content: /*
   *  This file is part of AndroidIDE.
   *
   *  AndroidIDE is free software: you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation, either version 3 of the License, or
   *  (at your option) any later version.
   *
   *  AndroidIDE is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
   */
  
  /*
   * reserved comment block
   * DO NOT REMOVE OR ALTER!
   */
  /*
   * Copyright 1999-2005 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.
   */
  
  package jaxp.sun.org.apache.xerces.internal.util;
  
  import java.io.IOException;
  import java.io.Serializable;
  import java.util.Objects;
  
  /**********************************************************************
  * A class to represent a Uniform Resource Identifier (URI). This class
  * is designed to handle the parsing of URIs and provide access to
  * the various components (scheme, host, port, userinfo, path, query
  * string and fragment) that may constitute a URI.
  * <p>
  * Parsing of a URI specification is done according to the URI
  * syntax described in
  * <a href="http://www.ietf.org/rfc/rfc2396.txt?number=2396">RFC 2396</a>,
  * and amended by
  * <a href="http://www.ietf.org/rfc/rfc2732.txt?number=2732">RFC 2732</a>.
  * <p>
  * Every absolute URI consists of a scheme, followed by a colon (':'),
  * followed by a scheme-specific part. For URIs that follow the
  * "generic URI" syntax, the scheme-specific part begins with two
  * slashes ("//") and may be followed by an authority segment (comprised
  * of user information, host, and port), path segment, query segment
  * and fragment. Note that RFC 2396 no longer specifies the use of the
  * parameters segment and excludes the "user:password" syntax as part of
  * the authority segment. If "user:password" appears in a URI, the entire
  * user/password string is stored as userinfo.
  * <p>
  * For URIs that do not follow the "generic URI" syntax (e.g. mailto),
  * the entire scheme-specific part is treated as the "path" portion
  * of the URI.
  * <p>
  * Note that, unlike the java.net.URL class, this class does not provide
  * any built-in network access functionality nor does it provide any
  * scheme-specific functionality (for example, it does not know a
  * default port for a specific scheme). Rather, it only knows the
  * grammar and basic set of operations that can be applied to a URI.
  *
  *
  **********************************************************************/
   public class URI implements Serializable {
  
    /*******************************************************************
    * MalformedURIExceptions are thrown in the process of building a URI
    * or setting fields on a URI when an operation would result in an
    * invalid URI specification.
    *
    ********************************************************************/
    public static class MalformedURIException extends IOException {
  
     /** Serialization version. */
     static final long serialVersionUID = -6695054834342951930L;
  
     /******************************************************************
      * Constructs a <code>MalformedURIException</code> with no specified
      * detail message.
      ******************************************************************/
      public MalformedURIException() {
        super();
      }
  
      /*****************************************************************
      * Constructs a <code>MalformedURIException</code> with the
      * specified detail message.
      *
      * @param p_msg the detail message.
      ******************************************************************/
      public MalformedURIException(String p_msg) {
        super(p_msg);
      }
    }
  
    /** Serialization version. */
    static final long serialVersionUID = 1601921774685357214L;
  
    private static final byte [] fgLookupTable = new byte[128];
  
    /**
     * Character Classes
     */
  
    /** reserved characters ;/?:@&=+$,[] */
    //RFC 2732 added '[' and ']' as reserved characters
    private static final int RESERVED_CHARACTERS = 0x01;
  
    /** URI punctuation mark characters: -_.!~*'() - these, combined with
        alphanumerics, constitute the "unreserved" characters */
    private static final int MARK_CHARACTERS = 0x02;
  
    /** scheme can be composed of alphanumerics and these characters: +-. */
    private static final int SCHEME_CHARACTERS = 0x04;
  
    /** userinfo can be composed of unreserved, escaped and these
        characters: ;:&=+$, */
    private static final int USERINFO_CHARACTERS = 0x08;
  
    /** ASCII letter characters */
    private static final int ASCII_ALPHA_CHARACTERS = 0x10;
  
    /** ASCII digit characters */
    private static final int ASCII_DIGIT_CHARACTERS = 0x20;
  
    /** ASCII hex characters */
    private static final int ASCII_HEX_CHARACTERS = 0x40;
  
    /** Path characters */
    private static final int PATH_CHARACTERS = 0x80;
  
    /** Mask for alpha-numeric characters */
    private static final int MASK_ALPHA_NUMERIC = ASCII_ALPHA_CHARACTERS | ASCII_DIGIT_CHARACTERS;
  
    /** Mask for unreserved characters */
    private static final int MASK_UNRESERVED_MASK = MASK_ALPHA_NUMERIC | MARK_CHARACTERS;
  
    /** Mask for URI allowable characters except for % */
    private static final int MASK_URI_CHARACTER = MASK_UNRESERVED_MASK | RESERVED_CHARACTERS;
  
    /** Mask for scheme characters */
    private static final int MASK_SCHEME_CHARACTER = MASK_ALPHA_NUMERIC | SCHEME_CHARACTERS;
  
    /** Mask for userinfo characters */
    private static final int MASK_USERINFO_CHARACTER = MASK_UNRESERVED_MASK | USERINFO_CHARACTERS;
  
    /** Mask for path characters */
    private static final int MASK_PATH_CHARACTER = MASK_UNRESERVED_MASK | PATH_CHARACTERS;
  
    static {
        // Add ASCII Digits and ASCII Hex Numbers
        for (int i = '0'; i <= '9'; ++i) {
            fgLookupTable[i] |= ASCII_DIGIT_CHARACTERS | ASCII_HEX_CHARACTERS;
        }
  
        // Add ASCII Letters and ASCII Hex Numbers
        for (int i = 'A'; i <= 'F'; ++i) {
            fgLookupTable[i] |= ASCII_ALPHA_CHARACTERS | ASCII_HEX_CHARACTERS;
            fgLookupTable[i+0x00000020] |= ASCII_ALPHA_CHARACTERS | ASCII_HEX_CHARACTERS;
        }
  
        // Add ASCII Letters
        for (int i = 'G'; i <= 'Z'; ++i) {
            fgLookupTable[i] |= ASCII_ALPHA_CHARACTERS;
            fgLookupTable[i+0x00000020] |= ASCII_ALPHA_CHARACTERS;
        }
  
        // Add Reserved Characters
        fgLookupTable[';'] |= RESERVED_CHARACTERS;
        fgLookupTable['/'] |= RESERVED_CHARACTERS;
        fgLookupTable['?'] |= RESERVED_CHARACTERS;
        fgLookupTable[':'] |= RESERVED_CHARACTERS;
        fgLookupTable['@'] |= RESERVED_CHARACTERS;
        fgLookupTable['&'] |= RESERVED_CHARACTERS;
        fgLookupTable['='] |= RESERVED_CHARACTERS;
        fgLookupTable['+'] |= RESERVED_CHARACTERS;
        fgLookupTable['$'] |= RESERVED_CHARACTERS;
        fgLookupTable[','] |= RESERVED_CHARACTERS;
        fgLookupTable['['] |= RESERVED_CHARACTERS;
        fgLookupTable[']'] |= RESERVED_CHARACTERS;
  
        // Add Mark Characters
        fgLookupTable['-'] |= MARK_CHARACTERS;
        fgLookupTable['_'] |= MARK_CHARACTERS;
        fgLookupTable['.'] |= MARK_CHARACTERS;
        fgLookupTable['!'] |= MARK_CHARACTERS;
        fgLookupTable['~'] |= MARK_CHARACTERS;
        fgLookupTable['*'] |= MARK_CHARACTERS;
        fgLookupTable['\''] |= MARK_CHARACTERS;
        fgLookupTable['('] |= MARK_CHARACTERS;
        fgLookupTable[')'] |= MARK_CHARACTERS;
  
        // Add Scheme Characters
        fgLookupTable['+'] |= SCHEME_CHARACTERS;
        fgLookupTable['-'] |= SCHEME_CHARACTERS;
        fgLookupTable['.'] |= SCHEME_CHARACTERS;
  
