the actual iterator

Test two objects for inequality.

Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

Appends all elements of this iterator to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this iterator without any separator string.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> val h = a.addString(b)
h: StringBuilder = 1234

Appends all elements of this iterator 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 iterator, separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4

Appends all elements of this iterator 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 iterator are separated by the string sep.

Example:

scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)

scala> val b = new StringBuilder()
b: StringBuilder =

scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)

Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.

This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.

It is platform dependent whether asInstanceOf has any effect at runtime. It might do a runtime type test on the erasure of T0, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.

In particular, asInstanceOf is not a type test. It does **not** mean:

this match {
 case x: T0 => x
 case _     => throw ClassCastException("...")

Use pattern matching or isInstanceOf for type testing instead.

Situations where asInstanceOf is useful:

• when flow analysis fails to deduce T0 automatically
• when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.

Be careful of using asInstanceOf when T0 is a primitive type. When T0 is primitive, asInstanceOf may insert a conversion instead of a type test. If your intent is to convert, use a toT method (x.toChar, x.toByte, etc.).

Creates a buffered iterator from this iterator.

Create a copy of the receiver object.

The default implementation of the clone method is platform dependent.

The close() method closes the underlying resource.

Builds a new iterator by applying a partial function to all elements of this iterator on which the function is defined.

Finds the first element of the iterator for which the given partial function is defined, and applies the partial function to it.

Note: may not terminate for infinite iterators.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Tests whether this iterator contains a given value as an element.

Note: may not terminate for infinite iterators.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with at most len elements of this iterator.

Copying will stop once either all the elements of this iterator have been copied, or the end of the array is reached, or len elements have been copied.

Copies elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this iterator.

Copying will stop once either all the elements of this iterator have been copied, or the end of the array is reached.

Copies elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this iterator.

Copying will stop once either all the elements of this iterator have been copied, or the end of the array is reached.

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Note: will not terminate for infinite-sized collections.

Counts the number of elements in the iterator which satisfy a predicate.

Note: will not terminate for infinite-sized collections.

Builds a new iterator from this one without any duplicated elements on it.

Builds a new iterator from this one without any duplicated elements as determined by == after applying the transforming function f.

Selects all elements except the first n ones.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Selects all elements except the longest prefix that satisfies a predicate.

The matching prefix starts with the first element of this iterator, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may be empty, so that this method returns the entire iterator.

Example:

scala> List(1, 2, 3, 100, 4).dropWhile(n => n < 10)
val res0: List[Int] = List(100, 4)

scala> List(1, 2, 3, 100, 4).dropWhile(n => n == 0)
val res1: List[Int] = List(1, 2, 3, 100, 4)

Use span to obtain both the prefix and suffix. Use filterNot to drop all elements that satisfy the predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Creates two new iterators that both iterate over the same elements as this iterator (in the same order). The duplicate iterators are considered equal if they are positioned at the same element.

Given that most methods on iterators will make the original iterator unfit for further use, this methods provides a reliable way of calling multiple such methods on an iterator.

Tests whether the argument (that) is a reference to the receiver object (this).

The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional 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 equality method for reference types. Default implementation delegates to eq.

See also equals in scala.Any.

Tests whether a predicate holds for at least one element of this iterator.

Note: may not terminate for infinite iterators.

Selects all elements of this iterator which satisfy a predicate.

Selects all elements of this iterator which do not satisfy a predicate.

Called by the garbage collector on the receiver object when there are no more references to the object.

The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

Finds the first element of the iterator satisfying a predicate, if any.

Note: may not terminate for infinite iterators.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Builds a new iterator by applying a function to all elements of this iterator and using the elements of the resulting collections.

For example:

def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")

The type of the resulting collection is guided by the static type of iterator. This might cause unexpected results sometimes. For example:

// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)

// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq)

// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)

// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)

Converts this iterator of iterable collections into a iterator formed by the elements of these iterable collections.

The resulting collection's type will be guided by the type of iterator. For example:

val xs = List(
           Set(1, 2, 3),
           Set(1, 2, 3)
         ).flatten
// xs == List(1, 2, 3, 1, 2, 3)

val ys = Set(
           List(1, 2, 3),
           List(3, 2, 1)
         ).flatten
// ys == Set(1, 2, 3)

Applies the given binary operator op to the given initial value z and all elements of this iterator.

For each application of the operator, each operand is either an element of this iterator, the initial value, or another such application of the operator.

The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation. The initial value may be used an arbitrary number of times, but at least once.

If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.

Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative. In either case, it is also necessary that the initial value be a neutral value for the operator, e.g. Nil for List concatenation or 1 for multiplication.

The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to the given initial value z and all elements of this iterator, going left to right. Returns the initial value if this iterator is empty.

"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this iterator, the result is op( op( ... op( op(z, x1), x2) ... ), xn).

