Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/2919#discussion_r91123689
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/expressions/array.scala
---
@@ -0,0 +1,140 @@
+/*
+ * 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.api.table.expressions
+
+import org.apache.calcite.rex.RexNode
+import org.apache.calcite.sql.fun.SqlStdOperatorTable
+import org.apache.calcite.tools.RelBuilder
+import org.apache.flink.api.common.typeinfo.BasicTypeInfo.INT_TYPE_INFO
+import org.apache.flink.api.common.typeinfo.{BasicTypeInfo,
PrimitiveArrayTypeInfo, TypeInformation}
+import org.apache.flink.api.java.typeutils.ObjectArrayTypeInfo
+import org.apache.flink.api.table.FlinkRelBuilder
+import org.apache.flink.api.table.validate.{ValidationFailure,
ValidationResult, ValidationSuccess}
+
+import scala.collection.JavaConverters._
+
+case class ArrayConstructor(elements: Seq[Expression]) extends Expression {
+
+ override private[flink] def children: Seq[Expression] = elements
+
+ override private[flink] def toRexNode(implicit relBuilder: RelBuilder):
RexNode = {
+ val relDataType = relBuilder
+ .asInstanceOf[FlinkRelBuilder]
+ .getTypeFactory
+ .createTypeFromTypeInfo(resultType)
+ val values = elements.map(_.toRexNode).toList.asJava
+ relBuilder
+ .getRexBuilder
+ .makeCall(relDataType, SqlStdOperatorTable.ARRAY_VALUE_CONSTRUCTOR,
values)
+ }
+
+ override def toString = s"array(${elements.mkString(", ")})"
+
+ override private[flink] def resultType =
ObjectArrayTypeInfo.getInfoFor(elements.head.resultType)
+
+ override private[flink] def validateInput(): ValidationResult = {
+ if (elements.isEmpty) {
+ return ValidationFailure("Empty arrays are not supported yet.")
+ }
+ val elementType = elements.head.resultType
+ if (!elements.forall(_.resultType == elementType)) {
+ ValidationFailure("Not all elements of the array have the same
type.")
+ } else {
+ ValidationSuccess
+ }
+ }
+}
+
+case class ArrayElementAt(array: Expression, index: Expression) extends
Expression {
+
+ override private[flink] def children: Seq[Expression] = Seq(array, index)
+
+ override private[flink] def toRexNode(implicit relBuilder: RelBuilder):
RexNode = {
+ relBuilder
+ .getRexBuilder
+ .makeCall(SqlStdOperatorTable.ITEM, array.toRexNode, index.toRexNode)
+ }
+
+ override def toString = s"($array).at($index)"
+
+ override private[flink] def resultType = array.resultType match {
+ case oati: ObjectArrayTypeInfo[_, _] => oati.getComponentInfo
+ case pati: PrimitiveArrayTypeInfo[_] => pati.getComponentType
+ }
+
+ override private[flink] def validateInput(): ValidationResult = {
--- End diff --
Does it make sense to check that the index is `> 0` if it is a literal?
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