dawidwys commented on a change in pull request #10606: [FLINK-15009][table-common] Add a utility for creating type inference logic via reflection URL: https://github.com/apache/flink/pull/10606#discussion_r363734617
########## File path: flink-table/flink-table-common/src/main/java/org/apache/flink/table/types/extraction/TypeInferenceExtractor.java ########## @@ -0,0 +1,703 @@ +/* + * 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.extraction; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.annotation.DataTypeHint; +import org.apache.flink.table.annotation.FunctionHint; +import org.apache.flink.table.api.ValidationException; +import org.apache.flink.table.catalog.DataTypeLookup; +import org.apache.flink.table.functions.AggregateFunction; +import org.apache.flink.table.functions.AsyncTableFunction; +import org.apache.flink.table.functions.ScalarFunction; +import org.apache.flink.table.functions.TableAggregateFunction; +import org.apache.flink.table.functions.TableFunction; +import org.apache.flink.table.functions.UserDefinedFunction; +import org.apache.flink.table.types.CollectionDataType; +import org.apache.flink.table.types.DataType; +import org.apache.flink.table.types.extraction.utils.ExtractionUtils; +import org.apache.flink.table.types.extraction.utils.FunctionArgumentTemplate; +import org.apache.flink.table.types.extraction.utils.FunctionResultTemplate; +import org.apache.flink.table.types.extraction.utils.FunctionSignatureTemplate; +import org.apache.flink.table.types.extraction.utils.FunctionTemplate; +import org.apache.flink.table.types.inference.InputTypeStrategies; +import org.apache.flink.table.types.inference.InputTypeStrategy; +import org.apache.flink.table.types.inference.TypeInference; +import org.apache.flink.table.types.inference.TypeStrategies; +import org.apache.flink.table.types.inference.TypeStrategy; + +import javax.annotation.Nullable; + +import java.lang.reflect.Method; +import java.util.Arrays; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Set; +import java.util.concurrent.CompletableFuture; +import java.util.function.Function; +import java.util.stream.Collectors; +import java.util.stream.IntStream; +import java.util.stream.Stream; + +import static org.apache.flink.table.types.extraction.utils.ExtractionUtils.collectAnnotationsOfClass; +import static org.apache.flink.table.types.extraction.utils.ExtractionUtils.collectAnnotationsOfMethod; +import static org.apache.flink.table.types.extraction.utils.ExtractionUtils.collectMethods; +import static org.apache.flink.table.types.extraction.utils.ExtractionUtils.extractionError; +import static org.apache.flink.table.types.extraction.utils.ExtractionUtils.isAssignable; +import static org.apache.flink.table.types.extraction.utils.ExtractionUtils.isMethodInvokable; + +/** + * Reflection-based utility for extracting a {@link TypeInference} from a supported subclass of + * {@link UserDefinedFunction}. + * + * <p>The behavior of this utility can be influenced by {@link DataTypeHint}s and {@link FunctionHint}s + * which have higher precedence than the reflective information. + * + * <p>Note: This utility assumes that functions have been validated before regarding accessibility of + * class/methods and serializability. + */ +@Internal +public final class TypeInferenceExtractor { + + private final DataTypeLookup lookup; + + private final Class<? extends UserDefinedFunction> function; + + private final String functionExplanation; + + private final String methodName; + + private TypeInferenceExtractor( + DataTypeLookup lookup, + Class<? extends UserDefinedFunction> function, + String functionExplanation, + String methodName) { + this.lookup = lookup; + this.function = function; + this.functionExplanation = functionExplanation; + this.methodName = methodName; + } + + /** + * Extracts a type inference from a {@link ScalarFunction}. + */ + public static TypeInference forScalarFunction(DataTypeLookup lookup, Class<? extends ScalarFunction> function) { + final TypeInferenceExtractor extractor = new TypeInferenceExtractor(lookup, function, "scalar", "eval"); + return extractor.extractTypeInference( + extractor.createParameterSignatureExtraction(false), + null, + extractor.createReturnTypeResultExtraction(), + extractor.createParameterAndReturnTypeVerification() + ); + } + + /** + * Extracts a type inference from a {@link