between consecutive elements of this immutable parallel range,
going right to left:
op(x,,1,,, op(x,,2,,, ..., op(x,,n-1,,, x,,n,,)...))
where x,,1,,, ..., x,,n,, are the elements of this immutable parallel range.
Optionally applies a binary operator to all elements of this immutable parallel range, going right to left.
Optionally applies a binary operator to all elements of this immutable parallel range, going right to left.
Note: will not terminate for infinite-sized collections.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceRight(op) is this immutable parallel range is nonempty,
None otherwise.
The collection of type immutable parallel range underlying this TraversableLike object.
The collection of type immutable parallel range underlying this TraversableLike object.
By default this is implemented as the TraversableLike object itself,
but this can be overridden.
Optionally reuses an existing combiner for better performance.
Optionally reuses an existing combiner for better performance. By default it doesn't - subclasses may override this behaviour.
The provided combiner oldc that can potentially be reused will be either some combiner from the previous computational task, or None if there
was no previous phase (in which case this method must return newc).
The combiner that is the result of the previous task, or None if there was no previous task.
The new, empty combiner that can be used.
Either newc or oldc.
Returns new immutable parallel range wih elements in reversed order.
Returns new immutable parallel range wih elements in reversed order.
Note: will not terminate for infinite-sized collections.
A new immutable parallel range with all elements of this immutable parallel range in reversed order.
An iterator yielding elements in reversed order.
An iterator yielding elements in reversed order.
Note: will not terminate for infinite-sized collections.
Note: xs.reverseIterator is the same as xs.reverse.iterator but might be more efficient.
an iterator yielding the elements of this immutable parallel range in reversed order
[use case] Builds a new collection by applying a function to all elements of this immutable parallel range and collecting the results in reversed order.
Builds a new collection by applying a function to all elements of this immutable parallel range and collecting the results in reversed order.
the element type of the returned collection.
Note: xs.reverseMap(f) is the same as xs.reverse.map(f) but might be more efficient.
the function to apply to each element.
a new immutable parallel range resulting from applying the given function
f to each element of this immutable parallel range and collecting the results in reversed order.
Builds a new collection by applying a function to all elements of this immutable parallel range and collecting the results in reversed order.
Builds a new collection by applying a function to all elements of this immutable parallel range and collecting the results in reversed order.
Note: will not terminate for infinite-sized collections.
Note: xs.reverseMap(f) is the same as xs.reverse.map(f) but might be more efficient.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the function to apply to each element.
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That resulting from applying the given function
f to each element of this immutable parallel range and collecting the results in reversed order.
use reverseIterator' instead
[use case] Checks if the other iterable collection contains the same elements in the same order as this immutable parallel range.
Checks if the other iterable collection contains the same elements in the same order as this immutable parallel range.
the collection to compare with.
true, if both collections contain the same elements in the same order, false otherwise.
Checks if the other iterable collection contains the same elements in the same order as this immutable parallel range.
Checks if the other iterable collection contains the same elements in the same order as this immutable parallel range.
Note: will not terminate for infinite-sized collections.
the collection to compare with.
true, if both collections contain the same elements in the same order, false otherwise.
[use case] Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
neutral element for the operator op
the associative operator for the scan
a new immutable parallel range containing the prefix scan of the elements in this immutable parallel range
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once.
element type of the resulting collection
type of the resulting collection
neutral element for the operator op
the associative operator for the scan
combiner factory which provides a combiner
a collection containing the prefix scan of the elements in the original collection
Produces a collection containing cummulative results of applying the operator going left to right.
Produces a collection containing cummulative results of applying the operator going left to right.
Note: will not terminate for infinite-sized collections.
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
collection with intermediate results
Produces a collection containing cummulative results of applying the operator going right to left.
Produces a collection containing cummulative results of applying the operator going right to left. The head of the collection is the last cummulative result.
Note: will not terminate for infinite-sized collections.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
collection with intermediate results
Returns the length of the longest segment of elements starting at a given position satisfying some predicate.
