/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/URI.java,v 1.47 2004/05/13 04:03:25 mbecke Exp $
 * $Revision: 1.47 $
 * $Date: 2004/05/13 04:03:25 $
 *
 * ====================================================================
 *
 *  Copyright 2002-2004 The Apache Software Foundation
 *
 *  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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Locale;
import java.util.BitSet;
import java.util.Hashtable;

import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.net.URLCodec;
import org.apache.commons.httpclient.util.EncodingUtil;

/**
 * The interface for the URI(Uniform Resource Identifiers) version of RFC 2396.
 * This class has the purpose of supportting of parsing a URI reference to
 * extend any specific protocols, the character encoding of the protocol to 
 * be transported and the charset of the document.
 * <p>
 * A URI is always in an "escaped" form, since escaping or unescaping a
 * completed URI might change its semantics.  
 * <p>
 * Implementers should be careful not to escape or unescape the same string
 * more than once, since unescaping an already unescaped string might lead to
 * misinterpreting a percent data character as another escaped character,
 * or vice versa in the case of escaping an already escaped string.
 * <p>
 * In order to avoid these problems, data types used as follows:
 * <p><blockquote><pre>
 *   URI character sequence: char
 *   octet sequence: byte
 *   original character sequence: String
 * </pre></blockquote><p>
 *
 * So, a URI is a sequence of characters as an array of a char type, which
 * is not always represented as a sequence of octets as an array of byte.
 * <p>
 * 
 * URI Syntactic Components
 * <p><blockquote><pre>
 * - In general, written as follows:
 *   Absolute URI = <scheme>:<scheme-specific-part>
 *   Generic URI = <scheme>://<authority><path>?<query>
 *
 * - Syntax
 *   absoluteURI   = scheme ":" ( hier_part | opaque_part )
 *   hier_part     = ( net_path | abs_path ) [ "?" query ]
 *   net_path      = "//" authority [ abs_path ]
 *   abs_path      = "/"  path_segments
 * </pre></blockquote><p>
 *
 * The following examples illustrate URI that are in common use.
 * <pre>
 * ftp://ftp.is.co.za/rfc/rfc1808.txt
 *    -- ftp scheme for File Transfer Protocol services
 * gopher://spinaltap.micro.umn.edu/00/Weather/California/Los%20Angeles
 *    -- gopher scheme for Gopher and Gopher+ Protocol services
 * http://www.math.uio.no/faq/compression-faq/part1.html
 *    -- http scheme for Hypertext Transfer Protocol services
 * mailto:mduerst@ifi.unizh.ch
 *    -- mailto scheme for electronic mail addresses
 * news:comp.infosystems.www.servers.unix
 *    -- news scheme for USENET news groups and articles
 * telnet://melvyl.ucop.edu/
 *    -- telnet scheme for interactive services via the TELNET Protocol
 * </pre>
 * Please, notice that there are many modifications from URL(RFC 1738) and
 * relative URL(RFC 1808).
 * <p>
 * <b>The expressions for a URI</b>
 * <p><pre>
 * For escaped URI forms
 *  - URI(char[]) // constructor
 *  - char[] getRawXxx() // method
 *  - String getEscapedXxx() // method
 *  - String toString() // method
 * <p>
 * For unescaped URI forms
 *  - URI(String) // constructor
 *  - String getXXX() // method
 * </pre><p>
 *
 * @author <a href="mailto:jericho@apache.org">Sung-Gu</a>
 * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
 * @version $Revision: 1.47 $ $Date: 2002/03/14 15:14:01 
 */
public class URI implements Cloneable, Comparable, Serializable {


    // ----------------------------------------------------------- Constructors

    /** Create an instance as an internal use */
    protected URI() {
    }

    /**
     * Construct a URI from a string with the given charset. The input string can 
     * be either in escaped or unescaped form. 
     *
     * @param s URI character sequence
     * @param escaped <tt>true</tt> if URI character sequence is in escaped form. 
     *                <tt>false</tt> otherwise. 
     * @param charset the charset string to do escape encoding, if required
     * 
     * @throws URIException If the URI cannot be created.
     * @throws NullPointerException if input string is <code>null</code>
     * 
     * @see #getProtocolCharset
     * 
     * @since 3.0
     */
    public URI(String s, boolean escaped, String charset)
        throws URIException, NullPointerException {
        protocolCharset = charset;
        parseUriReference(s, escaped);
    }

    /**
     * Construct a URI from a string with the given charset. The input string can 
     * be either in escaped or unescaped form. 
     *
     * @param s URI character sequence
     * @param escaped <tt>true</tt> if URI character sequence is in escaped form. 
     *                <tt>false</tt> otherwise. 
     * 
     * @throws URIException If the URI cannot be created.
     * @throws NullPointerException if input string is <code>null</code>
     * 
     * @see #getProtocolCharset
     * 
     * @since 3.0
     */
    public URI(String s, boolean escaped)
        throws URIException, NullPointerException {
        parseUriReference(s, escaped);
    }

    /**
     * Construct a URI as an escaped form of a character array with the given
     * charset.
     *
     * @param escaped the URI character sequence
     * @param charset the charset string to do escape encoding
     * @throws URIException If the URI cannot be created.
     * @throws NullPointerException if <code>escaped</code> is <code>null</code>
     * @see #getProtocolCharset
     * 
     * @deprecated Use #URI(String, boolean, String)
     */
    public URI(char[] escaped, String charset) 
        throws URIException, NullPointerException {
        protocolCharset = charset;
        parseUriReference(new String(escaped), true);
    }


