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part2 done #2

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aa9bbc1
part2 done
AliyaMansurova Jul 9, 2017
5de5f22
part3 done
AliyaMansurova Jul 9, 2017
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23 changes: 13 additions & 10 deletions src/test/java/lambda/part2/exercise/ArrowNotationExercise.java
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Original file line number Diff line number Diff line change
@@ -1,8 +1,10 @@
package lambda.part2.exercise;

import data.Person;
import javafx.util.Pair;
import org.junit.Test;

import java.util.Comparator;
import java.util.function.BiFunction;
import java.util.function.BiPredicate;
import java.util.function.Function;
Expand All @@ -14,35 +16,36 @@ public class ArrowNotationExercise {
@Test
public void getAge() {
// Person -> Integer
final Function<Person, Integer> getAge = null; // TODO

final Function<Person, Integer> getAge = Person::getAge;
assertEquals(Integer.valueOf(33), getAge.apply(new Person("", "", 33)));
}

@Test
public void compareAges() {
// TODO use BiPredicate
// compareAges: (Person, Person) -> boolean

throw new UnsupportedOperationException("Not implemented");
//assertEquals(true, compareAges.test(new Person("a", "b", 22), new Person("c", "d", 22)));
final BiPredicate<Person, Person> compareAges = (p1, p2) -> p1.getAge() == p2.getAge();
assertEquals(true, compareAges.test(new Person("a", "b", 22), new Person("c", "d", 22)));
}

// TODO
// getFullName: Person -> String
final Function<Person, String> getFullName = person -> person.getFirstName() + person.getLastName();
final BiPredicate<Person, Person> compareNamesLength = (p1, p2) -> p1.getAge() == p2.getAge();

// TODO
// ageOfPersonWithTheLongestFullName: (Person -> String) -> (Person, Person) -> int
//
final BiFunction<Person, Person, Integer> ageOfPersonWithTheLongestFullName(Function<Person, String> fullName) {
return (Person p1, Person p2) ->
(fullName.apply(p1).length() > fullName.apply(p2).length()) ? p1.getAge() : p2.getAge();
}

@Test
public void getAgeOfPersonWithTheLongestFullName() {
// Person -> String
final Function<Person, String> getFullName = null; // TODO
final Function<Person, String> getFullName = person -> person.getFirstName() + person.getLastName();

// (Person, Person) -> Integer
// TODO use ageOfPersonWithTheLongestFullName(getFullName)
final BiFunction<Person, Person, Integer> ageOfPersonWithTheLongestFullName = null;
final BiFunction<Person, Person, Integer> ageOfPersonWithTheLongestFullName = ageOfPersonWithTheLongestFullName(getFullName);

assertEquals(
Integer.valueOf(1),
Expand Down
37 changes: 16 additions & 21 deletions src/test/java/lambda/part2/exercise/FunctionCombinationExercise.java
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Expand Up @@ -22,19 +22,16 @@ public void personHasNotEmptyLastNameAndFirstName0() {
// TODO
// negate1: (Person -> boolean) -> (Person -> boolean)
private Predicate<Person> negate1(Predicate<Person> test) {
return p -> {
// TODO
throw new UnsupportedOperationException();
};
return p -> !(test.test(p));

}

// TODO

// validateFirstNameAndLastName: (Person -> boolean, Person -> boolean) -> (Person -> boolean)
private Predicate<Person> validateFirstNameAndLastName(Predicate<Person> t1, Predicate<Person> t2) {
return p -> {
// TODO
throw new UnsupportedOperationException();
};
return p ->
t1.test(p)&& t2.test(p);

}

@Test
Expand All @@ -52,29 +49,27 @@ public void personHasNotEmptyLastNameAndFirstName1() {
assertEquals(false, validate.test(new Person("a", "", 0)));
}

// TODO
// negate: (T -> boolean) -> (T -> boolean)
private <T> Predicate<T> negate(Predicate<T> test) {
// TODO
throw new UnsupportedOperationException();
return t -> !test.test(t);
//throw new UnsupportedOperationException();
}

