| /* |
| * Copyright (c) 2016, 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 2016 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.dynalink; |
| |
| import java.util.Arrays; |
| import java.util.Objects; |
| |
| /** |
| * Describes an operation that operates on at least one {@link Namespace} of |
| * an object. E.g. a property getter would be described as |
| * <pre> |
| * Operation propertyGetter = new NamespaceOperation( |
| * StandardOperation.GET, |
| * StandardNamespace.PROPERTY); |
| * </pre> |
| * They are often combined with {@link NamedOperation}, e.g. to express a |
| * property getter for a property named "color", you would construct: |
| * <pre> |
| * Operation colorPropertyGetter = new NamedOperation( |
| * new NamespaceOperation( |
| * StandardOperation.GET, |
| * StandardNamespace.PROPERTY), |
| * "color"); |
| * </pre> |
| * <p>While {@code NamespaceOperation} can be constructed directly, it is often convenient |
| * to use the {@link Operation#withNamespace(Namespace)} and {@link Operation#withNamespaces(Namespace...)} factory |
| * methods instead, e.g.: |
| * <pre> |
| * Operation getElementOrPropertyEmpty = |
| * StandardOperation.GET |
| * .withNamespace(StandardNamespace.PROPERTY) |
| * .named("color"); |
| * </pre> |
| * <h3>Operations on multiple namespaces</h3> |
| * If multiple namespaces are specified, the namespaces are treated as |
| * alternatives to each other in order of preference. The semantics of |
| * such operation is "first applicable". |
| * That is, a composite of {@code GET:PROPERTY|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> |
| * Operations with multiple namespaces are helpful in implementation of languages that |
| * don't distinguish between one or more of the 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 {@code GET:PROPERTY|ELEMENT:empty} operation |
| * against a Java map will always match |
| * the {@link java.util.Map#isEmpty()} property, but |
| * {@code GET:ELEMENT|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 |
| * operations on multiple namespaces. |
| * <p> |
| * Even if the language itself doesn't distinguish between some of the |
| * namespaces, it can be helpful to map different syntaxes to different namespace orderings. |
| * E.g. the source expression {@code obj.color} could map to |
| * {@code GET:PROPERTY|ELEMENT|METHOD:color}, but a different source |
| * expression that looks like collection element access {@code obj[key]} could |
| * be expressed instead as {@code GET:ELEMENT|PROPERTY|METHOD} in order to favor the |
| * element semantics. Finally, if the retrieved value is subsequently called, then it makes sense |
| * to bring {@code METHOD} to the front of the namespace list: the getter part of the |
| * source expression {@code obj.color()} could be |
| * {@code GET:METHOD|PROPERTY|ELEMENT:color} and the one for |
| * {@code obj[key]()} could be {@code GET:METHOD|ELEMENT|PROPERTY}. |
| * <p> |
| * The base operation of a namespace operation can not itself be a namespace or named |
| * operation, but rather one of simple operations such are elements of |
| * {@link StandardOperation}. A namespace operation itself can serve as the base |
| * operation of a named operation, though; a typical way to construct e.g. the |
| * {@code GET:ELEMENT|PROPERTY:empty} from above would be: |
| * <pre> |
| * Operation getElementOrPropertyEmpty = StandardOperation.GET |
| * .withNamespaces( |
| * StandardNamespace.ELEMENT, |
| * StandardNamespace.PROPERTY) |
| * .named("empty"); |
| * </pre> |
| */ |
| public final class NamespaceOperation implements Operation { |
| private final Operation baseOperation; |
| private final Namespace[] namespaces; |
| |
| /** |
| * Constructs a new namespace operation. |
| * @param baseOperation the base operation that operates on one or more namespaces. |
| * @param namespaces one or more namespaces this operation operates on. |
| * @throws IllegalArgumentException if less than one namespace is |
| * specified, or the base operation is itself a {@link NamespaceOperation} or a |
| * {@link NamedOperation}. |
| * @throws NullPointerException if either the {@code namespaces} array or any of its |
| * elements are {@code null}, or if {@code baseOperation} is {@code null}. |
| */ |
| public NamespaceOperation(final Operation baseOperation, final Namespace... namespaces) { |
| this.baseOperation = Objects.requireNonNull(baseOperation, "baseOperation is null"); |
| if (baseOperation instanceof NamedOperation) { |
| throw new IllegalArgumentException("baseOperation is a NamedOperation"); |
| } else if (baseOperation instanceof NamespaceOperation) { |
| throw new IllegalArgumentException("baseOperation is a NamespaceOperation"); |
| } |
| |
| this.namespaces = Objects.requireNonNull(namespaces, "namespaces array is null").clone(); |
| if (namespaces.length < 1) { |
| throw new IllegalArgumentException("Must specify at least one namespace"); |
| } |
| for(int i = 0; i < namespaces.length; ++i) { |
| final int fi = i; |