    /**
     * Construct a URI as an escaped form of a character array.
     * An URI can be placed within double-quotes or angle brackets like 
     * "http://test.com/" and <http://test.com/>
     * 
     * @param escaped the URI character sequence
     * @throws URIException If the URI cannot be created.
     * @throws NullPointerException if <code>escaped</code> is <code>null</code>
     * @see #getDefaultProtocolCharset
     * 
     * @deprecated Use #URI(String, boolean)
     */
    public URI(char[] escaped) 
        throws URIException, NullPointerException {
        parseUriReference(new String(escaped), true);
    }


    /**
     * Construct a URI from the given string with the given charset.
     *
     * @param original the string to be represented to URI character sequence
     * It is one of absoluteURI and relativeURI.
     * @param charset the charset string to do escape encoding
     * @throws URIException If the URI cannot be created.
     * @see #getProtocolCharset
     * 
     * @deprecated Use #URI(String, boolean, String)
     */
    public URI(String original, String charset) throws URIException {
        protocolCharset = charset;
        parseUriReference(original, false);
    }


    /**
     * Construct a URI from the given string.
     * <p><blockquote><pre>
     *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
     * </pre></blockquote><p>
     * An URI can be placed within double-quotes or angle brackets like 
     * "http://test.com/" and <http://test.com/>
     *
     * @param original the string to be represented to URI character sequence
     * It is one of absoluteURI and relativeURI.
     * @throws URIException If the URI cannot be created.
     * @see #getDefaultProtocolCharset
     * 
     * @deprecated Use #URI(String, boolean)
     */
    public URI(String original) throws URIException {
        parseUriReference(original, false);
    }


    /**
     * Construct a general URI from the given components.
     * <p><blockquote><pre>
     *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
     *   absoluteURI   = scheme ":" ( hier_part | opaque_part )
     *   opaque_part   = uric_no_slash *uric
     * </pre></blockquote><p>
     * It's for absolute URI = <scheme>:<scheme-specific-part>#
     * <fragment>.
     *
     * @param scheme the scheme string
     * @param schemeSpecificPart scheme_specific_part
     * @param fragment the fragment string
     * @throws URIException If the URI cannot be created.
     * @see #getDefaultProtocolCharset
     */
    public URI(String scheme, String schemeSpecificPart, String fragment)
        throws URIException {

        // validate and contruct the URI character sequence
        if (scheme == null) {
           throw new URIException(URIException.PARSING, "scheme required");
        }
        char[] s = scheme.toLowerCase().toCharArray();
        if (validate(s, URI.scheme)) {
            _scheme = s; // is_absoluteURI
        } else {
            throw new URIException(URIException.PARSING, "incorrect scheme");
        }
        _opaque = encode(schemeSpecificPart, allowed_opaque_part,
                getProtocolCharset());
        // Set flag
        _is_opaque_part = true;
        _fragment = fragment.toCharArray(); 

        setURI();
    }


    /**
     * Construct a general URI from the given components.
     * <p><blockquote><pre>
     *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
     *   absoluteURI   = scheme ":" ( hier_part | opaque_part )
     *   relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
     *   hier_part     = ( net_path | abs_path ) [ "?" query ]
     * </pre></blockquote><p>
     * It's for absolute URI = <scheme>:<path>?<query>#<
     * fragment> and relative URI = <path>?<query>#<fragment
     * >.
     *
     * @param scheme the scheme string
     * @param authority the authority string
     * @param path the path string
     * @param query the query string
     * @param fragment the fragment string
     * @throws URIException If the new URI cannot be created.
     * @see #getDefaultProtocolCharset
     */
    public URI(String scheme, String authority, String path, String query,
               String fragment) throws URIException {

        // validate and contruct the URI character sequence
        StringBuffer buff = new StringBuffer();
        if (scheme != null) {
            buff.append(scheme);
            buff.append(':');
        }
        if (authority != null) {
            buff.append("//");
            buff.append(authority);
        }
        if (path != null) {  // accept empty path
            if ((scheme != null || authority != null)
                    && !path.startsWith("/")) {
                throw new URIException(URIException.PARSING,
                        "abs_path requested");
            }
            buff.append(path);
        }
        if (query != null) {
            buff.append('?');
            buff.append(query);
        }
        if (fragment != null) {
            buff.append('#');
            buff.append(fragment);
        }
        parseUriReference(buff.toString(), false);
    }


    /**
     * Construct a general URI from the given components.
     *
     * @param scheme the scheme string
     * @param userinfo the userinfo string
     * @param host the host string
     * @param port the port number
     * @throws URIException If the new URI cannot be created.
     * @see #getDefaultProtocolCharset
     */
    public URI(String scheme, String userinfo, String host, int port)
        throws URIException {

        this(scheme, userinfo, host, port, null, null, null);
    }


    /**
     * Construct a general URI from the given components.
     *
     * @param scheme the scheme string
     * @param userinfo the userinfo string
     * @param host the host string
     * @param port the port number
     * @param path the path string
     * @throws URIException If the new URI cannot be created.
     * @see #getDefaultProtocolCharset
     */
    public URI(String scheme, String userinfo, String host, int port,
            String path) throws URIException {

