1/*
2 * Copyright (C) 2006 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
17package android.text;
18
19// XXX should this really be in the public API at all?
20/**
21 * An AlteredCharSequence is a CharSequence that is largely mirrored from
22 * another CharSequence, except that a specified range of characters are
23 * mirrored from a different char array instead.
24 */
25public class AlteredCharSequence
26implements CharSequence, GetChars
27{
28    /**
29     * Create an AlteredCharSequence whose text (and possibly spans)
30     * are mirrored from <code>source</code>, except that the range of
31     * offsets <code>substart</code> inclusive to <code>subend</code> exclusive
32     * are mirrored instead from <code>sub</code>, beginning at offset 0.
33     */
34    public static AlteredCharSequence make(CharSequence source, char[] sub,
35                                           int substart, int subend) {
36        if (source instanceof Spanned)
37            return new AlteredSpanned(source, sub, substart, subend);
38        else
39            return new AlteredCharSequence(source, sub, substart, subend);
40    }
41
42    private AlteredCharSequence(CharSequence source, char[] sub,
43                                int substart, int subend) {
44        mSource = source;
45        mChars = sub;
46        mStart = substart;
47        mEnd = subend;
48    }
49
50    /* package */ void update(char[] sub, int substart, int subend) {
51        mChars = sub;
52        mStart = substart;
53        mEnd = subend;
54    }
55
56    private static class AlteredSpanned
57    extends AlteredCharSequence
58    implements Spanned
59    {
60        private AlteredSpanned(CharSequence source, char[] sub,
61                               int substart, int subend) {
62            super(source, sub, substart, subend);
63            mSpanned = (Spanned) source;
64        }
65
66        public <T> T[] getSpans(int start, int end, Class<T> kind) {
67            return mSpanned.getSpans(start, end, kind);
68        }
69
70        public int getSpanStart(Object span) {
71            return mSpanned.getSpanStart(span);
72        }
73
74        public int getSpanEnd(Object span) {
75            return mSpanned.getSpanEnd(span);
76        }
77
78        public int getSpanFlags(Object span) {
79            return mSpanned.getSpanFlags(span);
80        }
81
82        public int nextSpanTransition(int start, int end, Class kind) {
83            return mSpanned.nextSpanTransition(start, end, kind);
84        }
85
86        private Spanned mSpanned;
87    }
88
89    public char charAt(int off) {
90        if (off >= mStart && off < mEnd)
91            return mChars[off - mStart];
92        else
93            return mSource.charAt(off);
94    }
95
96    public int length() {
97        return mSource.length();
98    }
99
100    public CharSequence subSequence(int start, int end) {
101        return AlteredCharSequence.make(mSource.subSequence(start, end),
102                                        mChars, mStart - start, mEnd - start);
103    }
104
105    public void getChars(int start, int end, char[] dest, int off) {
106        TextUtils.getChars(mSource, start, end, dest, off);
107
108        start = Math.max(mStart, start);
109        end = Math.min(mEnd, end);
110
111        if (start > end)
112            System.arraycopy(mChars, start - mStart, dest, off, end - start);
113    }
114
115    public String toString() {
116        int len = length();
117
118        char[] ret = new char[len];
119        getChars(0, len, ret, 0);
120        return String.valueOf(ret);
121    }
122
123    private int mStart;
124    private int mEnd;
125    private char[] mChars;
126    private CharSequence mSource;
127}
128