org.shapelogic.streams
Class BaseCommonStream<E>

java.lang.Object
  org.shapelogic.streams.BaseCommonStream<E>

All Implemented Interfaces:

java.util.Iterator<E>, CalcValue<E>, ContextGettable, LazyCalc<E>, RecursiveContext, NumberedStream<E>, Stream<E>, StreamProperties

Direct Known Subclasses:

BaseCommonNumberedStream, BaseListCommonStream

public abstract class BaseCommonStream<E>
extends java.lang.Object
implements NumberedStream<E>, StreamProperties, ContextGettable, RecursiveContext

Implementation of ListStream.
Close to
1: a lazy stream.
2: a UNIX pipe.

This is close to org.apache.commons.collections.list.LazyList, but that takes a factory to calculate next element, and that works badly here. How should a step work?
Normally call the hasNext, in order for this to work it would have to do the calculation.

So _current should be the last element that has been returned.

So when you call hasNext it will add that element to the list. When you call next it will bump the counter up one element if goes too high then do the calculation. At the end it will get to a point where the calculation fails. At that point last will be set to the current element. I will ignore synchronization to begin with. I think that there could be a _nextElement that is calculated when hasNext() is called. When next is called check if this exist and return it. After that set it to null.

Author:

Sami Badawi

Field Summary

protected java.util.Map	_context
protected int	_current The last value that was calculated and looked at So if you want to see that again use this for a lookup
protected boolean	_dirty
protected int	_last Last value that can be calculated.
protected int	_maxLast Highest value that last can take.
protected java.lang.String	_name Does not always exist.
protected boolean	_nullLegalValue
protected RecursiveContext	_parentContext
protected IQueryCalc	_query
protected E	_value

Constructor Summary

BaseCommonStream()

Method Summary

protected abstract boolean	calcAddNext() Try to calculate one more, independent of the _current.
java.util.Map	getContext() The context if needed.
java.lang.Object	getInContext(java.lang.Object key)
int	getIndex() Index of last successfully processed element.
int	getLast() Last possible element.
int	getMaxLast() Manually set max value for last possible element.
java.lang.String	getName() If a stream has a name.
RecursiveContext	getParentContext()
E	getValue() Starts a lazy calculation.
abstract E	invokeIndex(int index) Calculate the value at an index.
boolean	isDeterministic() Is the result of a calculation deterministic.
boolean	isDirty() When dirty is false that means that the calculated value can be used
boolean	isNullLegalValue() If null is a legal value.
void	remove()
protected void	setLastFromInput()
void	setMaxLast(int maxLast) Set a max value for last possible element.
void	setNullLegalValue(boolean nullLegalValue)
void	setup() Currently not super well define used for 2 purposes: Reset: called from the outside if you want to reuse it init: Called from the inside when calculation start to have everything setup maybe the semantic could work for both? TODO: This should be separated better.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.shapelogic.streams.NumberedStream

get

Methods inherited from interface java.util.Iterator

hasNext, next

Methods inherited from interface org.shapelogic.streams.StreamProperties

isCached, isRandomAccess

Field Detail

_current

protected int _current

The last value that was calculated and looked at So if you want to see that again use this for a lookup

_last

protected int _last

Last value that can be calculated. When _maxLast is set then _last should first be set to the same. If lower limit is found move down.

_maxLast

protected int _maxLast

Highest value that last can take.

_name

protected java.lang.String _name

Does not always exist.

_dirty

protected boolean _dirty

_value

protected E _value

_context

protected java.util.Map _context

_query

protected IQueryCalc _query

_parentContext

protected RecursiveContext _parentContext

_nullLegalValue

protected boolean _nullLegalValue

Constructor Detail

BaseCommonStream

public BaseCommonStream()

Method Detail

invokeIndex

public abstract E invokeIndex(int index)

Calculate the value at an index.
So it gets the needed input value and call the appropriate invoke function.
Can this be used for a filter call?
The index does not make sense for a filter since you do not know where the input is coming from. So maybe just ignore it.
This is a little messy but less messy that what is there now.

calcAddNext

protected abstract boolean calcAddNext()

Try to calculate one more, independent of the _current.

setLastFromInput

protected void setLastFromInput()

getLast

public int getLast()

Description copied from interface: NumberedStream

Last possible element.
If last is not known then this is set to LAST_UNKNOWN.
When you add a new element this will not grow.
When maxLast is set so it this, but this can can get lower.
Set when you find the end.

If you use this for iteration you need to call the function at each iteration.

Specified by:

getLast in interface NumberedStream<E>

getMaxLast

public int getMaxLast()

Description copied from interface: NumberedStream

Manually set max value for last possible element.

Specified by:

getMaxLast in interface NumberedStream<E>

setMaxLast

public void setMaxLast(int maxLast)

Set a max value for last possible element. This also set last.

Specified by:

setMaxLast in interface NumberedStream<E>

isNullLegalValue

public boolean isNullLegalValue()

Description copied from interface: StreamProperties

If null is a legal value. Otherwise when a null if encountered the stream has ended.

Specified by:

isNullLegalValue in interface StreamProperties

setNullLegalValue

public void setNullLegalValue(boolean nullLegalValue)

getIndex

public int getIndex()

Description copied from interface: NumberedStream

Index of last successfully processed element.

Specified by:

getIndex in interface NumberedStream<E>

getName

public java.lang.String getName()

Description copied from interface: StreamProperties

If a stream has a name.

Specified by:

getName in interface StreamProperties

setup

public void setup()

Description copied from interface: LazyCalc

Currently not super well define used for 2 purposes: Reset: called from the outside if you want to reuse it init: Called from the inside when calculation start to have everything setup maybe the semantic could work for both? TODO: This should be separated better.

Specified by:

setup in interface LazyCalc<E>

getContext

public java.util.Map getContext()

Description copied from interface: StreamProperties

The context if needed. Maybe it would be better to make a link to the task that contains the context.

Specified by:

getContext in interface RecursiveContext

Specified by:

getContext in interface StreamProperties

getParentContext

public RecursiveContext getParentContext()

Specified by:

getParentContext in interface RecursiveContext

getValue

public E getValue()

Description copied from interface: CalcValue

Starts a lazy calculation. If dirty do calc() else return cached value. This should maybe be moved up in the hierarchy

Specified by:

getValue in interface CalcValue<E>

isDeterministic

public boolean isDeterministic()

Description copied from interface: StreamProperties

Is the result of a calculation deterministic.

Specified by:

isDeterministic in interface StreamProperties

isDirty

public boolean isDirty()

Description copied from interface: LazyCalc

When dirty is false that means that the calculated value can be used

Specified by:

isDirty in interface LazyCalc<E>

remove

public void remove()

Specified by:

remove in interface java.util.Iterator<E>

getInContext

public java.lang.Object getInContext(java.lang.Object key)

Specified by:

getInContext in interface ContextGettable