Add new classes and utils for Hive metastore entities

presto-hive/src/main/java/com/facebook/presto/hive/metastore/Column.java

@@ -0,0 +1,71 @@
+/*
+ * 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.hive.metastore;
+
+import com.facebook.presto.hive.HiveType;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import javax.annotation.concurrent.Immutable;
+
+import java.util.Optional;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+import static java.util.Objects.requireNonNull;
+
+@Immutable
+public class Column
+{
+    private final String name;
+    private final HiveType type;
+    private final Optional<String> comment;
+
+    @JsonCreator
+    public Column(
+            @JsonProperty("name") String name,
+            @JsonProperty("type") HiveType type,
+            @JsonProperty("comment") Optional<String> comment)
+    {
+        this.name = requireNonNull(name, "name is null");
+        this.type = requireNonNull(type, "type is null");
+        this.comment = requireNonNull(comment, "comment is null");
+    }
+
+    @JsonProperty
+    public String getName()
+    {
+        return name;
+    }
+
+    @JsonProperty
+    public HiveType getType()
+    {
+        return type;
+    }
+
+    @JsonProperty
+    public Optional<String> getComment()
+    {
+        return comment;
+    }
+
+    @Override
+    public String toString()
+    {
+        return toStringHelper(this)
+                .add("name", name)
+                .add("type", type)
+                .toString();
+    }
+}