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From mbalassi <...@git.apache.org>
Subject [GitHub] flink pull request #2094: [FLINK-3702] Make FieldAccessors support nested fi...
Date Fri, 18 Nov 2016 08:31:19 GMT
Github user mbalassi commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2094#discussion_r88616007
  
    --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/util/typeutils/FieldAccessorFactory.java
---
    @@ -0,0 +1,197 @@
    +/*
    + * 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.streaming.util.typeutils;
    +
    +import org.apache.flink.annotation.Internal;
    +import org.apache.flink.api.common.ExecutionConfig;
    +import org.apache.flink.api.common.typeinfo.BasicArrayTypeInfo;
    +import org.apache.flink.api.common.typeinfo.BasicTypeInfo;
    +import org.apache.flink.api.common.typeinfo.PrimitiveArrayTypeInfo;
    +import org.apache.flink.api.common.typeinfo.TypeInformation;
    +import org.apache.flink.api.common.typeutils.CompositeType;
    +import org.apache.flink.api.java.typeutils.PojoField;
    +import org.apache.flink.api.java.typeutils.PojoTypeInfo;
    +import org.apache.flink.api.java.typeutils.TupleTypeInfo;
    +import org.apache.flink.api.java.typeutils.TupleTypeInfoBase;
    +
    +import java.io.Serializable;
    +
    +
    +/**
    + * Static factories for the {@link FieldAccessor} utilities.
    + */
    +@Internal
    +public class FieldAccessorFactory implements Serializable {
    +
    +	/**
    +	 * Creates a {@link FieldAccessor} for the given field position, which can be used to
get and set
    +	 * the specified field on instances of this type.
    +	 *
    +	 * @param pos The field position (zero-based)
    +	 * @param config Configuration object
    +	 * @param <F> The type of the field to access
    +	 * @return The created FieldAccessor
    +	 */
    +	@Internal
    +	public static <T, F> FieldAccessor<T, F> getAccessor(TypeInformation<T>
typeInfo, int pos, ExecutionConfig config){
    +
    +		// In case of arrays
    +		if (typeInfo instanceof BasicArrayTypeInfo || typeInfo instanceof PrimitiveArrayTypeInfo)
{
    +			return new FieldAccessor.ArrayFieldAccessor<>(pos, typeInfo);
    +
    +		// In case of basic types
    +		} else if (typeInfo instanceof BasicTypeInfo) {
    +			if (pos != 0) {
    +				throw new CompositeType.InvalidFieldReferenceException("The " + ((Integer) pos).toString()
+ ". field selected on a " +
    +					"basic type (" + typeInfo.toString() + "). A field expression on a basic type can
only select " +
    +					"the 0th field (which means selecting the entire basic type).");
    +			}
    +			return (FieldAccessor<T, F>) new FieldAccessor.SimpleFieldAccessor<>(typeInfo);
    +
    +		// In case of case classes
    +		} else if (typeInfo.isTupleType() && ((TupleTypeInfoBase) typeInfo).isCaseClass())
{
    +			TupleTypeInfoBase tupleTypeInfo = (TupleTypeInfoBase) typeInfo;
    +			TypeInformation<?>[] types = new TypeInformation<?>[tupleTypeInfo.getArity()];
    +			for (int i = 0; i < types.length; i++) {
    +				types[i] = tupleTypeInfo.getTypeAt(i);
    +			}
    +			return new FieldAccessor.ProductFieldAccessor<>(
    +				pos, typeInfo, new FieldAccessor.SimpleFieldAccessor<>((TypeInformation<F>)types[pos]),
config);
    +
    +		// In case of tuples
    +		} else if (typeInfo.isTupleType()) {
    +			return new FieldAccessor.SimpleTupleFieldAccessor<>(pos, typeInfo);
    +
    +		// Default case, PojoType is directed to this statement
    +		} else {
    +			throw new CompositeType.InvalidFieldReferenceException("Cannot reference field by
position on " + typeInfo.toString()
    +				+ "Referencing a field by position is supported on tuples, case classes, and arrays.
"
    +				+ "Additionally, you can select the 0th field of a primitive/basic type (e.g. int).");
    +		}
    +	}
    +
    +	/**
    +	 * Creates a {@link FieldAccessor} for the field that is given by a field expression,
    +	 * which can be used to get and set the specified field on instances of this type.
    +	 *
    +	 * @param field The field expression
    +	 * @param config Configuration object
    +	 * @param <F> The type of the field to access
    +	 * @return The created FieldAccessor
    +	 */
    +	@Internal
    +	public static <T, F> FieldAccessor<T, F> getAccessor(TypeInformation<T>
typeInfo, String field, ExecutionConfig config) {
    +
    +		// In case of arrays
    +		if (typeInfo instanceof BasicArrayTypeInfo || typeInfo instanceof PrimitiveArrayTypeInfo)
{
    +			try {
    +				return new FieldAccessor.ArrayFieldAccessor<>(Integer.parseInt(field), typeInfo);
    +			} catch (NumberFormatException ex) {
    +				throw new CompositeType.InvalidFieldReferenceException
    +					("A field expression on an array must be an integer index (that might be given as
a string).");
    +			}
    +
    +		// In case of basic types
    +		} else if (typeInfo instanceof BasicTypeInfo) {
    +			try {
    +				int pos = field.equals("*") ? 0 : Integer.parseInt(field);
    --- End diff --
    
    Thanks.


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