The document discusses the use of the Guava Java library for manipulating collections and implementing predicates and functions. It includes code examples demonstrating how to filter and transform collections and introducing concepts like laziness and containment tree walking. The presentation emphasizes the integration between Guava and EMF, highlighting the usefulness of the emfpath library.

1. Mikaël Barbero
OBEO

2. public void demo(Library l) {
List<Book> books = l.getBooks();
Set<Borrower> allBorrowers = new HashSet<Borrower>();
List<Writer> allWriters = new ArrayList<Writer>();
for (Book book : books) {
List<Borrower> borrowers = book.getBorrowers();
allBorrowers.addAll(borrowers);
allWriters.add(book.getAuthor());
}
Set<Borrower> filteredBorowers = new HashSet<Borrower>();
for (Borrower borrower : allBorrowers) {
if (borrower.getLastName().startsWith("B") &&
borrower.getBorrowed().contains(aSpecificBook)) {
filteredBorowers.add(borrower);
}
}
}

3. About Guava
Java library used internally Superset of Google
@ Google for years Collections
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2007 2008 2009 2010 2011

6. About Guava

7. About Guava
IO

8. About Guava
IO Networking

9. About Guava
IO Networking Concurrency

10. About Guava
IO Networking Concurrency
Primitive types

11. About Guava
IO Networking Concurrency
Primitive types Collections

12. About Guava
IO Networking Concurrency
Primitive types Collections

13. in com.google.common.base package
public interface Predicate<T> {
Predicate<T> to filter boolean apply(T from);
out a collection }
pu blic interface Function<F, T> {
T apply(F from);
Function<F, T> to
} transform a collection

14. in com.google.common.collect package
Iterables.filter()
Iterators.filter()
Collections2.filter()
Sets.filter()

15. 24 42 13 7 128

16. 24 42 13 7 128
public static void demo(Collection<Integer> c) {
Predicate<Integer> isEven = new Predicate<Integer>() {
@Override
public boolean apply(Integer input) {
return (input.intValue() % 2 == 0);
}
};
Collections2.filter(c, isEven);
}

17. 24 42 13 7 128
public static void demo(Collection<Integer> c) {
Predicate<Integer> isEven = new Predicate<Integer>() {
@Override
public boolean apply(Integer input) {
return (input.intValue() % 2 == 0);
}
};
Collections2.filter(c, isEven);
}
24 42 128

18. in com.google.common.collect package
Iterables.transform()
Iterators.transform()
Collections2.transform()
Lists.transform()

19. Apple Orange Banana Kiwi Pear

20. Apple Orange Banana Kiwi Pear
public void demo(Collection<String> c) {
Function<String, String> toUpperCase = new Function<String, String>() {
@Override
public String apply(String input) {
return input.toUpperCase();
}
};
Collections2.transform(c, toUpperCase);
}

21. Apple Orange Banana Kiwi Pear
public void demo(Collection<String> c) {
Function<String, String> toUpperCase = new Function<String, String>() {
@Override
public String apply(String input) {
return input.toUpperCase();
}
};
Collections2.transform(c, toUpperCase);
}
APPLE ORANGE BANANA KIWI PEAR

22. Compose and combine
Functions
compose
forPredicate
Predicates
and
or
not
compose

23. Beware
of

24. Beware
of
lazyness

25. Copy!
Lists.newArrayList()
Lists.newLinkedList()
Sets.newHashSet()
Sets.newLinkedHashSet()
Sets.newTreeSet()
and make it immutable...
ImmutableList.copyOf()
ImmutableSet.copyOf()

26. Path

27. {
public interface Function<F, T>
Set of functions and }
T apply(F from);
public interface Predicate<T> {
predicates for EMF objects }
boolean apply(T from);
Code generators for your
own Ecore models
and few other utility classes

28. Lazy EObjects containment tree walking
‣ parent (eContainer)
‣ ancestor
‣ ancestorOrSelf
‣ child (eContents)
‣ descendant (eAllContents)
‣ descendantOrSelf
‣ following
‣ followingSibling
‣ preceding
‣ precedingSibling
EObject myObject;
Collection<EObject> fs = followingSibling.of(myObject);

