com.mojang.serialization

Class KeyCompressor<T>

java.lang.Object

com.mojang.serialization.KeyCompressor<T>

Type Parameters:

T - The type of the serialized form.

public final class KeyCompressor<T>
extends Object

An immutable collection of indexed, string-convertible keys. When serializing and deserializing maps with compressed keys, a key compressor is used to associate an integer index with each possible key.

Implementation Note:

The implementation uses two hash tables to associate contiguous indices with keys in order to ensure both compression and decompression run in constant time. Using a single array of T[this.size()] is more straightforward, but incurs linear run time for compression.

See Also:

DynamicOps.compressMaps()

Constructor Summary

Constructors

Constructor and Description
KeyCompressor(DynamicOps<T> ops, Stream<T> keyStream) Constructs a new key compressor for the given key stream.

Method Summary

Modifier and Type	Method and Description
int	compress(String key) Returns the key index associated with the key the given string represents.
int	compress(T key) Returns the key index associated with the given key.
T	decompress(int key) Returns the key associated with the given key index, or null if the key index does not correspond to a key.
int	size() The size of the key set represented by this key compressor.

Methods inherited from class java.lang.Object

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

Constructor Detail

KeyCompressor

public KeyCompressor(DynamicOps<T> ops,
                     Stream<T> keyStream)

Constructs a new key compressor for the given key stream. If a key appears in the key stream more than once, the second and subsequent appearances are ignored.

The key stream is consumed in the constructor. It should be finite, or else this constructor will run forever.

Parameters:

ops - The DynamicOps instance defining the serialized form.

keyStream - A stream of keys this key compressor compresses.

Method Detail

decompress

public T decompress(int key)

Returns the key associated with the given key index, or null if the key index does not correspond to a key.

Caution: This is one of the few methods in DFU that may return null.

Implementation Note:

This method incurs one lookup and runs in constant time.

Parameters:

key - The key index.

Returns:

The key associated with the key index, or null if the key index is invalid.

compress

public int compress(String key)

Returns the key index associated with the key the given string represents. If the argument does not represent a valid key, -1 is returned.

Implementation Note:

This method incurs at most two lookups and runs in constant time.

Parameters:

key - The string representation of a key.

Returns:

The index associated with that key, or -1 if the key does not exist.

See Also:

compress(Object)

compress

public int compress(T key)

Returns the key index associated with the given key. If the argument is not a valid key, -1 is returned.

Implementation Note:

This method incurs one lookup and runs in constant time.

Parameters:

key - The key.

Returns:

The key index associated with the key, or -1 if the key is invalid.

size

public int size()

The size of the key set represented by this key compressor.