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/*
* Copyright (C) 2012 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 com.android.inputmethod.latin.utils;
import java.util.Locale;
import java.util.TreeMap;
/**
* A class to help with handling different writing scripts.
*/
public class ScriptUtils {
// Used for hardware keyboards
public static final int SCRIPT_UNKNOWN = -1;
// TODO: should we use ISO 15924 identifiers instead?
public static final int SCRIPT_LATIN = 0;
public static final int SCRIPT_CYRILLIC = 1;
public static final int SCRIPT_GREEK = 2;
public static final int SCRIPT_ARABIC = 3;
public static final int SCRIPT_HEBREW = 4;
public static final TreeMap<String, Integer> mLanguageToScript;
static {
// List of the supported languages and their associated script. We won't check
// words written in another script than the selected script, because we know we
// don't have those in our dictionary so we will underline everything and we
// will never have any suggestions, so it makes no sense checking them, and this
// is done in {@link #shouldFilterOut}. Also, the script is used to choose which
// proximity to pass to the dictionary descent algorithm.
// IMPORTANT: this only contains languages - do not write countries in there.
// Only the language is searched from the map.
mLanguageToScript = new TreeMap<>();
mLanguageToScript.put("cs", SCRIPT_LATIN);
mLanguageToScript.put("da", SCRIPT_LATIN);
mLanguageToScript.put("de", SCRIPT_LATIN);
mLanguageToScript.put("el", SCRIPT_GREEK);
mLanguageToScript.put("en", SCRIPT_LATIN);
mLanguageToScript.put("es", SCRIPT_LATIN);
mLanguageToScript.put("fi", SCRIPT_LATIN);
mLanguageToScript.put("fr", SCRIPT_LATIN);
mLanguageToScript.put("hr", SCRIPT_LATIN);
mLanguageToScript.put("it", SCRIPT_LATIN);
mLanguageToScript.put("lt", SCRIPT_LATIN);
mLanguageToScript.put("lv", SCRIPT_LATIN);
mLanguageToScript.put("nb", SCRIPT_LATIN);
mLanguageToScript.put("nl", SCRIPT_LATIN);
mLanguageToScript.put("pt", SCRIPT_LATIN);
mLanguageToScript.put("sl", SCRIPT_LATIN);
mLanguageToScript.put("ru", SCRIPT_CYRILLIC);
}
/*
* Returns whether the code point is a letter that makes sense for the specified
* locale for this spell checker.
* The dictionaries supported by Latin IME are described in res/xml/spellchecker.xml
* and is limited to EFIGS languages and Russian.
* Hence at the moment this explicitly tests for Cyrillic characters or Latin characters
* as appropriate, and explicitly excludes CJK, Arabic and Hebrew characters.
*/
public static boolean isLetterPartOfScript(final int codePoint, final int scriptId) {
switch (scriptId) {
case SCRIPT_LATIN:
// Our supported latin script dictionaries (EFIGS) at the moment only include
// characters in the C0, C1, Latin Extended A and B, IPA extensions unicode
// blocks. As it happens, those are back-to-back in the code range 0x40 to 0x2AF,
// so the below is a very efficient way to test for it. As for the 0-0x3F, it's
// excluded from isLetter anyway.
return codePoint <= 0x2AF && Character.isLetter(codePoint);
case SCRIPT_CYRILLIC:
// All Cyrillic characters are in the 400~52F block. There are some in the upper
// Unicode range, but they are archaic characters that are not used in modern
// Russian and are not used by our dictionary.
return codePoint >= 0x400 && codePoint <= 0x52F && Character.isLetter(codePoint);
case SCRIPT_GREEK:
// Greek letters are either in the 370~3FF range (Greek & Coptic), or in the
// 1F00~1FFF range (Greek extended). Our dictionary contains both sort of characters.
// Our dictionary also contains a few words with 0xF2; it would be best to check
// if that's correct, but a web search does return results for these words so
// they are probably okay.
return (codePoint >= 0x370 && codePoint <= 0x3FF)
|| (codePoint >= 0x1F00 && codePoint <= 0x1FFF)
|| codePoint == 0xF2;
case SCRIPT_ARABIC:
// Arabic letters can be in any of the following blocks:
// Arabic U+0600..U+06FF
// Arabic Supplement U+0750..U+077F
// Arabic Extended-A U+08A0..U+08FF
// Arabic Presentation Forms-A U+FB50..U+FDFF
// Arabic Presentation Forms-B U+FE70..U+FEFF
return (codePoint >= 0x600 && codePoint <= 0x6FF)
|| (codePoint >= 0x750 && codePoint <= 0x77F)
|| (codePoint >= 0x8A0 && codePoint <= 0x8FF)
|| (codePoint >= 0xFB50 && codePoint <= 0xFDFF)
|| (codePoint >= 0xFE70 && codePoint <= 0xFEFF);
case SCRIPT_HEBREW:
// Hebrew letters are in the Hebrew unicode block, which spans from U+0590 to U+05FF,
// or in the Alphabetic Presentation Forms block, U+FB00..U+FB4F, but only in the
// Hebrew part of that block, which is U+FB1D..U+FB4F.
return (codePoint >= 0x590 && codePoint <= 0x5FF
|| codePoint >= 0xFB1D && codePoint <= 0xFB4F);
case SCRIPT_UNKNOWN:
return true;
default:
// Should never come here
throw new RuntimeException("Impossible value of script: " + scriptId);
}
}
public static int getScriptFromLocale(final Locale locale) {
final Integer script = mLanguageToScript.get(locale.getLanguage());
if (null == script) {
throw new RuntimeException("We have been called with an unsupported language: \""
+ locale.getLanguage() + "\". Framework bug?");
}
return script;
}
}
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