fiftyone.mobile.detection.entities.memory

Class MemoryVariableList<T extends BaseEntity>

java.lang.Object

fiftyone.mobile.detection.entities.memory.MemoryBaseList<T>

fiftyone.mobile.detection.entities.memory.MemoryVariableList<T>

Type Parameters:

T - The type of BaseEntity the list will contain

All Implemented Interfaces:

IReadonlyList<T>, Closeable, AutoCloseable, Iterable<T>

public class MemoryVariableList<T extends BaseEntity>
extends MemoryBaseList<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.

Objects of this class should not be created directly as they are part of the internal logic.

Field Summary

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

array, dataSet, entityFactory, header

Constructor Summary

Constructors

Constructor and Description
MemoryVariableList(Dataset dataSet, BinaryReader reader, BaseEntityFactory<T> entityFactory) Constructs a new instance of VariableList of type T.

Method Summary

Modifier and Type	Method and Description
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.MemoryBaseList

close, iterator, size

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

MemoryVariableList

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

Constructs a new instance of VariableList of type T.

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.

Specified by:

read in class MemoryBaseList<T extends BaseEntity>

Parameters:

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

Throws:

IOException - if there was a problem accessing data file.

get

public T get(int offset)
      throws IOException

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.

Throws:

IOException - if there was a problem accessing data file.