        // Add Userinfo Characters
        fgLookupTable[';'] |= USERINFO_CHARACTERS;
        fgLookupTable[':'] |= USERINFO_CHARACTERS;
        fgLookupTable['&'] |= USERINFO_CHARACTERS;
        fgLookupTable['='] |= USERINFO_CHARACTERS;
        fgLookupTable['+'] |= USERINFO_CHARACTERS;
        fgLookupTable['$'] |= USERINFO_CHARACTERS;
        fgLookupTable[','] |= USERINFO_CHARACTERS;
  
        // Add Path Characters
        fgLookupTable[';'] |= PATH_CHARACTERS;
        fgLookupTable['/'] |= PATH_CHARACTERS;
        fgLookupTable[':'] |= PATH_CHARACTERS;
        fgLookupTable['@'] |= PATH_CHARACTERS;
        fgLookupTable['&'] |= PATH_CHARACTERS;
        fgLookupTable['='] |= PATH_CHARACTERS;
        fgLookupTable['+'] |= PATH_CHARACTERS;
        fgLookupTable['$'] |= PATH_CHARACTERS;
        fgLookupTable[','] |= PATH_CHARACTERS;
    }
  
    /** Stores the scheme (usually the protocol) for this URI. */
    private String m_scheme = null;
  
    /** If specified, stores the userinfo for this URI; otherwise null */
    private String m_userinfo = null;
  
    /** If specified, stores the host for this URI; otherwise null */
    private String m_host = null;
  
    /** If specified, stores the port for this URI; otherwise -1 */
    private int m_port = -1;
  
    /** If specified, stores the registry based authority for this URI; otherwise -1 */
    private String m_regAuthority = null;
  
    /** If specified, stores the path for this URI; otherwise null */
    private String m_path = null;
  
    /** If specified, stores the query string for this URI; otherwise
        null.  */
    private String m_queryString = null;
  
    /** If specified, stores the fragment for this URI; otherwise null */
    private String m_fragment = null;
  
    private static boolean DEBUG = false;
  
    /**
    * Construct a new and uninitialized URI.
    */
    public URI() {
    }
  
   /**
    * Construct a new URI from another URI. All fields for this URI are
    * set equal to the fields of the URI passed in.
    *
    * @param p_other the URI to copy (cannot be null)
    */
    public URI(URI p_other) {
      initialize(p_other);
    }
  
   /**
    * Construct a new URI from a URI specification string. If the
    * specification follows the "generic URI" syntax, (two slashes
    * following the first colon), the specification will be parsed
    * accordingly - setting the scheme, userinfo, host,port, path, query
    * string and fragment fields as necessary. If the specification does
    * not follow the "generic URI" syntax, the specification is parsed
    * into a scheme and scheme-specific part (stored as the path) only.
    *
    * @param p_uriSpec the URI specification string (cannot be null or
    *                  empty)
    *
    * @exception MalformedURIException if p_uriSpec violates any syntax
    *                                   rules
    */
    public URI(String p_uriSpec) throws MalformedURIException {
      this((URI)null, p_uriSpec);
    }
  
    /**
     * Construct a new URI from a URI specification string. If the
     * specification follows the "generic URI" syntax, (two slashes
     * following the first colon), the specification will be parsed
     * accordingly - setting the scheme, userinfo, host,port, path, query
     * string and fragment fields as necessary. If the specification does
     * not follow the "generic URI" syntax, the specification is parsed
     * into a scheme and scheme-specific part (stored as the path) only.
     * Construct a relative URI if boolean is assigned to "true"
     * and p_uriSpec is not valid absolute URI, instead of throwing an exception.
     *
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty)
     * @param allowNonAbsoluteURI true to permit non-absolute URIs,
     *                            false otherwise.
     *
     * @exception MalformedURIException if p_uriSpec violates any syntax
     *                                   rules
     */
    public URI(String p_uriSpec, boolean allowNonAbsoluteURI) throws MalformedURIException {
        this((URI)null, p_uriSpec, allowNonAbsoluteURI);
    }
  
   /**
    * Construct a new URI from a base URI and a URI specification string.
    * The URI specification string may be a relative URI.
    *
    * @param p_base the base URI (cannot be null if p_uriSpec is null or
    *               empty)
    * @param p_uriSpec the URI specification string (cannot be null or
    *                  empty if p_base is null)
    *
    * @exception MalformedURIException if p_uriSpec violates any syntax
    *                                  rules
    */
    public URI(URI p_base, String p_uriSpec) throws MalformedURIException {
      initialize(p_base, p_uriSpec);
    }
  
    /**
     * Construct a new URI from a base URI and a URI specification string.
     * The URI specification string may be a relative URI.
     * Construct a relative URI if boolean is assigned to "true"
     * and p_uriSpec is not valid absolute URI and p_base is null
     * instead of throwing an exception.
     *
     * @param p_base the base URI (cannot be null if p_uriSpec is null or
     *               empty)
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty if p_base is null)
     * @param allowNonAbsoluteURI true to permit non-absolute URIs,
     *                            false otherwise.
     *
     * @exception MalformedURIException if p_uriSpec violates any syntax
     *                                  rules
     */
    public URI(URI p_base, String p_uriSpec, boolean allowNonAbsoluteURI) throws MalformedURIException {
        initialize(p_base, p_uriSpec, allowNonAbsoluteURI);
    }
  
   /**
    * Construct a new URI that does not follow the generic URI syntax.
    * Only the scheme and scheme-specific part (stored as the path) are
    * initialized.
    *
    * @param p_scheme the URI scheme (cannot be null or empty)
    * @param p_schemeSpecificPart the scheme-specific part (cannot be
    *                             null or empty)
    *
    * @exception MalformedURIException if p_scheme violates any
    *                                  syntax rules
    */
    public URI(String p_scheme, String p_schemeSpecificPart)
               throws MalformedURIException {
      if (p_scheme == null || p_scheme.trim().length() == 0) {
        throw new MalformedURIException(
              "Cannot construct URI with null/empty scheme!");
      }
      if (p_schemeSpecificPart == null ||
          p_schemeSpecificPart.trim().length() == 0) {
        throw new MalformedURIException(
            "Cannot construct URI with null/empty scheme-specific part!");
      }
      setScheme(p_scheme);
      setPath(p_schemeSpecificPart);
    }
  
   /**
    * Construct a new URI that follows the generic URI syntax from its
    * component parts. Each component is validated for syntax and some
    * basic semantic checks are performed as well.  See the individual
    * setter methods for specifics.
    *
    * @param p_scheme the URI scheme (cannot be null or empty)
    * @param p_host the hostname, IPv4 address or IPv6 reference for the URI
    * @param p_path the URI path - if the path contains '?' or '#',
    *               then the query string and/or fragment will be
    *               set from the path; however, if the query and
    *               fragment are specified both in the path and as
    *               separate parameters, an exception is thrown
    * @param p_queryString the URI query string (cannot be specified
    *                      if path is null)
    * @param p_fragment the URI fragment (cannot be specified if path
    *                   is null)
    *
    * @exception MalformedURIException if any of the parameters violates
    *                                  syntax rules or semantic rules
    */
    public URI(String p_scheme, String p_host, String p_path,
               String p_queryString, String p_fragment)
           throws MalformedURIException {
      this(p_scheme, null, p_host, -1, p_path, p_queryString, p_fragment);
    }
  
   /**
    * Construct a new URI that follows the generic URI syntax from its
    * component parts. Each component is validated for syntax and some
    * basic semantic checks are performed as well.  See the individual
    * setter methods for specifics.
    *
    * @param p_scheme the URI scheme (cannot be null or empty)
    * @param p_userinfo the URI userinfo (cannot be specified if host
    *                   is null)
    * @param p_host the hostname, IPv4 address or IPv6 reference for the URI
    * @param p_port the URI port (may be -1 for "unspecified"; cannot
    *               be specified if host is null)
    * @param p_path the URI path - if the path contains '?' or '#',
    *               then the query string and/or fragment will be
    *               set from the path; however, if the query and
    *               fragment are specified both in the path and as
    *               separate parameters, an exception is thrown
    * @param p_queryString the URI query string (cannot be specified
    *                      if path is null)
    * @param p_fragment the URI fragment (cannot be specified if path
    *                   is null)
    *
    * @exception MalformedURIException if any of the parameters violates
    *                                  syntax rules or semantic rules
    */
    public URI(String p_scheme, String p_userinfo,
               String p_host, int p_port, String p_path,
               String p_queryString, String p_fragment)
           throws MalformedURIException {
      if (p_scheme == null || p_scheme.trim().length() == 0) {
        throw new MalformedURIException("Scheme is required!");
      }
  
      if (p_host == null) {
        if (p_userinfo != null) {
          throw new MalformedURIException(
               "Userinfo may not be specified if host is not specified!");
        }
        if (p_port != -1) {
          throw new MalformedURIException(
               "Port may not be specified if host is not specified!");
        }
      }
  
      if (p_path != null) {
        if (p_path.indexOf('?') != -1 && p_queryString != null) {
          throw new MalformedURIException(
            "Query string cannot be specified in path and query string!");
        }
  
        if (p_path.indexOf('#') != -1 && p_fragment != null) {
          throw new MalformedURIException(
            "Fragment cannot be specified in both the path and fragment!");
        }
      }
  
      setScheme(p_scheme);
      setHost(p_host);
      setPort(p_port);
      setUserinfo(p_userinfo);
      setPath(p_path);
      setQueryString(p_queryString);
      setFragment(p_fragment);
    }
  
