Add hash operation (#110)

Author: 0aix

src/main/java/com/yahoo/bullet/query/expressions/Operation.java

@@ -65,7 +65,8 @@ public enum Operation {
     SUBSTRING("SUBSTRING"),
     UNIX_TIMESTAMP("UNIXTIMESTAMP"),
     LOWER("LOWER"),
-    UPPER("UPPER");
+    UPPER("UPPER"),
+    HASH("HASH");
 
     public static final Set<Operation> BINARY_OPERATIONS =
             new HashSet<>(asList(ADD, SUB, MUL, DIV, MOD,
@@ -75,7 +76,7 @@ public enum Operation {
                                  LESS_THAN_OR_EQUALS, LESS_THAN_OR_EQUALS_ANY, LESS_THAN_OR_EQUALS_ALL, REGEX_LIKE, REGEX_LIKE_ANY,
                                  NOT_REGEX_LIKE, NOT_REGEX_LIKE_ANY, SIZE_IS, CONTAINS_KEY, CONTAINS_VALUE, IN, NOT_IN,
                                  AND, OR, XOR, FILTER));
-    public static final Set<Operation> UNARY_OPERATIONS = new HashSet<>(asList(NOT, SIZE_OF, IS_NULL, IS_NOT_NULL, TRIM, ABS, LOWER, UPPER));
+    public static final Set<Operation> UNARY_OPERATIONS = new HashSet<>(asList(NOT, SIZE_OF, IS_NULL, IS_NOT_NULL, TRIM, ABS, LOWER, UPPER, HASH));
     public static final Set<Operation> N_ARY_OPERATIONS = new HashSet<>(asList(AND, OR, IF, BETWEEN, NOT_BETWEEN, SUBSTRING, UNIX_TIMESTAMP));
 
     private String name;

src/main/java/com/yahoo/bullet/querying/evaluators/UnaryOperations.java

@@ -14,6 +14,7 @@
 import java.io.Serializable;
 import java.util.EnumMap;
 import java.util.Map;
+import java.util.Objects;
 import java.util.function.Function;
 
 /**
@@ -36,6 +37,7 @@ public interface UnaryOperator extends Serializable {
         UNARY_OPERATORS.put(Operation.ABS, UnaryOperations::abs);
         UNARY_OPERATORS.put(Operation.LOWER, UnaryOperations::lower);
         UNARY_OPERATORS.put(Operation.UPPER, UnaryOperations::upper);
+        UNARY_OPERATORS.put(Operation.HASH, UnaryOperations::hash);
     }
 
     static TypedObject not(Evaluator evaluator, BulletRecord record) {
@@ -61,20 +63,6 @@ static TypedObject trim(Evaluator evaluator, BulletRecord record) {
         });
     }
 
-    static TypedObject lower(Evaluator evaluator, BulletRecord record) {
-        return checkNull(evaluator, record, value -> {
-            String str = (String) value.getValue();
-            return TypedObject.valueOf(str.toLowerCase());
-        });
-    }
-
-    static TypedObject upper(Evaluator evaluator, BulletRecord record) {
-        return checkNull(evaluator, record, value -> {
-            String str = (String) value.getValue();
-            return TypedObject.valueOf(str.toUpperCase());
-        });
-    }
-
     static TypedObject abs(Evaluator evaluator, BulletRecord record) {
         return checkNull(evaluator, record, value -> {
             Number number = (Number) value.getValue();
@@ -91,6 +79,24 @@ static TypedObject abs(Evaluator evaluator, BulletRecord record) {
         });
     }
 
+    static TypedObject lower(Evaluator evaluator, BulletRecord record) {
+        return checkNull(evaluator, record, value -> {
+            String str = (String) value.getValue();
+            return TypedObject.valueOf(str.toLowerCase());
+        });
+    }
+
+    static TypedObject upper(Evaluator evaluator, BulletRecord record) {
+        return checkNull(evaluator, record, value -> {
+            String str = (String) value.getValue();
+            return TypedObject.valueOf(str.toUpperCase());
+        });
+    }
+
+    static TypedObject hash(Evaluator evaluator, BulletRecord record) {
+        return TypedObject.valueOf(Objects.hashCode(evaluator.evaluate(record).getValue()));
+    }
+
     private static TypedObject checkNull(Evaluator evaluator, BulletRecord record, Function<TypedObject, TypedObject> operator) {
         TypedObject value = evaluator.evaluate(record);
         if (Utilities.isNull(value)) {

src/test/java/com/yahoo/bullet/querying/evaluators/UnaryOperationsTest.java

@@ -10,6 +10,8 @@
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
+import java.util.Objects;
+
 import static com.yahoo.bullet.querying.evaluators.EvaluatorUtils.listEvaluator;
 import static com.yahoo.bullet.querying.evaluators.EvaluatorUtils.valueEvaluator;
 
@@ -83,4 +85,10 @@ public void testUpper() {
         Assert.assertEquals(UnaryOperations.upper(valueEvaluator("hello"), null), TypedObject.valueOf("HELLO"));
         Assert.assertEquals(UnaryOperations.upper(valueEvaluator(null), null), TypedObject.NULL);
     }
+
+    @Test
+    public void testHash() {
+        Assert.assertEquals(UnaryOperations.hash(valueEvaluator(null), null), TypedObject.valueOf(Objects.hashCode(null)));
+        Assert.assertEquals(UnaryOperations.hash(valueEvaluator("hello"), null), TypedObject.valueOf(Objects.hashCode("hello")));
+    }
 }