        this(scheme, userinfo, host, port, path, null, null);
    }


    /**
     * Construct a general URI from the given components.
     *
     * @param scheme the scheme string
     * @param userinfo the userinfo string
     * @param host the host string
     * @param port the port number
     * @param path the path string
     * @param query the query string
     * @throws URIException If the new URI cannot be created.
     * @see #getDefaultProtocolCharset
     */
    public URI(String scheme, String userinfo, String host, int port,
            String path, String query) throws URIException {

        this(scheme, userinfo, host, port, path, query, null);
    }


    /**
     * Construct a general URI from the given components.
     *
     * @param scheme the scheme string
     * @param userinfo the userinfo string
     * @param host the host string
     * @param port the port number
     * @param path the path string
     * @param query the query string
     * @param fragment the fragment string
     * @throws URIException If the new URI cannot be created.
     * @see #getDefaultProtocolCharset
     */
    public URI(String scheme, String userinfo, String host, int port,
            String path, String query, String fragment) throws URIException {

        this(scheme, (host == null) ? null 
            : ((userinfo != null) ? userinfo + '@' : "") + host 
                + ((port != -1) ? ":" + port : ""), path, query, fragment);
    }


    /**
     * Construct a general URI from the given components.
     *
     * @param scheme the scheme string
     * @param host the host string
     * @param path the path string
     * @param fragment the fragment string
     * @throws URIException If the new URI cannot be created.
     * @see #getDefaultProtocolCharset
     */
    public URI(String scheme, String host, String path, String fragment)
        throws URIException {

        this(scheme, host, path, null, fragment);
    }


    /**
     * Construct a general URI with the given relative URI string.
     *
     * @param base the base URI
     * @param relative the relative URI string
     * @throws URIException If the new URI cannot be created.
     * 
     * @deprecated Use #URI(URI, String, boolean)
     */
    public URI(URI base, String relative) throws URIException {
        this(base, new URI(relative));
    }


    /**
     * Construct a general URI with the given relative URI string.
     *
     * @param base the base URI
     * @param relative the relative URI string
     * @param escaped <tt>true</tt> if URI character sequence is in escaped form. 
     *                <tt>false</tt> otherwise.
     *  
     * @throws URIException If the new URI cannot be created.
     * 
     * @since 3.0
     */
    public URI(URI base, String relative, boolean escaped) throws URIException {
        this(base, new URI(relative, escaped));
    }


    /**
     * Construct a general URI with the given relative URI.
     * <p><blockquote><pre>
     *   URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
     *   relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
     * </pre></blockquote><p>
     * Resolving Relative References to Absolute Form.
     *
     * <strong>Examples of Resolving Relative URI References</strong>
     *
     * Within an object with a well-defined base URI of
     * <p><blockquote><pre>
     *   http://a/b/c/d;p?q
     * </pre></blockquote><p>
     * the relative URI would be resolved as follows:
     *
     * Normal Examples
     *
     * <p><blockquote><pre>
     *   g:h           =  g:h
     *   g             =  http://a/b/c/g
     *   ./g           =  http://a/b/c/g
     *   g/            =  http://a/b/c/g/
     *   /g            =  http://a/g
     *   //g           =  http://g
     *   ?y            =  http://a/b/c/?y
     *   g?y           =  http://a/b/c/g?y
     *   #s            =  (current document)#s
     *   g#s           =  http://a/b/c/g#s
     *   g?y#s         =  http://a/b/c/g?y#s
     *   ;x            =  http://a/b/c/;x
     *   g;x           =  http://a/b/c/g;x
     *   g;x?y#s       =  http://a/b/c/g;x?y#s
     *   .             =  http://a/b/c/
     *   ./            =  http://a/b/c/
     *   ..            =  http://a/b/
     *   ../           =  http://a/b/
     *   ../g          =  http://a/b/g
     *   ../..         =  http://a/
     *   ../../        =  http://a/ 
     *   ../../g       =  http://a/g
     * </pre></blockquote><p>
     *
     * Some URI schemes do not allow a hierarchical syntax matching the
     * <hier_part> syntax, and thus cannot use relative references.
     *
     * @param base the base URI
     * @param relative the relative URI
     * @throws URIException If the new URI cannot be created.
     */
    public URI(URI base, URI relative) throws URIException {

        if (base._scheme == null) {
            throw new URIException(URIException.PARSING, "base URI required");
        }
        if (base._scheme != null) {
            this._scheme = base._scheme;
            this._authority = base._authority;
        }
        if (base._is_opaque_part || relative._is_opaque_part) {
            this._scheme = base._scheme;
            this._is_opaque_part = base._is_opaque_part 
                || relative._is_opaque_part;
            this._opaque = relative._opaque;
            this._fragment = relative._fragment;
            this.setURI();
            return;
        }
        if (relative._scheme != null) {
            this._scheme = relative._scheme;
            this._is_net_path = relative._is_net_path;
            this._authority = relative._authority;
            if (relative._is_server) {
                this._is_server = relative._is_server;
                this._userinfo = relative._userinfo;
                this._host = relative._host;
                this._port = relative._port;
            } else if (relative._is_reg_name) {
                this._is_reg_name = relative._is_reg_name;
            }
            this._is_abs_path = relative._is_abs_path;
            this._is_rel_path = relative._is_rel_path;
            this._path = relative._path;
        } else if (base._authority != null && relative._scheme == null) {
            this._is_net_path = base._is_net_path;
            this._authority = base._authority;
            if (base._is_server) {
                this._is_server = base._is_server;
                this._userinfo = base._userinfo;
                this._host = base._host;
                this._port = base._port;
            } else if (base._is_reg_name) {
                this._is_reg_name = base._is_reg_name;
            }
        }
        if (relative._authority != null) {
            this._is_net_path = relative._is_net_path;
            this._authority = relative._authority;
            if (relative._is_server) {
                this._is_server = relative._is_server;
                this._userinfo = relative._userinfo;
                this._host = relative._host;
                this._port = relative._port;
            } else if (relative._is_reg_name) {
                this._is_reg_name = relative._is_reg_name;
            }
            this._is_abs_path = relative._is_abs_path;
            this._is_rel_path = relative._is_rel_path;
            this._path = relative._path;
        }
        // resolve the path and query if necessary
        if (relative._scheme == null && relative._authority == null) {
            if ((relative._path == null || relative._path.length == 0)
                && relative._query == null) {
                // handle a reference to the current document, see RFC 2396 
                // section 5.2 step 2
                this._path = base._path;
                this._query = base._query;
            } else {
                this._path = resolvePath(base._path, relative._path);
            }
        }
        // base._query removed
        if (relative._query != null) {
            this._query = relative._query;
        }
        // base._fragment removed
        if (relative._fragment != null) {
            this._fragment = relative._fragment;
        }
        this.setURI();
        // reparse the newly built URI, this will ensure that all flags are set correctly.
        // TODO there must be a better way to do this
        parseUriReference(new String(_uri), true);
    }