   /**
    * Initialize all fields of this URI from another URI.
    *
    * @param p_other the URI to copy (cannot be null)
    */
    private void initialize(URI p_other) {
      m_scheme = p_other.getScheme();
      m_userinfo = p_other.getUserinfo();
      m_host = p_other.getHost();
      m_port = p_other.getPort();
      m_regAuthority = p_other.getRegBasedAuthority();
      m_path = p_other.getPath();
      m_queryString = p_other.getQueryString();
      m_fragment = p_other.getFragment();
    }
  
    /**
     * Initializes this URI from a base URI and a URI specification string.
     * See RFC 2396 Section 4 and Appendix B for specifications on parsing
     * the URI and Section 5 for specifications on resolving relative URIs
     * and relative paths.
     *
     * @param p_base the base URI (may be null if p_uriSpec is an absolute
     *               URI)
     * @param p_uriSpec the URI spec string which may be an absolute or
     *                  relative URI (can only be null/empty if p_base
     *                  is not null)
     * @param allowNonAbsoluteURI true to permit non-absolute URIs,
     *                         in case of relative URI, false otherwise.
     *
     * @exception MalformedURIException if p_base is null and p_uriSpec
     *                                  is not an absolute URI or if
     *                                  p_uriSpec violates syntax rules
     */
    private void initialize(URI p_base, String p_uriSpec, boolean allowNonAbsoluteURI)
        throws MalformedURIException {
  
        String uriSpec = p_uriSpec;
        int uriSpecLen = (uriSpec != null) ? uriSpec.length() : 0;
  
        if (p_base == null && uriSpecLen == 0) {
            if (allowNonAbsoluteURI) {
                m_path = "";
                return;
            }
            throw new MalformedURIException("Cannot initialize URI with empty parameters.");
        }
  
        // just make a copy of the base if spec is empty
        if (uriSpecLen == 0) {
            initialize(p_base);
            return;
        }
  
        int index = 0;
  
        // Check for scheme, which must be before '/', '?' or '#'.
        int colonIdx = uriSpec.indexOf(':');
        if (colonIdx != -1) {
            final int searchFrom = colonIdx - 1;
            // search backwards starting from character before ':'.
            int slashIdx = uriSpec.lastIndexOf('/', searchFrom);
            int queryIdx = uriSpec.lastIndexOf('?', searchFrom);
            int fragmentIdx = uriSpec.lastIndexOf('#', searchFrom);
  
            if (colonIdx == 0 || slashIdx != -1 ||
                queryIdx != -1 || fragmentIdx != -1) {
                // A standalone base is a valid URI according to spec
                if (colonIdx == 0 || (p_base == null && fragmentIdx != 0 && !allowNonAbsoluteURI)) {
                    throw new MalformedURIException("No scheme found in URI.");
                }
            }
            else {
                initializeScheme(uriSpec);
                index = m_scheme.length()+1;
  
                // Neither 'scheme:' or 'scheme:#fragment' are valid URIs.
                if (colonIdx == uriSpecLen - 1 || uriSpec.charAt(colonIdx+1) == '#') {
                    throw new MalformedURIException("Scheme specific part cannot be empty.");
                }
            }
        }
        else if (p_base == null && uriSpec.indexOf('#') != 0 && !allowNonAbsoluteURI) {
            throw new MalformedURIException("No scheme found in URI.");
        }
  
        // Two slashes means we may have authority, but definitely means we're either
        // matching net_path or abs_path. These two productions are ambiguous in that
        // every net_path (except those containing an IPv6Reference) is an abs_path.
        // RFC 2396 resolves this ambiguity by applying a greedy left most matching rule.
        // Try matching net_path first, and if that fails we don't have authority so
        // then attempt to match abs_path.
        //
        // net_path = "//" authority [ abs_path ]
        // abs_path = "/"  path_segments
        if (((index+1) < uriSpecLen) &&
            (uriSpec.charAt(index) == '/' && uriSpec.charAt(index+1) == '/')) {
            index += 2;
            int startPos = index;
  
            // Authority will be everything up to path, query or fragment
            char testChar = '\0';
            while (index < uriSpecLen) {
                testChar = uriSpec.charAt(index);
                if (testChar == '/' || testChar == '?' || testChar == '#') {
                    break;
                }
                index++;
            }
  
            // Attempt to parse authority. If the section is an empty string
            // this is a valid server based authority, so set the host to this
            // value.
            if (index > startPos) {
                // If we didn't find authority we need to back up. Attempt to
                // match against abs_path next.
                if (!initializeAuthority(uriSpec.substring(startPos, index))) {
                    index = startPos - 2;
                }
            }
            else {
                m_host = "";
            }
        }
  
        initializePath(uriSpec, index);
  
        // Resolve relative URI to base URI - see RFC 2396 Section 5.2
        // In some cases, it might make more sense to throw an exception
        // (when scheme is specified is the string spec and the base URI
        // is also specified, for example), but we're just following the
        // RFC specifications
        if (p_base != null) {
            absolutize(p_base);
        }
    }
  
   /**
    * Initializes this URI from a base URI and a URI specification string.
    * See RFC 2396 Section 4 and Appendix B for specifications on parsing
    * the URI and Section 5 for specifications on resolving relative URIs
    * and relative paths.
    *
    * @param p_base the base URI (may be null if p_uriSpec is an absolute
    *               URI)
    * @param p_uriSpec the URI spec string which may be an absolute or
    *                  relative URI (can only be null/empty if p_base
    *                  is not null)
    *
    * @exception MalformedURIException if p_base is null and p_uriSpec
    *                                  is not an absolute URI or if
    *                                  p_uriSpec violates syntax rules
    */
    private void initialize(URI p_base, String p_uriSpec)
                           throws MalformedURIException {
  
      String uriSpec = p_uriSpec;
      int uriSpecLen = (uriSpec != null) ? uriSpec.length() : 0;
  
      if (p_base == null && uriSpecLen == 0) {
        throw new MalformedURIException(
                    "Cannot initialize URI with empty parameters.");
      }
  
      // just make a copy of the base if spec is empty
      if (uriSpecLen == 0) {
        initialize(p_base);
        return;
      }
  
      int index = 0;
  
      // Check for scheme, which must be before '/', '?' or '#'.
      int colonIdx = uriSpec.indexOf(':');
      if (colonIdx != -1) {
          final int searchFrom = colonIdx - 1;
          // search backwards starting from character before ':'.
          int slashIdx = uriSpec.lastIndexOf('/', searchFrom);
          int queryIdx = uriSpec.lastIndexOf('?', searchFrom);
          int fragmentIdx = uriSpec.lastIndexOf('#', searchFrom);
  
          if (colonIdx == 0 || slashIdx != -1 ||
              queryIdx != -1 || fragmentIdx != -1) {
              // A standalone base is a valid URI according to spec
              if (colonIdx == 0 || (p_base == null && fragmentIdx != 0)) {
                  throw new MalformedURIException("No scheme found in URI.");
              }
          }
          else {
              initializeScheme(uriSpec);
              index = m_scheme.length()+1;
  
