/*
 File: SeqView.d

 Originally written by Doug Lea and released into the public domain. 
 Thanks for the assistance and support of Sun Microsystems Labs, Agorics 
 Inc, Loral, and everyone contributing, testing, and using this code.

 History:
 Date     Who                What
 24Sep95  dl@cs.oswego.edu   Create from collections.d  working file

*/


module tango.util.collection.model.SeqView;

private import tango.util.collection.model.View;


/**
 * 
 *
 * Seqs are indexed, sequentially ordered collections.
 * Indices are always in the range 0 .. size() -1. All accesses by index
 * are checked, raising exceptions if the index falls out of range.
 * <P>
 * The elements() enumeration for all seqs is guaranteed to be
 * traversed (via nextElement) in sequential order.
 * 
        author: Doug Lea
 * @version 0.93
 *
 * <P> For an introduction to this package see <A HREF="index.html"> Overview </A>.
**/

public interface SeqView(T) : View!(T)
{
        /**
         * Return the element at the indicated index
         * @param index 
         * Returns: the element at the index
         * Throws: NoSuchElementException if index is not in range 0..size()-1
        **/

        public T get(int index);
        public alias get opIndex;


        /**
         * Return the first element, if it exists.
         * Behaviorally equivalent to at(0)
         * Throws: NoSuchElementException if isEmpty
        **/

        public T head();


        /**
         * Return the last element, if it exists.
         * Behaviorally equivalent to at(size()-1)
         * Throws: NoSuchElementException if isEmpty
        **/

        public T tail();


        /**
         * Report the index of leftmost occurrence of an element from a 
         * given starting point, or -1 if there is no such index.
         * @param element the element to look for
         * @param 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
         * <PRE> 
         * 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)
         * </PRE>
        **/

        public int first(T element, int startingIndex = 0);

        /**
         * Report the index of righttmost occurrence of an element from a 
         * given starting point, or -1 if there is no such index.
         * @param element the element to look for
         * @param 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
         * <PRE> 
         * 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)
         * </PRE>
         *
        **/
        public int last(T element, int startingIndex = 0);


        /**
         * Construct a new SeqView 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 SeqView.
         * @param index of the element that will be the 0th index in new SeqView
         * @param length the number of elements in the new SeqView
         * Returns: new seq such that
         * <PRE>
         * s.size() == max(0, length) &&
         * foreach (int i in 0 .. s.size()-1) s.at(i).equals(at(i+index)); 
         * </PRE>
         * Throws: NoSuchElementException if index is not in range 0..size()-1
        **/
        public SeqView subset(int index, int length);

        /**
         * Construct a new SeqView that is a clone of self except
         * that it does not contain the elements before begin or
         * after end-1. If length is less than or equal to zero,
         * return an empty SeqView.
         * @param index of the element that will be the 0th index in new SeqView
         * @param index of the last element in the SeqView plus 1
         * Returns: new seq such that
         * <PRE>
         * s.size() == max(0, length) &&
         * foreach (int i in 0 .. s.size()-1) s.at(i).equals(at(i+index)); 
         * </PRE>
         * Throws: NoSuchElementException if index is not in range 0..size()-1
        **/
        public SeqView opSlice(int begin, int end);


version (VERBOSE)
{
        /**
         * Construct a new SeqView that is a clone of self except
         * that it adds (inserts) the indicated element at the
         * indicated index.
         * @param index the index at which the new element will be placed
         * @param element The element to insert in the new collection
         * Returns: new seq s, such that
         * <PRE>
         *  s.at(index) == element &&
         *  foreach (int i in 1 .. s.size()-1) s.at(i).equals(at(i-1));
         * </PRE>
         * Throws: NoSuchElementException if index is not in range 0..size()-1
        **/

        public SeqView insertingAt(int index, T element);


        /**
         * Construct a new SeqView that is a clone of self except
         * that the indicated element is placed at the indicated index.
         * @param index the index at which to replace the element
         * @param element The new value of at(index)
         * Returns: new seq, s, such that
         * <PRE>
         *  s.at(index) == element &&
         *  foreach (int i in 0 .. s.size()-1) 
         *     (i != index) --&gt; s.at(i).equals(at(i));
         * </PRE>
         * Throws: NoSuchElementException if index is not in range 0..size()-1
        **/

        public SeqView replacingAt(int index, T element);


        /**
         * Construct a new SeqView 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.
         *
         * @param index the index at which to remove an element
         * Returns: new seq such that
         * <PRE>
         *  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));
         * </PRE>
         * Throws: NoSuchElementException if index is not in range 0..size()-1
        **/
        public SeqView removingAt(int index);
} // version
}