src/com/android/i18n/addressinput/Util.java

/*
 * Copyright (C) 2010 Google Inc.
 *
 * 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 com.android.i18n.addressinput;

import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Utility functions used by the address widget.
 */
public class Util {
    /**
     * This variable is in upper-case, since we convert the language code to upper case before doing
     * string comparison.
     */
    private static final String LATIN_SCRIPT = "LATN";

    /**
     * Cannot instantiate this class - private constructor.
     */
    private Util() {
    }

    /**
     * Returns true if the language code is explicitly marked to be in the latin script. For
     * example, "zh-Latn" would return true, but "zh-TW", "en" and "zh" would all return false.
     */
    public static boolean isExplicitLatinScript(String languageCode) {
        // Convert to upper-case for easier comparison.
        languageCode = languageCode.toUpperCase();
        // Check to see if the language code contains a script modifier.
        final Pattern languageCodePattern = Pattern.compile("\\w{2,3}[-_](\\w{4})");
        Matcher m = languageCodePattern.matcher(languageCode);
        if (m.lookingAt()) {
            String script = m.group(1);
            if (script.equals(LATIN_SCRIPT)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Returns the language subtag of a language code. For example, returns "zh" if given "zh-Hans",
     * "zh-CN" or other "zh" variants. If no language subtag can be found or the language tag is
     * malformed, returns "und".
     */
    public static String getLanguageSubtag(String languageCode) {
        final Pattern languageCodePattern = Pattern
                .compile("(\\w{2,3})(?:[-_]\\w{4})?(?:[-_]\\w{2})?");
        Matcher m = languageCodePattern.matcher(languageCode);
        if (m.matches()) {
            return m.group(1).toLowerCase();
        }
        return "und";
    }

    /**
     * Trims the string. If the field is empty after trimming, returns null instead. Note that this
     * only trims ASCII white-space.
     */
    public static String trimToNull(String originalStr) {
        if (originalStr == null) {
            return null;
        }
        String trimmedString = originalStr.trim();
        return (trimmedString.length() == 0) ? null : trimmedString;
    }

    /**
     * Throws an exception if the object is null, with a generic error message.
     */
    public static void checkNotNull(Object o) throws NullPointerException {
        checkNotNull(o, "This object should not be null.");
    }

    /**
     * Throws an exception if the object is null, with the error message supplied.
     */
    public static void checkNotNull(Object o, String message) throws NullPointerException {
        if (o == null) {
            throw new NullPointerException(message);
        }
    }

    /**
     * Joins input string with the given separator. If an input string is null, it will be skipped.
     */
    public static String joinAndSkipNulls(String separator, String... strings) {
        StringBuilder sb = null;
        for (String s : strings) {
            if (s != null) {
                s = s.trim();
                if (s.length() > 0) {
                    if (sb == null) {
                        sb = new StringBuilder(s);
                    } else {
                        sb.append(separator).append(s);
                    }
                }
            }
        }
        return sb == null ? null : sb.toString();
    }

    protected static Map<String, String> buildNameToKeyMap(String[] keys,
            String[] names, String[] lnames) {
        if (keys == null) {
            return null;
        }

        Map<String, String> nameToKeyMap = new HashMap<String, String>();

        int len = keys.length;
        for (String k : keys) {
            nameToKeyMap.put(k.toLowerCase(), k);
        }
        if (names != null) {
            if (names.length != len) {
                throw new IllegalStateException("names (" + names.toString() + ") length"
                        + " does not match keys (" + keys.toString() + ") length");
            }
            for (int i = 0; i < len; ++i) {
                nameToKeyMap.put(names[i].toLowerCase(), keys[i]);
            }
        }
        if (lnames != null) {
            if (lnames.length != len) {
                throw new IllegalStateException("lnames (" + lnames.toString() + ") length"
                        + " does not match keys (" + keys.toString() + ") length");
            }
            for (int i = 0; i < len; ++i) {
                nameToKeyMap.put(lnames[i].toLowerCase(), keys[i]);
            }
        }
        return nameToKeyMap;
    }

    /**
     * Returns a language code that the widget can use when fetching data, based on a {@link
     * java.util.Locale} language and the current selected country in the address widget. This
     * method is necessary since we have to determine later whether a language is "local" or "latin"
     * for certain countries.
     *
     * @param language the current user language
     * @param currentCountry the current selected country
     * @return a language code string in BCP-47 format (e.g. "en", "zh-Latn", "zh-Hans" or
     * "en-US").
     */
    public static String getWidgetCompatibleLanguageCode(Locale language, String currentCountry) {
        String country = currentCountry.toUpperCase();
        // Only do something if the country is China, Taiwan, Japan, or South or North Korea.
        if (country.equals("CN") || country.equals("TW") || country.equals("JP") ||
            country.equals("KR") || country.equals("KP")) {
            String languageTag = language.getLanguage();
            // Only do something if the language tag is _not_ Chinese, Japanese or Korean.
            if (!languageTag.equals("zh") && !languageTag.equals("ja") &&
                !languageTag.equals("ko")) {
                // Build up the language tag with the country and language specified, and add in the
                // script-tag of "Latn" explicitly, since this is _not_ a local language.
                StringBuilder languageTagBuilder = new StringBuilder(languageTag);
                languageTagBuilder.append("_latn");
                if (language.getCountry().length() > 0) {
                    languageTagBuilder.append("_");
                    languageTagBuilder.append(language.getCountry());
                }
                return languageTagBuilder.toString();
            }
        }
        return language.toString();
    }
}