de.zib.scalaris.operations
Class ReadSublistOp

java.lang.Object
  de.zib.scalaris.operations.PartialReadOp
      de.zib.scalaris.operations.ReadSublistOp

All Implemented Interfaces:

Operation, TransactionOperation, TransactionSingleOpOperation

public class ReadSublistOp
extends PartialReadOp

Operation reading a sublist from a value. Extracts a sublist of length Length starting at Start.

• If Start is negative, we count from the end, e.g. -1 is the last element, -2 the second last.
• If Length is negative, the sublist is created in reversed direction, e.g. sublist([a,b,c], -1, -2) gets [c, b].
• If Start is less than -ListLength and Length is non-negative, it will be set to 1. If Length is negative in this case, an empty sublist will be returned.
• If Start is greater than ListLength and Length is non-negative, an empty sublist will be returned. If Length is negative in this case, it will be set to ListLength.
• Note: sublists never wrap between start and end, i.e. sublist([a,b,c], 1, -2) gets []!
• Examples:
  • first 10: sublist(L, 1, 10) | sublist(L, 10, -10) (reverse order)
  • last 10 : sublist(L, -10, 10) | sublist(L, -1, -10) (reverse order)

Since:

3.18

Version:

3.18

Author:

Nico Kruber, kruber@zib.de

Nested Class Summary

static class

ReadSublistOp.Result Result type of sublist operations.

Constructor Summary

ReadSublistOp(OtpErlangString key, OtpErlangInt start, OtpErlangInt length)
Constructor

ReadSublistOp(String key, int start, int length)
Constructor

Method Summary

OtpErlangObject	getErlang(boolean compressed) Gets the erlang representation of the operation.
ReadSublistOp.Result	processResult() Processes the result set by Operation.setResult(OtpErlangObject, boolean).
ReadSublistOp.Result	processResultSingle() Processes the result set by Operation.setResult(OtpErlangObject, boolean) assuming that operation was committed.
String	toString()

Methods inherited from class de.zib.scalaris.operations.PartialReadOp

getKey, getResult, getResultCompressed, setResult

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ReadSublistOp

public ReadSublistOp(OtpErlangString key,
                     OtpErlangInt start,
                     OtpErlangInt length)

Constructor

Parameters:

key - the key to read

start - the start of the sublist (may be negative - see ReadSublistOp)

length - the length of the sublist (may be negative - see ReadSublistOp)

ReadSublistOp

public ReadSublistOp(String key,
                     int start,
                     int length)

Constructor

Parameters:

key - the key to read

start - the start of the sublist (may be negative - see ReadSublistOp)

length - the length of the sublist (may be negative - see ReadSublistOp)

Method Detail

getErlang

public OtpErlangObject getErlang(boolean compressed)

Description copied from interface: Operation

Gets the erlang representation of the operation.

Parameters:

compressed - whether the value part in the term should be encoded, i.e. compressed into an Erlang binary, or not

Returns:

erlang representation for api_tx:req_list

processResult

public ReadSublistOp.Result processResult()
                                   throws NotFoundException,
                                          NotAListException,
                                          UnknownException

Description copied from interface: Operation

Processes the result set by Operation.setResult(OtpErlangObject, boolean). Note: the created value is not cached!

Returns:

a (potentially) read value (may be null)

Throws:

NotFoundException - if the requested key does not exist

NotAListException - if the previously stored value was no list

UnknownException - if any other error occurs

processResultSingle

public ReadSublistOp.Result processResultSingle()
                                         throws NotFoundException,
                                                NotAListException,
                                                UnknownException

Description copied from interface: TransactionSingleOpOperation

Processes the result set by Operation.setResult(OtpErlangObject, boolean) assuming that operation was committed. In contrast to Operation.processResult() operations like WriteOp will throw a proper AbortException for their commit part instead of an UnknownException. Note: the created value is not cached!

Returns:

a (potentially) read value (may be null)

Throws:

NotFoundException - if the requested key does not exist

NotAListException - if the previously stored value was no list

UnknownException - if any other error occurs

toString

public String toString()

Overrides:

toString in class Object