Returns the length of the longest segment of elements starting at a given position satisfying some predicate.
This method will use indexFlag signalling capabilities. This means
that splitters may set and read the indexFlag state.
The index flag is initially set to maximum integer value.
the predicate used to test the elements
the starting offset for the search
the length of the longest segment of elements starting at from and
satisfying the predicate
A version of this collection with all of the operations implemented sequentially (i.
A version of this collection with all of the operations implemented sequentially (i.e. in a single-threaded manner).
This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.
a sequential view of the collection.
The size of this immutable parallel range, equivalent to length.
The size of this immutable parallel range, equivalent to length.
Note: will not terminate for infinite-sized collections.@return the number of elements in this immutable parallel range.
Selects an interval of elements.
Selects an interval of elements. The returned collection is made up
of all elements x which satisfy the invariant:
from <= indexOf(x) < until
a immutable parallel range containing the elements greater than or equal to
index from extending up to (but not including) index until
of this immutable parallel range.
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
the number of elements per group
An iterator producing immutable parallel ranges of size size, except the
last and the only element will be truncated if there are
fewer elements than size.
Iterator#sliding
Sorts this immutable.
Sorts this immutable.ParRange according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
the target type of the transformation f, and the type where
the ordering ord is defined.
the transformation function mapping elements
to some other domain B.
the ordering assumed on domain B.
a immutable parallel range consisting of the elements of this immutable parallel range
sorted according to the ordering where x < y if
ord.lt(f(x), f(y)).
val words = "The quick brown fox jumped over the lazy dog".split(' ')
// this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]]
words.sortBy(x => (x.length, x.head))
res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)
scala.math.Ordering
Note: will not terminate for infinite-sized collections.
Sorts this immutable parallel range according to a comparison function.
Sorts this immutable parallel range according to a comparison function.
Note: will not terminate for infinite-sized collections.
The sort is stable. That is, elements that are equal wrt lt appear in the
same order in the sorted sequence as in the original.
the comparison function which tests whether its first argument precedes its second argument in the desired ordering.
a immutable parallel range consisting of the elements of this immutable parallel range
sorted according to the comparison function lt.
List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) =
List("Bob", "John", "Steve", "Tom")
Sorts this immutable parallel range according to an Ordering.
Sorts this immutable parallel range according to an Ordering.
The sort is stable. That is, elements that are equal wrt lt appear in the
same order in the sorted sequence as in the original.
the ordering to be used to compare elements.
a immutable parallel range consisting of the elements of this immutable parallel range
sorted according to the ordering ord.
scala.math.Ordering
Splits this immutable parallel range into a prefix/suffix pair according to a predicate.
Splits this immutable parallel range into a prefix/suffix pair according to a predicate.
This method will use indexFlag signalling capabilities. This means
that splitters may set and read the indexFlag state.
The index flag is initially set to maximum integer value.
the predicate used to test the elements
a pair consisting of the longest prefix of the collection for which all
the elements satisfy pred, and the rest of the collection
Splits this immutable parallel range into two at a given position.
Splits this immutable parallel range into two at a given position.
Note: c splitAt n is equivalent to (but possibly more efficient than)
(c take n, c drop n).
the position at which to split.
a pair of immutable parallel ranges consisting of the first n
elements of this immutable parallel range, and the other elements.
Tests whether this immutable parallel range contains the given sequence at a given index.
Tests whether this immutable parallel range contains the given sequence at a given index.
This method will use abort signalling capabilities. This means
that splitters may send and read abort signals.
the parallel sequence this sequence is being searched for
the starting offset for the search
true if there is a sequence that starting at offset in this sequence, false otherwise
Tests whether this immutable parallel range starts with the given sequence.
Tests whether this immutable parallel range starts with the given sequence.
the sequence to test
true if this collection has that as a prefix, false otherwise.
Defines the prefix of this object's toString representation.
