Java02. ДЗ 03, Гусев Андрей

build.gradle

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+version '1.0-SNAPSHOT'
+
+apply plugin: 'java'
+
+sourceCompatibility = 1.5
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testCompile group: 'junit', name: 'junit', version: '4.11'
+}

gradle/wrapper/gradle-wrapper.properties

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+#Wed Oct 12 15:32:21 MSK 2016
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.13-bin.zip

settings.gradle

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+rootProject.name = 'FunctionalJava'
+

src/main/java/Collections.java

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+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+
+public class Collections {
+    public static <SourceType, DestType> List < DestType > map (Iterable<SourceType> iterable,
+                                                                Function1<? super SourceType, DestType> function) throws Exception {
+        List<DestType> resList = new LinkedList<DestType>();
+        for (SourceType curElement: iterable) {
+            resList.add(function.apply(curElement));
+        }
+        return resList;
+    }
+
+    public static <T> List<T> filter(Iterable<T> iterable,
+                                     Predicate<? super T> predicate) throws Exception{
+        List<T> trueList = new LinkedList<T>();
+        for (T curElement : iterable) {
+            if (predicate.apply(curElement)) {
+                trueList.add(curElement);
+            }
+        }
+        return trueList;
+    }
+
+    public static <T> List<T> takeWhile(Iterable<T> iterable,
+                                        Predicate<? super T> predicate) throws Exception {
+        List<T> resList = new LinkedList<T>();
+        Iterator<T> it = iterable.iterator();
+        while (it.hasNext()) {
+            T curElem = it.next();
+            if (!predicate.apply(curElem)) {
+                break;
+            }
+            resList.add(curElem);
+        }
+        return resList;
+    }
+
+    public static <T> List<T> takeUnless(Iterable<T> iterable, Predicate<? super T>
+            predicate) throws Exception {
+        return takeWhile(iterable, predicate.not());
+    }
+
+    public static <SourceType, DestType> DestType foldl(
+            Function2<? super DestType,? super SourceType,DestType> function,
+            DestType init, Iterable<SourceType> iterable) throws Exception {
+        DestType res = init;
+        for (SourceType elem : iterable) {
+            res = function.apply(res, elem);
+        }
+        return res;
+    }
+
+    public static <SourceType, DestType> DestType foldr(Function2<? super SourceType, ?super DestType, DestType> function,
+                                                        DestType init, Iterable<SourceType> iterable) throws Exception {
+        return foldrImpl(function, init, iterable.iterator());
+    }
+
+    private static <SourceType, DestType> DestType foldrImpl(Function2<? super SourceType, ? super DestType, DestType> function,
+                                                             DestType init, Iterator<SourceType> iterator) throws Exception {
+        if (iterator.hasNext()) {
+            SourceType curElem = iterator.next();
+            return function.apply(curElem, foldrImpl(function, init, iterator));
+        }
+        return init;
+    }
+}

src/main/java/Function1.java

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+public abstract class Function1 < ArgType, ValueType > {
+    public abstract ValueType apply(ArgType x) throws Exception;
+
+    public < GValue > Function1 < ArgType, GValue > compose(final Function1 < ? super ValueType, GValue > g) {
+        return new Function1<ArgType, GValue>() {
+            @Override
+            public GValue apply(ArgType x) throws Exception{
+                return g.apply(Function1.this.apply(x));
+            }
+        };
+    }
+}