| /* |
| * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * This file is available under and governed by the GNU General Public |
| * License version 2 only, as published by the Free Software Foundation. |
| * However, the following notice accompanied the original version of this |
| * file, and Oracle licenses the original version of this file under the BSD |
| * license: |
| */ |
| /* |
| Copyright 2015 Attila Szegedi |
| |
| Licensed under both the Apache License, Version 2.0 (the "Apache License") |
| and the BSD License (the "BSD License"), with licensee being free to |
| choose either of the two at their discretion. |
| |
| You may not use this file except in compliance with either the Apache |
| License or the BSD License. |
| |
| If you choose to use this file in compliance with the Apache License, the |
| following notice applies to you: |
| |
| You may obtain a copy of the Apache 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. |
| |
| If you choose to use this file in compliance with the BSD License, the |
| following notice applies to you: |
| |
| Redistribution and use in source and binary forms, with or without |
| modification, are permitted provided that the following conditions are |
| met: |
| * Redistributions of source code must retain the above copyright |
| notice, this list of conditions and the following disclaimer. |
| * Redistributions in binary form must reproduce the above copyright |
| notice, this list of conditions and the following disclaimer in the |
| documentation and/or other materials provided with the distribution. |
| * Neither the name of the copyright holder nor the names of |
| contributors may be used to endorse or promote products derived from |
| this software without specific prior written permission. |
| |
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
| IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A |
| PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER |
| BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
| OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package jdk.internal.dynalink; |
| |
| import java.util.Arrays; |
| import java.util.Objects; |
| |
| /** |
| * Describes an operation that is composed of at least two other operations. The |
| * component operations are treated as alternatives to each other in order of |
| * preference. The semantics of the composite operation is "first successful". |
| * That is, a composite of {@code GET_PROPERTY|GET_ELEMENT:color} should be |
| * interpreted as <i>get the property named "color" on the object, but if the |
| * property does not exist, then get the collection element named "color" |
| * instead</i>. |
| * <p> |
| * Composite operations are helpful in implementation of languages that |
| * don't distinguish between one or more of the property, method, and element |
| * namespaces, or when expressing operations against objects that can be |
| * considered both ordinary objects and collections, e.g. Java |
| * {@link java.util.Map} objects. A composite operation |
| * {@code GET_PROPERTY|GET_ELEMENT:empty} against a Java map will always match |
| * the {@link java.util.Map#isEmpty()} property, but |
| * {@code GET_ELEMENT|GET_PROPERTY:empty} will actually match a map element with |
| * key {@code "empty"} if the map contains that key, and only fall back to the |
| * {@code isEmpty()} property getter if the map does not contain the key. If |
| * the source language mandates this semantics, it can be easily achieved using |
| * composite operations. |
| * <p> |
| * Even if the language itself doesn't distinguish between some of the |
| * namespaces, it can be helpful to map different syntaxes to different |
| * compositions. E.g. the source expression {@code obj.color} could map to |
| * {@code GET_PROPERTY|GET_ELEMENT|GET_METHOD:color}, but a different source |
| * expression that looks like collection element access {@code obj[key]} could |
| * be expressed instead as {@code GET_ELEMENT|GET_PROPERTY|GET_METHOD}. |
| * Finally, if the retrieved value is subsequently called, then it makes sense |
| * to bring {@code GET_METHOD} to the front of the list: the getter part of the |
| * source expression {@code obj.color()} should be |
| * {@code GET_METHOD|GET_PROPERTY|GET_ELEMENT:color} and the one for |
| * {@code obj[key]()} should be {@code GET_METHOD|GET_ELEMENT|GET_PROPERTY}. |
| * <p> |
| * The elements of a composite operation can not be composites or named |
| * operations, but rather simple operations such are elements of |
| * {@link StandardOperation}. A composite operation itself can serve as the base |
| * operation of a named operation, though; a typical way to construct e.g. the |
| * {@code GET_ELEMENT|GET_PROPERTY:empty} from above would be: |
| * <pre> |
| * Operation getElementOrPropertyEmpty = new NamedOperation( |
| * new CompositeOperation( |
| * StandardOperation.GET_ELEMENT, |
| * StandardOperation.GET_PROPERTY), |
| * "empty"); |
| * </pre> |
| * <p> |
| * Not all compositions make sense. Typically, any combination in any order of |
| * standard getter operations {@code GET_PROPERTY}, {@code GET_ELEMENT}, and |
| * {@code GET_METHOD} make sense, as do combinations of {@code SET_PROPERTY} and |
| * {@code SET_ELEMENT}; other standard operations should not be combined. The |
| * constructor will allow any combination of operations, though. |
| */ |
| public class CompositeOperation implements Operation { |
| private final Operation[] operations; |
| |
| /** |
| * Constructs a new composite operation. |
| * @param operations the components for this composite operation. The passed |
| * array will be cloned. |
| * @throws IllegalArgumentException if less than two components are |