Defines the prefix of this object's toString representation.
a string representation which starts the result of toString
applied to this immutable parallel range. By default the string prefix is the
simple name of the collection class immutable parallel range.
[use case] Sums up the elements of this collection.
Sums up the elements of this collection.
the sum of all elements in this immutable parallel range of numbers of type Int.
Instead of Int, any other type T with an implicit Numeric[T] implementation
can be used as element type of the immutable parallel range and as result type of sum.
Examples of such types are: Long, Float, Double, BigInt.
Sums up the elements of this collection.
Sums up the elements of this collection.
an implicit parameter defining a set of numeric operations
which includes the + operator to be used in forming the sum.
the sum of all elements of this immutable parallel range with respect to the + operator in num.
Selects all elements except the first.
Selects all elements except the first.
a immutable parallel range consisting of all elements of this immutable parallel range except the first one.
Iterates over the tails of this immutable parallel range.
Iterates over the tails of this immutable parallel range. The first value will be this
immutable parallel range and the final one will be an empty immutable parallel range, with the intervening
values the results of successive applications of tail.
an iterator over all the tails of this immutable parallel range
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Selects first n elements.
Selects first n elements.
Tt number of elements to take from this immutable parallel range.
a immutable parallel range consisting only of the first n elements of this immutable parallel range,
or else the whole immutable parallel range, if it has less than n elements.
Selects last n elements.
Selects last n elements.
the number of elements to take
a immutable parallel range consisting only of the last n elements of this immutable parallel range, or else the
whole immutable parallel range, if it has less than n elements.
Takes the longest prefix of elements that satisfy the predicate.
Takes the longest prefix of elements that satisfy the predicate.
This method will use indexFlag signalling capabilities. This means
that splitters may set and read the indexFlag state.
The index flag is initially set to maximum integer value.
the predicate used to test the elements
the longest prefix of this immutable parallel range of elements that satisy the predicate pred
The underlying collection seen as an instance of immutable.ParRange.
The underlying collection seen as an instance of immutable.ParRange.
By default this is implemented as the current collection object itself,
but this can be overridden.
Some minimal number of elements after which this collection should be handled sequentially by different processors.
Some minimal number of elements after which this collection should be handled sequentially by different processors.
This method depends on the size of the collection and the parallelism level, which are both specified as arguments.
the size based on which to compute the threshold
the parallelism level based on which to compute the threshold
the maximum number of elements for performing operations sequentially
[use case] Converts this immutable parallel range to an array.
Converts this immutable parallel range to an array.
Note: will not terminate for infinite-sized collections.
an array containing all elements of this immutable parallel range.
A ClassManifest must be available for the element type of this immutable parallel range.
Converts this immutable parallel range to an array.
Converts this immutable parallel range to an array.
Note: will not terminate for infinite-sized collections.
an array containing all elements of this immutable parallel range.
Converts this immutable parallel range to a mutable buffer.
Converts this immutable parallel range to a mutable buffer.
Note: will not terminate for infinite-sized collections.
a buffer containing all elements of this immutable parallel range.
A conversion from collections of type Repr to immutable.ParRange objects.
A conversion from collections of type Repr to immutable.ParRange objects.
By default this is implemented as just a cast, but this can be overridden.
Converts this immutable parallel range to an indexed sequence.
Converts this immutable parallel range to an indexed sequence.
Note: will not terminate for infinite-sized collections.
an indexed sequence containing all elements of this immutable parallel range.
Converts this immutable parallel range to an iterable collection.
Converts this immutable parallel range to an iterable collection. Note that
the choice of target Iterable is lazy in this default implementation
as this TraversableOnce may be lazy and unevaluated (i.e. it may
be an iterator which is only traversable once).
Note: will not terminate for infinite-sized collections.
an Iterable containing all elements of this immutable parallel range.
Returns an Iterator over the elements in this immutable parallel range.
Returns an Iterator over the elements in this immutable parallel range. Will return the same Iterator if this instance is already an Iterator.