              // Neither 'scheme:' or 'scheme:#fragment' are valid URIs.
              if (colonIdx == uriSpecLen - 1 || uriSpec.charAt(colonIdx+1) == '#') {
                  throw new MalformedURIException("Scheme specific part cannot be empty.");
              }
          }
      }
      else if (p_base == null && uriSpec.indexOf('#') != 0) {
          throw new MalformedURIException("No scheme found in URI.");
      }
  
      // Two slashes means we may have authority, but definitely means we're either
      // matching net_path or abs_path. These two productions are ambiguous in that
      // every net_path (except those containing an IPv6Reference) is an abs_path.
      // RFC 2396 resolves this ambiguity by applying a greedy left most matching rule.
      // Try matching net_path first, and if that fails we don't have authority so
      // then attempt to match abs_path.
      //
      // net_path = "//" authority [ abs_path ]
      // abs_path = "/"  path_segments
      if (((index+1) < uriSpecLen) &&
          (uriSpec.charAt(index) == '/' && uriSpec.charAt(index+1) == '/')) {
        index += 2;
        int startPos = index;
  
        // Authority will be everything up to path, query or fragment
        char testChar = '\0';
        while (index < uriSpecLen) {
          testChar = uriSpec.charAt(index);
          if (testChar == '/' || testChar == '?' || testChar == '#') {
            break;
          }
          index++;
        }
  
        // Attempt to parse authority. If the section is an empty string
        // this is a valid server based authority, so set the host to this
        // value.
        if (index > startPos) {
          // If we didn't find authority we need to back up. Attempt to
          // match against abs_path next.
          if (!initializeAuthority(uriSpec.substring(startPos, index))) {
            index = startPos - 2;
          }
        } else if (index < uriSpecLen) {
          //Same as java.net.URI:
          // DEVIATION: Allow empty authority prior to non-empty
          // path, query component or fragment identifier
          m_host = "";
        } else {
          throw new MalformedURIException("Expected authority.");
        }
      }
  
      initializePath(uriSpec, index);
  
      // Resolve relative URI to base URI - see RFC 2396 Section 5.2
      // In some cases, it might make more sense to throw an exception
      // (when scheme is specified is the string spec and the base URI
      // is also specified, for example), but we're just following the
      // RFC specifications
      if (p_base != null) {
          absolutize(p_base);
      }
    }
  
    /**
     * Absolutize URI with given base URI.
     *
     * @param p_base base URI for absolutization
     */
    public void absolutize(URI p_base) {
  
        // check to see if this is the current doc - RFC 2396 5.2 #2
        // note that this is slightly different from the RFC spec in that
        // we don't include the check for query string being null
        // - this handles cases where the urispec is just a query
        // string or a fragment (e.g. "?y" or "#s") -
        // see <http://www.ics.uci.edu/~fielding/url/test1.html> which
        // identified this as a bug in the RFC
        if (m_path.length() == 0 && m_scheme == null &&
            m_host == null && m_regAuthority == null) {
            m_scheme = p_base.getScheme();
            m_userinfo = p_base.getUserinfo();
            m_host = p_base.getHost();
            m_port = p_base.getPort();
            m_regAuthority = p_base.getRegBasedAuthority();
            m_path = p_base.getPath();
  
            if (m_queryString == null) {
                m_queryString = p_base.getQueryString();
  
                if (m_fragment == null) {
                    m_fragment = p_base.getFragment();
                }
            }
            return;
        }
  
        // check for scheme - RFC 2396 5.2 #3
        // if we found a scheme, it means absolute URI, so we're done
        if (m_scheme == null) {
            m_scheme = p_base.getScheme();
        }
        else {
            return;
        }
  
        // check for authority - RFC 2396 5.2 #4
        // if we found a host, then we've got a network path, so we're done
        if (m_host == null && m_regAuthority == null) {
            m_userinfo = p_base.getUserinfo();
            m_host = p_base.getHost();
            m_port = p_base.getPort();
            m_regAuthority = p_base.getRegBasedAuthority();
        }
        else {
            return;
        }
  
        // check for absolute path - RFC 2396 5.2 #5
        if (m_path.length() > 0 &&
                m_path.startsWith("/")) {
            return;
        }
  
        // if we get to this point, we need to resolve relative path
        // RFC 2396 5.2 #6
        String path = "";
        String basePath = p_base.getPath();
  
        // 6a - get all but the last segment of the base URI path
        if (basePath != null && basePath.length() > 0) {
            int lastSlash = basePath.lastIndexOf('/');
            if (lastSlash != -1) {
                path = basePath.substring(0, lastSlash+1);
            }
        }
        else if (m_path.length() > 0) {
            path = "/";
        }
  
        // 6b - append the relative URI path
        path = path.concat(m_path);
  
        // 6c - remove all "./" where "." is a complete path segment
        int index = -1;
        while ((index = path.indexOf("/./")) != -1) {
            path = path.substring(0, index+1).concat(path.substring(index+3));
        }
  
        // 6d - remove "." if path ends with "." as a complete path segment
        if (path.endsWith("/.")) {
            path = path.substring(0, path.length()-1);
        }
  
        // 6e - remove all "<segment>/../" where "<segment>" is a complete
        // path segment not equal to ".."
        index = 1;
        int segIndex = -1;
        String tempString = null;
  
        while ((index = path.indexOf("/../", index)) > 0) {
            tempString = path.substring(0, path.indexOf("/../"));
            segIndex = tempString.lastIndexOf('/');
            if (segIndex != -1) {
                if (!tempString.substring(segIndex).equals("..")) {
                    path = path.substring(0, segIndex+1).concat(path.substring(index+4));
                    index = segIndex;
                }
                else {
                    index += 4;
                }
            }
            else {
                index += 4;
            }
        }
  
        // 6f - remove ending "<segment>/.." where "<segment>" is a
        // complete path segment
        if (path.endsWith("/..")) {
            tempString = path.substring(0, path.length()-3);
            segIndex = tempString.lastIndexOf('/');
            if (segIndex != -1) {
                path = path.substring(0, segIndex+1);
            }
        }
        m_path = path;
    }
  
   /**
    * Initialize the scheme for this URI from a URI string spec.
    *
    * @param p_uriSpec the URI specification (cannot be null)
    *
    * @exception MalformedURIException if URI does not have a conformant
    *                                  scheme
    */
    private void initializeScheme(String p_uriSpec)
                   throws MalformedURIException {
      int uriSpecLen = p_uriSpec.length();
      int index = 0;
      String scheme = null;
      char testChar = '\0';
  
      while (index < uriSpecLen) {
        testChar = p_uriSpec.charAt(index);
        if (testChar == ':' || testChar == '/' ||
            testChar == '?' || testChar == '#') {
          break;
        }
        index++;
      }
      scheme = p_uriSpec.substring(0, index);
  
      if (scheme.length() == 0) {
        throw new MalformedURIException("No scheme found in URI.");
      }
      else {
        setScheme(scheme);
      }
    }
  
   /**
    * Initialize the authority (either server or registry based)
    * for this URI from a URI string spec.
    *
    * @param p_uriSpec the URI specification (cannot be null)
    *
    * @return true if the given string matched server or registry
    * based authority
    */
    private boolean initializeAuthority(String p_uriSpec) {
  
      int index = 0;
      int start = 0;
      int end = p_uriSpec.length();
  
      char testChar = '\0';
      String userinfo = null;
  
      // userinfo is everything up to @
      if (p_uriSpec.indexOf('@', start) != -1) {
        while (index < end) {
          testChar = p_uriSpec.charAt(index);
          if (testChar == '@') {
            break;
          }
          index++;
        }
        userinfo = p_uriSpec.substring(start, index);
        index++;
      }
  
