Add support for map_key_exists

presto-docs/src/main/sphinx/functions/map.rst

@@ -99,6 +99,12 @@ Map Functions
         SELECT map_subset(MAP(ARRAY[1,2], ARRAY['a','b']), ARRAY[]); -- {}
         SELECT map_subset(MAP(ARRAY[], ARRAY[]), ARRAY[1,2]); -- {}
 
+.. function:: map_key_exists(x(K, V), k) -> boolean
+
+    Returns whether the given key exists in the map. Returns ``true`` if key is present in the input map, returns ``false`` if not present.
+
+        SELECT map_key_exists(MAP(ARRAY['x','y'], ARRAY[100,200]), 'x'); -- TRUE
+
 .. function:: map_keys(x(K,V)) -> array(K)
 
     Returns all the keys in the map ``x``.

presto-main/src/main/java/com/facebook/presto/operator/scalar/sql/MapSqlFunctions.java

@@ -35,6 +35,17 @@ public static String mapKeysByTopNValues()
         return "RETURN IF(n < 0, fail('n must be greater than or equal to 0'), map_keys(map_top_n(input, n)))";
     }
 
+    @SqlInvokedScalarFunction(value = "map_key_exists", deterministic = true, calledOnNullInput = false)
+    @Description("Returns whether a given key exists in a map.")
+    @TypeParameter("K")
+    @TypeParameter("V")
+    @SqlParameters({@SqlParameter(name = "input", type = "map(K, V)"), @SqlParameter(name = "k", type = "K")})
+    @SqlType("boolean")
+    public static String mapKeysExists()
+    {
+        return "RETURN CONTAINS(MAP_KEYS(input), k)";
+    }
+
     @SqlInvokedScalarFunction(value = "map_top_n", deterministic = true, calledOnNullInput = true)
     @Description("Truncates map items. Keeps only the top N elements by value.")
     @TypeParameter("K")

presto-main/src/test/java/com/facebook/presto/operator/scalar/sql/TestMapKeyExists.java

@@ -0,0 +1,85 @@
+/*
+ * Licensed 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 com.facebook.presto.operator.scalar.sql;
+
+import com.facebook.presto.operator.scalar.AbstractTestFunctions;
+import org.testng.annotations.Test;
+
+import static com.facebook.presto.common.type.BooleanType.BOOLEAN;
+
+public class TestMapKeyExists
+        extends AbstractTestFunctions
+{
+    @Test
+    public void testBasic()
+    {
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY[1, 2, 3], ARRAY[4, 5, 6]), 2)",
+                BOOLEAN,
+                true);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY[-1, -2, -3], ARRAY[4, 5, 6]), 2)",
+                BOOLEAN,
+                false);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY['ab', 'bc', 'cd'], ARRAY['x', 'y', 'z']), 'abc')",
+                BOOLEAN,
+                false);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY[123.0, 99.5, 1000.99], ARRAY['x', 'y', 'z']), 123.0)",
+                BOOLEAN,
+                true);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY['x', 'y'], ARRAY[NULL, 1]), 'x')",
+                BOOLEAN,
+                true);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY['x', 'y'], ARRAY[NULL, NULL]), 'z')",
+                BOOLEAN,
+                false);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY[NAN(), 123.21], ARRAY['val1', 'val2']), 123.21)",
+                BOOLEAN,
+                true);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY[NAN(), 123.21], ARRAY['val1', 'val2']), NAN())",
+                BOOLEAN,
+                false);
+    }
+
+    @Test
+    public void testEmpty()
+    {
+        assertFunction("MAP_KEY_EXISTS(MAP(ARRAY[], ARRAY[]), 5)", BOOLEAN, false);
+    }
+
+    @Test
+    public void testNull()
+    {
+        assertFunction("MAP_KEY_EXISTS(NULL, 1)", BOOLEAN, null);
+    }
+
+    @Test
+    public void testComplexKeys()
+    {
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY[ROW('x', 1), ROW('y', 2)], ARRAY[1, 2]), ROW('x', 1))",
+                BOOLEAN,
+                true);
+        assertFunction(
+                "MAP_KEY_EXISTS(MAP(ARRAY[ROW('x', 1), ROW('x', -2)], ARRAY[2, 1]), ROW('y', 1))",
+                BOOLEAN,
+                false);
+    }
+}