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Interface collections.Seq

public interface interface Seq

extends Collection

The elements() enumeration for all seqs is guaranteed to be traversed (via nextElement) in sequential order.

at(int)

Return the element at the indicated index

first()

Return the first element, if it exists.

firstIndexOf(Object)

Find the leftmost occurrence of an element.

firstIndexOf(Object, int)

Report the index of leftmost occurrence of an element from a given starting point, or -1 if there is no such index.

insertingAt(int, Object)

Construct a new Seq that is a clone of self except that it adds (inserts) the indicated element at the indicated index.

last()

Return the last element, if it exists.

lastIndexOf(Object)

Find the rightmost occurrence of an element.

lastIndexOf(Object, int)

Report the index of righttmost occurrence of an element from a given starting point, or -1 if there is no such index.

removingAt(int)

Construct a new Seq that is a clone of self except that it does not contain the element at the indeicated index; all elements to its right are slided left by one.

replacingAt(int, Object)

Construct a new Seq that is a clone of self except that the indicated element is placed at the indicated index.

subseq(int, int)

Construct a new Seq that is a clone of self except that it does not contain the elements before index or after index+length.

 public abstract Object at(int index) throws NoSuchElementException

Return the element at the indicated index

Returns:

the element at the index

Throws: NoSuchElementException

if index is not in range 0..size()-1

 public abstract Object first() throws NoSuchElementException

Return the first element, if it exists. Behaviorally equivalent to at(0)

Throws: NoSuchElementException

if isEmpty

 public abstract Object last() throws NoSuchElementException

Return the last element, if it exists. Behaviorally equivalent to at(size()-1)

Throws: NoSuchElementException

if isEmpty

 public abstract int firstIndexOf(Object element,
                                  int startingIndex)

Report the index of leftmost occurrence of an element from a given starting point, or -1 if there is no such index.

Parameters:

element - the element to look for

startingIndex - the index to start looking from. The startingIndex need not be a valid index. If less than zero it is treated as 0. If greater than or equal to size(), the result will always be -1.

Returns:

index such that

 
 let int si = max(0, startingIndex) in
  index == -1 &&
   foreach (int i in si .. size()-1) !at(index).equals(element)
  ||
  at(index).equals(element) &&
   foreach (int i in si .. index-1) !at(index).equals(element)
 

 public abstract int firstIndexOf(Object element)

Find the leftmost occurrence of an element. Behaviorally equivalent to firstIndexOf(element, 0)

 public abstract int lastIndexOf(Object element,
                                 int startingIndex)

Report the index of righttmost occurrence of an element from a given starting point, or -1 if there is no such index.

Parameters:

element - the element to look for

startingIndex - the index to start looking from. The startingIndex need not be a valid index. If less than zero the result will always be -1. If greater than or equal to size(), it is treated as size()-1.

Returns:

index such that

 
 let int si = min(size()-1, startingIndex) in
  index == -1 &&
   foreach (int i in 0 .. si) !at(index).equals(element)
  ||
  at(index).equals(element) &&
   foreach (int i in index+1 .. si) !at(index).equals(element)
 

 public abstract int lastIndexOf(Object element)

Find the rightmost occurrence of an element. Behaviorally equivalent to lastIndexOf(element, size()-1)

 public abstract Seq subseq(int index,
                            int length) throws NoSuchElementException

Construct a new Seq that is a clone of self except that it does not contain the elements before index or after index+length. If length is less than or equal to zero, return an empty Seq.

Parameters:

index - of the element that will be the 0th index in new Seq

length - the number of elements in the new Seq

Returns:

new seq such that

 s.size() == max(0, length) &&
 foreach (int i in 0 .. s.size()-1) s.at(i).equals(at(i+index)); 
 

Throws: NoSuchElementException

if index is not in range 0..size()-1

 public abstract Seq insertingAt(int index,
                                 Object element) throws IllegalElementException, NoSuchElementException

Construct a new Seq that is a clone of self except that it adds (inserts) the indicated element at the indicated index.

Parameters:

index - the index at which the new element will be placed

element - The element to insert in the new collection

Returns:

new seq s, such that

  s.at(index) == element &&
  foreach (int i in 1 .. s.size()-1) s.at(i).equals(at(i-1));
 

Throws: NoSuchElementException

if index is not in range 0..size()-1

 public abstract Seq replacingAt(int index,
                                 Object element) throws IllegalElementException, NoSuchElementException

Construct a new Seq that is a clone of self except that the indicated element is placed at the indicated index.

Parameters:

index - the index at which to replace the element

element - The new value of at(index)

Returns:

new seq, s, such that

  s.at(index) == element &&
  foreach (int i in 0 .. s.size()-1) 
     (i != index) --> s.at(i).equals(at(i));
 

Throws: NoSuchElementException

if index is not in range 0..size()-1

 public abstract Seq removingAt(int index) throws NoSuchElementException

Construct a new Seq that is a clone of self except that it does not contain the element at the indeicated index; all elements to its right are slided left by one.

Parameters:

index - the index at which to remove an element

Returns:

new seq such that

  foreach (int i in 0.. index-1) s.at(i).equals(at(i)); &&
  foreach (int i in index .. s.size()-1) s.at(i).equals(at(i+1));
 

Throws: NoSuchElementException

if index is not in range 0..size()-1

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