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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 android.sax;
     18 
     19 /**
     20  * Contains element children. Using this class instead of HashMap results in
     21  * measurably better performance.
     22  */
     23 class Children {
     24 
     25     Child[] children = new Child[16];
     26 
     27     /**
     28      * Looks up a child by name and creates a new one if necessary.
     29      */
     30     Element getOrCreate(Element parent, String uri, String localName) {
     31         int hash = uri.hashCode() * 31 + localName.hashCode();
     32         int index = hash & 15;
     33 
     34         Child current = children[index];
     35         if (current == null) {
     36             // We have no children in this bucket yet.
     37             current = new Child(parent, uri, localName, parent.depth + 1, hash);
     38             children[index] = current;
     39             return current;
     40         } else {
     41             // Search this bucket.
     42             Child previous;
     43             do {
     44                 if (current.hash == hash
     45                         && current.uri.compareTo(uri) == 0
     46                         && current.localName.compareTo(localName) == 0) {
     47                     // We already have a child with that name.
     48                     return current;
     49                 }
     50 
     51                 previous = current;
     52                 current = current.next;
     53             } while (current != null);
     54 
     55             // Add a new child to the bucket.
     56             current = new Child(parent, uri, localName, parent.depth + 1, hash);
     57             previous.next = current;
     58             return current;
     59         }
     60     }
     61 
     62     /**
     63      * Looks up a child by name.
     64      */
     65     Element get(String uri, String localName) {
     66         int hash = uri.hashCode() * 31 + localName.hashCode();
     67         int index = hash & 15;
     68 
     69         Child current = children[index];
     70         if (current == null) {
     71             return null;
     72         } else {
     73             do {
     74                 if (current.hash == hash
     75                         && current.uri.compareTo(uri) == 0
     76                         && current.localName.compareTo(localName) == 0) {
     77                     return current;
     78                 }
     79                 current = current.next;
     80             } while (current != null);
     81 
     82             return null;
     83         }
     84     }
     85 
     86     static class Child extends Element {
     87 
     88         final int hash;
     89         Child next;
     90 
     91         Child(Element parent, String uri, String localName, int depth,
     92                 int hash) {
     93             super(parent, uri, localName, depth);
     94             this.hash = hash;
     95         }
     96     }
     97 }
     98