dawidwys commented on a change in pull request #8865: [FLINK-12924][table] Introduce basic type inference interfaces URL: https://github.com/apache/flink/pull/8865#discussion_r297045313
########## File path: flink-table/flink-table-common/src/main/java/org/apache/flink/table/types/inference/TypeInferenceUtil.java ########## @@ -0,0 +1,307 @@ +/* + * 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.types.inference; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.api.TableException; +import org.apache.flink.table.api.ValidationException; +import org.apache.flink.table.functions.FunctionDefinition; +import org.apache.flink.table.functions.FunctionKind; +import org.apache.flink.table.types.DataType; + +import java.util.List; +import java.util.Optional; +import java.util.stream.Collectors; +import java.util.stream.IntStream; + +/** + * Utility for performing type inference. + */ +@Internal +public class TypeInferenceUtil { + + public static Result runTypeInference(TypeInference typeInference, CallContext callContext) { + try { + return runTypeInferenceInternal(typeInference, callContext); + } catch (ValidationException e) { + throw new ValidationException( + String.format( + "Invalid call to function '%s'. Given arguments: %s", + callContext.getName(), + callContext.getArgumentDataTypes().stream() + .map(DataType::toString) + .collect(Collectors.joining())), + e); + } catch (Throwable t) { + throw new TableException( + String.format( + "Unexpected error in type inference logic of function '%s'. This is a bug.", + callContext.getName()), + t); + } + } + + /** + * The result of a type inference run. It contains information about how arguments need to be + * adapted in order to comply with the function's signature. + * + * <p>This includes casts that need to be inserted, reordering of arguments (*), or insertion of default + * values (*) where (*) is future work. + */ + public static class Result { + + private final List<DataType> expectedArgumentTypes; + + private final DataType accumulatorDataType; + + private final DataType outputDataType; + + public Result( + List<DataType> expectedArgumentTypes, + DataType accumulatorDataType, + DataType outputDataType) { + this.expectedArgumentTypes = expectedArgumentTypes; + this.accumulatorDataType = accumulatorDataType; + this.outputDataType = outputDataType; + } + + public List<DataType> getExpectedArgumentTypes() { + return expectedArgumentTypes; + } + + public DataType getAccumulatorDataType() { + return accumulatorDataType; + } + + public DataType getOutputDataType() { + return outputDataType; + } + } + + // -------------------------------------------------------------------------------------------- + + private static Result runTypeInferenceInternal(TypeInference typeInference, CallContext callContext) { + final List<DataType> argumentTypes = callContext.getArgumentDataTypes(); + + try { + validateArgumentCount( + typeInference.getInputTypeValidator().getArgumentCount(), + callContext.getArgumentDataTypes().size()); + } catch (ValidationException e) { + throw getInvalidInputException(typeInference.getInputTypeValidator(), callContext); + } + + final List<DataType> expectedTypes = typeInference.getArgumentTypes() + .orElse(callContext.getArgumentDataTypes()); + + final List<String> expectedNames = typeInference.getArgumentNames() + .orElse(getDefaultArgumentNames(expectedTypes.size())); + + final AdaptedCallContext adaptedCallContext = adaptArguments( + callContext, + expectedNames, + expectedTypes); + + try { + validateInputTypes( + typeInference.getInputTypeValidator(), + adaptedCallContext); + } catch (ValidationException e) { + throw getInvalidInputException(typeInference.getInputTypeValidator(), adaptedCallContext); + } + + return inferTypes( + adaptedCallContext, + typeInference.getAccumulatorTypeStrategy(), + typeInference.getOutputTypeStrategy()); + } + + private static List<String> getDefaultArgumentNames(int argumentCount) { + return IntStream.range(0, argumentCount) + .mapToObj(i -> "arg" + i) + .collect(Collectors.toList()); + } + + private static ValidationException getInvalidInputException( + InputTypeValidator validator, + CallContext callContext) { + return new ValidationException( + String.format( + "Invalid input arguments. Expected signatures are:\n%s", + String.join( + "\n", + validator.getExpectedSignatures( + callContext.getName(), + callContext.getFunctionDefinition())))); + } + + private static void validateArgumentCount(ArgumentCount argumentCount, int actualCount) { + argumentCount.getMinCount().ifPresent((min) -> { + if (actualCount < min) { + throw new ValidationException( + String.format( + "Invalid number of arguments. At least %d arguments expected but %d passed.", + min, + actualCount)); + } + }); + + argumentCount.getMaxCount().ifPresent((max) -> { + if (actualCount > max) { + throw new ValidationException( + String.format( + "Invalid number of arguments. At most %d arguments expected but %d passed.", + max, + actualCount)); + } + }); + + if (argumentCount.isValidCount(actualCount)) { + throw new ValidationException( + String.format( + "Invalid number of arguments. %d arguments passed.", + actualCount)); + } + } + + private static void validateInputTypes(InputTypeValidator inputTypeValidator, CallContext callContext) { + if (!inputTypeValidator.validate(callContext, true)) { + throw new ValidationException("Invalid input arguments."); + } + } + + /** + * Adapts the call's argument if necessary. + * + * <p>This includes casts that need to be inserted, reordering of arguments (*), or insertion of default + * values (*) where (*) is future work. + */ + private static AdaptedCallContext adaptArguments( + CallContext callContext, + List<String> expectedNames, + List<DataType> expectedTypes) { + + for (int pos = 0; pos < callContext.getArgumentDataTypes().size(); pos++) { + final DataType expectedType = expectedTypes.get(pos); + final DataType actualType = callContext.getArgumentDataTypes().get(pos); + + if (!actualType.equals(expectedType) && !canCast(actualType, expectedType)) { + throw new ValidationException( + String.format( + "Invalid argument type at position %d. Data type %s expected but %s passed.", + pos, + expectedType, + actualType)); + } + } + + return new AdaptedCallContext(callContext, expectedTypes); + } + + private static boolean canCast(DataType sourceDataType, DataType targetDataType) { + return false; // TODO unsupported for now + } + + private static Result inferTypes( + AdaptedCallContext adaptedCallContext, + TypeStrategy accumulatorTypeStrategy, + TypeStrategy outputTypeStrategy) { + + // infer output type first for better error message + // (logically an accumulator type should be inferred first) + final Optional<DataType> potentialOutputType = outputTypeStrategy.inferType(adaptedCallContext); + if (!potentialOutputType.isPresent()) { + throw new ValidationException("Could not infer an output type for the given arguments."); + } + final DataType outputType = potentialOutputType.get(); + + if (adaptedCallContext.getFunctionDefinition().getKind() == FunctionKind.TABLE_AGGREGATE || + adaptedCallContext.getFunctionDefinition().getKind() == FunctionKind.AGGREGATE) { + final Optional<DataType> potentialAccumulatorType = accumulatorTypeStrategy.inferType(adaptedCallContext); + if (!potentialAccumulatorType.isPresent()) { + throw new ValidationException("Could not infer an accumulator type for the given arguments."); + } + return new Result(adaptedCallContext.expectedArguments, potentialAccumulatorType.get(), outputType); + } else { + return new Result(adaptedCallContext.expectedArguments, outputType, outputType); Review comment: isn't it a bit misleading that we pass output type as accumulator type even though we do not expect accumulator at all? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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