twalthr commented on code in PR #28758: URL: https://github.com/apache/flink/pull/28758#discussion_r3636605204
########## flink-table/flink-table-runtime/src/main/java/org/apache/flink/table/runtime/functions/VariantCastUtils.java: ########## @@ -0,0 +1,137 @@ +/* + * 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.DecimalData; +import org.apache.flink.types.variant.Variant; + +import java.math.BigDecimal; +import java.math.BigInteger; + +/** + * Runtime helpers for casting a {@code VARIANT} value to a SQL type. + * + * <p>Numeric targets are range-checked and raise {@link TableRuntimeException} on overflow instead + * of wrapping. Casting to a character string extracts the scalar value (a string stays unquoted); a + * variant holding an object, array, or binary value is not castable and raises {@link + * TableRuntimeException} (use {@code JSON_STRING} for its JSON representation). + */ +@Internal +public final class VariantCastUtils { + + private VariantCastUtils() {} + + public static byte toByteExact(Number value) { + return (byte) toIntegralExact(value, Byte.MIN_VALUE, Byte.MAX_VALUE, "TINYINT"); + } + + public static short toShortExact(Number value) { + return (short) toIntegralExact(value, Short.MIN_VALUE, Short.MAX_VALUE, "SMALLINT"); + } + + public static int toIntExact(Number value) { + return (int) toIntegralExact(value, Integer.MIN_VALUE, Integer.MAX_VALUE, "INTEGER"); + } + + public static long toLongExact(Number value) { + return toIntegralExact(value, Long.MIN_VALUE, Long.MAX_VALUE, "BIGINT"); + } + + public static DecimalData toDecimalExact(Number value, int precision, int scale) { + final DecimalData decimal = + DecimalData.fromBigDecimal(toBigDecimal(value), precision, scale); + if (decimal == null) { + throw new TableRuntimeException( + String.format( + "Casting the VARIANT value %s to DECIMAL(%d, %d) overflowed.", + value, precision, scale)); + } + return decimal; + } + + /** + * Casts a {@code VARIANT} to its SQL string value for a {@code CHAR(targetLength)} or {@code + * VARCHAR(targetLength)} target. Scalars use their raw value (a string stays unquoted, unlike + * {@code JSON_STRING}); a variant holding an object, array, or binary value is not castable and + * raises {@link TableRuntimeException}. + * + * <p>The target length is enforced strictly, with no padding or truncation: a {@code VARCHAR} + * value must not be longer than {@code targetLength}, and a {@code CHAR} value must match it + * exactly. A value that does not fit raises {@link TableRuntimeException}. + */ + public static String toStringValue(Variant variant, int targetLength, boolean charTarget) { + switch (variant.getType()) { + case OBJECT: + case ARRAY: + case BYTES: + throw new TableRuntimeException( + String.format( + "Cannot cast a VARIANT %s value to a character string. Use the " + + "JSON_STRING function to obtain its JSON representation.", + variant.getType())); + default: + // Scalars are cast to their raw string value. + } + final String value = String.valueOf(variant.get()); + final int length = value.length(); + final boolean fits = charTarget ? length == targetLength : length <= targetLength; + if (!fits) { + throw new TableRuntimeException( + String.format( + "The VARIANT string value of length %d does not fit %s(%d); VARIANT " + + "string casts do not pad or truncate.", + length, charTarget ? "CHAR" : "VARCHAR", targetLength)); + } + return value; + } + + private static long toIntegralExact(Number value, long min, long max, String targetType) { + // toBigInteger truncates any fractional part toward zero, matching regular numeric casts. + final BigInteger integral = toBigDecimal(value).toBigInteger(); + if (integral.compareTo(BigInteger.valueOf(min)) < 0 + || integral.compareTo(BigInteger.valueOf(max)) > 0) { + throw new TableRuntimeException( + String.format( + "Casting the VARIANT value %s to %s overflowed.", value, targetType)); + } + return integral.longValue(); + } + + private static BigDecimal toBigDecimal(Number value) { + return value instanceof BigDecimal ? (BigDecimal) value : convertToBigDecimal(value); + } + + private static BigDecimal convertToBigDecimal(Number number) { + if (number == null) { Review Comment: Why this null check here? -- This is an automated message from the Apache Git Service. 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