raminqaf commented on code in PR #29369: URL: https://github.com/apache/flink/pull/29369#discussion_r4184318671
########## flink-table/flink-table-runtime/src/main/java/org/apache/flink/table/runtime/functions/ToVariantConverter.java: ########## @@ -0,0 +1,260 @@ +/* + * 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.runtime.functions; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.api.TableRuntimeException; +import org.apache.flink.table.data.ArrayData; +import org.apache.flink.table.data.DecimalData; +import org.apache.flink.table.data.MapData; +import org.apache.flink.table.data.RowData; +import org.apache.flink.table.data.TimestampData; +import org.apache.flink.table.types.logical.ArrayType; +import org.apache.flink.table.types.logical.DistinctType; +import org.apache.flink.table.types.logical.LogicalType; +import org.apache.flink.table.types.logical.LogicalTypeRoot; +import org.apache.flink.table.types.logical.MapType; +import org.apache.flink.table.types.logical.utils.LogicalTypeChecks; +import org.apache.flink.table.types.logical.utils.UuidUtils; +import org.apache.flink.types.variant.BinaryVariant; +import org.apache.flink.types.variant.BinaryVariantInternalBuilder; +import org.apache.flink.types.variant.BinaryVariantInternalBuilder.FieldEntry; +import org.apache.flink.types.variant.Variant; +import org.apache.flink.types.variant.VariantTypeException; + +import java.io.Serializable; +import java.util.ArrayList; +import java.util.List; + +/** + * Converts internal data of a SQL type into a {@link Variant}, like {@code CAST(x AS VARIANT)}. + * + * <p>An {@code ARRAY} becomes a variant array. A {@code ROW} or {@code STRUCTURED} value becomes a + * variant object keyed by its field names, and a {@code MAP} one keyed by its character string + * keys. A {@code NULL} element, field or map value becomes a variant null. A leaf is stored like + * the cast stores it on its own, see {@link VariantCastUtils}, and a nested {@code VARIANT} is + * embedded as is. + * + * <p>The converter is created once per type and writes a whole value into one builder, so a nested + * value is encoded in a single pass. It keeps no state between calls. + */ +@Internal +public final class ToVariantConverter implements Serializable { + + private static final long serialVersionUID = 1L; + + private final String sourceType; + private final ValueWriter writer; + + private ToVariantConverter(String sourceType, ValueWriter writer) { + this.sourceType = sourceType; + this.writer = writer; + } + + /** Creates a converter for a type that {@code LogicalTypeCasts} allows to cast to VARIANT. */ + public static ToVariantConverter create(LogicalType type) { + return new ToVariantConverter(type.asSummaryString(), createWriter(type)); + } + + /** + * Converts a value that is not {@code NULL}. + * + * @throws TableRuntimeException if the value has a {@code NULL} map key, a timestamp outside + * the range of its variant kind, or does not fit into the 16 MiB of a {@code VARIANT} + */ + public Variant convert(Object value) { + // A MAP can hold the same key twice at runtime. The builder keeps the last one, like the + // MAP constructor does. + final BinaryVariantInternalBuilder builder = new BinaryVariantInternalBuilder(true); + try { + writer.write(builder, value); + return builder.build(); + } catch (VariantTypeException e) { + if (e != BinaryVariantInternalBuilder.VARIANT_SIZE_LIMIT_EXCEPTION) { + throw e; + } + throw new TableRuntimeException( + String.format( + "Cannot cast a value of type %s to VARIANT. A VARIANT is limited to " + + "16 MiB.", + sourceType)); + } + } + + @FunctionalInterface + private interface ValueWriter extends Serializable { + void write(BinaryVariantInternalBuilder builder, Object value); + } + + private static ValueWriter createNullableWriter(LogicalType type) { + final ValueWriter writer = createWriter(type); + return (builder, value) -> { + if (value == null) { + builder.appendNull(); + } else { + writer.write(builder, value); + } + }; + } + + private static ValueWriter createWriter(LogicalType type) { Review Comment: Done, with your second option. `ToVariantCastRule` replaces `PrimitiveToVariantCastRule`, and the primitive cast now calls `ToVariantConverter` too. `createWriter` is now the only mapping from a SQL type to a variant kind, and the `VariantCastUtils.from*` methods are gone. The string and decimal fast paths from #29370 will move into the converter's writers. -- This is an automated message from the Apache Git Service. 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