spark.debug

Class Iterables

java.lang.Object

spark.debug.Iterables

public class Iterables
extends Object

Provides utility functions for efficiently wrapping Iterable objects. Note: Some of these are provided in Guava as well.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Iterables.Filter<T>
static interface	Iterables.Mapper<T,S>
static interface	Iterables.Reducer<T,S>

Constructor Summary

Constructors

Constructor and Description
Iterables()

Method Summary

Modifier and Type	Method and Description
static <T> Iterable<T>	filter(Iterable<T> input, Iterables.Filter<T> filter)
static <T> T	first(Iterable<T> collection)
static <T> com.google.common.base.Optional<T>	first(Iterable<T> collection, Iterables.Filter<T> filter)
static <T,S> Iterable<S>	map(Iterable<T> input, Iterables.Mapper<T,S> mapper)
static <T,S> List<S>	mapList(List<T> input, Iterables.Mapper<T,S> mapper)
static <T,S> S	reduce(Iterable<T> collection, S initialValue, Iterables.Reducer<T,S> reducer)

Methods inherited from class java.lang.Object

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

Constructor Detail

Iterables

public Iterables()

Method Detail

filter

public static <T> Iterable<T> filter(Iterable<T> input,
                                     Iterables.Filter<T> filter)

Parameters:

input - An input iterable.

filter - A filtering function.

Returns:

An iterable that provides a view of input which only contains items matching filter.

map

public static <T,S> Iterable<S> map(Iterable<T> input,
                                    Iterables.Mapper<T,S> mapper)

Parameters:

input - An input Iterable.

mapper - A map function.

Returns:

A view of input which is obtained by executing the map function on all values in input.

mapList

public static <T,S> List<S> mapList(List<T> input,
                                    Iterables.Mapper<T,S> mapper)

Parameters:

input - An input list.

mapper - A map function.

Returns:

The input list of type List (modified in-place from List).

reduce

public static <T,S> S reduce(Iterable<T> collection,
                             S initialValue,
                             Iterables.Reducer<T,S> reducer)

Parameters:

collection - An iterable.

initialValue - An initial value.

reducer - A reduction function.

Returns:

The reduced value.

first

public static <T> com.google.common.base.Optional<T> first(Iterable<T> collection,
                                                           Iterables.Filter<T> filter)

Parameters:

collection - An iterable.

filter - A filter.

Returns:

The first item matching the filter (if any).

first

public static <T> T first(Iterable<T> collection)

Parameters:

collection - An iterable (non-empty).

Returns:

The first item in the given iterable.