29. Common predicates
Having
IsKind/IsType
IsAncestor/IsChild
public static Collection<EObject> demoHaving(Collection<EObject> c) {
return Collections2.filter(c,
Having.feature(EcorePackage.Literals.ENAMED_ELEMENT__NAME,
StringPredicates.firstUpperCase)
);
}

30. non-EMF functions & predicates
Strings
length : Function<String, Integer>
toL1Case : Function<String, String> Comparable
toLowerCase : Function<String, String>
toU1Case : Function<String, String> Predicates to
toUpperCase : Function<String, String> test ordering:
trim : Function<String, String> equal
replaceAll(Pattern, String) less than
replaceAll(String, String) greater than
replaceFirst(Pattern, String) less or equal
replaceFirst(String, String) greater or equal
substring(int)
substring(int, int)

31. Ecore API has been Guava-ified
‣ EObject.eResource() is wrapped as a Function in
EObjectPath.eResource
‣ EObject.eIsProxy() is wrapped as a Predicate in
EObjectPath.eIsProxy
‣ EClass.getESuperTypes() is wrapped as a
Function in EClass.eSuperTypes
‣ EReference.isContainment() is wrapped as a
Predicate in ERefrencePath.isContainment

32. Ecore has been Guava-ified through a generator
+
that is available for your own Ecore model

33. time to play

34. public void demo(Library l) {
List<Book> books = l.getBooks();
Set<Borrower> allBorrowers = new HashSet<Borrower>();
List<Writer> allWriters = new ArrayList<Writer>();
for (Book book : books) {
List<Borrower> borrowers = book.getBorrowers();
allBorrowers.addAll(borrowers);
allWriters.add(book.getAuthor());
}
Set<Borrower> filteredBorowers = new HashSet<Borrower>();
for (Borrower borrower : allBorrowers) {
if (borrower.getLastName().startsWith("B") &&
borrower.getBorrowed().contains(aSpecificBook)) {
filteredBorowers.add(borrower);
}
}
}

35. public void demo2(Library l) {
List<Book> books = l.getBooks();
Set<Borrower> allBorrowers =
ImmutableSet.copyOf(
Iterables.concat(
Collections2.transform(books, BookPath.borrowers)));
List<Writer> allWriters = Lists.transform(books, BookPath.author);
Predicate<Borrower> predicate = new Predicate<Borrower>() {
@Override
public boolean apply(Borrower borrower) {
return borrower.getLastName().startsWith("B") &&
borrower.getBorrowed().contains(aSpecificBook);
}
};
Set<Borrower> filteredBorrowers = Sets.filter(allBorrowers, predicate);
}

36. public void demo2(Library l) {
List<Book> books = l.getBooks();
Set<Borrower> allBorrowers =
ImmutableSet.copyOf(
Iterables.concat(
Collections2.transform(books, BookPath.borrowers)));
List<Writer> allWriters = Lists.transform(books, BookPath.author);
Predicate<Borrower> predicate = new Predicate<Borrower>() {
@Override
public boolean apply(Borrower borrower) {
return borrower.getLastName().startsWith("B") &&
borrower.getBorrowed().contains(aSpecificBook);
}
};
Set<Borrower> filteredBorrowers = Sets.filter(allBorrowers, predicate);
}

37. public void demo2(Library l) {
List<Book> books = l.getBooks();
Set<Borrower> allBorrowers =
ImmutableSet.copyOf(
Iterables.concat(
Collections2.transform(books, BookPath.borrowers)));
List<Writer> allWriters = Lists.transform(books, BookPath.author);
Set<Borrower> filteredBorrowers = Sets.filter(allBorrowers, predicate);
}

38. Wha t you should remember
about this presentation
1. Function and Predicate
2. Lazyness
3. Walking EObjects containment tree
along XPath-like axes
4. Code generators for your own Ecore
model

39. What you should REALLY remember
about this presentation
1. Guava is cool!
2. EMF is cool too!
3. EMFPath bridges the gap between
Guava and EMF
4. EMFPath is cool - Q.E.D
EMFPath v0.4.0 is available NOW!
http://code.google.com/a/eclipselabs.org/p/emfpath/

40. Q&A