| Objects.requireNonNull(namespaces[i], () -> "operations[" + fi + "] is null"); |
| } |
| } |
| |
| /** |
| * Returns the base operation of this named operation. |
| * @return the base operation of this named operation. |
| */ |
| public Operation getBaseOperation() { |
| return baseOperation; |
| } |
| |
| /** |
| * Returns the namespaces in this namespace operation. The returned |
| * array is a copy and changes to it don't have effect on this |
| * object. |
| * @return the namespaces in this namespace operation. |
| */ |
| public Namespace[] getNamespaces() { |
| return namespaces.clone(); |
| } |
| |
| /** |
| * Returns the number of namespaces in this namespace operation. |
| * @return the number of namespaces in this namespace operation. |
| */ |
| public int getNamespaceCount() { |
| return namespaces.length; |
| } |
| |
| /** |
| * Returns the i-th namespace in this namespace operation. |
| * @param i the namespace index |
| * @return the i-th namespace in this namespace operation. |
| * @throws IndexOutOfBoundsException if the index is out of range. |
| */ |
| public Namespace getNamespace(final int i) { |
| try { |
| return namespaces[i]; |
| } catch (final ArrayIndexOutOfBoundsException e) { |
| throw new IndexOutOfBoundsException(Integer.toString(i)); |
| } |
| } |
| |
| /** |
| * Returns true if this namespace operation contains a namespace equal to |
| * the specified namespace. |
| * @param namespace the namespace being searched for. Must not be null. |
| * @return true if the if this namespace operation contains a namespace |
| * equal to the specified namespace. |
| */ |
| public boolean contains(final Namespace namespace) { |
| Objects.requireNonNull(namespace); |
| for(final Namespace component: namespaces) { |
| if (component.equals(namespace)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /** |
| * Returns true if the other object is also a namespace operation and their |
| * base operation and namespaces 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 instanceof NamespaceOperation) { |
| final NamespaceOperation other = (NamespaceOperation)obj; |
| return baseOperation.equals(other.baseOperation) && Arrays.equals(namespaces, other.namespaces); |
| } |
| return false; |
| } |
| |
| /** |
| * Returns the hash code of this namespace operation. Defined to be equal |
| * to {@code baseOperation.hashCode() + 31 * Arrays.hashCode(namespaces)}. |
| */ |
| @Override |
| public int hashCode() { |
| return baseOperation.hashCode() + 31 * Arrays.hashCode(namespaces); |
| }; |
| |
| /** |
| * Returns the string representation of this namespace operation. Defined to |
| * be the {@code toString} of its base operation, followed by a colon character, |
| * followed with the list of its namespaces separated with the vertical line |
| * character (e.g. {@code "GET:PROPERTY|ELEMENT"}). |
| * @return the string representation of this namespace operation. |
| */ |
| @Override |
| public String toString() { |
| final StringBuilder b = new StringBuilder(); |
| b.append(baseOperation).append(':'); |
| b.append(namespaces[0]); |
| for(int i = 1; i < namespaces.length; ++i) { |
| b.append('|').append(namespaces[i]); |
| } |
| return b.toString(); |
| } |
| |
| /** |
| * If the passed operation is a namespace operation, returns its |
| * {@link #getBaseOperation()}, otherwise returns the operation as is. |
| * @param op the operation |
| * @return the base operation of the passed operation. |
| */ |
| public static Operation getBaseOperation(final Operation op) { |
| return op instanceof NamespaceOperation ? ((NamespaceOperation )op).getBaseOperation() : op; |
| } |
| |
| /** |
| * If the passed operation is a namespace operation, returns its |
| * {@link #getNamespaces()}, otherwise returns an empty array. |
| * @param op the operation |
| * @return the namespaces of the passed operation. |
| */ |
| public static Namespace[] getNamespaces(final Operation op) { |
| return op instanceof NamespaceOperation ? ((NamespaceOperation)op).getNamespaces() : new Namespace[0]; |
| } |
| |
| /** |
| * Returns true if the specified operation is a {@link NamespaceOperation} |
| * and its base operation is equal to the specified operation, and it |
| * contains the specified namespace. If it is not a {@link NamespaceOperation}, |
| * then it returns false. |
| * @param op the operation. Must not be null. |
| * @param baseOperation the base operation being searched for. Must not be null. |
| * @param namespace the namespace being searched for. Must not be null. |
| * @return true if the if the passed operation is a {@link NamespaceOperation}, |
| * its base operation equals the searched base operation, and contains a namespace |
| * equal to the searched namespace. |
| */ |
| public static boolean contains(final Operation op, final Operation baseOperation, final Namespace namespace) { |
| if (op instanceof NamespaceOperation) { |
| final NamespaceOperation no = (NamespaceOperation)op; |
| return no.baseOperation.equals(baseOperation) && no.contains(namespace); |
| } |
| return false; |
| } |
| } |