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 
17 package 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  */
25 public class AlteredCharSequence
26 implements 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      */
make(CharSequence source, char[] sub, int substart, int subend)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 
AlteredCharSequence(CharSequence source, char[] sub, int substart, int subend)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 
update(char[] sub, int substart, int subend)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     {
AlteredSpanned(CharSequence source, char[] sub, int substart, int subend)60         private AlteredSpanned(CharSequence source, char[] sub,
61                                int substart, int subend) {
62             super(source, sub, substart, subend);
63             mSpanned = (Spanned) source;
64         }
65 
getSpans(int start, int end, Class<T> kind)66         public <T> T[] getSpans(int start, int end, Class<T> kind) {
67             return mSpanned.getSpans(start, end, kind);
68         }
69 
getSpanStart(Object span)70         public int getSpanStart(Object span) {
71             return mSpanned.getSpanStart(span);
72         }
73 
getSpanEnd(Object span)74         public int getSpanEnd(Object span) {
75             return mSpanned.getSpanEnd(span);
76         }
77 
getSpanFlags(Object span)78         public int getSpanFlags(Object span) {
79             return mSpanned.getSpanFlags(span);
80         }
81 
nextSpanTransition(int start, int end, Class kind)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 
charAt(int off)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 
length()96     public int length() {
97         return mSource.length();
98     }
99 
subSequence(int start, int end)100     public CharSequence subSequence(int start, int end) {
101         return AlteredCharSequence.make(mSource.subSequence(start, end),
102                                         mChars, mStart - start, mEnd - start);
103     }
104 
getChars(int start, int end, char[] dest, int off)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 
toString()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