Note: will not terminate for infinite-sized collections.
an Iterator containing all elements of this immutable parallel range.
Converts this immutable parallel range to a list.
Converts this immutable parallel range to a list.
Note: will not terminate for infinite-sized collections.
a list containing all elements of this immutable parallel range.
[use case] Converts this immutable parallel range to a map.
Converts this immutable parallel range to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.
Note: will not terminate for infinite-sized collections.
a map of type immutable.Map[T, U]
containing all key/value pairs of type (T, U) of this immutable parallel range.
Converts this immutable parallel range to a map.
Converts this immutable parallel range to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.
Note: will not terminate for infinite-sized collections.
a map containing all elements of this immutable parallel range.
Converts this immutable parallel range to a sequence.
Converts this immutable parallel range to a sequence. As with toIterable, it's lazy
in this default implementation, as this TraversableOnce may be
lazy and unevaluated.
Note: will not terminate for infinite-sized collections.
a sequence containing all elements of this immutable parallel range.
Converts this immutable parallel range to a set.
Converts this immutable parallel range to a set.
Note: will not terminate for infinite-sized collections.
a set containing all elements of this immutable parallel range.
Converts this immutable parallel range to a stream.
Converts this immutable parallel range to a stream.
Note: will not terminate for infinite-sized collections.
a stream containing all elements of this immutable parallel range.
Converts this immutable parallel range to a string.
Converts this immutable parallel range to a string.
a string representation of this collection. By default this
string consists of the stringPrefix of this immutable parallel range,
followed by all elements separated by commas and enclosed in parentheses.
Converts this immutable parallel range to an unspecified Traversable.
Converts this immutable parallel range to an unspecified Traversable. Will return the same collection if this instance is already Traversable.
Note: will not terminate for infinite-sized collections.
a Traversable containing all elements of this immutable parallel range.
Transposes this immutable parallel range of traversable collections into a immutable parallel range of immutable parallel ranges.
Transposes this immutable parallel range of traversable collections into a immutable parallel range of immutable parallel ranges.
the type of the elements of each traversable collection.
an implicit conversion which asserts that the
element type of this immutable parallel range is a Traversable.
a two-dimensional immutable parallel range of immutable parallel ranges which has as nth row the nth column of this immutable parallel range.
[use case] Produces a new sequence which contains all elements of this immutable parallel range and also all elements of a given sequence.
Produces a new sequence which contains all elements of this immutable parallel range and also all elements of
a given sequence. xs union ys is equivalent to xs ++ ys.
Note: will not terminate for infinite-sized collections.
the sequence to add.
a new immutable parallel range which contains all elements of this immutable parallel range
followed by all elements of that.
Produces a new sequence which contains all elements of this immutable parallel range and also all elements of a given sequence.
Produces a new sequence which contains all elements of this immutable parallel range and also all elements of
a given sequence. xs union ys is equivalent to xs ++ ys.
Note: will not terminate for infinite-sized collections.
Another way to express this
is that xs union ys computes the order-presevring multi-set union of xs and ys.
union is hence a counter-part of diff and intersect which also work on multi-sets.
Note: will not terminate for infinite-sized collections.
the element type of the returned immutable parallel range.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the sequence to add.
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new collection of type That which contains all elements of this immutable parallel range
followed by all elements of that.
Converts this immutable parallel range of pairs into two collections of the first and second half of each pair.
Converts this immutable parallel range of pairs into two collections of the first and second half of each pair.
an implicit conversion which asserts that the element type of this immutable parallel range is a pair.
a pair immutable parallel ranges, containing the first, respectively second half of each element pair of this immutable parallel range.
Converts this immutable parallel range of triples into three collections of the first, second, and third element of each triple.
Converts this immutable parallel range of triples into three collections of the first, second, and third element of each triple.
a triple immutable parallel ranges, containing the first, second, respectively third member of each element triple of this immutable parallel range.
