1 /*

     2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package org.graalvm.options;

    26 

    27 import java.util.Arrays;

    28 import java.util.Collections;

    29 import java.util.Iterator;

    30 import java.util.LinkedHashMap;

    31 import java.util.List;

    32 import java.util.Map;

    33 import java.util.NoSuchElementException;

    34 

    35 /**

    36  * An interface to a set of {@link OptionDescriptor}s.

    37  *

    38  * @since 1.0

    39  */

    40 public interface OptionDescriptors extends Iterable<OptionDescriptor> {

    41 

    42     /**

    43      * An empty set of option descriptors.

    44      *

    45      * @since 1.0

    46      */

    47     OptionDescriptors EMPTY = new OptionDescriptors() {

    48 

    49         public Iterator<OptionDescriptor> iterator() {

    50             return Collections.<OptionDescriptor> emptyList().iterator();

    51         }

    52 

    53         public OptionDescriptor get(String key) {

    54             return null;

    55         }

    56     };

    57 

    58     /**

    59      * Gets the {@link OptionDescriptor} matching a given option name or {@code null} if this option

    60      * descriptor set does not contain a matching option name.

    61      *

    62      * @since 1.0

    63      */

    64     OptionDescriptor get(String optionName);

    65 

    66     /**

    67      * Creates a union options descriptor out of multiple given descriptors. The operation

    68      * descriptors are not checked for duplicate keys. The option descriptors are iterated in

    69      * declaration order.

    70      *

    71      * @since 1.0

    72      */

    73     static OptionDescriptors createUnion(OptionDescriptors... descriptors) {

    74         if (descriptors.length == 0) {

    75             return EMPTY;

    76         } else if (descriptors.length == 1) {

    77             return descriptors[0];

    78         } else {

    79             return new UnionOptionDescriptors(descriptors);

    80         }

    81     }

    82 

    83     /**

    84      * {@inheritDoc}

    85      *

    86      * @since 1.0

    87      */

    88     @Override

    89     Iterator<OptionDescriptor> iterator();

    90 

    91     /**

    92      * Creates an {@link OptionDescriptors} instance from a list. The option descriptors

    93      * implementation is backed by a {@link LinkedHashMap} that preserves ordering.

    94      *

    95      * @since 1.0

    96      */

    97     static OptionDescriptors create(List<OptionDescriptor> descriptors) {

    98         if (descriptors == null || descriptors.isEmpty()) {

    99             return EMPTY;

   100         }

   101         return new OptionDescriptorsMap(descriptors);

   102     }

   103 }

   104 

   105 class OptionDescriptorsMap implements OptionDescriptors {

   106 

   107     final Map<String, OptionDescriptor> descriptors = new LinkedHashMap<>();

   108 

   109     OptionDescriptorsMap(List<OptionDescriptor> descriptorList) {

   110         for (OptionDescriptor descriptor : descriptorList) {

   111             descriptors.put(descriptor.getName(), descriptor);

   112         }

   113     }

   114 

   115     @Override

   116     public OptionDescriptor get(String optionName) {

   117         return descriptors.get(optionName);

   118     }

   119 

   120     @Override

   121     public Iterator<OptionDescriptor> iterator() {

   122         return descriptors.values().iterator();

   123     }

   124 

   125 }

   126 

   127 final class UnionOptionDescriptors implements OptionDescriptors {

   128 

   129     final OptionDescriptors[] descriptorsList;

   130 

   131     UnionOptionDescriptors(OptionDescriptors[] descriptors) {

   132         // defensive copy

   133         this.descriptorsList = Arrays.copyOf(descriptors, descriptors.length);

   134     }

   135 

   136     public Iterator<OptionDescriptor> iterator() {

   137         return new Iterator<OptionDescriptor>() {

   138 

   139             Iterator<OptionDescriptor> descriptors = descriptorsList[0].iterator();

   140             int descriptorsIndex = 0;

   141             OptionDescriptor next = null;

   142 

   143             public boolean hasNext() {

   144                 return fetchNext() != null;

   145             }

   146 

   147             private OptionDescriptor fetchNext() {

   148                 if (next != null) {

   149                     return next;

   150                 }

   151                 if (descriptors.hasNext()) {

   152                     next = descriptors.next();

   153                     return next;

   154                 } else if (descriptorsIndex < descriptorsList.length - 1) {

   155                     descriptorsIndex++;

   156                     descriptors = descriptorsList[descriptorsIndex].iterator();

   157                     return fetchNext();

   158                 } else {

   159                     return null;

   160                 }

   161             }

   162 

   163             public OptionDescriptor next() {

   164                 OptionDescriptor fetchedNext = fetchNext();

   165                 if (fetchedNext != null) {

   166                     // consume next

   167                     this.next = null;

   168                     return fetchedNext;

   169                 } else {

   170                     throw new NoSuchElementException();

   171                 }

   172             }

   173         };

   174     }

   175 

   176     public OptionDescriptor get(String value) {

   177         for (OptionDescriptors descriptors : descriptorsList) {

   178             OptionDescriptor descriptor = descriptors.get(value);

   179             if (descriptor != null) {

   180                 return descriptor;

   181             }

   182         }

   183         return null;

   184     }

   185 

   186 }