io.github.mmm.base.i18n.LocaleHelper Maven / Gradle / Ivy
/* Copyright (c) The m-m-m Team, Licensed under the Apache License, Version 2.0
* http://www.apache.org/licenses/LICENSE-2.0 */
package io.github.mmm.base.i18n;
import java.util.Locale;
import java.util.Locale.Builder;
import io.github.mmm.base.filter.CharFilter;
/**
* Simple helper for {@link Locale} specific stuff.
*
* @since 1.0.0
*/
public final class LocaleHelper {
/** The default separator used for {@link #toInfixes(Locale) locale-infixes}. */
public static final char SEPARATOR_DEFAULT = '_';
/** The separator used for {@link Locale#forLanguageTag(String) language tag}. */
public static final char SEPARATOR_FOR_LANGUAGE_TAG = '-';
/** The separator used for {@link Locale#getExtensionKeys() extension keys}. */
public static final char SEPARATOR_EXTENSION = '-';
/** The separator used for {@link Locale#getScript() script}. */
public static final char SEPARATOR_SCRIPT = '#';
private LocaleHelper() {
super();
}
/**
* @param locale is the {@link Locale}.
* @return the localization-infix in the form
* [_{@link Locale#getLanguage() language}[_{@link Locale#getCountry() country}[_{@link Locale#getVariant() variant}]]].
* Will be the empty {@link String} for the {@link Locale#ROOT root locale}. E.g. for {@link Locale#GERMANY}
* this method will return "_de_DE".
*/
public static String toInfix(Locale locale) {
StringBuilder infix = new StringBuilder();
String language = locale.getLanguage();
boolean hasLanguage = (language != null) && (language.length() == 2);
if (hasLanguage) {
infix.append(SEPARATOR_DEFAULT);
infix.append(language);
}
String country = locale.getCountry();
boolean hasCountry = (country != null) && (country.length() == 2);
if (hasCountry) {
if (!hasLanguage) {
infix.append(SEPARATOR_DEFAULT);
}
infix.append(SEPARATOR_DEFAULT);
infix.append(country);
}
String variant = locale.getVariant();
if ((variant != null) && (variant.length() > 0)) {
if (!hasCountry) {
infix.append(SEPARATOR_DEFAULT);
if (!hasLanguage) {
infix.append(SEPARATOR_DEFAULT);
}
}
infix.append(SEPARATOR_DEFAULT);
infix.append(variant);
}
return infix.toString();
}
/**
* This method determines the infix-strings for localization lookup ordered from most specific to least specific
* (empty string representing {@link Locale#ROOT}). Each infix is defined as:
*
*
* [_{@link Locale#getLanguage() language}[_{@link Locale#getCountry() country}[_{@link Locale#getVariant() variant}]]]
*
*
* Please note that if a segment is empty but a following segment is present, multiple underscores ('_') will occur.
*
* Examples:
*
*
* locale
* result
*
*
* {@link Locale#GERMANY}
* {"_de_DE", "_de", ""}
*
* new {@link Locale#Locale(String, String) Locale}("", "CM"){"__CM", ""}
*
* new {@link Locale#Locale(String, String, String) Locale}("", "", "variant"){"___variant", ""}
*
*
* @param locale is the {@link Locale}.
* @return the localization-infixes ordered from most specific to least specific. The returned array will always
* contain the empty string as last entry.
