rdblue commented on code in PR #17343: URL: https://github.com/apache/iceberg/pull/17343#discussion_r4169822615
########## api/src/main/java/org/apache/iceberg/expressions/UnboundApply.java: ########## @@ -0,0 +1,95 @@ +/* + * 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.iceberg.expressions; + +import java.util.List; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; +import org.apache.iceberg.relocated.com.google.common.collect.Lists; +import org.apache.iceberg.types.Types; + +/** + * Represents a function application expression. This is the general form for invoking functions on + * value expressions. + * + * @param <T> the Java type of values produced by this expression + */ +public class UnboundApply<T> implements UnboundTerm<T> { + private final FunctionReference function; + private final List<Object> arguments; + + UnboundApply(FunctionReference function, List<Object> arguments) { + Preconditions.checkArgument(function != null, "Invalid function: null"); + this.function = function; + // not an immutable list so that Kryo can deserialize this class + this.arguments = + arguments == null + ? Lists.newArrayList() + : Lists.newArrayList(Lists.transform(arguments, UnboundApply::toArgument)); + } + + /** + * Converts an argument to the type used to represent it, or throws if it cannot be an argument. + * + * <p>An argument is either a value expression or a predicate. Value expressions are {@link Term} + * (a reference or a nested apply) or a constant, which is converted to a {@link Literal}. + * Predicates are {@link Expression}. + */ + private static Object toArgument(Object argument) { + Preconditions.checkArgument(argument != null, "Invalid function argument: null"); + if (argument instanceof Term || argument instanceof Expression) { + return argument; + } + + return Literals.from(argument); + } + + public FunctionReference function() { + return function; + } + + /** + * Returns the arguments passed to the function. + * + * <p>Each argument is a {@link Term} (a value expression), an {@link Expression} (a predicate), + * or a {@link Literal} (a constant value expression). Java has no union type, so the arguments + * are typed as {@link Object} and validated when this expression is created. + */ + public List<Object> arguments() { + return arguments; + } + + @Override + public NamedReference<T> ref() { + // a function may be called with any number of references, so there is no single reference that + // this term produces values from + throw new UnsupportedOperationException("Cannot determine reference for function: " + function); + } + + @Override + public BoundTerm<T> bind(Types.StructType struct, boolean caseSensitive) { + // binding requires a function definition to determine the result type, and function definitions + // are not available in this API + throw new UnsupportedOperationException("Cannot bind function: " + function); Review Comment: This should recursively call `bind` on each argument and return a `BoundApply` from those bound arguments. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