| * specified, or any component is itself a {@link CompositeOperation} or a |
| * {@link NamedOperation}. |
| * @throws NullPointerException if either the operations array or any of its |
| * elements are {@code null}. |
| */ |
| public CompositeOperation(final Operation... operations) { |
| Objects.requireNonNull(operations, "operations array is null"); |
| if (operations.length < 2) { |
| throw new IllegalArgumentException("Must have at least two operations"); |
| } |
| final Operation[] clonedOps = operations.clone(); |
| for(int i = 0; i < clonedOps.length; ++i) { |
| final Operation op = clonedOps[i]; |
| if (op == null) { |
| throw new NullPointerException("operations[" + i + "] is null"); |
| } else if (op instanceof NamedOperation) { |
| throw new IllegalArgumentException("operations[" + i + "] is a NamedOperation"); |
| } else if (op instanceof CompositeOperation) { |
| throw new IllegalArgumentException("operations[" + i + "] is a CompositeOperation"); |
| } |
| } |
| this.operations = clonedOps; |
| } |
| |
| /** |
| * Returns the component operations in this composite operation. The |
| * returned array is a copy and changes to it don't have effect on this |
| * object. |
| * @return the component operations in this composite operation. |
| */ |
| public Operation[] getOperations() { |
| return operations.clone(); |
| } |
| |
| /** |
| * Returns the number of component operations in this composite operation. |
| * @return the number of component operations in this composite operation. |
| */ |
| public int getOperationCount() { |
| return operations.length; |
| } |
| |
| /** |
| * Returns the i-th component operation in this composite operation. |
| * @param i the operation index |
| * @return the i-th component operation in this composite operation. |
| * @throws IndexOutOfBoundsException if the index is out of range. |
| */ |
| public Operation getOperation(final int i) { |
| try { |
| return operations[i]; |
| } catch (final ArrayIndexOutOfBoundsException e) { |
| throw new IndexOutOfBoundsException(Integer.toString(i)); |
| } |
| } |
| |
| /** |
| * Returns true if this composite operation contains an operation equal to |
| * the specified operation. |
| * @param operation the operation being searched for. Must not be null. |
| * @return true if the if this composite operation contains an operation |
| * equal to the specified operation. |
| */ |
| public boolean contains(final Operation operation) { |
| Objects.requireNonNull(operation); |
| for(final Operation component: operations) { |
| if (component.equals(operation)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /** |
| * Returns true if the other object is also a composite operation and their |
| * component operations are equal. |
| * @param obj the object to compare to |
| * @return true if this object is equal to the other one, false otherwise. |
| */ |
| @Override |
| public boolean equals(final Object obj) { |
| if (obj == null || obj.getClass() != CompositeOperation.class) { |
| return false; |
| } |
| return Arrays.equals(operations, ((CompositeOperation)obj).operations); |
| } |
| |
| /** |
| * Returns the hash code of this composite operation. Defined to be equal |
| * to {@code java.util.Arrays.hashCode(operations)}. |
| */ |
| @Override |
| public int hashCode() { |
| return Arrays.hashCode(operations); |
| }; |
| |
| /** |
| * Returns the string representation of this composite operation. Defined to |
| * be the {@code toString} of its component operations, each separated by |
| * the vertical line character (e.g. {@code "GET_PROPERTY|GET_ELEMENT"}). |
| * @return the string representation of this composite operation. |
| */ |
| @Override |
| public String toString() { |
| final StringBuilder b = new StringBuilder(); |
| b.append(operations[0]); |
| for(int i = 1; i < operations.length; ++i) { |
| b.append('|').append(operations[i]); |
| } |
| return b.toString(); |
| } |
| |
| /** |
| * Returns the components of the passed operation if it is a composite |
| * operation, otherwise returns an array containing the operation itself. |
| * This allows for returning an array of component even if it is not known |
| * whether the operation is itself a composite (treating a non-composite |
| * operation as if it were a single-element composite of itself). |
| * @param op the operation whose components are retrieved. |
| * @return if the passed operation is a composite operation, returns its |
| * {@link #getOperations()}, otherwise returns the operation itself. |
| */ |
| public static Operation[] getOperations(final Operation op) { |
| return op instanceof CompositeOperation |
| ? ((CompositeOperation)op).operations.clone() |
| : new Operation[] { op }; |
| } |
| |
| /** |
| * Returns true if the specified potentially composite operation is a |
| * {@link CompositeOperation} and contains an operation equal to the |
| * specified operation. If {@code composite} is not a |
| * {@link CompositeOperation}, then the two operations are compared for |
| * equality. |
| * @param composite the potentially composite operation. Must not be null. |
| * @param operation the operation being searched for. Must not be null. |
| * @return true if the if the passed operation is a |
| * {@link CompositeOperation} and contains a component operation equal to |
| * the specified operation, or if it is not a {@link CompositeOperation} and |
| * is equal to {@code operation}. |
| */ |
| public static boolean contains(final Operation composite, final Operation operation) { |
| if (composite instanceof CompositeOperation) { |
| return ((CompositeOperation)composite).contains(operation); |
| } |
| return composite.equals(Objects.requireNonNull(operation)); |
| } |
| } |