      // host is everything up to last ':', or up to
      // and including ']' if followed by ':'.
      String host = null;
      start = index;
      boolean hasPort = false;
      if (index < end) {
        if (p_uriSpec.charAt(start) == '[') {
          int bracketIndex = p_uriSpec.indexOf(']', start);
          index = (bracketIndex != -1) ? bracketIndex : end;
          if (index+1 < end && p_uriSpec.charAt(index+1) == ':') {
            ++index;
            hasPort = true;
          }
          else {
            index = end;
          }
        }
        else {
          int colonIndex = p_uriSpec.lastIndexOf(':', end);
          index = (colonIndex > start) ? colonIndex : end;
          hasPort = (index != end);
        }
      }
      host = p_uriSpec.substring(start, index);
      int port = -1;
      if (host.length() > 0) {
        // port
        if (hasPort) {
          index++;
          start = index;
          while (index < end) {
            index++;
          }
          String portStr = p_uriSpec.substring(start, index);
          if (portStr.length() > 0) {
            // REVISIT: Remove this code.
            /** for (int i = 0; i < portStr.length(); i++) {
              if (!isDigit(portStr.charAt(i))) {
                throw new MalformedURIException(
                     portStr +
                     " is invalid. Port should only contain digits!");
              }
            }**/
            // REVISIT: Remove this code.
            // Store port value as string instead of integer.
            try {
              port = Integer.parseInt(portStr);
              if (port == -1) --port;
            }
            catch (NumberFormatException nfe) {
              port = -2;
            }
          }
        }
      }
  
      if (isValidServerBasedAuthority(host, port, userinfo)) {
        m_host = host;
        m_port = port;
        m_userinfo = userinfo;
        return true;
      }
      // Note: Registry based authority is being removed from a
      // new spec for URI which would obsolete RFC 2396. If the
      // spec is added to XML errata, processing of reg_name
      // needs to be removed. - mrglavas.
      else if (isValidRegistryBasedAuthority(p_uriSpec)) {
        m_regAuthority = p_uriSpec;
        return true;
      }
      return false;
    }
  
    /**
     * Determines whether the components host, port, and user info
     * are valid as a server authority.
     *
     * @param host the host component of authority
     * @param port the port number component of authority
     * @param userinfo the user info component of authority
     *
     * @return true if the given host, port, and userinfo compose
     * a valid server authority
     */
    private boolean isValidServerBasedAuthority(String host, int port, String userinfo) {
  
      // Check if the host is well formed.
      if (!isWellFormedAddress(host)) {
        return false;
      }
  
      // Check that port is well formed if it exists.
      // REVISIT: There's no restriction on port value ranges, but
      // perform the same check as in setPort to be consistent. Pass
      // in a string to this method instead of an integer.
      if (port < -1 || port > 65535) {
        return false;
      }
  
      // Check that userinfo is well formed if it exists.
      if (userinfo != null) {
        // Userinfo can contain alphanumerics, mark characters, escaped
        // and ';',':','&','=','+','$',','
        int index = 0;
        int end = userinfo.length();
        char testChar = '\0';
        while (index < end) {
          testChar = userinfo.charAt(index);
          if (testChar == '%') {
            if (index+2 >= end ||
              !isHex(userinfo.charAt(index+1)) ||
              !isHex(userinfo.charAt(index+2))) {
              return false;
            }
            index += 2;
          }
          else if (!isUserinfoCharacter(testChar)) {
            return false;
          }
          ++index;
        }
      }
      return true;
    }
  
    /**
     * Determines whether the given string is a registry based authority.
     *
     * @param authority the authority component of a URI
     *
     * @return true if the given string is a registry based authority
     */
    private boolean isValidRegistryBasedAuthority(String authority) {
      int index = 0;
      int end = authority.length();
      char testChar;
  
      while (index < end) {
        testChar = authority.charAt(index);
  
        // check for valid escape sequence
        if (testChar == '%') {
          if (index+2 >= end ||
              !isHex(authority.charAt(index+1)) ||
              !isHex(authority.charAt(index+2))) {
              return false;
          }
          index += 2;
        }
        // can check against path characters because the set
        // is the same except for '/' which we've already excluded.
        else if (!isPathCharacter(testChar)) {
          return false;
        }
        ++index;
      }
      return true;
    }
  
   /**
    * Initialize the path for this URI from a URI string spec.
    *
    * @param p_uriSpec the URI specification (cannot be null)
    * @param p_nStartIndex the index to begin scanning from
    *
    * @exception MalformedURIException if p_uriSpec violates syntax rules
    */
    private void initializePath(String p_uriSpec, int p_nStartIndex)
                   throws MalformedURIException {
      if (p_uriSpec == null) {
        throw new MalformedURIException(
                  "Cannot initialize path from null string!");
      }
  
      int index = p_nStartIndex;
      int start = p_nStartIndex;
      int end = p_uriSpec.length();
      char testChar = '\0';
  
      // path - everything up to query string or fragment
      if (start < end) {
          // RFC 2732 only allows '[' and ']' to appear in the opaque part.
          if (getScheme() == null || p_uriSpec.charAt(start) == '/') {
  
              // Scan path.
              // abs_path = "/"  path_segments
              // rel_path = rel_segment [ abs_path ]
              while (index < end) {
                  testChar = p_uriSpec.charAt(index);
  
                  // check for valid escape sequence
                  if (testChar == '%') {
                      if (index+2 >= end ||
                      !isHex(p_uriSpec.charAt(index+1)) ||
                      !isHex(p_uriSpec.charAt(index+2))) {
                          throw new MalformedURIException(
                              "Path contains invalid escape sequence!");
                      }
                      index += 2;
                  }
                  // Path segments cannot contain '[' or ']' since pchar
                  // production was not changed by RFC 2732.
                  else if (!isPathCharacter(testChar)) {
                      if (testChar == '?' || testChar == '#') {
                          break;
                      }
                      throw new MalformedURIException(
                          "Path contains invalid character: " + testChar);
                  }
                  ++index;
              }
          }
          else {
  
              // Scan opaque part.
              // opaque_part = uric_no_slash *uric
              while (index < end) {
                  testChar = p_uriSpec.charAt(index);
  
                  if (testChar == '?' || testChar == '#') {
                      break;
                  }
  
                  // check for valid escape sequence
                  if (testChar == '%') {
                      if (index+2 >= end ||
                      !isHex(p_uriSpec.charAt(index+1)) ||
                      !isHex(p_uriSpec.charAt(index+2))) {
                          throw new MalformedURIException(
                              "Opaque part contains invalid escape sequence!");
                      }
                      index += 2;
                  }
                  // If the scheme specific part is opaque, it can contain '['
                  // and ']'. uric_no_slash wasn't modified by RFC 2732, which
                  // I've interpreted as an error in the spec, since the
                  // production should be equivalent to (uric - '/'), and uric
                  // contains '[' and ']'. - mrglavas
                  else if (!isURICharacter(testChar)) {
                      throw new MalformedURIException(
                          "Opaque part contains invalid character: " + testChar);
                  }
                  ++index;
              }
          }
      }
      m_path = p_uriSpec.substring(start, index);
  
      // query - starts with ? and up to fragment or end
      if (testChar == '?') {
        index++;
        start = index;
        while (index < end) {
          testChar = p_uriSpec.charAt(index);
          if (testChar == '#') {
            break;
          }
          if (testChar == '%') {
             if (index+2 >= end ||
                !isHex(p_uriSpec.charAt(index+1)) ||
                !isHex(p_uriSpec.charAt(index+2))) {
              throw new MalformedURIException(
                      "Query string contains invalid escape sequence!");
             }
             index += 2;
          }
          else if (!isURICharacter(testChar)) {
            throw new MalformedURIException(
                  "Query string contains invalid character: " + testChar);
          }
          index++;
        }
        m_queryString = p_uriSpec.substring(start, index);
      }
  
      // fragment - starts with #
      if (testChar == '#') {
        index++;
        start = index;
        while (index < end) {
          testChar = p_uriSpec.charAt(index);
  
          if (testChar == '%') {
             if (index+2 >= end ||
                !isHex(p_uriSpec.charAt(index+1)) ||
                !isHex(p_uriSpec.charAt(index+2))) {
              throw new MalformedURIException(
                      "Fragment contains invalid escape sequence!");
             }
             index += 2;
          }
          else if (!isURICharacter(testChar)) {
            throw new MalformedURIException(
                  "Fragment contains invalid character: "+testChar);
          }
          index++;
        }
        m_fragment = p_uriSpec.substring(start, index);
      }
    }
  
   /**
    * Get the scheme for this URI.
    *
    * @return the scheme for this URI
    */
    public String getScheme() {
      return m_scheme;
    }
  
   /**
    * Get the scheme-specific part for this URI (everything following the
    * scheme and the first colon). See RFC 2396 Section 5.2 for spec.
    *
    * @return the scheme-specific part for this URI
    */
    public String getSchemeSpecificPart() {
      final StringBuilder schemespec = new StringBuilder();
  
      if (m_host != null || m_regAuthority != null) {
        schemespec.append("//");
  
