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package bjc.utils.esodata;
/**
* Interface for something that acts like a tape.
*
* A tape is essentially a 1D array with a cursor attached to it, and you can
* only affect elements at that cursor. The size of the array is theoretically
* unbounded to the right, but in practice bounded by available memory.
*
* @param <T>
* The element type of the tape.
*
* @author bjculkin
*/
public interface Tape<T> {
/**
* Get the item the tape is currently on.
*
* @return The item the tape is on.
*/
T item();
/**
* Set the item the tape is currently on.
*
* @param itm
* The new value for the tape item.
*/
void item(T itm);
/**
* Get the current number of elements in the tape.
*
* @return The current number of elements in the tape.
*/
int size();
/**
* Get the position of the current item.
*
* @return The position of the current item.
*/
int position();
/**
* Insert an element before the current item.
*
* @param itm
* The item to add.
*/
void insertBefore(T itm);
/**
* Insert an element after the current item.
*
* @param itm
* The item to insert.
*/
void insertAfter(T itm);
/**
* Remove the current element.
*
* Also moves the cursor back one step if possible to maintain relative
* position.
*
* @return The removed item.
*/
T remove();
/** Move the cursor to the left-most position. */
void first();
/** Move the cursor to the right-most position. */
void last();
/**
* Move the cursor one space left.
*
* The cursor can't go past zero.
*
* @return True if the cursor was moved left.
*/
boolean left();
/**
* Move the cursor the specified amount left.
*
* The cursor can't go past zero. Attempts to move the cursor by amounts
* that would exceed zero don't move the cursor at all.
*
* @param amt
* The amount to attempt to move the cursor left.
*
* @return True if the cursor was moved left.
*/
boolean left(int amt);
/**
* Move the cursor one space right.
*
* @return Whether the cursor was moved right.
*/
boolean right();
/**
* Move the cursor the specified amount right.
*
* @param amt
* The amount to move the cursor right by.
*
* @return Whether the cursor was moved right.
*/
boolean right(int amt);
}
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