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io.undertow.protocols.http2

public Class HPackHuffman

extends Object
Class Inheritance
Imports
io.undertow.UndertowMessages, java.nio.ByteBuffer, java.util.Arrays, .HashSet, .Set

Author
Stuart Douglas

Nested and Inner Type Summary

Modifier and TypeClass and Description
protected static class

Field Summary

Modifier and TypeField and Description
private static final int[]
DECODING_TABLE

array based tree representation of a huffman code.

private static final int
private static final HPackHuffman.HuffmanCode[]
private static final int
private static final int

Constructor Summary

AccessConstructor and Description
public

Method Summary

Modifier and TypeMethod and Description
public static void
decode(ByteBuffer
The byte buffer
data
,
int
The data length
length
,
StringBuilder
The target for the decompressed data
target
)

Decodes a huffman encoded string into the target StringBuilder.

public static boolean

Returns:

true if encoding succeeded
encode
(ByteBuffer
The buffer to encode into
buffer
,
String
The string to encode
toEncode
,
boolean
If the string should be encoded in lower case
forceLowercase
)

Encodes the given string into the buffer.

Inherited from java.lang.Object:
cloneequalsfinalizegetClasshashCodenotifynotifyAlltoStringwaitwaitwait

Field Detail

DECODING_TABLEback to summary
private static final int[] DECODING_TABLE

array based tree representation of a huffman code.

the high two bytes corresponds to the tree node if the bit is set, and the low two bytes for if it is clear if the high bit is set it is a terminal node, otherwise it contains the next node position.

HIGH_TERMINAL_BITback to summary
private static final int HIGH_TERMINAL_BIT
HUFFMAN_CODESback to summary
private static final HPackHuffman.HuffmanCode[] HUFFMAN_CODES
LOW_MASKback to summary
private static final int LOW_MASK
LOW_TERMINAL_BITback to summary
private static final int LOW_TERMINAL_BIT

Constructor Detail

HPackHuffmanback to summary
public HPackHuffman()

Method Detail

decodeback to summary
public static void decode(ByteBuffer data, int length, StringBuilder target) throws HpackException

Decodes a huffman encoded string into the target StringBuilder. There must be enough space left in the buffer for this method to succeed.

Parameters
data:ByteBuffer

The byte buffer

length:int

The data length

target:StringBuilder

The target for the decompressed data

encodeback to summary
public static boolean encode(ByteBuffer buffer, String toEncode, boolean forceLowercase)

Encodes the given string into the buffer. If there is not enough space in the buffer, or the encoded version is bigger than the original it will return false and not modify the buffers position

Parameters
buffer:ByteBuffer

The buffer to encode into

toEncode:String

The string to encode

forceLowercase:boolean

If the string should be encoded in lower case

Returns:boolean

true if encoding succeeded

io.undertow.protocols.http2 back to summary

protected Class HPackHuffman.HuffmanCode

extends Object
Class Inheritance

Field Summary

Modifier and TypeField and Description
pack-priv int
length

length of the code, in bits

pack-priv int
value

The value of the least significan't bits of the code

Constructor Summary

AccessConstructor and Description
public
HuffmanCode(int value, int length)

Method Summary

Modifier and TypeMethod and Description
public boolean
equals(Object
the reference object with which to compare.
o
)

Overrides java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

public int
public int
public int
hashCode()

Overrides java.lang.Object.hashCode.

Returns a hash code value for this object.

public String
toString()

Overrides java.lang.Object.toString.

Returns a string representation of the object.

Inherited from java.lang.Object:
clonefinalizegetClassnotifynotifyAllwaitwaitwait

Field Detail

lengthback to summary
pack-priv int length

length of the code, in bits

valueback to summary
pack-priv int value

The value of the least significan't bits of the code

Constructor Detail

HuffmanCodeback to summary
public HuffmanCode(int value, int length)

Method Detail

equalsback to summary
public boolean equals(Object o)

Overrides java.lang.Object.equals.

Doc from java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

  • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
  • For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

Parameters
o:Object

the reference object with which to compare.

Returns:boolean

true if this object is the same as the obj argument; false otherwise.

Annotations
@Override
getLengthback to summary
public int getLength()
getValueback to summary
public int getValue()
hashCodeback to summary
public int hashCode()

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
  • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
Returns:int

a hash code value for this object

Annotations
@Override
toStringback to summary
public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object. Satisfying this method's contract implies a non-null result must be returned.

Returns:String

a string representation of the object

Annotations
@Override