generate enum cast functions on-the-fly in BuiltinFunctionNamespaceMa…

…nager
prestodb · Jun 22, 2020 · 8ee5838 · 8ee5838
1 parent 0df59a1
commit 8ee5838
Showing 1 changed file with 11 additions and 0 deletions.
diff --git a/presto-main/src/main/java/com/facebook/presto/metadata/BuiltInFunctionNamespaceManager.java b/presto-main/src/main/java/com/facebook/presto/metadata/BuiltInFunctionNamespaceManager.java
@@ -19,6 +19,7 @@
 import com.facebook.presto.common.block.BlockSerdeUtil;
 import com.facebook.presto.common.function.OperatorType;
 import com.facebook.presto.common.function.QualifiedFunctionName;
+import com.facebook.presto.common.type.EnumType;
 import com.facebook.presto.common.type.Type;
 import com.facebook.presto.common.type.TypeManager;
 import com.facebook.presto.common.type.TypeSignature;
@@ -191,6 +192,7 @@
 import com.facebook.presto.type.DateTimeOperators;
 import com.facebook.presto.type.DecimalOperators;
 import com.facebook.presto.type.DoubleOperators;
+import com.facebook.presto.type.EnumOperators;
 import com.facebook.presto.type.HyperLogLogOperators;
 import com.facebook.presto.type.IntegerOperators;
 import com.facebook.presto.type.IntervalDayTimeOperators;
@@ -223,6 +225,7 @@
 import com.google.common.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.collect.Iterables;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Multimaps;
 import com.google.common.util.concurrent.UncheckedExecutionException;
@@ -901,6 +904,14 @@ private SpecializedFunctionKey doGetSpecializedFunctionKey(Signature signature)
         Iterable<SqlFunction> candidates = getFunctions(null, signature.getName());
         // search for exact match
         Type returnType = typeManager.getType(signature.getReturnType());
+
+        if (returnType instanceof EnumType && CastType.CAST.getCastName().equals(signature.getName())) {
+            // Specific enum types are not known in advance at server startup time, but all enum types
+            // support the same CAST functions. So here, we build these cast functions on-the-fly
+            // for the particular enum type encountered in the signature.
+            candidates = Iterables.concat(candidates, EnumOperators.makeEnumCastFunctions((EnumType) returnType));
+        }
+
         List<TypeSignatureProvider> argumentTypeSignatureProviders = fromTypeSignatures(signature.getArgumentTypes());
         for (SqlFunction candidate : candidates) {
             Optional<BoundVariables> boundVariables = new SignatureBinder(typeManager, candidate.getSignature(), false)