        // Server based authority.
        if (m_host != null) {
  
          if (m_userinfo != null) {
            schemespec.append(m_userinfo);
            schemespec.append('@');
          }
  
          schemespec.append(m_host);
  
          if (m_port != -1) {
            schemespec.append(':');
            schemespec.append(m_port);
          }
        }
        // Registry based authority.
        else {
          schemespec.append(m_regAuthority);
        }
      }
  
      if (m_path != null) {
        schemespec.append((m_path));
      }
  
      if (m_queryString != null) {
        schemespec.append('?');
        schemespec.append(m_queryString);
      }
  
      if (m_fragment != null) {
        schemespec.append('#');
        schemespec.append(m_fragment);
      }
  
      return schemespec.toString();
    }
  
   /**
    * Get the userinfo for this URI.
    *
    * @return the userinfo for this URI (null if not specified).
    */
    public String getUserinfo() {
      return m_userinfo;
    }
  
    /**
    * Get the host for this URI.
    *
    * @return the host for this URI (null if not specified).
    */
    public String getHost() {
      return m_host;
    }
  
   /**
    * Get the port for this URI.
    *
    * @return the port for this URI (-1 if not specified).
    */
    public int getPort() {
      return m_port;
    }
  
    /**
     * Get the registry based authority for this URI.
     *
     * @return the registry based authority (null if not specified).
     */
    public String getRegBasedAuthority() {
      return m_regAuthority;
    }
  
    /**
     * Get the authority for this URI.
     *
     * @return the authority
     */
    public String getAuthority() {
        final StringBuilder authority = new StringBuilder();
        if (m_host != null || m_regAuthority != null) {
            authority.append("//");
  
            // Server based authority.
            if (m_host != null) {
  
                if (m_userinfo != null) {
                    authority.append(m_userinfo);
                    authority.append('@');
                }
  
                authority.append(m_host);
  
                if (m_port != -1) {
                    authority.append(':');
                    authority.append(m_port);
                }
            }
            // Registry based authority.
            else {
                authority.append(m_regAuthority);
            }
        }
        return authority.toString();
    }
  
   /**
    * Get the path for this URI (optionally with the query string and
    * fragment).
    *
    * @param p_includeQueryString if true (and query string is not null),
    *                             then a "?" followed by the query string
    *                             will be appended
    * @param p_includeFragment if true (and fragment is not null),
    *                             then a "#" followed by the fragment
    *                             will be appended
    *
    * @return the path for this URI possibly including the query string
    *         and fragment
    */
    public String getPath(boolean p_includeQueryString,
                          boolean p_includeFragment) {
      final StringBuilder pathString = new StringBuilder(m_path);
  
      if (p_includeQueryString && m_queryString != null) {
        pathString.append('?');
        pathString.append(m_queryString);
      }
  
      if (p_includeFragment && m_fragment != null) {
        pathString.append('#');
        pathString.append(m_fragment);
      }
      return pathString.toString();
    }
  
   /**
    * Get the path for this URI. Note that the value returned is the path
    * only and does not include the query string or fragment.
    *
    * @return the path for this URI.
    */
    public String getPath() {
      return m_path;
    }
  
   /**
    * Get the query string for this URI.
    *
    * @return the query string for this URI. Null is returned if there
    *         was no "?" in the URI spec, empty string if there was a
    *         "?" but no query string following it.
    */
    public String getQueryString() {
      return m_queryString;
    }
  
   /**
    * Get the fragment for this URI.
    *
    * @return the fragment for this URI. Null is returned if there
    *         was no "#" in the URI spec, empty string if there was a
    *         "#" but no fragment following it.
    */
    public String getFragment() {
      return m_fragment;
    }
  
   /**
    * Set the scheme for this URI. The scheme is converted to lowercase
    * before it is set.
    *
    * @param p_scheme the scheme for this URI (cannot be null)
    *
    * @exception MalformedURIException if p_scheme is not a conformant
    *                                  scheme name
    */
    public void setScheme(String p_scheme) throws MalformedURIException {
      if (p_scheme == null) {
        throw new MalformedURIException(
                  "Cannot set scheme from null string!");
      }
      if (!isConformantSchemeName(p_scheme)) {
        throw new MalformedURIException("The scheme is not conformant.");
      }
  
      m_scheme = p_scheme.toLowerCase();
    }
  
   /**
    * Set the userinfo for this URI. If a non-null value is passed in and
    * the host value is null, then an exception is thrown.
    *
    * @param p_userinfo the userinfo for this URI
    *
    * @exception MalformedURIException if p_userinfo contains invalid
    *                                  characters
    */
    public void setUserinfo(String p_userinfo) throws MalformedURIException {
      if (p_userinfo == null) {
        m_userinfo = null;
        return;
      }
      else {
        if (m_host == null) {
          throw new MalformedURIException(
                       "Userinfo cannot be set when host is null!");
        }
  
        // userinfo can contain alphanumerics, mark characters, escaped
        // and ';',':','&','=','+','$',','
        int index = 0;
        int end = p_userinfo.length();
        char testChar = '\0';
        while (index < end) {
          testChar = p_userinfo.charAt(index);
          if (testChar == '%') {
            if (index+2 >= end ||
                !isHex(p_userinfo.charAt(index+1)) ||
                !isHex(p_userinfo.charAt(index+2))) {
              throw new MalformedURIException(
                    "Userinfo contains invalid escape sequence!");
            }
          }
          else if (!isUserinfoCharacter(testChar)) {
            throw new MalformedURIException(
                    "Userinfo contains invalid character:"+testChar);
          }
          index++;
        }
      }
      m_userinfo = p_userinfo;
    }
  
   /**
    * <p>Set the host for this URI. If null is passed in, the userinfo
    * field is also set to null and the port is set to -1.</p>
    *
    * <p>Note: This method overwrites registry based authority if it
    * previously existed in this URI.</p>
    *
    * @param p_host the host for this URI
    *
    * @exception MalformedURIException if p_host is not a valid IP
    *                                  address or DNS hostname.
    */
    public void setHost(String p_host) throws MalformedURIException {
      if (p_host == null || p_host.length() == 0) {
        if (p_host != null) {
          m_regAuthority = null;
        }
        m_host = p_host;
        m_userinfo = null;
        m_port = -1;
        return;
      }
      else if (!isWellFormedAddress(p_host)) {
        throw new MalformedURIException("Host is not a well formed address!");
      }
      m_host = p_host;
      m_regAuthority = null;
    }
  
   /**
    * Set the port for this URI. -1 is used to indicate that the port is
    * not specified, otherwise valid port numbers are  between 0 and 65535.
    * If a valid port number is passed in and the host field is null,
    * an exception is thrown.
    *
    * @param p_port the port number for this URI
    *
    * @exception MalformedURIException if p_port is not -1 and not a
    *                                  valid port number
    */
    public void setPort(int p_port) throws MalformedURIException {
      if (p_port >= 0 && p_port <= 65535) {
        if (m_host == null) {
          throw new MalformedURIException(
                        "Port cannot be set when host is null!");
        }
      }
      else if (p_port != -1) {
        throw new MalformedURIException("Invalid port number!");
      }
      m_port = p_port;
    }
  
    /**
     * <p>Sets the registry based authority for this URI.</p>
     *
     * <p>Note: This method overwrites server based authority
     * if it previously existed in this URI.</p>
     *
     * @param authority the registry based authority for this URI
     *
     * @exception MalformedURIException it authority is not a
     * well formed registry based authority
     */
    public void setRegBasedAuthority(String authority)
      throws MalformedURIException {
  
          if (authority == null) {
            m_regAuthority = null;
            return;
          }
          // reg_name = 1*( unreserved | escaped | "$" | "," |
          //            ";" | ":" | "@" | "&" | "=" | "+" )
          else if (authority.length() < 1 ||
            !isValidRegistryBasedAuthority(authority) ||
            authority.indexOf('/') != -1) {
        throw new MalformedURIException("Registry based authority is not well formed.");
          }
          m_regAuthority = authority;
          m_host = null;
          m_userinfo = null;
          m_port = -1;
    }
  