    // --------------------------------------------------- Instance Variables

    /** Version ID for serialization */
    static final long serialVersionUID = 604752400577948726L;


    /**
     * Cache the hash code for this URI.
     */
    protected int hash = 0;


    /**
     * This Uniform Resource Identifier (URI).
     * The URI is always in an "escaped" form, since escaping or unescaping
     * a completed URI might change its semantics.  
     */
    protected char[] _uri = null;


    /**
     * The charset of the protocol used by this URI instance.
     */
    protected String protocolCharset = null;


    /**
     * The default charset of the protocol.  RFC 2277, 2396
     */
    protected static String defaultProtocolCharset = "UTF-8";


    /**
     * The default charset of the document.  RFC 2277, 2396
     * The platform's charset is used for the document by default.
     */
    protected static String defaultDocumentCharset = null;
    protected static String defaultDocumentCharsetByLocale = null;
    protected static String defaultDocumentCharsetByPlatform = null;
    // Static initializer for defaultDocumentCharset
    static {
        Locale locale = Locale.getDefault();
        // in order to support backward compatiblity
        if (locale != null) {
            defaultDocumentCharsetByLocale =
                LocaleToCharsetMap.getCharset(locale);
            // set the default document charset
            defaultDocumentCharset = defaultDocumentCharsetByLocale;
        }
        // in order to support platform encoding
        try {
            defaultDocumentCharsetByPlatform = System.getProperty("file.encoding");
        } catch (SecurityException ignore) {
        }
        if (defaultDocumentCharset == null) {
            // set the default document charset
            defaultDocumentCharset = defaultDocumentCharsetByPlatform;
        }
    }


    /**
     * The scheme.
     */
    protected char[] _scheme = null;


    /**
     * The opaque.
     */
    protected char[] _opaque = null;


    /**
     * The authority.
     */
    protected char[] _authority = null;


    /**
     * The userinfo.
     */
    protected char[] _userinfo = null;


    /**
     * The host.
     */
    protected char[] _host = null;


    /**
     * The port.
     */
    protected int _port = -1;


    /**
     * The path.
     */
    protected char[] _path = null;


    /**
     * The query.
     */
    protected char[] _query = null;


    /**
     * The fragment.
     */
    protected char[] _fragment = null;


    /**
     * The root path.
     */
    protected static char[] rootPath = { '/' };

    // ---------------------- Generous characters for each component validation

    /**
     * The percent "%" character always has the reserved purpose of being the
     * escape indicator, it must be escaped as "%25" in order to be used as
     * data within a URI.
     */
    protected static final BitSet percent = new BitSet(256);
    // Static initializer for percent
    static {
        percent.set('%');
    }


    /**
     * BitSet for digit.
     * <p><blockquote><pre>
     * digit    = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |
     *            "8" | "9"
     * </pre></blockquote><p>
     */
    protected static final BitSet digit = new BitSet(256);
    // Static initializer for digit
    static {
        for (int i = '0'; i <= '9'; i++) {
            digit.set(i);
        }
    }


    /**
     * BitSet for alpha.
     * <p><blockquote><pre>
     * alpha         = lowalpha | upalpha
     * </pre></blockquote><p>
     */
    protected static final BitSet alpha = new BitSet(256);
    // Static initializer for alpha
    static {
        for (int i = 'a'; i <= 'z'; i++) {
            alpha.set(i);
        }
        for (int i = 'A'; i <= 'Z'; i++) {
            alpha.set(i);
        }
    }


    /**
     * BitSet for alphanum (join of alpha & digit).
     * <p><blockquote><pre>
     *  alphanum      = alpha | digit
     * </pre></blockquote><p>
     */
    protected static final BitSet alphanum = new BitSet(256);
    // Static initializer for alphanum
    static {
        alphanum.or(alpha);
        alphanum.or(digit);
    }


    /**
     * BitSet for hex.
     * <p><blockquote><pre>
     * hex           = digit | "A" | "B" | "C" | "D" | "E" | "F" |
     *                         "a" | "b" | "c" | "d" | "e" | "f"
     * </pre></blockquote><p>
     */
    protected static final BitSet hex = new BitSet(256);
    // Static initializer for hex
    static {
        hex.or(digit);
        for (int i = 'a'; i <= 'f'; i++) {
            hex.set(i);
        }
        for (int i = 'A'; i <= 'F'; i++) {
            hex.set(i);
        }
    }


