sdks/java/extensions/sql/zetasql/src/main/java/org/apache/beam/sdk/extensions/sql/zetasql/translation/ArrayScanToUncollectConverter.java

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 * 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
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 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.beam.sdk.extensions.sql.zetasql.translation;

import com.google.zetasql.resolvedast.ResolvedNodes.ResolvedArrayScan;
import com.google.zetasql.resolvedast.ResolvedNodes.ResolvedLiteral;
import java.util.Collections;
import java.util.List;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.RelNode;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.core.Uncollect;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.logical.LogicalProject;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.logical.LogicalValues;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexNode;
import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableList;

/** Converts array scan that represents an array literal to uncollect. */
class ArrayScanToUncollectConverter extends RelConverter<ResolvedArrayScan> {

  ArrayScanToUncollectConverter(ConversionContext context) {
    super(context);
  }

  @Override
  public boolean canConvert(ResolvedArrayScan zetaNode) {
    return zetaNode.getInputScan() == null;
  }

  @Override
  public RelNode convert(ResolvedArrayScan zetaNode, List<RelNode> inputs) {
    RexNode arrayLiteralExpression =
        getExpressionConverter().convertResolvedLiteral((ResolvedLiteral) zetaNode.getArrayExpr());

    String fieldName =
        String.format(
            "%s%s",
            zetaNode.getElementColumn().getTableName(), zetaNode.getElementColumn().getName());

    RelNode projectNode =
        LogicalProject.create(
            LogicalValues.createOneRow(getCluster()),
            Collections.singletonList(arrayLiteralExpression),
            ImmutableList.of(fieldName));

    // TODO: how to handle ordinarily.
    return Uncollect.create(projectNode.getTraitSet(), projectNode, false);
  }
}