   /**
    * Set the path for this URI. If the supplied path is null, then the
    * query string and fragment are set to null as well. If the supplied
    * path includes a query string and/or fragment, these fields will be
    * parsed and set as well. Note that, for URIs following the "generic
    * URI" syntax, the path specified should start with a slash.
    * For URIs that do not follow the generic URI syntax, this method
    * sets the scheme-specific part.
    *
    * @param p_path the path for this URI (may be null)
    *
    * @exception MalformedURIException if p_path contains invalid
    *                                  characters
    */
    public void setPath(String p_path) throws MalformedURIException {
      if (p_path == null) {
        m_path = null;
        m_queryString = null;
        m_fragment = null;
      }
      else {
        initializePath(p_path, 0);
      }
    }
  
   /**
    * Append to the end of the path of this URI. If the current path does
    * not end in a slash and the path to be appended does not begin with
    * a slash, a slash will be appended to the current path before the
    * new segment is added. Also, if the current path ends in a slash
    * and the new segment begins with a slash, the extra slash will be
    * removed before the new segment is appended.
    *
    * @param p_addToPath the new segment to be added to the current path
    *
    * @exception MalformedURIException if p_addToPath contains syntax
    *                                  errors
    */
    public void appendPath(String p_addToPath)
                           throws MalformedURIException {
      if (p_addToPath == null || p_addToPath.trim().length() == 0) {
        return;
      }
  
      if (!isURIString(p_addToPath)) {
        throw new MalformedURIException(
                "Path contains invalid character!");
      }
  
      if (m_path == null || m_path.trim().length() == 0) {
        if (p_addToPath.startsWith("/")) {
          m_path = p_addToPath;
        }
        else {
          m_path = "/" + p_addToPath;
        }
      }
      else if (m_path.endsWith("/")) {
        if (p_addToPath.startsWith("/")) {
          m_path = m_path.concat(p_addToPath.substring(1));
        }
        else {
          m_path = m_path.concat(p_addToPath);
        }
      }
      else {
        if (p_addToPath.startsWith("/")) {
          m_path = m_path.concat(p_addToPath);
        }
        else {
          m_path = m_path.concat("/" + p_addToPath);
        }
      }
    }
  
   /**
    * Set the query string for this URI. A non-null value is valid only
    * if this is an URI conforming to the generic URI syntax and
    * the path value is not null.
    *
    * @param p_queryString the query string for this URI
    *
    * @exception MalformedURIException if p_queryString is not null and this
    *                                  URI does not conform to the generic
    *                                  URI syntax or if the path is null
    */
    public void setQueryString(String p_queryString) throws MalformedURIException {
      if (p_queryString == null) {
        m_queryString = null;
      }
      else if (!isGenericURI()) {
        throw new MalformedURIException(
                "Query string can only be set for a generic URI!");
      }
      else if (getPath() == null) {
        throw new MalformedURIException(
                "Query string cannot be set when path is null!");
      }
      else if (!isURIString(p_queryString)) {
        throw new MalformedURIException(
                "Query string contains invalid character!");
      }
      else {
        m_queryString = p_queryString;
      }
    }
  
   /**
    * Set the fragment for this URI. A non-null value is valid only
    * if this is a URI conforming to the generic URI syntax and
    * the path value is not null.
    *
    * @param p_fragment the fragment for this URI
    *
    * @exception MalformedURIException if p_fragment is not null and this
    *                                  URI does not conform to the generic
    *                                  URI syntax or if the path is null
    */
    public void setFragment(String p_fragment) throws MalformedURIException {
      if (p_fragment == null) {
        m_fragment = null;
      }
      else if (!isGenericURI()) {
        throw new MalformedURIException(
           "Fragment can only be set for a generic URI!");
      }
      else if (getPath() == null) {
        throw new MalformedURIException(
                "Fragment cannot be set when path is null!");
      }
      else if (!isURIString(p_fragment)) {
        throw new MalformedURIException(
                "Fragment contains invalid character!");
      }
      else {
        m_fragment = p_fragment;
      }
    }
  
   /**
    * Determines if the passed-in Object is equivalent to this URI.
    *
    * @param p_test the Object to test for equality.
    *
    * @return true if p_test is a URI with all values equal to this
    *         URI, false otherwise
    */
    @Override
    public boolean equals(Object p_test) {
      if (p_test instanceof URI) {
        URI testURI = (URI) p_test;
        if (((m_scheme == null && testURI.m_scheme == null) ||
             (m_scheme != null && testURI.m_scheme != null &&
              m_scheme.equals(testURI.m_scheme))) &&
            ((m_userinfo == null && testURI.m_userinfo == null) ||
             (m_userinfo != null && testURI.m_userinfo != null &&
              m_userinfo.equals(testURI.m_userinfo))) &&
            ((m_host == null && testURI.m_host == null) ||
             (m_host != null && testURI.m_host != null &&
              m_host.equals(testURI.m_host))) &&
              m_port == testURI.m_port &&
            ((m_path == null && testURI.m_path == null) ||
             (m_path != null && testURI.m_path != null &&
              m_path.equals(testURI.m_path))) &&
            ((m_queryString == null && testURI.m_queryString == null) ||
             (m_queryString != null && testURI.m_queryString != null &&
              m_queryString.equals(testURI.m_queryString))) &&
            ((m_fragment == null && testURI.m_fragment == null) ||
             (m_fragment != null && testURI.m_fragment != null &&
              m_fragment.equals(testURI.m_fragment)))) {
          return true;
        }
      }
      return false;
    }
  
      @Override
      public int hashCode() {
          int hash = 5;
          hash = 47 * hash + Objects.hashCode(this.m_scheme);
          hash = 47 * hash + Objects.hashCode(this.m_userinfo);
          hash = 47 * hash + Objects.hashCode(this.m_host);
          hash = 47 * hash + this.m_port;
          hash = 47 * hash + Objects.hashCode(this.m_path);
          hash = 47 * hash + Objects.hashCode(this.m_queryString);
          hash = 47 * hash + Objects.hashCode(this.m_fragment);
          return hash;
      }
  
   /**
    * Get the URI as a string specification. See RFC 2396 Section 5.2.
    *
    * @return the URI string specification
    */
    @Override
    public String toString() {
      final StringBuilder uriSpecString = new StringBuilder();
  
      if (m_scheme != null) {
        uriSpecString.append(m_scheme);
        uriSpecString.append(':');
      }
      uriSpecString.append(getSchemeSpecificPart());
      return uriSpecString.toString();
    }
  
   /**
    * Get the indicator as to whether this URI uses the "generic URI"
    * syntax.
    *
    * @return true if this URI uses the "generic URI" syntax, false
    *         otherwise
    */
    public boolean isGenericURI() {
      // presence of the host (whether valid or empty) means
      // double-slashes which means generic uri
      return (m_host != null);
    }
  
    /**
     * Returns whether this URI represents an absolute URI.
     *
     * @return true if this URI represents an absolute URI, false
     *         otherwise
     */
    public boolean isAbsoluteURI() {
        // presence of the scheme means absolute uri
        return (m_scheme != null);
    }
  
   /**
    * Determine whether a scheme conforms to the rules for a scheme name.
    * A scheme is conformant if it starts with an alphanumeric, and
    * contains only alphanumerics, '+','-' and '.'.
    *
    * @return true if the scheme is conformant, false otherwise
    */
    public static boolean isConformantSchemeName(String p_scheme) {
      if (p_scheme == null || p_scheme.trim().length() == 0) {
        return false;
      }
  
      if (!isAlpha(p_scheme.charAt(0))) {
        return false;
      }
  
      char testChar;
      int schemeLength = p_scheme.length();
      for (int i = 1; i < schemeLength; ++i) {
        testChar = p_scheme.charAt(i);
        if (!isSchemeCharacter(testChar)) {
          return false;
        }
      }
  
      return true;
    }
  
   /**
    * Determine whether a string is syntactically capable of representing
    * a valid IPv4 address, IPv6 reference or the domain name of a network host.
    * A valid IPv4 address consists of four decimal digit groups separated by a
    * '.'. Each group must consist of one to three digits. See RFC 2732 Section 3,
    * and RFC 2373 Section 2.2, for the definition of IPv6 references. A hostname
    * consists of domain labels (each of which must begin and end with an alphanumeric
    * but may contain '-') separated & by a '.'. See RFC 2396 Section 3.2.2.
    *
    * @return true if the string is a syntactically valid IPv4 address,
    * IPv6 reference or hostname
    */
    public static boolean isWellFormedAddress(String address) {
      if (address == null) {
        return false;
      }
  
      int addrLength = address.length();
      if (addrLength == 0) {
        return false;
      }
  
