/*
 * Copyright (C) 2013 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.text;

public class TextUtils {
    private TextUtils() { /* cannot be instantiated */ }

    /**
     * Returns true if the string is null or 0-length.
     * @param str the string to be examined
     * @return true if str is null or zero length
     */
    public static boolean isEmpty(CharSequence str) {
        return (str == null || str.length() == 0);
    }

    /**
     * Returns true if a and b are equal, including if they are both null.
     * <p><i>Note: In platform versions 1.1 and earlier, this method only worked well if
     * both the arguments were instances of String.</i></p>
     * @param a first CharSequence to check
     * @param b second CharSequence to check
     * @return true if a and b are equal
     */
    public static boolean equals(CharSequence a, CharSequence b) {
        if (a == b) return true;
        int length;
        if (a != null && b != null && (length = a.length()) == b.length()) {
            if (a instanceof String && b instanceof String) {
                return a.equals(b);
            }
            for (int i = 0; i < length; i++) {
                if (a.charAt(i) != b.charAt(i)) return false;
            }
            return true;
        }
        return false;
    }

    /**
     * Returns list of multiple {@link CharSequence} joined into a single
     * {@link CharSequence} separated by localized delimiter such as ", ".
     *
     * @hide
     */
    public static CharSequence join(Iterable<CharSequence> list) {
        final CharSequence delimiter = ", ";
        return join(delimiter, list);
    }

    /**
     * Returns a string containing the tokens joined by delimiters.
     * @param tokens an array objects to be joined. Strings will be formed from
     *     the objects by calling object.toString().
     */
    public static String join(CharSequence delimiter, Object[] tokens) {
        StringBuilder sb = new StringBuilder();
        boolean firstTime = true;
        for (Object token: tokens) {
            if (firstTime) {
                firstTime = false;
            } else {
                sb.append(delimiter);
            }
            sb.append(token);
        }
        return sb.toString();
    }

    /**
     * Returns a string containing the tokens joined by delimiters.
     * @param tokens an array objects to be joined. Strings will be formed from
     *     the objects by calling object.toString().
     */
    public static String join(CharSequence delimiter, Iterable<?> tokens) {
        StringBuilder sb = new StringBuilder();
        boolean firstTime = true;
        for (Object token: tokens) {
            if (firstTime) {
                firstTime = false;
            } else {
                sb.append(delimiter);
            }
            sb.append(token);
        }
        return sb.toString();
    }

}