[use case] A copy of this immutable parallel range with one single replaced element.
A copy of this immutable parallel range with one single replaced element.
the position of the replacement
the replacing element
a copy of this immutable parallel range with the element at position index replaced by elem.
A copy of this immutable parallel range with one single replaced element.
A copy of this immutable parallel range with one single replaced element.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type B being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the position of the replacement
the replacing element
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type B.
a new immutable parallel range which is a copy of this immutable parallel range with the element at position index replaced by elem.
Creates a non-strict view of a slice of this immutable parallel range.
Creates a non-strict view of a slice of this immutable parallel range.
Note: the difference between view and slice is that view produces
a view of the current immutable parallel range, whereas slice produces a new immutable parallel range.
Note: view(from, to) is equivalent to view.slice(from, to)
the index of the first element of the view
the index of the element following the view
a non-strict view of a slice of this immutable parallel range, starting at index from
and extending up to (but not including) index until.
Creates a non-strict view of this immutable parallel range.
Creates a non-strict view of this immutable parallel range.
a non-strict view of this immutable parallel range.
Creates a non-strict filter of this immutable parallel range.
Creates a non-strict filter of this immutable parallel range.
Note: the difference between c filter p and c withFilter p is that
the former creates a new collection, whereas the latter only
restricts the domain of subsequent map, flatMap, foreach,
and withFilter operations.
the predicate used to test elements.
an object of class WithFilter, which supports
map, flatMap, foreach, and withFilter operations.
All these operations apply to those elements of this immutable parallel range which
satisfy the predicate p.
[use case] Returns a immutable parallel range formed from this immutable parallel range and another iterable collection by combining corresponding elements in pairs.
Returns a immutable parallel range formed from this immutable parallel range 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.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
a new immutable parallel range containing pairs consisting of
corresponding elements of this immutable parallel range and that. The length
of the returned collection is the minimum of the lengths of this immutable parallel range and that.
Returns a immutable parallel range formed from this immutable parallel range and another iterable collection by combining corresponding elements in pairs.
Returns a immutable parallel range formed from this immutable parallel range 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.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type (A1, B) being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, (A1, B), That].
is found.
The iterable providing the second half of each result pair
an implicit value of class CanBuildFrom which determines the
result class That from the current representation type Repr
and the new element type (A1, B).
a new collection of type That containing pairs consisting of
corresponding elements of this immutable parallel range and that. The length
of the returned collection is the minimum of the lengths of this immutable parallel range and that.
[use case] Returns a immutable parallel range formed from this immutable parallel range and another iterable collection by combining corresponding elements in pairs.
Returns a immutable parallel range formed from this immutable parallel range 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.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
the element to be used to fill up the result if this immutable parallel range is shorter than that.
the element to be used to fill up the result if that is shorter than this immutable parallel range.
a new immutable parallel range containing pairs consisting of
corresponding elements of this immutable parallel range and that. The length
of the returned collection is the maximum of the lengths of this immutable parallel range and that.
If this immutable parallel range is shorter than that, thisElem values are used to pad the result.
If that is shorter than this immutable parallel range, thatElem values are used to pad the result.
Returns a immutable parallel range formed from this immutable parallel range and another iterable collection by combining corresponding elements in pairs.
Returns a immutable parallel range formed from this immutable parallel range 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.
the iterable providing the second half of each result pair
the element to be used to fill up the result if this immutable parallel range is shorter than that.
the element to be used to fill up the result if that is shorter than this immutable parallel range.
a new collection of type That containing pairs consisting of
corresponding elements of this immutable parallel range and that. The length
of the returned collection is the maximum of the lengths of this immutable parallel range and that.
If this immutable parallel range is shorter than that, thisElem values are used to pad the result.
If that is shorter than this immutable parallel range, thatElem values are used to pad the result.
[use case] Zips this immutable parallel range with its indices.
Zips this immutable parallel range with its indices.
