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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.dx.rop.annotation;
     18 
     19 import com.android.dx.util.FixedSizeList;
     20 
     21 /**
     22  * List of {@link Annotations} instances.
     23  */
     24 public final class AnnotationsList
     25         extends FixedSizeList {
     26     /** {@code non-null;} immutable empty instance */
     27     public static final AnnotationsList EMPTY = new AnnotationsList(0);
     28 
     29     /**
     30      * Constructs an immutable instance which is the combination of
     31      * the two given instances. The two instances must each have the
     32      * same number of elements, and each pair of elements must contain
     33      * disjoint sets of types.
     34      *
     35      * @param list1 {@code non-null;} an instance
     36      * @param list2 {@code non-null;} the other instance
     37      * @return {@code non-null;} the combination
     38      */
     39     public static AnnotationsList combine(AnnotationsList list1,
     40             AnnotationsList list2) {
     41         int size = list1.size();
     42 
     43         if (size != list2.size()) {
     44             throw new IllegalArgumentException("list1.size() != list2.size()");
     45         }
     46 
     47         AnnotationsList result = new AnnotationsList(size);
     48 
     49         for (int i = 0; i < size; i++) {
     50             Annotations a1 = list1.get(i);
     51             Annotations a2 = list2.get(i);
     52             result.set(i, Annotations.combine(a1, a2));
     53         }
     54 
     55         result.setImmutable();
     56         return result;
     57     }
     58 
     59     /**
     60      * Constructs an instance. All indices initially contain {@code null}.
     61      *
     62      * @param size the size of the list
     63      */
     64     public AnnotationsList(int size) {
     65         super(size);
     66     }
     67 
     68     /**
     69      * Gets the element at the given index. It is an error to call
     70      * this with the index for an element which was never set; if you
     71      * do that, this will throw {@code NullPointerException}.
     72      *
     73      * @param n {@code >= 0, < size();} which index
     74      * @return {@code non-null;} element at that index
     75      */
     76     public Annotations get(int n) {
     77         return (Annotations) get0(n);
     78     }
     79 
     80     /**
     81      * Sets the element at the given index. The given element must be
     82      * immutable.
     83      *
     84      * @param n {@code >= 0, < size();} which index
     85      * @param a {@code null-ok;} the element to set at {@code n}
     86      */
     87     public void set(int n, Annotations a) {
     88         a.throwIfMutable();
     89         set0(n, a);
     90     }
     91 }
     92