    /**
     * BitSet for escaped.
     * <p><blockquote><pre>
     * escaped       = "%" hex hex
     * </pre></blockquote><p>
     */
    protected static final BitSet escaped = new BitSet(256);
    // Static initializer for escaped
    static {
        escaped.or(percent);
        escaped.or(hex);
    }


    /**
     * BitSet for mark.
     * <p><blockquote><pre>
     * mark          = "-" | "_" | "." | "!" | "~" | "*" | "'" |
     *                 "(" | ")"
     * </pre></blockquote><p>
     */
    protected static final BitSet mark = new BitSet(256);
    // Static initializer for mark
    static {
        mark.set('-');
        mark.set('_');
        mark.set('.');
        mark.set('!');
        mark.set('~');
        mark.set('*');
        mark.set('\'');
        mark.set('(');
        mark.set(')');
    }


    /**
     * Data characters that are allowed in a URI but do not have a reserved
     * purpose are called unreserved.
     * <p><blockquote><pre>
     * unreserved    = alphanum | mark
     * </pre></blockquote><p>
     */
    protected static final BitSet unreserved = new BitSet(256);
    // Static initializer for unreserved
    static {
        unreserved.or(alphanum);
        unreserved.or(mark);
    }


    /**
     * BitSet for reserved.
     * <p><blockquote><pre>
     * reserved      = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
     *                 "$" | ","
     * </pre></blockquote><p>
     */
    protected static final BitSet reserved = new BitSet(256);
    // Static initializer for reserved
    static {
        reserved.set(';');
        reserved.set('/');
        reserved.set('?');
        reserved.set(':');
        reserved.set('@');
        reserved.set('&');
        reserved.set('=');
        reserved.set('+');
        reserved.set('$');
        reserved.set(',');
    }


    /**
     * BitSet for uric.
     * <p><blockquote><pre>
     * uric          = reserved | unreserved | escaped
     * </pre></blockquote><p>
     */
    protected static final BitSet uric = new BitSet(256);
    // Static initializer for uric
    static {
        uric.or(reserved);
        uric.or(unreserved);
        uric.or(escaped);
    }


    /**
     * BitSet for fragment (alias for uric).
     * <p><blockquote><pre>
     * fragment      = *uric
     * </pre></blockquote><p>
     */
    protected static final BitSet fragment = uric;


    /**
     * BitSet for query (alias for uric).
     * <p><blockquote><pre>
     * query         = *uric
     * </pre></blockquote><p>
     */
    protected static final BitSet query = uric;


    /**
     * BitSet for pchar.
     * <p><blockquote><pre>
     * pchar         = unreserved | escaped |
     *                 ":" | "@" | "&" | "=" | "+" | "$" | ","
     * </pre></blockquote><p>
     */
    protected static final BitSet pchar = new BitSet(256);
    // Static initializer for pchar
    static {
        pchar.or(unreserved);
        pchar.or(escaped);
        pchar.set(':');
        pchar.set('@');
        pchar.set('&');
        pchar.set('=');
        pchar.set('+');
        pchar.set('$');
        pchar.set(',');
    }


    /**
     * BitSet for param (alias for pchar).
     * <p><blockquote><pre>
     * param         = *pchar
     * </pre></blockquote><p>
     */
    protected static final BitSet param = pchar;


    /**
     * BitSet for segment.
     * <p><blockquote><pre>
     * segment       = *pchar *( ";" param )
     * </pre></blockquote><p>
     */
    protected static final BitSet segment = new BitSet(256);
    // Static initializer for segment
    static {
        segment.or(pchar);
        segment.set(';');
        segment.or(param);
    }


    /**
     * BitSet for path segments.
     * <p><blockquote><pre>
     * path_segments = segment *( "/" segment )
     * </pre></blockquote><p>
     */
    protected static final BitSet path_segments = new BitSet(256);
    // Static initializer for path_segments
    static {
        path_segments.set('/');
        path_segments.or(segment);
    }


    /**
     * URI absolute path.
     * <p><blockquote><pre>
     * abs_path      = "/"  path_segments
     * </pre></blockquote><p>
     */
    protected static final BitSet abs_path = new BitSet(256);
    // Static initializer for abs_path
    static {
        abs_path.set('/');
        abs_path.or(path_segments);
    }


    /**
     * URI bitset for encoding typical non-slash characters.
     * <p><blockquote><pre>
     * uric_no_slash = unreserved | escaped | ";" | "?" | ":" | "@" |
     *                 "&" | "=" | "+" | "$" | ","
     * </pre></blockquote><p>
     */
    protected static final BitSet uric_no_slash = new BitSet(256);
    // Static initializer for uric_no_slash
    static {
        uric_no_slash.or(unreserved);
        uric_no_slash.or(escaped);
        uric_no_slash.set(';');
        uric_no_slash.set('?');
        uric_no_slash.set(';');
        uric_no_slash.set('@');
        uric_no_slash.set('&');
        uric_no_slash.set('=');
        uric_no_slash.set('+');
        uric_no_slash.set('$');
        uric_no_slash.set(',');
    }
    