A new immutable parallel range containing pairs consisting of all elements of this
immutable parallel range paired with their index. Indices start at 0.
@example
List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))
Zips this immutable parallel range with its indices.
Zips this immutable parallel range with its indices.
the class of the returned collection. Where possible, That is
the same class as the current collection class Repr, but this
depends on the element type (A1, Int) being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, (A1, Int), That].
is found.
A new collection of type That containing pairs consisting of all elements of this
immutable parallel range paired with their index. Indices start at 0.
Parallel ranges.
This is a base trait for Scala parallel collections. It defines behaviour common to all parallel collections. Concrete parallel collections should inherit this trait and
ParIterableif they want to define specific combiner factories.Parallel operations are implemented with divide and conquer style algorithms that parallelize well. The basic idea is to split the collection into smaller parts until they are small enough to be operated on sequentially.
All of the parallel operations are implemented as tasks within this trait. Tasks rely on the concept of splitters, which extend iterators. Every parallel collection defines:
def parallelIterator: ParIterableIterator[T]which returns an instance of
ParIterableIterator[T], which is a subtype ofSplitter[T]. Parallel iterators have a methodremainingto check the remaining number of elements, and methodsplitwhich is defined by splitters. Methodsplitdivides the splitters iterate over into disjunct subsets:def split: Seq[Splitter]which splits the splitter into a sequence of disjunct subsplitters. This is typically a very fast operation which simply creates wrappers around the receiver collection. This can be repeated recursively.
Method
newCombinerproduces a new combiner. Combiners are an extension of builders. They provide a methodcombinewhich combines two combiners and returns a combiner containing elements of both combiners. This method can be implemented by aggressively copying all the elements into the new combiner or by lazily binding their results. It is recommended to avoid copying all of the elements for performance reasons, although that cost might be negligible depending on the use case. Standard parallel collection combiners avoid copying when merging results, relying either on a two-step lazy construction or specific data-structure properties.Methods:
def seq: Sequential def par: Reprproduce the sequential or parallel implementation of the collection, respectively. Method
parjust returns a reference to this parallel collection. Methodseqis efficient - it will not copy the elements. Instead, it will create a sequential version of the collection using the same underlying data structure. Note that this is not the case for sequential collections in general - they may copy the elements and produce a different underlying data structure.The combination of methods
toMap,toSeqortoSetalong withparandseqis a flexible way to change between different collection types.The method:
def threshold(sz: Int, p: Int): Intprovides an estimate on the minimum number of elements the collection has before the splitting stops and depends on the number of elements in the collection. A rule of the thumb is the number of elements divided by 8 times the parallelism level. This method may be overridden in concrete implementations if necessary.
Since this trait extends the
Iterabletrait, methods likesizemust also be implemented in concrete collections, whileiteratorforwards toparallelIteratorby default.Each parallel collection is bound to a specific fork/join pool, on which dormant worker threads are kept. The fork/join pool contains other information such as the parallelism level, that is, the number of processors used. When a collection is created, it is assigned the default fork/join pool found in the
scala.parallelpackage object.Parallel collections are not necessarily ordered in terms of the
foreachoperation (seeTraversable). Parallel sequences have a well defined order for iterators - creating an iterator and traversing the elements linearly will always yield the same order. However, bulk operations such asforeach,maporfilteralways occur in undefined orders for all parallel collections.Existing parallel collection implementations provide strict parallel iterators. Strict parallel iterators are aware of the number of elements they have yet to traverse. It's also possible to provide non-strict parallel iterators, which do not know the number of elements remaining. To do this, the new collection implementation must override
isStrictSplitterCollectiontofalse. This will make some operations unavailable.To create a new parallel collection, extend the
ParIterabletrait, and implementsize,parallelIterator,newCombinerandseq. Having an implicit combiner factory requires extending this trait in addition, as well as providing a companion object, as with regular collections.Method
sizeis implemented as a constant time operation for parallel collections, and parallel collection operations rely on this assumption.