[GitHub] [flink-table-store] JingsongLi commented on a diff in pull request #441: [FLINK-30423] Introduce generated codes for CastExecutor

[GitBox <gi...@apache.org>]

JingsongLi commented on code in PR #441:
URL: https://github.com/apache/flink-table-store/pull/441#discussion_r1054328340


##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/casting/CastExecutor.java:
##########
@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.table.store.file.casting;
+
+import org.apache.flink.table.api.TableException;
+
+import javax.annotation.Nullable;
+
+/**
+ * Interface to model a function that performs the casting of a value from one type to another.
+ * Copied from flink.
+ *
+ * @param <IN> Input internal type
+ * @param <OUT> Output internal type
+ */
+public interface CastExecutor<IN, OUT> {
+    /**
+     * Cast the input value. The output is null only and only if the input is null. The method
+     * throws an exception if something goes wrong when casting.
+     *
+     * @param value Input value.
+     */
+    @Nullable
+    OUT cast(@Nullable IN value) throws TableException;

Review Comment:
   I think all types of cast are null to null. So here this method can be `cast(IN value)`?



##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/casting/AbstractToStringCastExecutor.java:
##########
@@ -0,0 +1,73 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.table.store.file.casting;
+
+import org.apache.flink.table.api.TableException;
+import org.apache.flink.table.data.StringData;
+import org.apache.flink.table.data.binary.BinaryStringData;
+import org.apache.flink.table.data.binary.BinaryStringDataUtil;
+
+import javax.annotation.Nullable;
+
+/**
+ * Cast input to string base implementation.
+ *
+ * @param <IN> the input value type.
+ */
+public abstract class AbstractToStringCastExecutor<IN> implements CastExecutor<IN, StringData> {
+    protected final boolean targetCharType;
+    protected final int targetLength;
+
+    AbstractToStringCastExecutor(boolean targetCharType, int targetLength) {
+        this.targetCharType = targetCharType;
+        this.targetLength = targetLength;
+    }
+
+    @Nullable
+    @Override
+    public StringData cast(@Nullable IN value) throws TableException {
+        boolean inputIsNull = value == null;

Review Comment:
   if (is null) return null;
   You may have misunderstood the codegen in Flink.
   Please add tests too.



##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/casting/AbstractToStringCastExecutor.java:
##########
@@ -0,0 +1,73 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.table.store.file.casting;
+
+import org.apache.flink.table.api.TableException;
+import org.apache.flink.table.data.StringData;
+import org.apache.flink.table.data.binary.BinaryStringData;
+import org.apache.flink.table.data.binary.BinaryStringDataUtil;
+
+import javax.annotation.Nullable;
+
+/**
+ * Cast input to string base implementation.
+ *
+ * @param <IN> the input value type.
+ */
+public abstract class AbstractToStringCastExecutor<IN> implements CastExecutor<IN, StringData> {

Review Comment:
   We don't need to have so many small classes, we can do some aggregation.
   Maybe we can just have a `CastExecutors` class, it contains all executors.



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