1 files changed, 174 insertions, 0 deletions
diff --git a/core/java/android/provider/SettingsStringUtil.java b/core/java/android/provider/SettingsStringUtil.java
new file mode 100644
index 000000000000..f242d7936776
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+++ b/core/java/android/provider/SettingsStringUtil.java
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+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+package android.provider;
+
+import android.content.ComponentName;
+import android.content.ContentResolver;
+import android.text.TextUtils;
+
+import com.android.internal.util.ArrayUtils;
+
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.function.Function;
+
+/**
+ * Utilities for dealing with {@link String} values in {@link Settings}
+ *
+ * @hide
+ */
+public class SettingsStringUtil {
+    private SettingsStringUtil() {}
+
+    public static final String DELIMITER = ":";
+
+    /**
+     * A {@link HashSet} of items, that uses a common convention of setting string
+     * serialization/deserialization of separating multiple items with {@link #DELIMITER}
+     */
+    public static abstract class ColonDelimitedSet<T> extends HashSet<T> {
+
+        public ColonDelimitedSet(String colonSeparatedItems) {
+            for (String cn :
+                    TextUtils.split(TextUtils.emptyIfNull(colonSeparatedItems), DELIMITER)) {
+                add(itemFromString(cn));
+            }
+        }
+
+        protected abstract T itemFromString(String s);
+        protected String itemToString(T item) {
+            return String.valueOf(item);
+        }
+
+        @Override
+        public String toString() {
+            StringBuilder sb = new StringBuilder();
+            Iterator<T> it = iterator();
+            if (it.hasNext()) {
+                sb.append(it.next());
+                while (it.hasNext()) {
+                    sb.append(DELIMITER);
+                    sb.append(itemToString(it.next()));
+                }
+            }
+            return sb.toString();
+        }
+
+
+        public static class OfStrings extends ColonDelimitedSet<String> {
+            public OfStrings(String colonSeparatedItems) {
+                super(colonSeparatedItems);
+            }
+
+            @Override
+            protected String itemFromString(String s) {
+                return s;
+            }
+
+            public static String add(String delimitedElements, String element) {
+                final ColonDelimitedSet<String> set
+                        = new ColonDelimitedSet.OfStrings(delimitedElements);
+                if (set.contains(element)) {
+                    return delimitedElements;
+                }
+                set.add(element);
+                return set.toString();
+            }
+
+            public static String remove(String delimitedElements, String element) {
+                final ColonDelimitedSet<String> set
+                        = new ColonDelimitedSet.OfStrings(delimitedElements);
+                if (!set.contains(element)) {
+                    return delimitedElements;
+                }
+                set.remove(element);
+                return set.toString();
+            }
+
+            public static boolean contains(String delimitedElements, String element) {
+                final String[] elements = TextUtils.split(delimitedElements, DELIMITER);
+                return ArrayUtils.indexOf(elements, element) != -1;
+            }
+        }
+    }
+
+    public static class ComponentNameSet extends ColonDelimitedSet<ComponentName> {
+        public ComponentNameSet(String colonSeparatedPackageNames) {
+            super(colonSeparatedPackageNames);
+        }
+
+        @Override
+        protected ComponentName itemFromString(String s) {
+            return ComponentName.unflattenFromString(s);
+        }
+
+        @Override
+        protected String itemToString(ComponentName item) {
+            return item.flattenToString();
+        }
+
+        public static String add(String delimitedElements, ComponentName element) {
+            final ComponentNameSet set = new ComponentNameSet(delimitedElements);
+            if (set.contains(element)) {
+                return delimitedElements;
+            }
+            set.add(element);
+            return set.toString();
+        }
+
+        public static String remove(String delimitedElements, ComponentName element) {
+            final ComponentNameSet set = new ComponentNameSet(delimitedElements);
+            if (!set.contains(element)) {
+                return delimitedElements;
+            }
+            set.remove(element);
+            return set.toString();
+        }
+
+        public static boolean contains(String delimitedElements, ComponentName element) {
+            return ColonDelimitedSet.OfStrings.contains(
+                    delimitedElements, element.flattenToString());
+        }
+    }
+
+    public static class SettingStringHelper {
+        private final ContentResolver mContentResolver;
+        private final String mSettingName;
+        private final int mUserId;
+
+        public SettingStringHelper(ContentResolver contentResolver, String name, int userId) {
+            mContentResolver = contentResolver;
+            mUserId = userId;
+            mSettingName = name;
+        }
+
+        public String read() {
+            return Settings.Secure.getStringForUser(
+                    mContentResolver, mSettingName, mUserId);
+        }
+
+        public boolean write(String value) {
+            return Settings.Secure.putStringForUser(
+                    mContentResolver, mSettingName, value, mUserId);
+        }
+
+        public boolean modify(Function<String, String> change) {
+            return write(change.apply(read()));
+        }
+    }
+}