Калитова Ольга, 495, MiniORM

okalitova/pom.xml

@@ -16,12 +16,6 @@
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>
   <dependencies>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>3.8.1</version>
-      <scope>test</scope>
-    </dependency>
 
     <dependency>
       <groupId>org.twitter4j</groupId>
@@ -53,5 +47,17 @@
       <version>0.4</version>
     </dependency>
 
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.12</version>
+    </dependency>
+
+    <dependency>
+      <groupId>com.h2database</groupId>
+      <artifactId>h2</artifactId>
+      <version>1.4.190</version>
+    </dependency>
+
   </dependencies>
 </project>

okalitova/src/main/java/ru/fizteh/fivt/students/okalitova/collectionsql/Aggregates.java

@@ -0,0 +1,27 @@
+package ru.fizteh.fivt.students.okalitova.collectionsql;
+
+import ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators.Avg;
+import ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators.Count;
+import ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators.Max;
+import ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators.Min;
+
+import java.util.function.Function;
+
+public class Aggregates {
+    public static <T, R extends Comparable> Function<T, R> max(Function<T, R> expression) {
+        return new Max<>(expression);
+    }
+
+    public static <C, T extends Comparable<T>> Function<C, T> min(Function<C, T> expression) {
+        return new Min<>(expression);
+    }
+
+    public static <T> Function<T, Long> count(Function<T, ?> expression) {
+        return new Count<>(expression);
+    }
+
+    public static <T> Function<T, Double> avg(Function<T, ? extends Number> expression) {
+        return new Avg<>(expression);
+    }
+
+}

okalitova/src/main/java/ru/fizteh/fivt/students/okalitova/collectionsql/Aggregators/Aggregator.java

@@ -0,0 +1,11 @@
+package ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators;
+
+import java.util.List;
+import java.util.function.Function;
+
+/**
+ * Created by nimloth on 16.12.15.
+ */
+public interface Aggregator<T, R> extends Function<T, R> {
+    R apply(List<T> elements);
+}

okalitova/src/main/java/ru/fizteh/fivt/students/okalitova/collectionsql/Aggregators/Avg.java

@@ -0,0 +1,33 @@
+package ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators;
+
+/**
+ * Created by nimloth on 17.12.15.
+ */
+import java.util.List;
+import java.util.function.Function;
+
+public class Avg<T> implements Aggregator<T, Double> {
+
+    private Function<T, ? extends Number> function;
+    public Avg(Function<T, ? extends Number> expression) {
+        this.function = expression;
+    }
+
+    @Override
+    public Double apply(List<T> elements) {
+        return elements
+                .stream()
+                .map(function)
+                .mapToDouble(element -> (Double) element)
+                .average()
+                .getAsDouble();
+    }
+
+    @Override
+    public Double apply(T t) {
+        return null;
+    }
+}
+
+
+

okalitova/src/main/java/ru/fizteh/fivt/students/okalitova/collectionsql/Aggregators/Count.java

@@ -0,0 +1,30 @@
+package ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators;
+
+import java.util.List;
+import java.util.function.Function;
+
+/**
+ * Created by nimloth on 17.12.15.
+ */
+public class Count<T> implements Aggregator<T, Long> {
+
+    private Function<T, ?> function;
+    public Count(Function<T, ?> expression) {
+        this.function = expression;
+    }
+
+    @Override
+    public Long apply(List<T> elements) {
+        Long longAns = elements
+                .stream()
+                .map(function)
+                .distinct()
+                .count();
+        return longAns;
+    }
+
+    @Override
+    public Long apply(T t) {
+        return null;
+    }
+}

okalitova/src/main/java/ru/fizteh/fivt/students/okalitova/collectionsql/Aggregators/Max.java

@@ -0,0 +1,29 @@
+package ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators;
+
+import java.util.List;
+import java.util.function.Function;
+
+/**
+ * Created by nimloth on 16.12.15.
+ */
+public class Max<T, R extends Comparable<R>> implements Aggregator<T, R> {
+
+    private Function<T, R> function;
+    public Max(Function<T, R> expression) {
+        this.function = expression;
+    }
+
+    @Override
+    public R apply(List<T> elements) {
+        return elements
+                .stream()
+                .map(function)
+                .max(R::compareTo)
+                .get();
+    }
+
+    @Override
+    public R apply(T t) {
+        return null;
+    }
+}

okalitova/src/main/java/ru/fizteh/fivt/students/okalitova/collectionsql/Aggregators/Min.java

@@ -0,0 +1,29 @@
+package ru.fizteh.fivt.students.okalitova.collectionsql.Aggregators;
+
+import java.util.List;
+import java.util.function.Function;
+
+/**
+ * Created by nimloth on 17.12.15.
+ */
+public class Min<T, R extends Comparable<R>> implements Aggregator<T, R> {
+
+    private Function<T, R> function;
+    public Min(Function<T, R> expression) {
+        this.function = expression;
+    }
+
+    @Override
+    public R apply(List<T> elements) {
+        return elements
+                .stream()
+                .map(function)
+                .min(R::compareTo)
+                .get();
+    }
+
+    @Override
+    public R apply(T t) {
+        return null;
+    }
+}