If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the initial value, and each other left operand is itself an application of the operator. The elements of this iterator and the initial value all appear exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this iterator and the given initial value z, going right to left. Returns the initial value if this iterator is empty.

"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this iterator, the result is op(x1, op(x2, op( ... op(xn, z) ... ))).

If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the initial value, and each other right operand is itself an application of the operator. The elements of this iterator and the initial value all appear exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Note: will not terminate for infinite-sized collections.

Tests whether a predicate holds for all elements of this iterator.

Note: may not terminate for infinite iterators.

Applies f to each element for its side effects. Note: U parameter needed to help scalac's type inference.

Returns the runtime class representation of the object.

Returns an iterator who returns lines (NOT including newline character(s)). It will treat any of \r\n, \r, or \n as a line separator (longest match) - if you need more refined behavior you can subclass Source#LineIterator directly.

Returns an iterator which groups this iterator into fixed size blocks. Example usages:

// Returns List(List(1, 2, 3), List(4, 5, 6), List(7)))
(1 to 7).iterator.grouped(3).toList
// Returns List(List(1, 2, 3), List(4, 5, 6))
(1 to 7).iterator.grouped(3).withPartial(false).toList
// Returns List(List(1, 2, 3), List(4, 5, 6), List(7, 20, 25)
// Illustrating that withPadding's argument is by-name.
val it2 = Iterator.iterate(20)(_ + 5)
(1 to 7).iterator.grouped(3).withPadding(it2.next).toList

Returns true if this source has more characters.

The hashCode method for reference types. See hashCode in scala.Any.

Returns the index of the first occurrence of the specified object in this iterable object after or at some start index.

Note: may not terminate for infinite iterators.

Returns the index of the first occurrence of the specified object in this iterable object.

Note: may not terminate for infinite iterators.

Tests whether the iterator is empty.

Note: The default implementation creates and discards an iterator.

Note: Implementations in subclasses that are not repeatedly iterable must take care not to consume any elements when isEmpty is called.

Test whether the dynamic type of the receiver object has the same erasure as T0.

Depending on what T0 is, the test is done in one of the below ways:

• T0 is a non-parameterized class type, e.g. BigDecimal: this method returns true if the value of the receiver object is a BigDecimal or a subtype of BigDecimal.
• T0 is a parameterized class type, e.g. List[Int]: this method returns true if the value of the receiver object is some List[X] for any X. For example, List(1, 2, 3).isInstanceOf[List[String]] will return true.
• T0 is some singleton type x.type or literal x: this method returns this.eq(x). For example, x.isInstanceOf[1] is equivalent to x.eq(1)
• T0 is an intersection X with Y or X & Y: this method is equivalent to x.isInstanceOf[X] && x.isInstanceOf[Y]
• T0 is a union X | Y: this method is equivalent to x.isInstanceOf[X] || x.isInstanceOf[Y]
• T0 is a type parameter or an abstract type member: this method is equivalent to isInstanceOf[U] where U is T0's upper bound, Any if T0 is unbounded. For example, x.isInstanceOf[A] where A is an unbounded type parameter will return true for any value of x.

This is exactly equivalent to the type pattern _: T0

Tests whether this iterator can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.

An scala.collection.Iterator over the elements of this iterator.

If an IterableOnce object is in fact an scala.collection.Iterator, this method always returns itself, in its current state, but if it is an scala.collection.Iterable, this method always returns a new scala.collection.Iterator.

The number of elements in this iterator, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

Builds a new iterator by applying a function to all elements of this iterator.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Finds the first element which yields the largest value measured by function f.

Note: will not terminate for infinite-sized collections.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Finds the first element which yields the smallest value measured by function f.

Note: will not terminate for infinite-sized collections.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Displays all elements of this iterator in a string.

Delegates to addString, which can be overridden.

Displays all elements of this iterator in a string using a separator string.

Delegates to addString, which can be overridden.

Displays all elements of this iterator in a string using start, end, and separator strings.

Delegates to addString, which can be overridden.

Equivalent to !(this eq that).

Returns next character.

Wraps the value of next() in an option.

Tests whether the iterator is not empty.

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.

A copy of this iterator with an element value appended until a given target length is reached.

Partitions this iterator in two iterators according to a predicate.

Returns this iterator with patched values. Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original iterator appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.

Multiplies together the elements of this collection.

The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this iterator.

For each application of the operator, each operand is either an element of this iterator or another such application of the operator. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.

If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.

Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this iterator, going left to right.

"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this iterator, the result is op( op( op( ... op(x1, x2) ... ), xn-1), xn).

If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the first element of this iterator and each other left operand is itself an application of the operator. Each element appears exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

If this iterator is nonempty, reduces it with the given binary operator op, going left to right.