// TODO
// and: (T -> boolean, T -> boolean) -> (T -> boolean)
private <T> Predicate<T> and(Predicate<T> t1, Predicate<T> t2) {
// TODO
throw new UnsupportedOperationException();
return t -> t1.test(t) && t2.test(t);
// throw new UnsupportedOperationException();
}

@Test
public void personHasNotEmptyLastNameAndFirstName2() {
final Predicate<Person> hasEmptyFirstName = p -> p.getFirstName().isEmpty();
final Predicate<Person> hasEmptyLastName = p -> p.getLastName().isEmpty();

final Predicate<Person> validateFirstName = null; // TODO use negate
final Predicate<Person> validateLastName = null; // TODO use negate
final Predicate<Person> validateFirstName = negate(hasEmptyFirstName); // TODO use negate
final Predicate<Person> validateLastName = negate(hasEmptyLastName); // TODO use negate

final Predicate<Person> validate = null; // TODO use and
final Predicate<Person> validate = and(validateFirstName,validateLastName); // TODO use and

assertEquals(true, validate.test(new Person("a", "b", 0)));
assertEquals(false, validate.test(new Person("", "b", 0)));
Expand All @@ -86,10 +81,10 @@ public void personHasNotEmptyLastNameAndFirstName3() {
final Predicate<Person> hasEmptyFirstName = p -> p.getFirstName().isEmpty();
final Predicate<Person> hasEmptyLastName = p -> p.getLastName().isEmpty();

final Predicate<Person> validateFirstName = null; // TODO use Predicate::negate
final Predicate<Person> validateLastName = null; // TODO use Predicate::negate
final Predicate<Person> validateFirstName = hasEmptyFirstName.negate(); // TODO use Predicate::negate
final Predicate<Person> validateLastName = hasEmptyLastName.negate(); // TODO use Predicate::negate

final Predicate<Person> validate = null; // TODO use Predicate::and
final Predicate<Person> validate = validateFirstName.and(validateLastName); // TODO use Predicate::and

assertEquals(true, validate.test(new Person("a", "b", 0)));
assertEquals(false, validate.test(new Person("", "b", 0)));
Expand Down
61 changes: 52 additions & 9 deletions src/test/java/lambda/part3/exercise/Mapping.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,10 +32,15 @@ public List<T> getList() {
// [T] -> (T -> R) -> [R]
// [T1, T2, T3] -> (T -> R) -> [R1, R2, R3]
public <R> MapHelper<R> map(Function<T, R> f) {
final List<R> result = new ArrayList<R>();
list.forEach(t -> result.add(f.apply(t)));
return new MapHelper<R>(result);
// TODO
throw new UnsupportedOperationException();
// throw new UnsupportedOperationException();
}

;

// [T] -> (T -> [R]) -> [R]

// map: [T, T, T], T -> [R] => [[], [R1, R2], [R3, R4, R5]]
Expand Down Expand Up @@ -76,12 +81,15 @@ public void mapping() {

final List<Employee> mappedEmployees =
new MapHelper<>(employees)
.map(e -> e.withPerson(e.getPerson().withFirstName("John")))
.map(e -> e.withJobHistory(addOneYear(e.getJobHistory())))
.map(e -> e.withJobHistory(replaceQaWithQA(e.getJobHistory())))
.getList();
/*
.map(TODO) // change name to John .map(e -> e.withPerson(e.getPerson().withFirstName("John")))
.map(TODO) // add 1 year to experience duration .map(e -> e.withJobHistory(addOneYear(e.getJobHistory())))
.map(TODO) // replace qa with QA
* */
.getList();

final List<Employee> expectedResult =
Arrays.asList(
Expand All @@ -108,10 +116,27 @@ public void mapping() {
assertEquals(mappedEmployees, expectedResult);
}

