rdblue commented on code in PR #12139: URL: https://github.com/apache/iceberg/pull/12139#discussion_r1960602946
########## parquet/src/main/java/org/apache/iceberg/parquet/ParquetVariantVisitor.java: ########## @@ -0,0 +1,285 @@ +/* + * 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.iceberg.parquet; + +import java.util.List; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; +import org.apache.iceberg.relocated.com.google.common.collect.Lists; +import org.apache.parquet.schema.GroupType; +import org.apache.parquet.schema.LogicalTypeAnnotation.ListLogicalTypeAnnotation; +import org.apache.parquet.schema.PrimitiveType; +import org.apache.parquet.schema.PrimitiveType.PrimitiveTypeName; +import org.apache.parquet.schema.Type; + +public abstract class ParquetVariantVisitor<R> { + static final String METADATA = "metadata"; + static final String VALUE = "value"; + static final String TYPED_VALUE = "typed_value"; + + /** + * Handles the root variant column group. + * + * <p>The value and typed_value results are combined by calling {@link #value}. + * + * <pre> + * group v (VARIANT) { <-- metadata result and combined value and typed_value result + * required binary metadata; + * optional binary value; + * optional ... typed_value; + * } + * </pre> + */ + public R variant(GroupType variant, R metadataResult, R valueResult) { + return null; + } + + /** + * Handles a serialized variant metadata column. + * + * <pre> + * group v (VARIANT) { + * required binary metadata; <-- this column + * optional binary value; + * optional ... typed_value; + * } + * </pre> + */ + public R metadata(PrimitiveType metadata) { + return null; + } + + /** + * Handles a serialized variant value column. + * + * <pre> + * group variant_value_pair { + * optional binary value; <-- this column + * optional ... typed_value; + * } + * </pre> + */ + public R serialized(PrimitiveType value) { + return null; + } + + /** + * Handles a shredded primitive typed_value column. + * + * <pre> + * group variant_value_pair { + * optional binary value; + * optional int32 typed_value; <-- this column when it is any primitive + * } + * </pre> + */ + public R primitive(PrimitiveType primitive) { + return null; + } + + /** + * Handles a variant value result and typed_value result pair. + * + * <p>The value and typed_value pair may be nested in an object field, array element, or in the + * root group of a variant. + * + * <p>This method is also called when the typed_value field is missing. + * + * <pre> + * group variant_value_pair { <-- value result and typed_value result + * optional binary value; + * optional ... typed_value; + * } + * </pre> + */ + public R value(GroupType value, R valueResult, R typedResult) { + return null; + } + + /** + * Handles a shredded object value result and a list of field value results. + * + * <p>Each field's value and typed_value results are combined by calling {@link #value}. + * + * <pre> + * group variant_value_pair { <-- value result and typed_value field results + * optional binary value; + * optional group typed_value { + * required group a { + * optional binary value; + * optional binary typed_value (UTF8); + * } + * ... + * } + * } + * </pre> + */ + public R object(GroupType object, R valueResult, List<R> fieldResults) { + return null; + } + + /** + * Handles a shredded array value result and an element value result. + * + * <p>The element's value and typed_value results are combined by calling {@link #value}. + * + * <pre> + * group variant_value_pair { <-- value result and element result + * optional binary value; + * optional group typed_value (LIST) { + * repeated group list { + * required group element { + * optional binary value; + * optional binary typed_value (UTF8); + * } + * } + * } + * } + * </pre> + */ + public R array(GroupType array, R valueResult, R elementResult) { + return null; + } + + /** Handler called before visiting any primitive or group type. */ + public void beforeField(Type type) {} + + /** Handler called after visiting any primitive or group type. */ + public void afterField(Type type) {} + + public static <R> R visit(GroupType type, ParquetVariantVisitor<R> visitor) { + Preconditions.checkArgument( + ParquetSchemaUtil.hasField(type, METADATA), "Invalid variant, missing metadata: %s", type); + + Type metadataType = type.getType(METADATA); + Preconditions.checkArgument( + isBinary(metadataType), "Invalid variant metadata, expecting BINARY: %s", metadataType); + + R metadataResult = + withBeforeAndAfter( + () -> visitor.metadata(metadataType.asPrimitiveType()), metadataType, visitor); + R valueResult = visitValue(type, visitor); + + return visitor.variant(type, metadataResult, valueResult); + } + + public static <R> R visitValue(GroupType valueGroup, ParquetVariantVisitor<R> visitor) { Review Comment: Fixed. -- This is an automated message from the Apache Git Service. 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