AggregateFunction}. + */ + public static TypeInference forAggregateFunction(DataTypeLookup lookup, Class<? extends AggregateFunction> function) { + final TypeInferenceExtractor extractor = new TypeInferenceExtractor(lookup, function, "aggregate", "accumulate"); + return extractor.extractTypeInference( + extractor.createParameterSignatureExtraction(true), + extractor.createGenericResultExtraction(AggregateFunction.class, 1), + extractor.createGenericResultExtraction(AggregateFunction.class, 0), + extractor.createParameterWithAccumulatorVerification() + ); + } + + /** + * Extracts a type inference from a {@link TableFunction}. + */ + public static TypeInference forTableFunction(DataTypeLookup lookup, Class<? extends TableFunction> function) { + final TypeInferenceExtractor extractor = new TypeInferenceExtractor(lookup, function, "table", "eval"); + return extractor.extractTypeInference( + extractor.createParameterSignatureExtraction(false), + null, + extractor.createGenericResultExtraction(TableFunction.class, 0), + extractor.createParameterVerification() + ); + } + + /** + * Extracts a type inference from a {@link TableAggregateFunction}. + */ + public static TypeInference forTableAggregateFunction(DataTypeLookup lookup, Class<? extends TableAggregateFunction> function) { + final TypeInferenceExtractor extractor = new TypeInferenceExtractor(lookup, function, "table aggregate", "accumulate"); + return extractor.extractTypeInference( + extractor.createParameterSignatureExtraction(true), + extractor.createGenericResultExtraction(TableAggregateFunction.class, 1), + extractor.createGenericResultExtraction(TableAggregateFunction.class, 0), + extractor.createParameterWithAccumulatorVerification() + ); + } + + /** + * Extracts a type inference from a {@link AsyncTableFunction}. + */ + public static TypeInference forAsyncTableFunction(DataTypeLookup lookup, Class<? extends AsyncTableFunction> function) { + final TypeInferenceExtractor extractor = new TypeInferenceExtractor(lookup, function, "async table", "eval"); + return extractor.extractTypeInference( + extractor.createParameterSignatureExtraction(true), + null, + extractor.createGenericResultExtraction(AsyncTableFunction.class, 0), + extractor.createParameterWithArgumentVerification(CompletableFuture.class) + ); + } + + // -------------------------------------------------------------------------------------------- + // Context sensitive extraction and verification logic + // -------------------------------------------------------------------------------------------- + + /** + * Extraction that uses the method parameters for producing a {@link FunctionSignatureTemplate}. + */ + private SignatureExtraction createParameterSignatureExtraction(boolean excludeFirstArg) { + final int offset; + if (excludeFirstArg) { + offset = 1; + } else { + offset = 0; + } + return method -> { + // argument types + final List<FunctionArgumentTemplate> parameterTypes = IntStream.range(offset, method.getParameterCount()) + .mapToObj(i -> { + final DataType type = DataTypeExtractor.extractFromMethodParameter(lookup, function, method, i); + // unwrap from ARRAY data type in case of varargs + if (method.isVarArgs() && i == method.getParameterCount() - 1 && type instanceof CollectionDataType) { + return ((CollectionDataType) type).getElementDataType(); + } else { + return type; + } + }) + .map(FunctionArgumentTemplate::of) + .collect(Collectors.toList()); + + // argument names + final List<String> methodParameterNames = ExtractionUtils.extractMethodParameterNames(method); + final String[] argumentNames; + if (methodParameterNames != null) { + argumentNames = methodParameterNames.subList(offset, methodParameterNames.size()) + .toArray(new String[0]); + } else { + argumentNames = null; + } + + return FunctionSignatureTemplate.of(parameterTypes, method.isVarArgs(), argumentNames); + }; + } + + /** + * Extraction that uses a generic type variable for producing a {@link FunctionResultTemplate}. + */ + private ResultExtraction createGenericResultExtraction( + Class<? extends UserDefinedFunction> baseClass, + int genericPos) { + return (method) -> { + final DataType dataType = DataTypeExtractor.extractFromGeneric(lookup, baseClass, genericPos, function); + return FunctionResultTemplate.of(dataType); + }; + } + + /** + * Extraction that uses the method return type for producing a {@link FunctionResultTemplate}. + */ + private ResultExtraction createReturnTypeResultExtraction() { + return (method) -> { + final DataType dataType = DataTypeExtractor.extractFromMethodOutput(lookup, function, method); + return FunctionResultTemplate.of(dataType); + }; + } + + /** + * Verification that checks a method by parameters and return type. + */ + private MethodVerification createParameterAndReturnTypeVerification() { + return (method, signature, accumulator, output) -> { + final Class<?