1/*
2 * Copyright (C) 2010 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 */
16package com.android.quicksearchbox;
17
18import org.json.JSONException;
19
20import java.util.Collection;
21import java.util.HashSet;
22
23/**
24 * Abstract SuggestionExtras supporting flattening to JSON.
25 */
26public abstract class AbstractSuggestionExtras implements SuggestionExtras {
27
28    private final SuggestionExtras mMore;
29
30    protected AbstractSuggestionExtras(SuggestionExtras more) {
31        mMore = more;
32    }
33
34    public Collection<String> getExtraColumnNames() {
35        HashSet<String> columns = new HashSet<String>();
36        columns.addAll(doGetExtraColumnNames());
37        if (mMore != null) {
38            columns.addAll(mMore.getExtraColumnNames());
39        }
40        return columns;
41    }
42
43    protected abstract Collection<String> doGetExtraColumnNames();
44
45    public String getExtra(String columnName) {
46        String extra = doGetExtra(columnName);
47        if (extra == null && mMore != null) {
48            extra = mMore.getExtra(columnName);
49        }
50        return extra;
51    }
52
53    protected abstract String doGetExtra(String columnName);
54
55    public String toJsonString() throws JSONException {
56        return new JsonBackedSuggestionExtras(this).toString();
57    }
58
59}
60