    /**
     * URI bitset that combines uric_no_slash and uric.
     * <p><blockquote><pre>
     * opaque_part   = uric_no_slash *uric
     * </pre></blockquote><p>
     */
    protected static final BitSet opaque_part = new BitSet(256);
    // Static initializer for opaque_part
    static {
        // it's generous. because first character must not include a slash
        opaque_part.or(uric_no_slash);
        opaque_part.or(uric);
    }
    

    /**
     * URI bitset that combines absolute path and opaque part.
     * <p><blockquote><pre>
     * path          = [ abs_path | opaque_part ]
     * </pre></blockquote><p>
     */
    protected static final BitSet path = new BitSet(256);
    // Static initializer for path
    static {
        path.or(abs_path);
        path.or(opaque_part);
    }


    /**
     * Port, a logical alias for digit.
     */
    protected static final BitSet port = digit;


    /**
     * Bitset that combines digit and dot fo IPv$address.
     * <p><blockquote><pre>
     * IPv4address   = 1*digit "." 1*digit "." 1*digit "." 1*digit
     * </pre></blockquote><p>
     */
    protected static final BitSet IPv4address = new BitSet(256);
    // Static initializer for IPv4address
    static {
        IPv4address.or(digit);
        IPv4address.set('.');
    }


    /**
     * RFC 2373.
     * <p><blockquote><pre>
     * IPv6address = hexpart [ ":" IPv4address ]
     * </pre></blockquote><p>
     */
    protected static final BitSet IPv6address = new BitSet(256);
    // Static initializer for IPv6address reference
    static {
        IPv6address.or(hex); // hexpart
        IPv6address.set(':');
        IPv6address.or(IPv4address);
    }


    /**
     * RFC 2732, 2373.
     * <p><blockquote><pre>
     * IPv6reference   = "[" IPv6address "]"
     * </pre></blockquote><p>
     */
    protected static final BitSet IPv6reference = new BitSet(256);
    // Static initializer for IPv6reference
    static {
        IPv6reference.set('[');
        IPv6reference.or(IPv6address);
        IPv6reference.set(']');
    }


    /**
     * BitSet for toplabel.
     * <p><blockquote><pre>
     * toplabel      = alpha | alpha *( alphanum | "-" ) alphanum
     * </pre></blockquote><p>
     */
    protected static final BitSet toplabel = new BitSet(256);
    // Static initializer for toplabel
    static {
        toplabel.or(alphanum);
        toplabel.set('-');
    }


    /**
     * BitSet for domainlabel.
     * <p><blockquote><pre>
     * domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
     * </pre></blockquote><p>
     */
    protected static final BitSet domainlabel = toplabel;


    /**
     * BitSet for hostname.
     * <p><blockquote><pre>
     * hostname      = *( domainlabel "." ) toplabel [ "." ]
     * </pre></blockquote><p>
     */
    protected static final BitSet hostname = new BitSet(256);
    // Static initializer for hostname
    static {
        hostname.or(toplabel);
        // hostname.or(domainlabel);
        hostname.set('.');
    }


    /**
     * BitSet for host.
     * <p><blockquote><pre>
     * host          = hostname | IPv4address | IPv6reference
     * </pre></blockquote><p>
     */
    protected static final BitSet host = new BitSet(256);
    // Static initializer for host
    static {
        host.or(hostname);
        // host.or(IPv4address);
        host.or(IPv6reference); // IPv4address
    }


    /**
     * BitSet for hostport.
     * <p><blockquote><pre>
     * hostport      = host [ ":" port ]
     * </pre></blockquote><p>
     */
    protected static final BitSet hostport = new BitSet(256);
    // Static initializer for hostport
    static {
        hostport.or(host);
        hostport.set(':');
        hostport.or(port);
    }


    /**
     * Bitset for userinfo.
     * <p><blockquote><pre>
     * userinfo      = *( unreserved | escaped |
     *                    ";" | ":" | "&" | "=" | "+" | "$" | "," )
     * </pre></blockquote><p>
     */
    protected static final BitSet userinfo = new BitSet(256);
    // Static initializer for userinfo
    static {
        userinfo.or(unreserved);
        userinfo.or(escaped);
        userinfo.set(';');
        userinfo.set(':');
        userinfo.set('&');
        userinfo.set('=');
        userinfo.set('+');
        userinfo.set('$');
        userinfo.set(',');
    }


    /**
     * BitSet for within the userinfo component like user and password.
     */
    public static final BitSet within_userinfo = new BitSet(256);
    // Static initializer for within_userinfo
    static {
        within_userinfo.or(userinfo);
        within_userinfo.clear(';'); // reserved within authority
        within_userinfo.clear(':');
        within_userinfo.clear('@');
        within_userinfo.clear('?');
        within_userinfo.clear('/');
    }


    /**
     * Bitset for server.
     * <p><blockquote><pre>
     * server        = [ [ userinfo "@" ] hostport ]
     * </pre></blockquote><p>
     */
    protected static final BitSet server = new BitSet(256);
    // Static initializer for server
    static {
        server.or(userinfo);
        server.set('@');
        server.or(hostport);
    }


    /**
     * BitSet for reg_name.
     * <p><blockquote><pre>
     * reg_name      = 1*( unreserved | escaped | "$" | "," |
     *                     ";" | ":" | "@" | "&" | "=" | "+" )
     * </pre></blockquote><p>
     */
    protected static final BitSet reg_name = new BitSet(256);
    // Static initializer for reg_name
    static {
        reg_name.or(unreserved);
        reg_name.or(escaped);
        reg_name.set('$');
        reg_name.set(',');
        reg_name.set(';');
        reg_name.set(':');
        reg_name.set('@');
        reg_name.set('&');
        reg_name.set('=');
        reg_name.set('+');
    }