>[] parameters = signature.toArray(new Class[0]); + final Class<?> returnType = method.getReturnType(); + final boolean isValid = isMethodInvokable(method, parameters) && + isAssignable(output, returnType, true); + if (!isValid) { + throw createMethodNotFoundError(parameters, returnType); + } + }; + } + + /** + * Verification that checks a method by parameters including an accumulator. + */ + private MethodVerification createParameterWithAccumulatorVerification() { + return (method, signature, accumulator, output) -> + createParameterWithArgumentVerification(accumulator) + .verify(method, signature, accumulator, output); + } + + /** + * Verification that checks a method by parameters including an additional first parameter. + */ + private MethodVerification createParameterWithArgumentVerification(@Nullable Class<?> argumentClass) { + return (method, signature, accumulator, output) -> { + final Class<?>[] parameters = Stream.concat(Stream.of(argumentClass), signature.stream()) + .toArray(Class[]::new); + if (!isMethodInvokable(method, parameters)) { + throw createMethodNotFoundError(parameters, null); + } + }; + } + + /** + * Verification that checks a method by parameters. + */ + private MethodVerification createParameterVerification() { + return (method, signature, accumulator, output) -> { + final Class<?>[] parameters = signature.toArray(new Class[0]); + if (!isMethodInvokable(method, parameters)) { + throw createMethodNotFoundError(parameters, null); + } + }; + } + + private ValidationException createMethodNotFoundError(Class<?>[] parameters, @Nullable Class<?> returnType) { + final StringBuilder builder = new StringBuilder(); + if (returnType != null) { + builder.append(returnType.getName()).append(" "); + } + builder + .append(methodName) + .append( + Stream.of(parameters) + .map(parameter -> { + // in case we don't know the parameter at this location (i.e. for accumulators) + if (parameter == null) { + return "_"; + } else { + return parameter.getName(); + } + }) + .collect(Collectors.joining(", ", "(", ")"))); + return extractionError( + "Considering all hints, the method should comply with the signature:\n%s", + builder.toString()); + } + + private TypeInference extractTypeInference( + SignatureExtraction signatureExtraction, + @Nullable ResultExtraction accumulatorExtraction, + ResultExtraction outputExtraction, + MethodVerification verification) { + try { + return extractTypeInferenceOrError( + signatureExtraction, + accumulatorExtraction, + outputExtraction, + verification + ); + } catch (Throwable t) { + throw extractionError( + t, + "Could not extract a valid type inference from %s function class '%s'. " + + "Please check for implementation mistakes and/or provide a corresponding hint.", + functionExplanation, + function.getName()); + } + } + + private TypeInference extractTypeInferenceOrError( + SignatureExtraction signatureExtraction, + @Nullable ResultExtraction accumulatorExtraction, + ResultExtraction outputExtraction, + MethodVerification verification) { + + final Map<FunctionSignatureTemplate, FunctionResultTemplate> outputMapping; + try { + outputMapping = extractResultMappings( + signatureExtraction, + outputExtraction, + verification, + false); + } catch (Throwable t) { + throw extractionError(t, "Error in extracting a signature to output strategy."); + } + + // function is accumulating + if (accumulatorExtraction != null) { + final Map<FunctionSignatureTemplate, FunctionResultTemplate> accumulatorMapping; + try { + accumulatorMapping = extractResultMappings( + signatureExtraction, + accumulatorExtraction, + verification, + true); + } catch (Throwable t) { + throw extractionError(t, "Error in extracting a signature to accumulator strategy."); + } + return buildInference(accumulatorMapping, outputMapping); + } + return buildInference(null, outputMapping); + } + + /** + * Extracts