com.google.cloud.dataflow.sdk.coders

Class DelegateCoder<T,IntermediateT>

java.lang.Object

com.google.cloud.dataflow.sdk.coders.StandardCoder<T>

com.google.cloud.dataflow.sdk.coders.DeterministicStandardCoder<T>

com.google.cloud.dataflow.sdk.coders.AtomicCoder<T>

com.google.cloud.dataflow.sdk.coders.CustomCoder<T>

com.google.cloud.dataflow.sdk.coders.DelegateCoder<T,IntermediateT>

Type Parameters:

T - The type of objects coded by this Coder.

IntermediateT - The type of objects a T will be converted to for coding.

All Implemented Interfaces:

Coder<T>, Serializable

Direct Known Subclasses:

StringDelegateCoder

public class DelegateCoder<T,IntermediateT>
extends CustomCoder<T>

A DelegateCoder<T, IntermediateT> wraps a Coder for IntermediateT and encodes/decodes values of type Ts by converting to/from IntermediateT and then encoding/decoding using the underlying Coder<IntermediateT>.

The conversions from T to IntermediateT and vice versa must be supplied as DelegateCoder.CodingFunction, a serializable function that may throw any Exception. If a thrown exception is an instance of CoderException or IOException, it will be re-thrown, otherwise it will be wrapped as a CoderException.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	DelegateCoder.CodingFunction<InputT,OutputT> A CodingFunction<InputT, OutputT> is a serializable function from InputT to OutputT that may throw any Exception.

Nested classes/interfaces inherited from interface com.google.cloud.dataflow.sdk.coders.Coder

Coder.Context, Coder.NonDeterministicException

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DelegateCoder(Coder<IntermediateT> coder, DelegateCoder.CodingFunction<T,IntermediateT> toFn, DelegateCoder.CodingFunction<IntermediateT,T> fromFn)

Method Summary

Modifier and Type	Method and Description
T	decode(InputStream inStream, Coder.Context context) Decodes a value of type T from the given input stream in the given context.
void	encode(T value, OutputStream outStream, Coder.Context context) Encodes the given value of type T onto the given output stream in the given context.
static <T,IntermediateT> DelegateCoder<T,IntermediateT>	of(Coder<IntermediateT> coder, DelegateCoder.CodingFunction<T,IntermediateT> toFn, DelegateCoder.CodingFunction<IntermediateT,T> fromFn)
Object	structuralValue(T value) Returns an object with an Object.equals() method that represents structural equality on the argument.
String	toString()
void	verifyDeterministic() A delegate coder is deterministic if the underlying coder is deterministic.

Methods inherited from class com.google.cloud.dataflow.sdk.coders.CustomCoder

asCloudObject, of

Methods inherited from class com.google.cloud.dataflow.sdk.coders.AtomicCoder

getCoderArguments, getInstanceComponents

Methods inherited from class com.google.cloud.dataflow.sdk.coders.StandardCoder

consistentWithEquals, equals, getComponents, getEncodedElementByteSize, hashCode, isRegisterByteSizeObserverCheap, registerByteSizeObserver, verifyDeterministic, verifyDeterministic

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

DelegateCoder

protected DelegateCoder(Coder<IntermediateT> coder,
                        DelegateCoder.CodingFunction<T,IntermediateT> toFn,
                        DelegateCoder.CodingFunction<IntermediateT,T> fromFn)

Method Detail

of

public static <T,IntermediateT> DelegateCoder<T,IntermediateT> of(Coder<IntermediateT> coder,
                                                                  DelegateCoder.CodingFunction<T,IntermediateT> toFn,
                                                                  DelegateCoder.CodingFunction<IntermediateT,T> fromFn)

encode

public void encode(T value,
                   OutputStream outStream,
                   Coder.Context context)
            throws CoderException,
                   IOException

Description copied from interface: Coder

Encodes the given value of type T onto the given output stream in the given context.

Throws:

CoderException - if the value could not be encoded for some reason

IOException - if writing to the OutputStream fails for some reason

decode

public T decode(InputStream inStream,
                Coder.Context context)
         throws CoderException,
                IOException

Description copied from interface: Coder

Decodes a value of type T from the given input stream in the given context. Returns the decoded value.

Throws:

CoderException - if the value could not be decoded for some reason

IOException - if reading from the InputStream fails for some reason

verifyDeterministic

public void verifyDeterministic()
                         throws Coder.NonDeterministicException

A delegate coder is deterministic if the underlying coder is deterministic. For this to be safe, the intermediate CodingFunction<T, IntermediateT> must also be deterministic.

Specified by:

verifyDeterministic in interface Coder<T>

Overrides:

verifyDeterministic in class CustomCoder<T>

Throws:

Coder.NonDeterministicException - if this coder is not deterministic.

structuralValue

public Object structuralValue(T value)
                       throws Exception

Description copied from interface: Coder

Returns an object with an Object.equals() method that represents structural equality on the argument. (and also implements a compatible Object.hashCode()).

For any two objects of type T, if their encoded bytes are the same, then their structural values are equal according to Object.equals().

Most notably, the structural value for an array coder should perform a structural comparison of the contents of the arrays, rather than the default behavior of comparing according to object identity.

See also Coder.consistentWithEquals().

Specified by:

structuralValue in interface Coder<T>

Overrides:

structuralValue in class StandardCoder<T>

Throws:

Exception

toString

public String toString()

Overrides:

toString in class StandardCoder<T>