Abstract supertype of ranged streams mapping a range of discrete indices to elements of the stream, and supporting operations that produce a subrange of indexed elements. The type parameter `Subrange` abstracts the type of the resulting subrange. A subrange may be obtained from an instance of `Ranged` using the span and measure operators.

Often, in a `List` or sorted map for example, an index and its element are distinct values. Sometimes, in a sorted set for example, the index and element are identical.

The span operator accepts the first and last indices of the subrange.

    print("hello world"[0..4]); //prints "hello"
    print("hello world"[6..6]); //prints "w"

If the last index is smaller than the first index, the subrange is reversed.

    print("hello world"[4..0]); //prints "olleh"

If the range of indices identified by the first and last indices is outside the range of indices of this object, an empty subrange is produced.

    print("hello world"[-5..-1]); //prints ""
    print("hello world"[11..11]); //prints ""

The first index may be omitted, implying that the subrange extends forward from the smallest possible index (in this case `runtime.minIntegerValue`) to the given index.

    print("hello world"[...4]) //prints "hello"

If the first index is before the first index of this object, the first index of the object is used.

    print("hello world"[-5...]); //prints "hello world"

The last index may be omitted, implying that the subrange extends forward from the given index to the largest possible index (in this case `runtime.maxIntegerValue`).

    print("hello world"[6...]) //prints "world"

If the last index is after the last index of this object, an empty subrange is produced. (A reversed subrange is never produced.)

    print("hello world"[11...]); //prints ""

The measure operator accepts the first index and maximum length of the subrange.

    print("hello world"[6:5]) //prints "world"
    print("hello world"[6:0]) //prints ""

If the length is nonpositive, the subrange is empty. If the range of indices identified by the first index and length is outside the range of indices of this object, an empty subrange is produced. (A reversed subrange is never produced.)

    print("hello world"[-3:3]) //prints ""
    print("hello world"[11:3]) //prints ""
    print("hello world"[6:-3]) //prints ""

The span and measure operations must be consistent. That is, for every pair of indices `x` and `y` in the ranged object `ranged` such that `y` does not occur before `x` and the span `ranged[x..y]` has length `n`:

- `ranged[x..y]==ranged[x:n]`.

See also `List`, `Sequence`, `String`

no type hierarchy

- `Ranged`
  - `Iterable`
    - `Category`

- `Ranged` of
  - `Array`
  - `Empty`
    - `empty`
  - `List`
    - `SearchableList`
      - `Array`
      - `String`
    - `Sequential`
      - `Empty`
        - `empty`
      - `Sequence`
        - `ArraySequence`
        - `Range`
        - `Singleton`
        - `Tuple`
    - `StringBuilder`
  - `Sequential`
    - `Empty`
      - `empty`
    - `Sequence`
      - `ArraySequence`
      - `Range`
      - `Singleton`
      - `Tuple`
  - `String`

Inherited Attributes
Attributes inherited from: `Object` `hash`, `string`
Attributes inherited from: `Iterable<Element,Absent>` `coalesced`, `cycled`, `distinct`, `empty`, `exceptLast`, `first`, `indexed`, `last`, `paired`, `rest`, `size`, `string`

Methods
`measure` | Source Code `shared formal Subrange measure(Index from, Integer length)` Obtain a measure containing the mapped values starting from the given starting index, with the given `length`. If `length<=0`, the resulting measure is empty. The measure should contain the given number of elements of this stream, starting from the element at the given starting index, in the same order as they are produced by the `Iterable.iterator()` of the stream. In the case where the iterator would be exhausted before `length` elements are produced, the resulting measure contains only those elements which were produced before the iterator was exhausted, and the length of the measure is less then the given `length`. When the given index does not belong to this ranged object, the behavior is implementation dependent.
`span` | Source Code `shared formal Subrange span(Index from, Index to)` Obtain a span containing the elements between the two given indices. The span should contain elements of this stream, starting from the element at the given starting index, and ending with the element at the given ending index, in the same order as they are produced by the `Iterable.iterator()` of the stream, except when the ending index occurs earlier than the starting index, in which case they occur in the opposite order. When one or both of the given indices does not belong to this ranged stream, the behavior is implementation dependent.
`spanFrom` | Source Code `shared formal Subrange spanFrom(Index from)` Obtain a span containing the elements between the given starting index and the last index of this ranged object. The span should contain elements of this stream, starting from the element at the given starting index, in the same order as they are produced by the `Iterable.iterator()` of the stream. When the given index does not belong to this ranged stream, the behavior is implementation dependent.
`spanTo` | Source Code `shared formal Subrange spanTo(Index to)` Obtain a span containing the elements between the first index of this ranged stream and given end index. The span should contain elements of this stream, up to the element at the given ending index, in the same order as they are produced by the `Iterable.iterator()` of the stream. When the given index does not belong to this ranged stream, the behavior is implementation dependent.

Inherited Methods
Methods inherited from: `Object` `equals()`
Methods inherited from: `Category<Element>` `contains()`, `containsAny()`, `containsEvery()`
Methods inherited from: `Iterable<Element,Absent>` `any()`, `by()`, `chain()`, `collect()`, `contains()`, `count()`, `defaultNullElements()`, `each()`, `every()`, `filter()`, `find()`, `findLast()`, `flatMap()`, `fold()`, `follow()`, `frequencies()`, `getFromFirst()`, `group()`, `indexes()`, `interpose()`, `iterator()`, `locate()`, `locateLast()`, `locations()`, `longerThan()`, `map()`, `max()`, `narrow()`, `partition()`, `product()`, `reduce()`, `repeat()`, `scan()`, `select()`, `sequence()`, `shorterThan()`, `skip()`, `skipWhile()`, `sort()`, `spread()`, `summarize()`, `tabulate()`, `take()`, `takeWhile()`