mappings from signature to result (either accumulator or output) for the entire + * function. Verifies if the extracted inference matches with the implementation. + * + * <p>For example, from {@code (INT, BOOLEAN, ANY) -> INT}. It does this by going through all implementation + * methods and collecting all "per-method" mappings. The function mapping is the union of all "per-method" + * mappings. + */ + private Map<FunctionSignatureTemplate, FunctionResultTemplate> extractResultMappings( + SignatureExtraction signatureExtraction, + ResultExtraction resultExtraction, + MethodVerification verification, + boolean isAccumulator) { + final Function<FunctionTemplate, FunctionResultTemplate> accessor; + if (isAccumulator) { + accessor = FunctionTemplate::getAccumulatorTemplate; + } else { + accessor = FunctionTemplate::getOutputTemplate; + } + + final Set<FunctionTemplate> global = extractGlobalFunctionTemplates(); + final Set<FunctionResultTemplate> globalResultOnly = findResultOnlyTemplates(global, accessor); + + // for each method find a signature that maps to results + final Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappings = new HashMap<>(); + final List<Method> methods = collectMethods(function, methodName); + if (methods.size() == 0) { + throw extractionError( + "Could not find a publicly accessible method named '%s'.", + methodName); + } + for (Method method : methods) { + try { + final Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappingsPerMethod = + collectMethodMappings(method, global, globalResultOnly, signatureExtraction, resultExtraction, accessor); + + // check if the method can be called + verifyMappingForMethod(method, collectedMappingsPerMethod, verification, isAccumulator); + + // check if method strategies conflict with function strategies + collectedMappingsPerMethod.forEach((signature, result) -> putMapping(collectedMappings, signature, result)); + } catch (Throwable t) { + throw extractionError( + t, + "Unable to extract a type inference from method:\n%s", + method.toString()); + } + } + return collectedMappings; + } + + /** + * Extracts mappings from signature to result (either accumulator or output) for the given method. It + * considers both global hints for the entire function and local hints just for this method. + * + * <p>The algorithm aims to find an input signature for every declared result. If no result is + * declared, it will be extracted. If no input signature is declared, it will be extracted. + */ + private Map<FunctionSignatureTemplate, FunctionResultTemplate> collectMethodMappings( + Method method, + Set<FunctionTemplate> global, + Set<FunctionResultTemplate> globalResultOnly, + SignatureExtraction signatureExtraction, + ResultExtraction resultExtraction, + Function<FunctionTemplate, FunctionResultTemplate> accessor) { + final Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappingsPerMethod = new HashMap<>(); + final Set<FunctionTemplate> local = extractLocalFunctionTemplates(method); + + final Set<FunctionResultTemplate> localResultOnly = findResultOnlyTemplates( + local, + accessor); + + final Set<FunctionTemplate> explicitMappings = findResultMappingTemplates( + global, + local, + accessor); + + final FunctionResultTemplate resultOnly = findResultOnlyTemplate( + globalResultOnly, + localResultOnly, + explicitMappings, + accessor); + + final Set<FunctionSignatureTemplate> inputOnly = findInputOnlyTemplates(global, local, accessor); + + // add all explicit mappings because they contain complete signatures + putExplicitMappings(collectedMappingsPerMethod, explicitMappings, inputOnly, accessor); + // add result only template with explicit or extracted signatures + putUniqueResultMapping(collectedMappingsPerMethod, resultOnly, inputOnly, signatureExtraction, method); + // handle missing result by extraction with explicit or extracted signatures + putExtractedResult(collectedMappingsPerMethod, inputOnly, signatureExtraction, resultExtraction, method); + + return collectedMappingsPerMethod; + } + + // -------------------------------------------------------------------------------------------- + // Helper methods (ordered by invocation order) + // -------------------------------------------------------------------------------------------- + + private Set<FunctionTemplate> extractGlobalFunctionTemplates() { + return