Repository: apache/incubator-fluo (java)
Issue: Add stream support to Scanners
It would be really nice if the fluo scanners had methods to return java streams.
Pull request description: fixes #867 - Stream support for Scanners

Patch:
diff --git a/modules/api/src/main/java/org/apache/fluo/api/client/scanner/CellScanner.java b/modules/api/src/main/java/org/apache/fluo/api/client/scanner/CellScanner.java
index b2bf50ec..90e631e4 100644
--- a/modules/api/src/main/java/org/apache/fluo/api/client/scanner/CellScanner.java
+++ b/modules/api/src/main/java/org/apache/fluo/api/client/scanner/CellScanner.java
@@ -15,6 +15,9 @@
 
 package org.apache.fluo.api.client.scanner;
 
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
 import org.apache.fluo.api.data.RowColumnValue;
 
 /**
@@ -22,4 +25,11 @@ import org.apache.fluo.api.data.RowColumnValue;
  */
 public interface CellScanner extends Iterable<RowColumnValue> {
 
+  /**
+   * @since 1.2.0
+   */
+  default Stream<RowColumnValue> stream() {
+    return StreamSupport.stream(spliterator(), false);
+  }
+
 }
diff --git a/modules/api/src/main/java/org/apache/fluo/api/client/scanner/ColumnScanner.java b/modules/api/src/main/java/org/apache/fluo/api/client/scanner/ColumnScanner.java
index dd28ce9f..6a61a888 100644
--- a/modules/api/src/main/java/org/apache/fluo/api/client/scanner/ColumnScanner.java
+++ b/modules/api/src/main/java/org/apache/fluo/api/client/scanner/ColumnScanner.java
@@ -15,6 +15,9 @@
 
 package org.apache.fluo.api.client.scanner;
 
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
 import org.apache.fluo.api.data.Bytes;
 import org.apache.fluo.api.data.ColumnValue;
 
@@ -24,12 +27,21 @@ import org.apache.fluo.api.data.ColumnValue;
 public interface ColumnScanner extends Iterable<ColumnValue> {
 
   /**
+   * @since 1.0.0
    * @return the row for all column values
    */
   Bytes getRow();
 
   /**
+   * @since 1.0.0
    * @return the row for all column values decoded as UTF-8
    */
   String getsRow();
+
+  /**
+   * @since 1.2.0
+   */
+  default Stream<ColumnValue> stream() {
+    return StreamSupport.stream(spliterator(), false);
+  }
 }
diff --git a/modules/api/src/main/java/org/apache/fluo/api/client/scanner/RowScanner.java b/modules/api/src/main/java/org/apache/fluo/api/client/scanner/RowScanner.java
index e65816b1..3d679f86 100644
--- a/modules/api/src/main/java/org/apache/fluo/api/client/scanner/RowScanner.java
+++ b/modules/api/src/main/java/org/apache/fluo/api/client/scanner/RowScanner.java
@@ -15,9 +15,19 @@
 
 package org.apache.fluo.api.client.scanner;
 
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
 /**
  * @since 1.0.0
  */
 public interface RowScanner extends Iterable<ColumnScanner> {
 
+  /**
+   * @since 1.2.0
+   */
+  default Stream<ColumnScanner> stream() {
+    return StreamSupport.stream(spliterator(), false);
+  }
+
 }


