com.amazon.carbonado.cursor
Class FilteredCursor<S>

java.lang.Object
  com.amazon.carbonado.cursor.AbstractCursor<S>
      com.amazon.carbonado.cursor.FilteredCursor<S>

All Implemented Interfaces:

Cursor<S>

public abstract class FilteredCursor<S>
extends AbstractCursor<S>

Wraps another cursor and applies custom filtering to reduce the set of results.

Author:

Brian S O'Neill

Constructor Summary

protected

FilteredCursor(Cursor<S> cursor)

Method Summary

static <S extends Storable> Cursor<S>	applyFilter(Cursor<S> cursor, Class<S> type, String filter, Object... filterValues) Returns a Cursor that is filtered by the given filter expression and values.
static <S extends Storable> Cursor<S>	applyFilter(Filter<S> filter, FilterValues<S> filterValues, Cursor<S> cursor) Returns a Cursor that is filtered by the given Filter and FilterValues.
void	close() Call close to release any resources being held by this cursor.
boolean	hasNext() Returns true if this cursor has more elements.
protected abstract boolean	isAllowed(S storable)
S	next() Returns the next element from this cursor.
int	skipNext(int amount) Skips forward by the specified amount of elements, returning the actual amount skipped.

Methods inherited from class com.amazon.carbonado.cursor.AbstractCursor

copyInto, copyInto, toList, toList

Methods inherited from class java.lang.Object

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

Constructor Detail

FilteredCursor

protected FilteredCursor(Cursor<S> cursor)

Method Detail

applyFilter

public static <S extends Storable> Cursor<S> applyFilter(Cursor<S> cursor,
                                                         Class<S> type,
                                                         String filter,
                                                         Object... filterValues)

Returns a Cursor that is filtered by the given filter expression and values.

Parameters:

cursor - cursor to wrap

type - type of storable

filter - filter to apply

filterValues - values for filter

Returns:

wrapped cursor which filters results

Throws:

IllegalStateException - if any values are not specified

IllegalArgumentException - if any argument is null

Since:

1.2

applyFilter

public static <S extends Storable> Cursor<S> applyFilter(Filter<S> filter,
                                                         FilterValues<S> filterValues,
                                                         Cursor<S> cursor)

Returns a Cursor that is filtered by the given Filter and FilterValues. The given Filter must be composed only of the same PropertyFilter instances as used to construct the FilterValues. An IllegalStateException will result otherwise.

Parameters:

filter - filter to apply

filterValues - values for filter, which may be null if filter has no parameters

cursor - cursor to wrap

Returns:

wrapped cursor which filters results

Throws:

IllegalStateException - if any values are not specified

IllegalArgumentException - if filter is closed

isAllowed

protected abstract boolean isAllowed(S storable)
                              throws FetchException

Returns:

false if object should not be in results

Throws:

FetchException

close

public void close()
           throws FetchException

Description copied from interface: Cursor

Call close to release any resources being held by this cursor. Further operations on this cursor will behave as if there are no results.

Throws:

FetchException

hasNext

public boolean hasNext()
                throws FetchException

Description copied from interface: Cursor

Returns true if this cursor has more elements. In other words, returns true if next would return an element rather than throwing an exception.

Throws:

FetchException - if storage layer throws an exception

next

public S next()
       throws FetchException

Description copied from interface: Cursor

Returns the next element from this cursor. This method may be called repeatedly to iterate through the results.

Throws:

FetchException - if storage layer throws an exception

skipNext

public int skipNext(int amount)
             throws FetchException

Description copied from interface: Cursor

Skips forward by the specified amount of elements, returning the actual amount skipped. The actual amount is less than the requested amount only if the end of the results was reached.

Specified by:

skipNext in interface Cursor<S>

Overrides:

skipNext in class AbstractCursor<S>

Parameters:

amount - maximum amount of elements to skip

Returns:

actual amount skipped

Throws:

FetchException - if storage layer throws an exception