mondrian.calc
Class TupleCollections

java.lang.Object
  mondrian.calc.TupleCollections

public final class TupleCollections
extends Object

Utility methods for tuple collections and iterators.

Author:

jhyde

See Also:

TupleList, TupleIterator

Method Summary

static Iterable<Member[]>	asMemberArrayIterable(TupleIterable tupleIterable) Converts a TupleIterable to an old-style iterable that creates an iterator over member arrays.
static List<Member[]>	asMemberArrayList(TupleList tupleList) Converts a TupleList to an old-style list of member arrays.
static TupleList	asTupleList(List list) Converts an old-style list (members or member arrays) to a TupleList.
static TupleList	createList(int arity) Creates a list of given arity.
static TupleList	createList(int arity, int initialCapacity) Creates a list of given arity and initial capacity.
static TupleList	emptyList(int arity) Returns an empty TupleList of given arity.
static TupleIterator	iterator(TupleCursor cursor) Adapts a TupleCursor into a TupleIterator.
static TupleList	materialize(TupleIterable tupleIterable, boolean eager) Converts a TupleIterable into a TupleList.
static Iterable<Member>	slice(TupleIterable tupleIterable, int column) Creates a slice of a TupleIterable.
static TupleList	unmodifiableList(TupleList list) Creates an unmodifiable TupleList backed by a given list.

Methods inherited from class java.lang.Object

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

Method Detail

createList

public static TupleList createList(int arity)

Creates a list of given arity.

If arity == 1, creates a UnaryTupleList; if arity == 0, creates a DelegatingTupleList; otherwise creates a ArrayTupleList.

Parameters:

arity - Arity

Returns:

Tuple list

See Also:

TupleList.cloneList(int), createList(int, int)

createList

public static TupleList createList(int arity,
                                   int initialCapacity)

Creates a list of given arity and initial capacity.

If arity == 1, creates a UnaryTupleList; if arity == 0, creates a DelegatingTupleList; otherwise creates a ArrayTupleList.

Parameters:

arity - Arity

initialCapacity - Initial capacity

Returns:

Tuple list

See Also:

TupleList.cloneList(int)

emptyList

public static TupleList emptyList(int arity)

Returns an empty TupleList of given arity.

Parameters:

arity - Number of members per tuple

Returns:

Empty tuple list

unmodifiableList

public static TupleList unmodifiableList(TupleList list)

Creates an unmodifiable TupleList backed by a given list.

Parameters:

list - the list for which an unmodifiable view is to be returned.

Returns:

an unmodifiable view of the specified list.

See Also:

Collections.unmodifiableList(java.util.List)

iterator

public static TupleIterator iterator(TupleCursor cursor)

Adapts a TupleCursor into a TupleIterator.

Since the latter is a more difficult API to implement, the wrapper has some extra state.

This method may be used to implement TupleIterable.tupleIterator() for a TupleIterable or TupleList that only has a TupleCursor implementation.

Parameters:

cursor - Cursor

Returns:

Tuple iterator view onto the cursor

slice

public static Iterable<Member> slice(TupleIterable tupleIterable,
                                     int column)

Creates a slice of a TupleIterable.

Can be used as an implementation for TupleList.slice(int).

Parameters:

tupleIterable - Iterable

column - Which member of each tuple of project.

Returns:

Iterable that returns a given member of each tuple

asMemberArrayIterable

public static Iterable<Member[]> asMemberArrayIterable(TupleIterable tupleIterable)

Converts a TupleIterable to an old-style iterable that creates an iterator over member arrays.

Parameters:

tupleIterable - Tuple iterable

Returns:

Iterable that creates an iterator over tuples represented as member arrays

asMemberArrayList

public static List<Member[]> asMemberArrayList(TupleList tupleList)

Converts a TupleList to an old-style list of member arrays.

Parameters:

tupleList - Tuple list

Returns:

List of member arrays

asTupleList

public static TupleList asTupleList(List list)

Converts an old-style list (members or member arrays) to a TupleList.

Deduces the arity of the list from the first element, if the list is not empty. Otherwise assumes arity 1.

If the list happens to be a tuple list, returns unchanged.

Parameters:

list - Old-style list

Returns:

Tuple list

materialize

public static TupleList materialize(TupleIterable tupleIterable,
                                    boolean eager)

Converts a TupleIterable into a TupleList.

If the iterable is already a list, returns the iterable. If it is not a list, the behavior depends on the eager parameter. With eager = true, creates a list and populates it with the contents of the iterable. With eager = false, wraps in an adapter that implements the list interface and materializes to a list the first time that an operation that is in TupleList but not TupleIterable -- for example, TupleList.get(int, int) or List.size() -- is called.

Parameters:

tupleIterable - Iterable

eager - Whether to convert into a list now, as opposed to on first use of a random-access method such as size or get.

Returns:

List