asFunctionTemplates(lookup, collectAnnotationsOfClass(FunctionHint.class, function)); + } + + private Set<FunctionTemplate> extractLocalFunctionTemplates(Method method) { + return asFunctionTemplates(lookup, collectAnnotationsOfMethod(FunctionHint.class, method)); + } + + private static Set<FunctionTemplate> asFunctionTemplates(DataTypeLookup lookup, Set<FunctionHint> hints) { + return hints.stream() + .map(hint -> { + try { + return FunctionTemplate.fromAnnotation(lookup, hint); + } catch (Throwable t) { + throw extractionError(t, "Error in function hint annotation."); + } + }) + .collect(Collectors.toSet()); + } + + /** + * Find a template that only specifies a result. + */ + private Set<FunctionResultTemplate> findResultOnlyTemplates( + Set<FunctionTemplate> functionTemplates, + Function<FunctionTemplate, FunctionResultTemplate> accessor) { + return functionTemplates.stream() + .filter(t -> t.getSignatureTemplate() == null && accessor.apply(t) != null) + .map(accessor) + .collect(Collectors.toSet()); + } + + /** + * Hints that only declare a result (either accumulator or output). + */ + private static @Nullable FunctionResultTemplate findResultOnlyTemplate( + Set<FunctionResultTemplate> globalResultOnly, + Set<FunctionResultTemplate> localResultOnly, + Set<FunctionTemplate> explicitMappings, + Function<FunctionTemplate, FunctionResultTemplate> accessor) { + final Set<FunctionResultTemplate> resultOnly = Stream.concat( + globalResultOnly.stream(), + localResultOnly.stream()) + .collect(Collectors.toSet()); + final Set<FunctionResultTemplate> allResults = Stream.concat( + resultOnly.stream(), + explicitMappings.stream().map(accessor)) + .collect(Collectors.toSet()); + if (resultOnly.size() == 1 && allResults.size() == 1) { + return resultOnly.stream().findFirst().orElse(null); + } + // different results is only fine as long as those come from a mapping + if (resultOnly.size() > 1 || (!resultOnly.isEmpty() && !explicitMappings.isEmpty())) { + throw extractionError("Function hints that lead to ambiguous results are not allowed."); + } + return null; + } + + /** + * Hints that map a signature to a result. + */ + private Set<FunctionTemplate> findResultMappingTemplates( + Set<FunctionTemplate> globalTemplates, + Set<FunctionTemplate> localTemplates, + Function<FunctionTemplate, FunctionResultTemplate> accessor) { + return Stream.concat(globalTemplates.stream(), localTemplates.stream()) + .filter(t -> t.getSignatureTemplate() != null && accessor.apply(t) != null) + .collect(Collectors.toSet()); + } + + /** + * Hints that only declare an input. + */ + private static Set<FunctionSignatureTemplate> findInputOnlyTemplates( + Set<FunctionTemplate> global, + Set<FunctionTemplate> local, + Function<FunctionTemplate, FunctionResultTemplate> accessor) { + return Stream.concat(global.stream(), local.stream()) + .filter(t -> + t.getSignatureTemplate() != null && + accessor.apply(t) == null) + .map(FunctionTemplate::getSignatureTemplate) + .collect(Collectors.toSet()); + } + + /** + * Explicit mappings with complete signature to result declaration. + */ + private static void putExplicitMappings( + Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappings, + Set<FunctionTemplate> explicitMappings, + Set<FunctionSignatureTemplate> signatureOnly, + Function<FunctionTemplate, FunctionResultTemplate> accessor) { + explicitMappings.forEach(t -> { + // signature templates are valid everywhere and are added to the explicit mapping + Stream.concat(signatureOnly.stream(), Stream.of(t.getSignatureTemplate())) + .forEach(v -> putMapping(collectedMappings, v, accessor.apply(t))); + }); + } + + /** + * Result only template with explicit or extracted signatures. + */ + private static void putUniqueResultMapping( + Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappings, + @Nullable FunctionResultTemplate uniqueResult, + Set<FunctionSignatureTemplate> signatureOnly, + SignatureExtraction signatureExtraction, + Method method) { + if (uniqueResult == null) { + return; + } + // input only templates are valid everywhere if they don't exist fallback to extraction + if (!signatureOnly.isEmpty()) { + signatureOnly.forEach(s -> putMapping(collectedMappings, s, uniqueResult)); + } else { + putMapping(collectedMappings, signatureExtraction.extract(method), uniqueResult); + } + } + + /** + * Missing result by extraction with explicit or extracted