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package com.sun.org.apache.xml.internal.serialize;


import java.io.UnsupportedEncodingException;
import java.util.Hashtable;
import java.util.Locale;

import com.sun.org.apache.xerces.internal.util.EncodingMap;


/**
 * Provides information about encodings. Depends on the Java runtime
 * to provides writers for the different encodings, but can be used
 * to override encoding names and provide the last printable character
 * for each encoding.
 *
 * @version $Id: Encodings.java,v 1.6 2010-11-01 04:40:36 joehw Exp $
 * @author Assaf Arkin
 */
public class Encodings
{


    /**
     * The last printable character for unknown encodings.
     */
    static final int DEFAULT_LAST_PRINTABLE = 0x7F;

    // last printable character for Unicode-compatible encodings
    static final int LAST_PRINTABLE_UNICODE = 0xffff;
    // unicode-compliant encodings; can express plane 0
    static final String[] UNICODE_ENCODINGS = {
        "Unicode", "UnicodeBig", "UnicodeLittle", "GB2312", "UTF8", "UTF-16",
    };
    // default (Java) encoding if none supplied:
    static final String DEFAULT_ENCODING = "UTF8";

    // note that the size of this Hashtable
    // is bounded by the number of encodings recognized by EncodingMap;
    // therefore it poses no static mutability risk.
    static Hashtable _encodings = new Hashtable();

    /**
     * @param encoding a MIME charset name, or null.
     */
    static EncodingInfo getEncodingInfo(String encoding, boolean allowJavaNames) throws UnsupportedEncodingException {
        EncodingInfo eInfo = null;
        if (encoding == null) {
            if((eInfo = (EncodingInfo)_encodings.get(DEFAULT_ENCODING)) != null) 
                return eInfo;
            eInfo = new EncodingInfo(EncodingMap.getJava2IANAMapping(DEFAULT_ENCODING), DEFAULT_ENCODING, LAST_PRINTABLE_UNICODE);
            _encodings.put(DEFAULT_ENCODING, eInfo);
            return eInfo;
        }
        // need to convert it to upper case:
        encoding = encoding.toUpperCase(Locale.ENGLISH);
        String jName = EncodingMap.getIANA2JavaMapping(encoding);
        if(jName == null) {
            // see if the encoding passed in is a Java encoding name.
            if(allowJavaNames ) {
                EncodingInfo.testJavaEncodingName(encoding);
                if((eInfo = (EncodingInfo)_encodings.get(encoding)) != null) 
                    return eInfo;
                // is it known to be unicode-compliant?
                int i=0;
                for(; i