1 /*
2  * Copyright (C) 2011 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.providers.contacts.util;
18 
19 import android.text.TextUtils;
20 
21 import java.util.ArrayList;
22 import java.util.List;
23 
24 /**
25  * Builds a selection clause by concatenating several clauses with AND.
26  */
27 public class SelectionBuilder {
28     private static final String[] EMPTY_STRING_ARRAY =  new String[0];
29     private final List<String> mWhereClauses;
30 
31     /**
32      * @param baseSelection The base selection to start with. This is typically
33      *      the user supplied selection arg. Pass null if no base selection is
34      *      required.
35      */
SelectionBuilder(String baseSelection)36     public SelectionBuilder(String baseSelection) {
37         mWhereClauses = new ArrayList<String>();
38         addClause(baseSelection);
39     }
40 
41     /**
42      * Adds a new clause to the selection. Nothing is added if the supplied clause
43      * is null or empty.
44      */
addClause(String clause)45     public SelectionBuilder addClause(String clause) {
46         if (!TextUtils.isEmpty(clause)) {
47             mWhereClauses.add(clause);
48         }
49         return this;
50     }
51 
52     /**
53      * Returns a combined selection clause with AND of all clauses added using
54      * {@link #addClause(String)}. Returns null if no clause has been added or
55      * only null/empty clauses have been added till now.
56      */
build()57     public String build() {
58         if (mWhereClauses.size() == 0) {
59             return null;
60         }
61         return DbQueryUtils.concatenateClauses(mWhereClauses.toArray(EMPTY_STRING_ARRAY));
62     }
63 }
64