Test patch:
diff --git a/modules/api/src/test/java/org/apache/fluo/api/client/scanner/ScannerStreamTest.java b/modules/api/src/test/java/org/apache/fluo/api/client/scanner/ScannerStreamTest.java
new file mode 100644
index 00000000..d885552c
--- /dev/null
+++ b/modules/api/src/test/java/org/apache/fluo/api/client/scanner/ScannerStreamTest.java
@@ -0,0 +1,238 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for additional information regarding
+ * copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License. You may obtain a
+ * copy of the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package org.apache.fluo.api.client.scanner;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.apache.fluo.api.data.Bytes;
+import org.apache.fluo.api.data.Column;
+import org.apache.fluo.api.data.ColumnValue;
+import org.apache.fluo.api.data.RowColumnValue;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * @since 1.2.0
+ */
+public class ScannerStreamTest {
+
+  @Test
+  public void testCellScannerStream() {
+    Set<RowColumnValue> rowCols = new HashSet<>();
+    Set<RowColumnValue> empty = new HashSet<>();
+
+    rowCols.add(new RowColumnValue("r1", new Column("f1", "q1"), "v1"));
+    rowCols.add(new RowColumnValue("r1", new Column("f2", "q3"), "v2"));
+    rowCols.add(new RowColumnValue("r2", new Column("f1", "q1"), "v3"));
+    rowCols.add(new RowColumnValue("r2", new Column("f1", "q2"), "v4"));
+    rowCols.add(new RowColumnValue("r4", new Column("f2", "q5"), "v5"));
+
+    CellScannerImpl cellScanner = new CellScannerImpl(rowCols);
+
+    Set<RowColumnValue> expected =
+        rowCols.stream().filter(rcv -> rcv.getColumn().getsFamily().equals("f2"))
+            .collect(Collectors.toSet());
+    Set<RowColumnValue> actualSubSet =
+        cellScanner.stream().filter(rcv -> rcv.getColumn().getsFamily().equals("f2"))
+            .collect(Collectors.toSet());
+
+    Assert.assertNotEquals(empty, actualSubSet);
+    Assert.assertNotEquals(empty, cellScanner.stream().collect(Collectors.toSet()));
+    Assert.assertEquals(rowCols, cellScanner.stream().collect(Collectors.toSet()));
+    Assert.assertEquals(expected, actualSubSet);
+  }
+
+  @Test
+  public void testColumnScannerStream() {
+    Set<ColumnValue> colsVal = new HashSet<>();
+    Set<ColumnValue> empty = new HashSet<>();
+
+    Bytes row = Bytes.of("123");
+    colsVal.add(new ColumnValue(new Column("f1", "q1"), Bytes.of("v1")));
+    colsVal.add(new ColumnValue(new Column("f2", "q3"), Bytes.of("v2")));
+    colsVal.add(new ColumnValue(new Column("f1", "q1"), Bytes.of("v3")));
+    colsVal.add(new ColumnValue(new Column("f1", "q2"), Bytes.of("v4")));
+    colsVal.add(new ColumnValue(new Column("f2", "q5"), Bytes.of("v5")));
+
+    ColumnScanner colScanner = new ColumnScannerImpl(row, colsVal);
+
+    Set<ColumnValue> expected =
+        colsVal.stream().filter(cv -> cv.getColumn().getsFamily().equals("f2"))
+            .collect(Collectors.toSet());
+    Set<ColumnValue> colSubSet =
+        colScanner.stream().filter(cv -> cv.getColumn().getsFamily().equals("f2"))
+            .collect(Collectors.toSet());
+
+    Assert.assertNotEquals(empty, colSubSet);
+    Assert.assertNotEquals(empty, colScanner.stream().collect(Collectors.toSet()));
+    Assert.assertEquals(colsVal, colScanner.stream().collect(Collectors.toSet()));
+    Assert.assertEquals(expected, colSubSet);
+  }
+
+  @Test
+  public void testRowScannerStream() {
+    List<ColumnScanner> rows = new ArrayList<>();
+    Set<ColumnValue> cv1 = new HashSet<>();
+    Set<ColumnValue> cv2 = new HashSet<>();
+
+    Bytes row1 = Bytes.of("555555555");
+    cv1.add(new ColumnValue(new Column("firstname"), Bytes.of("Chris")));
+    cv1.add(new ColumnValue(new Column("lastname"), Bytes.of("McTague")));
+    cv1.add(new ColumnValue(new Column("age"), Bytes.of("21")));
+
+    rows.add(new ColumnScannerImpl(row1, cv1));
+
+    Bytes row2 = Bytes.of("55234234");
+    cv2.add(new ColumnValue(new Column("firstname"), Bytes.of("Hulk")));
+    cv2.add(new ColumnValue(new Column("lastname"), Bytes.of("Hogan")));
+    cv2.add(new ColumnValue(new Column("age"), Bytes.of("60")));
+
+    rows.add(new ColumnScannerImpl(row2, cv2));
+
+    RowScannerImpl rsi = new RowScannerImpl(rows);
+
+    Set<Person> people = rsi.stream().map(cs -> toPerson(cs)).collect(Collectors.toSet());
+
+    Set<Person> expected = new HashSet<>();
+    expected.add(new Person("Chris", "McTague", 21, 555555555));
+    expected.add(new Person("Hulk", "Hogan", 60, 55234234));
+
+    Assert.assertEquals(expected, people);
+  }
+
+  private static Person toPerson(ColumnScanner cs) {
+    Person p = new Person();
+    p.id = Integer.parseInt(cs.getsRow());
+
+    for (ColumnValue cv : cs) {
+      switch (cv.getColumn().getsFamily()) {
+        case "firstname": {
+          p.firstname = cv.getsValue();
+          break;
+        }
+        case "lastname": {
+          p.lastname = cv.getsValue();
+          break;
+        }
+        case "age": {
+          p.age = Integer.parseInt(cv.getsValue());
+          break;
+        }
+        default: {
+          throw new IllegalArgumentException("unknown column " + cv.getColumn());
+        }
+      }
+    }
+    return p;
+  }
+
+  private static class CellScannerImpl implements CellScanner {
+    private Collection<RowColumnValue> rcv;
+
+    CellScannerImpl(Collection<RowColumnValue> rcv) {
+      this.rcv = rcv;
+    }
+
+    @Override
+    public Iterator<RowColumnValue> iterator() {
+      return rcv.iterator();
+    }
+  }
+
+  private static class RowScannerImpl implements RowScanner {
+    private Collection<ColumnScanner> scan;
+
+    RowScannerImpl(Collection<ColumnScanner> scan) {
+      this.scan = scan;
+    }
+
+    @Override
+    public Iterator<ColumnScanner> iterator() {
+      return scan.iterator();
+    }
+  }
+
+  private static class ColumnScannerImpl implements ColumnScanner {
+    private Collection<ColumnValue> scan;
+    private Bytes row;
+
+    ColumnScannerImpl(Bytes row, Collection<ColumnValue> scan) {
+      this.row = row;
+      this.scan = scan;
+    }
+
+    @Override
+    public Iterator<ColumnValue> iterator() {
+      return scan.iterator();
+    }
+
+    @Override
+    public Bytes getRow() {
+      return row;
+    }
+
+    @Override
+    public String getsRow() {
+      return row.toString();
+    }
+  }
+
+  private static class Person {
+    private String firstname;
+    private String lastname;
+    private int age;
+    private int id;
+
+    Person() {
+      this.firstname = "";
+      this.lastname = "";
+      this.age = 0;
+      this.id = 0;
+    }
+
+    Person(String f, String l, int a, int id) {
+      this.firstname = f;
+      this.lastname = l;
+      this.age = a;
+      this.id = id;
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(firstname, lastname, age, id);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (o == this) {
+        return true;
+      }
+
+      if (o instanceof Person) {
+        Person p = (Person) o;
+        return (this.firstname.equals(p.firstname)) && (this.lastname.equals(p.lastname))
+            && (this.age == p.age) && (this.id == p.id);
+      }
+      return false;
+    }
+  }
+}