Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3809#discussion_r114514562
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/AggSqlFunction.scala
---
@@ -0,0 +1,177 @@
+/*
+ * 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.functions.utils
+
+import org.apache.calcite.rel.`type`.RelDataType
+import org.apache.calcite.sql._
+import org.apache.calcite.sql.`type`._
+import org.apache.calcite.sql.`type`.SqlOperandTypeChecker.Consistency
+import org.apache.calcite.sql.parser.SqlParserPos
+import org.apache.calcite.sql.validate.SqlUserDefinedAggFunction
+import org.apache.flink.api.common.typeinfo._
+import org.apache.flink.table.api.ValidationException
+import org.apache.flink.table.calcite.FlinkTypeFactory
+import org.apache.flink.table.functions.AggregateFunction
+import
org.apache.flink.table.functions.utils.AggSqlFunction.{createOperandTypeChecker,
createOperandTypeInference, createReturnTypeInference}
+import org.apache.flink.table.functions.utils.UserDefinedFunctionUtils._
+
+/**
+ * Calcite wrapper for user-defined aggregate functions.
+ *
+ * @param name function name (used by SQL parser)
+ * @param aggregateFunction aggregate function to be called
+ * @param returnType the type information of returned value
+ * @param typeFactory type factory for converting Flink's between
Calcite's types
+ */
+class AggSqlFunction(
+ name: String,
+ aggregateFunction: AggregateFunction[_, _],
+ returnType: TypeInformation[_],
+ typeFactory: FlinkTypeFactory)
+ extends SqlUserDefinedAggFunction(
+ new SqlIdentifier(name, SqlParserPos.ZERO),
+ createReturnTypeInference(returnType, typeFactory),
+ createOperandTypeInference(aggregateFunction, typeFactory),
+ createOperandTypeChecker(aggregateFunction),
+ // Do not need to provide a calcite aggregateFunction here. Flink
aggregateion function
+ // will be generated when translating the calcite relnode to flink
runtime execution plan
+ null
+ ) {
+
+ def getFunction: AggregateFunction[_, _] = aggregateFunction
+}
+
+object AggSqlFunction {
+
+ def apply(
+ name: String,
+ aggregateFunction: AggregateFunction[_, _],
+ returnType: TypeInformation[_],
+ typeFactory: FlinkTypeFactory): AggSqlFunction = {
+
+ new AggSqlFunction(name, aggregateFunction, returnType, typeFactory)
+ }
+
+ private[flink] def createOperandTypeInference(
+ aggregateFunction: AggregateFunction[_, _],
+ typeFactory: FlinkTypeFactory)
+ : SqlOperandTypeInference = {
+ /**
+ * Operand type inference based on [[AggregateFunction]] given
information.
+ */
+ new SqlOperandTypeInference {
+ override def inferOperandTypes(
+ callBinding: SqlCallBinding,
+ returnType: RelDataType,
+ operandTypes: Array[RelDataType]): Unit = {
+
+ val operandTypeInfo = getOperandTypeInfo(callBinding)
+
+ val foundSignature =
getAccumulateMethodSignature(aggregateFunction, operandTypeInfo)
+ .getOrElse(throw new ValidationException(s"Operand types of
could not be inferred."))
+
+ val inferredTypes = getParameterTypes(aggregateFunction,
foundSignature.drop(1))
+ .map(typeFactory.createTypeFromTypeInfo)
+
+ for (i <- operandTypes.indices) {
+ if (i < inferredTypes.length - 1) {
+ operandTypes(i) = inferredTypes(i)
+ } else if (null != inferredTypes.last.getComponentType) {
+ // last argument is a collection, the array type
+ operandTypes(i) = inferredTypes.last.getComponentType
+ } else {
+ operandTypes(i) = inferredTypes.last
+ }
+ }
+ }
+ }
+ }
+
+ private[flink] def createReturnTypeInference(
+ resultType: TypeInformation[_],
+ typeFactory: FlinkTypeFactory)
+ : SqlReturnTypeInference = {
+
+ new SqlReturnTypeInference {
+ override def inferReturnType(opBinding: SqlOperatorBinding):
RelDataType = {
+ typeFactory.createTypeFromTypeInfo(resultType)
+ }
+ }
+ }
+
+ private[flink] def createOperandTypeChecker(aggregateFunction:
AggregateFunction[_, _])
+ : SqlOperandTypeChecker = {
+
+ val signatures = getMethodSignatures(aggregateFunction, "accumulate")
+
+ /**
+ * Operand type checker based on [[AggregateFunction]] given
information.
+ */
+ new SqlOperandTypeChecker {
+ override def getAllowedSignatures(op: SqlOperator, opName: String):
String = {
+ s"$opName[${signaturesToString(aggregateFunction, "accumulate")}]"
+ }
+
+ override def getOperandCountRange: SqlOperandCountRange = {
+ var min = 255
+ var max = -1
+ signatures.foreach(
+ sig => {
+ val inputSig = sig.drop(1)
+ //do not count accumulator as input
+ var len = inputSig.length
+ if (len > 0 && inputSig(inputSig.length - 1).isArray) {
+ max = 254 // according to JVM spec 4.3.3
--- End diff --
I think we should have a test case of the last argument is an Array case.
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