[WIP] Support for user-defined enums

presto-common/src/main/java/com/facebook/presto/common/type/StringEnumType.java

@@ -0,0 +1,53 @@
+/*
+ * 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.common.type;
+
+import java.util.Map;
+
+public class StringEnumType
+        extends VarcharType
+        implements EnumType<String>
+{
+    private final Map<String, String> entries;
+
+    public StringEnumType(String name, Map<String, String> entries)
+    {
+        super(VarcharType.MAX_LENGTH, TypeSignature.parseTypeSignature(name));
+        this.entries = entries;
+    }
+
+    @Override
+    public Map<String, String> getEntries()
+    {
+        return entries;
+    }
+
+    @Override
+    public boolean isOrderable()
+    {
+        return false;
+    }
+
+    @Override
+    public boolean isComparable()
+    {
+        return false;
+    }
+
+    @Override
+    public Type getValueType()
+    {
+        return VarcharType.VARCHAR;
+    }
+}

presto-common/src/main/java/com/facebook/presto/common/type/VarcharType.java

@@ -23,12 +23,12 @@
 
 import static java.util.Collections.singletonList;
 
-public final class VarcharType
+public class VarcharType
         extends AbstractVariableWidthType
 {
     public static final int UNBOUNDED_LENGTH = Integer.MAX_VALUE;
     public static final int MAX_LENGTH = Integer.MAX_VALUE - 1;
-    public static final VarcharType VARCHAR = new VarcharType(UNBOUNDED_LENGTH);
+    public static final VarcharType VARCHAR = createVarcharTypeInternal(UNBOUNDED_LENGTH);
 
     public static VarcharType createUnboundedVarcharType()
     {
@@ -41,7 +41,14 @@ public static VarcharType createVarcharType(int length)
             // Use createUnboundedVarcharType for unbounded VARCHAR.
             throw new IllegalArgumentException("Invalid VARCHAR length " + length);
         }
-        return new VarcharType(length);
+        return createVarcharTypeInternal(length);
+    }
+
+    private static VarcharType createVarcharTypeInternal(int length)
+    {
+        return new VarcharType(length, new TypeSignature(
+                StandardTypes.VARCHAR,
+                singletonList(TypeSignatureParameter.of((long) length))));
     }
 
     public static TypeSignature getParametrizedVarcharSignature(String param)
@@ -51,13 +58,9 @@ public static TypeSignature getParametrizedVarcharSignature(String param)
 
     private final int length;
 
-    private VarcharType(int length)
+    protected VarcharType(int length, TypeSignature typeSignature)
     {
-        super(
-                new TypeSignature(
-                        StandardTypes.VARCHAR,
-                        singletonList(TypeSignatureParameter.of((long) length))),
-                Slice.class);
+        super(typeSignature, Slice.class);
 
         if (length < 0) {
             throw new IllegalArgumentException("Invalid VARCHAR length " + length);