    /**
     * BitSet for authority.
     * <p><blockquote><pre>
     * authority     = server | reg_name
     * </pre></blockquote><p>
     */
    protected static final BitSet authority = new BitSet(256);
    // Static initializer for authority
    static {
        authority.or(server);
        authority.or(reg_name);
    }


    /**
     * BitSet for scheme.
     * <p><blockquote><pre>
     * scheme        = alpha *( alpha | digit | "+" | "-" | "." )
     * </pre></blockquote><p>
     */
    protected static final BitSet scheme = new BitSet(256);
    // Static initializer for scheme
    static {
        scheme.or(alpha);
        scheme.or(digit);
        scheme.set('+');
        scheme.set('-');
        scheme.set('.');
    }


    /**
     * BitSet for rel_segment.
     * <p><blockquote><pre>
     * rel_segment   = 1*( unreserved | escaped |
     *                     ";" | "@" | "&" | "=" | "+" | "$" | "," )
     * </pre></blockquote><p>
     */
    protected static final BitSet rel_segment = new BitSet(256);
    // Static initializer for rel_segment
    static {
        rel_segment.or(unreserved);
        rel_segment.or(escaped);
        rel_segment.set(';');
        rel_segment.set('@');
        rel_segment.set('&');
        rel_segment.set('=');
        rel_segment.set('+');
        rel_segment.set('$');
        rel_segment.set(',');
    }


    /**
     * BitSet for rel_path.
     * <p><blockquote><pre>
     * rel_path      = rel_segment [ abs_path ]
     * </pre></blockquote><p>
     */
    protected static final BitSet rel_path = new BitSet(256);
    // Static initializer for rel_path
    static {
        rel_path.or(rel_segment);
        rel_path.or(abs_path);
    }


    /**
     * BitSet for net_path.
     * <p><blockquote><pre>
     * net_path      = "//" authority [ abs_path ]
     * </pre></blockquote><p>
     */
    protected static final BitSet net_path = new BitSet(256);
    // Static initializer for net_path
    static {
        net_path.set('/');
        net_path.or(authority);
        net_path.or(abs_path);
    }
    

    /**
     * BitSet for hier_part.
     * <p><blockquote><pre>
     * hier_part     = ( net_path | abs_path ) [ "?" query ]
     * </pre></blockquote><p>
     */
    protected static final BitSet hier_part = new BitSet(256);
    // Static initializer for hier_part
    static {
        hier_part.or(net_path);
        hier_part.or(abs_path);
        // hier_part.set('?'); aleady included
        hier_part.or(query);
    }


    /**
     * BitSet for relativeURI.
     * <p><blockquote><pre>
     * relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ]
     * </pre></blockquote><p>
     */
    protected static final BitSet relativeURI = new BitSet(256);
    // Static initializer for relativeURI
    static {
        relativeURI.or(net_path);
        relativeURI.or(abs_path);
        relativeURI.or(rel_path);
        // relativeURI.set('?'); aleady included
        relativeURI.or(query);
    }


    /**
     * BitSet for absoluteURI.
     * <p><blockquote><pre>
     * absoluteURI   = scheme ":" ( hier_part | opaque_part )
     * </pre></blockquote><p>
     */
    protected static final BitSet absoluteURI = new BitSet(256);
    // Static initializer for absoluteURI
    static {
        absoluteURI.or(scheme);
        absoluteURI.set(':');
        absoluteURI.or(hier_part);
        absoluteURI.or(opaque_part);
    }


    /**
     * BitSet for URI-reference.
     * <p><blockquote><pre>
     * URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
     * </pre></blockquote><p>
     */
    protected static final BitSet URI_reference = new BitSet(256);
    // Static initializer for URI_reference
    static {
        URI_reference.or(absoluteURI);
        URI_reference.or(relativeURI);
        URI_reference.set('#');
        URI_reference.or(fragment);
    }

    // ---------------------------- Characters disallowed within the URI syntax
    // Excluded US-ASCII Characters are like control, space, delims and unwise

    /**
     * BitSet for control.
     */
    public static final BitSet control = new BitSet(256);
    // Static initializer for control
    static {
        for (int i = 0; i <= 0x1F; i++) {
            control.set(i);
        }
        control.set(0x7F);
    }

    /**
     * BitSet for space.
     */
    public static final BitSet space = new BitSet(256);
    // Static initializer for space
    static {
        space.set(0x20);
    }


    /**
     * BitSet for delims.
     */
    public static final BitSet delims = new BitSet(256);
    // Static initializer for delims
    static {
        delims.set('<');
        delims.set('>');
        delims.set('#');
        delims.set('%');
        delims.set('"');
    }


    /**
     * BitSet for unwise.
     */
    public static final BitSet unwise = new BitSet(256);
    // Static initializer for unwise
    static {
        unwise.set('{');
        unwise.set('}');
        unwise.set('|');
        unwise.set('\\');
        unwise.set('^');
        unwise.set('[');
        unwise.set(']');
        unwise.set('`');
    }


    /**
     * Disallowed rel_path before escaping.
     */
    public static final BitSet disallowed_rel_path = new BitSet(256);
    // Static initializer for disallowed_rel_path
    static {
        disallowed_rel_path.or(uric);
        disallowed_rel_path.andNot(rel_path);
    }