The behavior is the same as reduceLeft except that the value is None if the iterator is empty. Each element appears exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

If this iterator is nonempty, reduces it with the given binary operator op.

The behavior is the same as reduce except that the value is None if the iterator is empty. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.

Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this iterator, going right to left.

"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this iterator, the result is op(x1, op(x2, op( ... op(xn-1, xn) ... ))).

If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the last element of this iterator and each other right operand is itself an application of the operator. Each element appears exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

If this iterator is nonempty, reduces it with the given binary operator op, going right to left.

The behavior is the same as reduceRight except that the value is None if the iterator is empty. Each element appears exactly once in the computation.

Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

Reports an error message to the output stream out.

Checks whether corresponding elements of the given iterable collection compare equal (with respect to ==) to elements of this iterator.

Produces a iterator containing cumulative results of applying the operator going left to right, including the initial value.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

The size of this iterator.

Note: will not terminate for infinite-sized collections.

Selects an interval of elements. The returned iterator is made up of all elements x which satisfy the invariant:

from <= indexOf(x) < until

Note: might return different results for different runs, unless the underlying collection type is ordered.

Creates an optionally bounded slice, unbounded if until is negative.

Returns an iterator which presents a "sliding window" view of this iterator. The first argument is the window size, and the second argument step is how far to advance the window on each iteration. The step defaults to 1.

The returned GroupedIterator can be configured to either pad a partial result to size size or suppress the partial result entirely.

Example usages:

// Returns List(ArraySeq(1, 2, 3), ArraySeq(2, 3, 4), ArraySeq(3, 4, 5))
(1 to 5).iterator.sliding(3).toList
// Returns List(ArraySeq(1, 2, 3, 4), ArraySeq(4, 5))
(1 to 5).iterator.sliding(4, 3).toList
// Returns List(ArraySeq(1, 2, 3, 4))
(1 to 5).iterator.sliding(4, 3).withPartial(false).toList
// Returns List(ArraySeq(1, 2, 3, 4), ArraySeq(4, 5, 20, 25))
// Illustrating that withPadding's argument is by-name.
val it2 = Iterator.iterate(20)(_ + 5)
(1 to 5).iterator.sliding(4, 3).withPadding(it2.next).toList

Splits this iterator into a prefix/suffix pair according to a predicate.

Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p), provided the evaluation of the predicate p does not cause any side-effects.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Splits this iterator into a prefix/suffix pair at a given position.

Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).

Note: might return different results for different runs, unless the underlying collection type is ordered.

Returns a scala.collection.Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

• For collections of Int, Short, Byte or Char, an scala.collection.IntStepper is returned
• For collections of Double or Float, a scala.collection.DoubleStepper is returned
• For collections of Long a scala.collection.LongStepper is returned
• For any other element type, an scala.collection.AnyStepper is returned

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

Sums the elements of this collection.

The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.

Note: will not terminate for infinite-sized collections.

Executes the code in body with an exclusive lock on this.

Selects the first n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Selects the longest prefix of elements that satisfy a predicate.

The matching prefix starts with the first element of this iterator, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may empty, so that this method returns an empty iterator.

Example:

scala> List(1, 2, 3, 100, 4).takeWhile(n => n < 10)
val res0: List[Int] = List(1, 2, 3)

scala> List(1, 2, 3, 100, 4).takeWhile(n => n == 0)
val res1: List[Int] = List()

Use span to obtain both the prefix and suffix. Use filter to retain only those elements from the entire iterator that satisfy the predicate.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.

Given a collection factory factory, converts this iterator to the appropriate representation for the current element type A. Example uses:

xs.to(List)
xs.to(ArrayBuffer)
xs.to(BitSet) // for xs: Iterable[Int]

Converts this iterator to an Array.

Implementation note: DO NOT call Array.from from this method.

Converts this iterator to a Buffer.

Converts this iterator to an IndexedSeq.

Converts this iterator to a List.

Converts this iterator to a Map, given an implicit coercion from the iterator's type to a key-value tuple.

Converts this iterator to a Set.

Converts this iterator to a string.

Converts this iterator to a Vector.

See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait--.

See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-int-

See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait-long-.

Creates an iterator over all the elements of this iterator that satisfy the predicate p. The order of the elements is preserved.

Note: withFilter is the same as filter on iterators. It exists so that for-expressions with filters work over iterators.

Zips this iterator with its indices.

A Position implementation which ignores errors in the positions.

Aggregates the results of applying an operator to subsequent elements.

Since this method degenerates to foldLeft for sequential (non-parallel) collections, where the combining operation is ignored, it is advisable to prefer foldLeft for that case.

For parallel collections, use the aggregate method specified by scala.collection.parallel.ParIterableLike.

Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

Tests whether this iterator is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. Non-empty Iterators usually return false even if they were created from a collection with a known finite size.

Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns true. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.