/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.value;
import java.text.Collator;
import java.util.Locale;
import org.h2.util.StringUtils;
/**
* Instances of this class can compare strings. Case sensitive and case
* insensitive comparison is supported, and comparison using a collator.
*/
public class CompareMode {
/**
* This constant means there is no collator set, and the default string
* comparison is to be used.
*/
public static final String OFF = "OFF";
/**
* This constant means the default collator should be used, even if ICU4J is
* in the classpath.
*/
public static final String DEFAULT = "DEFAULT_";
/**
* This constant means ICU4J should be used (this will fail if it is not in
* the classpath).
*/
public static final String ICU4J = "ICU4J_";
private static CompareMode lastUsed;
private static boolean canUseICU4J;
static {
try {
Class.forName("com.ibm.icu.text.Collator");
canUseICU4J = true;
} catch (Exception e) {
// ignore
}
}
private final String name;
private final int strength;
protected CompareMode(String name, int strength) {
this.name = name;
this.strength = strength;
}
/**
* Create a new compare mode with the given collator and strength. If
* required, a new CompareMode is created, or if possible the last one is
* returned. A cache is used to speed up comparison when using a collator;
* CollationKey objects are cached.
*
* @param name the collation name or null
* @param strength the collation strength
* @return the compare mode
*/
public static synchronized CompareMode getInstance(String name, int strength) {
if (lastUsed != null) {
if (StringUtils.equals(lastUsed.name, name)) {
if (lastUsed.strength == strength) {
return lastUsed;
}
}
}
if (name == null || name.equals(OFF)) {
lastUsed = new CompareMode(name, strength);
} else {
boolean useICU4J;
if (name.startsWith(ICU4J)) {
useICU4J = true;
name = name.substring(ICU4J.length());
} else if (name.startsWith(DEFAULT)) {
useICU4J = false;
name = name.substring(DEFAULT.length());
} else {
useICU4J = canUseICU4J;
}
if (useICU4J) {
lastUsed = new CompareModeIcu4J(name, strength);
} else {
lastUsed = new CompareModeDefault(name, strength);
}
}
return lastUsed;
}
/**
* Compare two characters in a string.
*
* @param a the first string
* @param ai the character index in the first string
* @param b the second string
* @param bi the character index in the second string
* @param ignoreCase true if a case-insensitive comparison should be made
* @return true if the characters are equals
*/
public boolean equalsChars(String a, int ai, String b, int bi, boolean ignoreCase) {
char ca = a.charAt(ai);
char cb = b.charAt(bi);
if (ignoreCase) {
ca = Character.toUpperCase(ca);
cb = Character.toUpperCase(cb);
}
return ca == cb;
}
/**
* Compare two strings.
*
* @param a the first string
* @param b the second string
* @param ignoreCase true if a case-insensitive comparison should be made
* @return -1 if the first string is 'smaller', 1 if the second string is
* smaller, and 0 if they are equal
*/
public int compareString(String a, String b, boolean ignoreCase) {
if (ignoreCase) {
return a.compareToIgnoreCase(b);
}
return a.compareTo(b);
}
/**
* Get the collation name.
*
* @param l the locale
* @return the name of the collation
*/
public static String getName(Locale l) {
Locale english = Locale.ENGLISH;
String name = l.getDisplayLanguage(english) + ' ' + l.getDisplayCountry(english) + ' ' + l.getVariant();
name = StringUtils.toUpperEnglish(name.trim().replace(' ', '_'));
return name;
}
/**
* Compare name name of the locale with the given name. The case of the name
* is ignored.
*
* @param locale the locale
* @param name the name
* @return true if they match
*/
static boolean compareLocaleNames(Locale locale, String name) {
return name.equalsIgnoreCase(locale.toString()) || name.equalsIgnoreCase(getName(locale));
}
/**
* Get the collator object for the given language name or language / country
* combination.
*
* @param name the language name
* @return the collator
*/
public static Collator getCollator(String name) {
Collator result = null;
if (name.startsWith(ICU4J)) {
name = name.substring(ICU4J.length());
} else if (name.startsWith(DEFAULT)) {
name = name.substring(DEFAULT.length());
}
if (name.length() == 2) {
Locale locale = new Locale(StringUtils.toLowerEnglish(name), "");
if (compareLocaleNames(locale, name)) {
result = Collator.getInstance(locale);
}
} else if (name.length() == 5) {
// LL_CC (language_country)
int idx = name.indexOf('_');
if (idx >= 0) {
String language = StringUtils.toLowerEnglish(name.substring(0, idx));
String country = name.substring(idx + 1);
Locale locale = new Locale(language, country);
if (compareLocaleNames(locale, name)) {
result = Collator.getInstance(locale);
}
}
}
if (result == null) {
for (Locale locale : Collator.getAvailableLocales()) {
if (compareLocaleNames(locale, name)) {
result = Collator.getInstance(locale);
break;
}
}
}
return result;
}
public String getName() {
return name == null ? OFF : name;
}
public int getStrength() {
return strength;
}
}