randoop.util

Interface SimpleList<E>

All Known Implementing Classes:

ListOfLists, OneMoreElementList, SimpleArrayList

public interface SimpleList<E>

Stores a sequence of items, much like a regular List. Subclasses exist that permit efficient appending and concatenation:

• SimpleArrayList: a typical list is stored as an array list.
• ListOfLists: a list that only stores pointers to its constituent sub-lists.
• OneMoreElementList: stores a SimpleList plus one additional final element.

IMPLEMENTATION NOTE

Randoop's main generator (ForwardGenerator) creates new sequences by concatenating existing sequences and appending a statement at the end. When profiling Randoop, we observed that naive concatenation took up a large portion of the tool's running time, and the component set (i.e. the set of stored sequences used to create more sequences) quickly exhausted the memory available.

To improve memory and time efficiency, we now do concatenation differently.

When concatenating N Sequences to create a new sequence, we store the concatenated sequence statements in a ListofLists, which takes space (and creation time) proportional to N, not to the length of the new sequence.

When extending a Sequence with a new statement, we store the old sequence's statements plus the new statement in a OneMoreElementList, which takes up only 2 references in memory (and constant creation time).

Method Summary

Modifier and Type	Method and Description
E	get(int index) Return the element at the given position of this list.
SimpleList<E>	getSublist(int index) Return a sublist of this list that contains the index.
boolean	isEmpty() Test if this list is empty.
int	size() Return the number of elements in this list.
java.util.List<E>	toJDKList() Returns a java.util.List version of this list.

Method Detail

size

int size()

Return the number of elements in this list.

Returns:

the number of elements in this list

isEmpty

boolean isEmpty()

Test if this list is empty.

Returns:

true if this list is empty, false otherwise

get

E get(int index)

Return the element at the given position of this list.

Parameters:

index - the position for the element

Returns:

the element at the index

getSublist

SimpleList<E> getSublist(int index)

Return a sublist of this list that contains the index. Does not necessarily contain the first element.

The result is always an existing SimpleList, the smallest one that contains the index. Currently, it is always a SimpleArrayList.

Parameters:

index - the index into this list

Returns:

the sublist containing this index

toJDKList

java.util.List<E> toJDKList()

Returns a java.util.List version of this list. Caution: this operation can be expensive.

Returns:

List for this list