*/
public static String[] toInfixes(Locale locale) {
String[] infixes;
int length = 1;
StringBuilder infix = new StringBuilder();
String infixLang = null;
String language = locale.getLanguage();
infix.append(SEPARATOR_DEFAULT);
if ((language != null) && (language.length() == 2)) {
infix.append(language);
infixLang = infix.toString();
length++;
}
String infixCountry = null;
String country = locale.getCountry();
infix.append(SEPARATOR_DEFAULT);
if ((country != null) && (country.length() == 2)) {
infix.append(country);
infixCountry = infix.toString();
length++;
}
String infixVariant = null;
String variant = locale.getVariant();
infix.append(SEPARATOR_DEFAULT);
if ((variant != null) && (variant.length() > 0)) {
infix.append(variant);
infixVariant = infix.toString();
length++;
}
infixes = new String[length];
int i = 0;
if (infixVariant != null) {
infixes[i] = infixVariant;
i++;
}
if (infixCountry != null) {
infixes[i] = infixCountry;
i++;
}
if (infixLang != null) {
infixes[i] = infixLang;
i++;
}
infixes[i] = "";
return infixes;
}
/**
* Create a {@link Locale} from a given {@link String} representation such as {@link Locale#toString()} or
* {@link Locale#forLanguageTag(String)}.
*
* @param locale the {@link String} representation of the {@link Locale}. May be an from {@link Locale#toString()},
* {@link Locale#toLanguageTag()} or {@link #toInfix(Locale)}.
* @return the parsed {@link Locale}.
*/
public static Locale fromString(String locale) {
if (locale == null) {
return null;
}
if (locale.isEmpty()) {
return Locale.ROOT;
}
int start = 0;
int end = locale.indexOf(SEPARATOR_DEFAULT);
if (end == -1) {
if (locale.charAt(0) == SEPARATOR_FOR_LANGUAGE_TAG) {
locale = locale.substring(1); // tolerant for accepting suffixes like "-en-US"
}
return Locale.forLanguageTag(locale);
} else if (end == 0) {
start = end + 1;
end = locale.indexOf(SEPARATOR_DEFAULT, start);
}
Builder builder = new Builder();
if (end == -1) {
builder.setLanguage(locale.substring(start));
} else {
String language = locale.substring(start, end);
builder.setLanguage(language);
start = end + 1;
end = locale.indexOf(SEPARATOR_DEFAULT, start);
if (end == -1) {
builder.setRegion(locale.substring(start));
} else {
String region = locale.substring(start, end);
builder.setRegion(region);
String variant = fromStringDetails(locale, end + 1, builder);
if (variant != null) {
return new Locale(language, region, variant);
}
}
}
return builder.build();
}
private static String fromStringDetails(String locale, int start, Builder builder) {
int len = locale.length();
if (start >= len) {
return null;
}
int end;
char c = locale.charAt(start);
if (c != SEPARATOR_SCRIPT) { // variant?
end = locale.indexOf(SEPARATOR_DEFAULT, start);
String variant;
if (end == -1) {
variant = locale.substring(start);
} else {
variant = locale.substring(start, end);
start = end + 1;
if (start < len) {
c = locale.charAt(start);
}
}
try {
builder.setVariant(variant);
} catch (Exception e) {
return variant;
}
}
if (c == SEPARATOR_SCRIPT) { // script/extension?
start++;
end = locale.indexOf(SEPARATOR_EXTENSION, start);
if (end == -1) {
builder.setScript(locale.substring(start));
} else if (end > start + 1) {
builder.setScript(locale.substring(start, end));
start = end + 1;
}
end = findExtensionKey(locale, start);
while (end != -1) {
char extensionKey = locale.charAt(end);
start = end + 2;
end = findExtensionKey(locale, start);
String value;
if (end == -1) {
value = locale.substring(start);
} else {
value = locale.substring(start, end - 1);
}
if (!value.isEmpty()) {
builder.setExtension(extensionKey, value);
}
}
}
return null;
}
private static int findExtensionKey(String locale, int start) {
while (true) {
int end = locale.indexOf(SEPARATOR_EXTENSION, start);
if (end == -1) {
return -1;
}
if (end == start + 1) {
char extensionKey = locale.charAt(start);
if (CharFilter.LATIN_LETTER_OR_DIGIT.accept(extensionKey)) {
return start;
}
} else {
start = end + 1;
}
}
}
}
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