signatures. + */ + private static void putExtractedResult( + Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappings, + Set<FunctionSignatureTemplate> inputOnly, + SignatureExtraction signatureExtraction, + ResultExtraction resultExtraction, + Method method) { + if (!collectedMappings.isEmpty()) { + return; + } + final FunctionResultTemplate result = resultExtraction.extract(method); + // input only validators are valid everywhere if they don't exist fallback to extraction + if (!inputOnly.isEmpty()) { + inputOnly.forEach(signature -> putMapping(collectedMappings, signature, result)); + } else { + final FunctionSignatureTemplate signature = signatureExtraction.extract(method); + putMapping(collectedMappings, signature, result); + } + } + + private static void putMapping( + Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappings, + FunctionSignatureTemplate signature, + FunctionResultTemplate result) { + final FunctionResultTemplate existingResult = collectedMappings.get(signature); + if (existingResult == null) { + collectedMappings.put(signature, result); + } + // template must not conflict with same input + else if (!existingResult.equals(result)) { + throw extractionError( + "Function hints with same input definition but different result types are not allowed."); + } + } + + /** + * Checks if the given method can be called and returns what hints declare. + */ + private void verifyMappingForMethod( + Method method, + Map<FunctionSignatureTemplate, FunctionResultTemplate> collectedMappingsPerMethod, + MethodVerification verification, + boolean isAccumulator) { + collectedMappingsPerMethod.forEach((signature, result) -> { + if (isAccumulator) { + verification.verify(method, signature.toClass(), result.toClass(), null); + } else { + verification.verify(method, signature.toClass(), null, result.toClass()); + } + }); + } + + private static TypeInference buildInference( + @Nullable Map<FunctionSignatureTemplate, FunctionResultTemplate> accumulatorMapping, + Map<FunctionSignatureTemplate, FunctionResultTemplate> outputMapping) { + final TypeInference.Builder builder = TypeInference.newBuilder(); + + configureNamedAndTypedArguments(builder, outputMapping); + + builder.inputTypeStrategy(translateInputTypeStrategy(outputMapping)); + + if (accumulatorMapping != null) { + // verify that accumulator and output are derived from the same input strategy + if (!accumulatorMapping.keySet().equals(outputMapping.keySet())) { + throw extractionError( + "Mismatch between accumulator signature and output signature. " + + "Both intermediate and output results must be derived from the same input strategy."); + } + builder.accumulatorTypeStrategy(translateResultTypeStrategy(accumulatorMapping)); + } + + builder.outputTypeStrategy(translateResultTypeStrategy(outputMapping)); + return builder.build(); + } + + private static void configureNamedAndTypedArguments( + TypeInference.Builder builder, + Map<FunctionSignatureTemplate, FunctionResultTemplate> outputMapping) { + if (outputMapping.size() != 1) { + return; + } + final FunctionSignatureTemplate signature = outputMapping.keySet().iterator().next(); + final List<DataType> dataTypes = signature.argumentTemplates.stream() + .map(a -> a.dataType) + .collect(Collectors.toList()); + if (!signature.isVarArgs && dataTypes.stream().allMatch(Objects::nonNull)) { + builder.typedArguments(dataTypes); + if (signature.argumentNames != null) { + builder.namedArguments(Arrays.asList(signature.argumentNames)); + } + } + } + + private static TypeStrategy translateResultTypeStrategy(Map<FunctionSignatureTemplate, FunctionResultTemplate> resultMapping) { + final Map<InputTypeStrategy, TypeStrategy> mappings = resultMapping.entrySet() + .stream() + .collect( + Collectors.toMap( + e -> e.getKey().toInputTypeStrategy(), + e -> e.getValue().toTypeStrategy())); + return TypeStrategies.mapping(mappings); + } + + private static InputTypeStrategy translateInputTypeStrategy(Map<FunctionSignatureTemplate, FunctionResultTemplate> outputMapping) { + return outputMapping.keySet().stream() + .map(FunctionSignatureTemplate::toInputTypeStrategy) + .reduce(InputTypeStrategies::or) + .orElse(InputTypeStrategies.sequence()); + } Review comment: Could we extract that to a separate class? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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