fiftyone.mobile.detection.entities.memory
Class MemoryVariableList<T extends BaseEntity>

java.lang.Object
  fiftyone.mobile.detection.entities.memory.BaseList<T>
      fiftyone.mobile.detection.entities.memory.MemoryVariableList<T>

All Implemented Interfaces:

Disposable, ReadonlyList<T>, Iterable<T>

public class MemoryVariableList<T extends BaseEntity>
extends BaseList<T>

A readonly list of variable length entity types held in memory.

Entities in the underlying data structure are either fixed length where the data that represents them always contains the same number of bytes, or variable length where the number of bytes to represent the entity varies.

This class uses the offset of the first byte of the entities data in the underlying data structure in the accessor. As such the list isn't being used as a traditional list because items are not retrieved by their index in the list, but by there offset in the underlying data structure.

The constructor will read the header information about the underlying data structure and the entities are added to the list when the Read method is called.

The class supports source stream that do not support seeking.

Should not be referenced directly.

Field Summary

Fields inherited from class fiftyone.mobile.detection.entities.memory.BaseList

array, dataSet, entityFactory, header

Constructor Summary

MemoryVariableList(Dataset dataSet, BinaryReader reader, BaseEntityFactory<T> entityFactory)
Constructs a new instance of VariableList

Method Summary

private int	binarySearch(int offset) Uses a divide and conquer method to search the ordered list of entities that are held in memory.
T	get(int offset) Accessor for the variable list.
void	read(BinaryReader reader) Reads the list into memory.

Methods inherited from class fiftyone.mobile.detection.entities.memory.BaseList

dispose, iterator, size

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MemoryVariableList

public MemoryVariableList(Dataset dataSet,
                          BinaryReader reader,
                          BaseEntityFactory<T> entityFactory)

Constructs a new instance of VariableList

Parameters:

dataSet - The DetectorDataSet being created

reader - Reader connected to the source data structure and positioned to start reading

entityFactory - Interface implementation used to create and size new entities of type T

Method Detail

read

public void read(BinaryReader reader)
          throws IOException

Reads the list into memory.

Parameters:

reader - Reader connected to the source data structure and positioned to start reading

Throws:

IOException

get

public T get(int offset)

Accessor for the variable list.

As all the entities are held in memory and in ascending order of offset a BinarySearch can be used to determine the one that relates to the given offset rapidly.

Parameters:

offset - The offset position in the data structure to the entity to be returned from the list

Returns:

Entity at the offset requested

binarySearch

private int binarySearch(int offset)

Uses a divide and conquer method to search the ordered list of entities that are held in memory.

Parameters:

offset - The offset position in the data structure to the entity to be returned from the list

Returns:

Entity at the offset requested