private List<JobHistoryEntry> replaceQaWithQA(List<JobHistoryEntry> jobHistory) {
return new MapHelper<JobHistoryEntry>(jobHistory).map(jobHistoryEntry -> {
String position = jobHistoryEntry.getPosition();
return jobHistoryEntry.withPosition(position.equals("qa") ? "QA" : position);
}).getList();
}

private List<JobHistoryEntry> addOneYear(List<JobHistoryEntry> jobHistory) {
return new MapHelper<JobHistoryEntry>(jobHistory).map(jobHistoryEntry ->
jobHistoryEntry.withDuration(jobHistoryEntry.getDuration() + 1)
).getList();
}


private static class LazyMapHelper<T, R> {
private final List<T> list;
private final Function<T, R> function;

public LazyMapHelper(List<T> list, Function<T, R> function) {
this.list = list;
this.function = function;
}

public static <T> LazyMapHelper<T, T> from(List<T> list) {
Expand All @@ -120,19 +145,25 @@ public static <T> LazyMapHelper<T, T> from(List<T> list) {

public List<R> force() {
// TODO
throw new UnsupportedOperationException();
List<R> result = new ArrayList<R>(list.size());
list.forEach(item -> result.add(function.apply(item)));
return result;
}

public <R2> LazyMapHelper<T, R2> map(Function<R, R2> f) {
// TODO
throw new UnsupportedOperationException();
return new LazyMapHelper<T, R2>(list, function.andThen(f));
}

}

private static class LazyFlatMapHelper<T, R> {
private final List<T> list;
private final Function<T, List<R>> function;

public LazyFlatMapHelper(List<T> list, Function<T, List<R>> function) {
this.list = list;
this.function = function;
}

public static <T> LazyFlatMapHelper<T, T> from(List<T> list) {
Expand All @@ -141,13 +172,23 @@ public static <T> LazyFlatMapHelper<T, T> from(List<T> list) {

public List<R> force() {
// TODO
throw new UnsupportedOperationException();
List<R> result = new ArrayList<R>(list.size());
list.forEach(item -> result.addAll(function.apply(item)));
return result;
}

// TODO filter
// (T -> boolean) -> (T -> [T])
// filter: [T1, T2] -> (T -> boolean) -> [T2]
// flatMap": [T1, T2] -> (T -> [T]) -> [T2]
public LazyFlatMapHelper<T, R> filter(Predicate<R> p) {
final Function<R, List<R>> listFunction = rTorListR(p);
return flatMap(listFunction);
}

private Function<R, List<R>> rTorListR(Predicate<R> p) {
return r -> p.test(r) ? Collections.singletonList(r) : Collections.emptyList();
}

public <R2> LazyFlatMapHelper<T, R2> map(Function<R, R2> f) {
final Function<R, List<R2>> listFunction = rR2TorListR2(f);
Expand All @@ -156,7 +197,7 @@ public <R2> LazyFlatMapHelper<T, R2> map(Function<R, R2> f) {

// (R -> R2) -> (R -> [R2])
private <R2> Function<R, List<R2>> rR2TorListR2(Function<R, R2> f) {
throw new UnsupportedOperationException();
return f.andThen(Arrays::asList);
}

// TODO *
Expand All @@ -166,7 +207,6 @@ public <R2> LazyFlatMapHelper<T, R2> flatMap(Function<R, List<R2>> f) {
}



@Test
public void lazy_mapping() {
final List<Employee> employees =
Expand All @@ -193,13 +233,16 @@ public void lazy_mapping() {

final List<Employee> mappedEmployees =
LazyMapHelper.from(employees)
.map(e -> e.withPerson(e.getPerson().withFirstName("John"))) // change name to John
.map(e -> e.withJobHistory(addOneYear(e.getJobHistory()))) // add 1 year to experience duration
.map(e -> e.withJobHistory(replaceQaWithQA(e.getJobHistory()))) // replace qa with QA
.force();

/*
.map(TODO) // change name to John
.map(TODO) // add 1 year to experience duration
.map(TODO) // replace qa with QA
* */
.force();

final List<Employee> expectedResult =
Arrays.asList(
new Employee(
Expand Down