    /**
     * Disallowed opaque_part before escaping.
     */
    public static final BitSet disallowed_opaque_part = new BitSet(256);
    // Static initializer for disallowed_opaque_part
    static {
        disallowed_opaque_part.or(uric);
        disallowed_opaque_part.andNot(opaque_part);
    }

    // ----------------------- Characters allowed within and for each component

    /**
     * Those characters that are allowed for the authority component.
     */
    public static final BitSet allowed_authority = new BitSet(256);
    // Static initializer for allowed_authority
    static {
        allowed_authority.or(authority);
        allowed_authority.clear('%');
    }


    /**
     * Those characters that are allowed for the opaque_part.
     */
    public static final BitSet allowed_opaque_part = new BitSet(256);
    // Static initializer for allowed_opaque_part 
    static {
        allowed_opaque_part.or(opaque_part);
        allowed_opaque_part.clear('%');
    }


    /**
     * Those characters that are allowed for the reg_name.
     */
    public static final BitSet allowed_reg_name = new BitSet(256);
    // Static initializer for allowed_reg_name 
    static {
        allowed_reg_name.or(reg_name);
        // allowed_reg_name.andNot(percent);
        allowed_reg_name.clear('%');
    }


    /**
     * Those characters that are allowed for the userinfo component.
     */
    public static final BitSet allowed_userinfo = new BitSet(256);
    // Static initializer for allowed_userinfo
    static {
        allowed_userinfo.or(userinfo);
        // allowed_userinfo.andNot(percent);
        allowed_userinfo.clear('%');
    }


    /**
     * Those characters that are allowed for within the userinfo component.
     */
    public static final BitSet allowed_within_userinfo = new BitSet(256);
    // Static initializer for allowed_within_userinfo
    static {
        allowed_within_userinfo.or(within_userinfo);
        allowed_within_userinfo.clear('%');
    }


    /**
     * Those characters that are allowed for the IPv6reference component.
     * The characters '[', ']' in IPv6reference should be excluded.
     */
    public static final BitSet allowed_IPv6reference = new BitSet(256);
    // Static initializer for allowed_IPv6reference
    static {
        allowed_IPv6reference.or(IPv6reference);
        // allowed_IPv6reference.andNot(unwise);
        allowed_IPv6reference.clear('[');
        allowed_IPv6reference.clear(']');
    }


    /**
     * Those characters that are allowed for the host component.
     * The characters '[', ']' in IPv6reference should be excluded.
     */
    public static final BitSet allowed_host = new BitSet(256);
    // Static initializer for allowed_host
    static {
        allowed_host.or(hostname);
        allowed_host.or(allowed_IPv6reference);
    }


    /**
     * Those characters that are allowed for the authority component.
     */
    public static final BitSet allowed_within_authority = new BitSet(256);
    // Static initializer for allowed_within_authority
    static {
        allowed_within_authority.or(server);
        allowed_within_authority.or(reg_name);
        allowed_within_authority.clear(';');
        allowed_within_authority.clear(':');
        allowed_within_authority.clear('@');
        allowed_within_authority.clear('?');
        allowed_within_authority.clear('/');
    }


    /**
     * Those characters that are allowed for the abs_path.
     */
    public static final BitSet allowed_abs_path = new BitSet(256);
    // Static initializer for allowed_abs_path
    static {
        allowed_abs_path.or(abs_path);
        // allowed_abs_path.set('/');  // aleady included
        allowed_abs_path.andNot(percent);
    }


    /**
     * Those characters that are allowed for the rel_path.
     */
    public static final BitSet allowed_rel_path = new BitSet(256);
    // Static initializer for allowed_rel_path
    static {
        allowed_rel_path.or(rel_path);
        allowed_rel_path.clear('%');
    }


    /**
     * Those characters that are allowed within the path.
     */
    public static final BitSet allowed_within_path = new BitSet(256);
    // Static initializer for allowed_within_path
    static {
        allowed_within_path.or(abs_path);
        allowed_within_path.clear('/');
        allowed_within_path.clear(';');
        allowed_within_path.clear('=');
        allowed_within_path.clear('?');
    }


    /**
     * Those characters that are allowed for the query component.
     */
    public static final BitSet allowed_query = new BitSet(256);
    // Static initializer for allowed_query
    static {
        allowed_query.or(uric);
        allowed_query.clear('%');
    }


    /**
     * Those characters that are allowed within the query component.
     */
    public static final BitSet allowed_within_query = new BitSet(256);
    // Static initializer for allowed_within_query
    static {
        allowed_within_query.or(allowed_query);
        allowed_within_query.andNot(reserved); // excluded 'reserved'
    }


    /**
     * Those characters that are allowed for the fragment component.
     */
    public static final BitSet allowed_fragment = new BitSet(256);
    // Static initializer for allowed_fragment
    static {
        allowed_fragment.or(uric);
        allowed_fragment.clear('%');
    }

    // ------------------------------------------- Flags for this URI-reference

    // TODO: Figure out what all these variables are for and provide javadoc

    // URI-reference = [ absoluteURI | relativeURI ] [ "#" fragment ]
    // absoluteURI   = scheme ":" ( hier_part | opaque_part )
    protected boolean _is_hier_part;
    protected boolean _is_opaque_part;
    // relativeURI   = ( net_path | abs_path | rel_path ) [ "?" query ] 
    // hier_part     = ( net_path | abs_path ) [ "?" query ]
    protected boolean _is_net_path;
    protected boolean _is_abs_path;
    protected boolean _is_rel_path;
    // net_path      = "//" authority [ abs_path ]