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      1 /*
      2  * Copyright (C) 2008 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.calculator2;
     18 
     19 import android.widget.BaseAdapter;
     20 
     21 import java.io.DataInput;
     22 import java.io.DataOutput;
     23 import java.io.IOException;
     24 import java.util.Vector;
     25 
     26 class History {
     27     private static final int VERSION_1 = 1;
     28     private static final int MAX_ENTRIES = 100;
     29     Vector<HistoryEntry> mEntries = new Vector<HistoryEntry>();
     30     int mPos;
     31     BaseAdapter mObserver;
     32 
     33     History() {
     34         clear();
     35     }
     36 
     37     History(int version, DataInput in) throws IOException {
     38         if (version >= VERSION_1) {
     39             int size = in.readInt();
     40             for (int i = 0; i < size; ++i) {
     41                 mEntries.add(new HistoryEntry(version, in));
     42             }
     43             mPos = in.readInt();
     44         } else {
     45             throw new IOException("invalid version " + version);
     46         }
     47     }
     48 
     49     void setObserver(BaseAdapter observer) {
     50         mObserver = observer;
     51     }
     52 
     53     private void notifyChanged() {
     54         if (mObserver != null) {
     55             mObserver.notifyDataSetChanged();
     56         }
     57     }
     58 
     59     void clear() {
     60         mEntries.clear();
     61         mEntries.add(new HistoryEntry(""));
     62         mPos = 0;
     63         notifyChanged();
     64     }
     65 
     66     void write(DataOutput out) throws IOException {
     67         out.writeInt(mEntries.size());
     68         for (HistoryEntry entry : mEntries) {
     69             entry.write(out);
     70         }
     71         out.writeInt(mPos);
     72     }
     73 
     74     void update(String text) {
     75         current().setEdited(text);
     76     }
     77 
     78     boolean moveToPrevious() {
     79         if (mPos > 0) {
     80             --mPos;
     81             return true;
     82         }
     83         return false;
     84     }
     85 
     86     boolean moveToNext() {
     87         if (mPos < mEntries.size() - 1) {
     88             ++mPos;
     89             return true;
     90         }
     91         return false;
     92     }
     93 
     94     void enter(String text) {
     95         current().clearEdited();
     96         if (mEntries.size() >= MAX_ENTRIES) {
     97             mEntries.remove(0);
     98         }
     99         if (mEntries.size() < 2 ||
    100             !text.equals(mEntries.elementAt(mEntries.size() - 2).getBase())) {
    101             mEntries.insertElementAt(new HistoryEntry(text), mEntries.size() - 1);
    102         }
    103         mPos = mEntries.size() - 1;
    104         notifyChanged();
    105     }
    106 
    107     HistoryEntry current() {
    108         return mEntries.elementAt(mPos);
    109     }
    110 
    111     String getText() {
    112         return current().getEdited();
    113     }
    114 
    115     String getBase() {
    116         return current().getBase();
    117     }
    118 }
    119