      // Check if the host is a valid IPv6reference.
      if (address.startsWith("[")) {
        return isWellFormedIPv6Reference(address);
      }
  
      // Cannot start with a '.', '-', or end with a '-'.
      if (address.startsWith(".") ||
          address.startsWith("-") ||
          address.endsWith("-")) {
        return false;
      }
  
      // rightmost domain label starting with digit indicates IP address
      // since top level domain label can only start with an alpha
      // see RFC 2396 Section 3.2.2
      int index = address.lastIndexOf('.');
      if (address.endsWith(".")) {
        index = address.substring(0, index).lastIndexOf('.');
      }
  
      if (index+1 < addrLength && isDigit(address.charAt(index+1))) {
        return isWellFormedIPv4Address(address);
      }
      else {
        // hostname      = *( domainlabel "." ) toplabel [ "." ]
        // domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
        // toplabel      = alpha | alpha *( alphanum | "-" ) alphanum
  
        // RFC 2396 states that hostnames take the form described in
        // RFC 1034 (Section 3) and RFC 1123 (Section 2.1). According
        // to RFC 1034, hostnames are limited to 255 characters.
        if (addrLength > 255) {
          return false;
        }
  
        // domain labels can contain alphanumerics and '-"
        // but must start and end with an alphanumeric
        char testChar;
        int labelCharCount = 0;
  
        for (int i = 0; i < addrLength; i++) {
          testChar = address.charAt(i);
          if (testChar == '.') {
            if (!isAlphanum(address.charAt(i-1))) {
              return false;
            }
            if (i+1 < addrLength && !isAlphanum(address.charAt(i+1))) {
              return false;
            }
            labelCharCount = 0;
          }
          else if (!isAlphanum(testChar) && testChar != '-') {
            return false;
          }
          // RFC 1034: Labels must be 63 characters or less.
          else if (++labelCharCount > 63) {
            return false;
          }
        }
      }
      return true;
    }
  
    /**
     * <p>Determines whether a string is an IPv4 address as defined by
     * RFC 2373, and under the further constraint that it must be a 32-bit
     * address. Though not expressed in the grammar, in order to satisfy
     * the 32-bit address constraint, each segment of the address cannot
     * be greater than 255 (8 bits of information).</p>
     *
     * <p><code>IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT</code></p>
     *
     * @return true if the string is a syntactically valid IPv4 address
     */
    public static boolean isWellFormedIPv4Address(String address) {
  
        int addrLength = address.length();
        char testChar;
        int numDots = 0;
        int numDigits = 0;
  
        // make sure that 1) we see only digits and dot separators, 2) that
        // any dot separator is preceded and followed by a digit and
        // 3) that we find 3 dots
        //
        // RFC 2732 amended RFC 2396 by replacing the definition
        // of IPv4address with the one defined by RFC 2373. - mrglavas
        //
        // IPv4address = 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT "." 1*3DIGIT
        //
        // One to three digits must be in each segment.
        for (int i = 0; i < addrLength; i++) {
          testChar = address.charAt(i);
          if (testChar == '.') {
            if ((i > 0 && !isDigit(address.charAt(i-1))) ||
                (i+1 < addrLength && !isDigit(address.charAt(i+1)))) {
              return false;
            }
            numDigits = 0;
            if (++numDots > 3) {
              return false;
            }
          }
          else if (!isDigit(testChar)) {
            return false;
          }
          // Check that that there are no more than three digits
          // in this segment.
          else if (++numDigits > 3) {
            return false;
          }
          // Check that this segment is not greater than 255.
          else if (numDigits == 3) {
            char first = address.charAt(i-2);
            char second = address.charAt(i-1);
            if (!(first < '2' ||
                 (first == '2' &&
                 (second < '5' ||
                 (second == '5' && testChar <= '5'))))) {
              return false;
            }
          }
        }
        return (numDots == 3);
    }
  
    /**
     * <p>Determines whether a string is an IPv6 reference as defined
     * by RFC 2732, where IPv6address is defined in RFC 2373. The
     * IPv6 address is parsed according to Section 2.2 of RFC 2373,
     * with the additional constraint that the address be composed of
     * 128 bits of information.</p>
     *
     * <p><code>IPv6reference = "[" IPv6address "]"</code></p>
     *
     * <p>Note: The BNF expressed in RFC 2373 Appendix B does not
     * accurately describe section 2.2, and was in fact removed from
     * RFC 3513, the successor of RFC 2373.</p>
     *
     * @return true if the string is a syntactically valid IPv6 reference
     */
    public static boolean isWellFormedIPv6Reference(String address) {
  
        int addrLength = address.length();
        int index = 1;
        int end = addrLength-1;
  
        // Check if string is a potential match for IPv6reference.
        if (!(addrLength > 2 && address.charAt(0) == '['
            && address.charAt(end) == ']')) {
            return false;
        }
  
        // Counter for the number of 16-bit sections read in the address.
        int [] counter = new int[1];
  
        // Scan hex sequence before possible '::' or IPv4 address.
        index = scanHexSequence(address, index, end, counter);
        if (index == -1) {
            return false;
        }
        // Address must contain 128-bits of information.
        else if (index == end) {
            return (counter[0] == 8);
        }
  
        if (index+1 < end && address.charAt(index) == ':') {
            if (address.charAt(index+1) == ':') {
                // '::' represents at least one 16-bit group of zeros.
                if (++counter[0] > 8) {
                    return false;
                }
                index += 2;
                // Trailing zeros will fill out the rest of the address.
                if (index == end) {
                   return true;
                }
            }
            // If the second character wasn't ':', in order to be valid,
            // the remainder of the string must match IPv4Address,
            // and we must have read exactly 6 16-bit groups.
            else {
                return (counter[0] == 6) &&
                    isWellFormedIPv4Address(address.substring(index+1, end));
            }
        }
        else {
            return false;
        }
  
        // 3. Scan hex sequence after '::'.
        int prevCount = counter[0];
        index = scanHexSequence(address, index, end, counter);
  
        // We've either reached the end of the string, the address ends in
        // an IPv4 address, or it is invalid. scanHexSequence has already
        // made sure that we have the right number of bits.
        return (index == end) ||
            (index != -1 && isWellFormedIPv4Address(
            address.substring((counter[0] > prevCount) ? index+1 : index, end)));
    }
  
    /**
     * Helper method for isWellFormedIPv6Reference which scans the
     * hex sequences of an IPv6 address. It returns the index of the
     * next character to scan in the address, or -1 if the string
     * cannot match a valid IPv6 address.
     *
     * @param address the string to be scanned
     * @param index the beginning index (inclusive)
     * @param end the ending index (exclusive)
     * @param counter a counter for the number of 16-bit sections read
     * in the address
     *
     * @return the index of the next character to scan, or -1 if the
     * string cannot match a valid IPv6 address
     */
    private static int scanHexSequence (String address, int index, int end, int [] counter) {
  
        char testChar;
        int numDigits = 0;
        int start = index;
  
        // Trying to match the following productions:
        // hexseq = hex4 *( ":" hex4)
        // hex4   = 1*4HEXDIG
        for (; index < end; ++index) {
          testChar = address.charAt(index);
          if (testChar == ':') {
              // IPv6 addresses are 128-bit, so there can be at most eight sections.
              if (numDigits > 0 && ++counter[0] > 8) {
                  return -1;
              }
              // This could be '::'.
              if (numDigits == 0 || ((index+1 < end) && address.charAt(index+1) == ':')) {
                  return index;
              }
              numDigits = 0;
          }
          // This might be invalid or an IPv4address. If it's potentially an IPv4address,
          // backup to just after the last valid character that matches hexseq.
          else if (!isHex(testChar)) {
              if (testChar == '.' && numDigits < 4 && numDigits > 0 && counter[0] <= 6) {
                  int back = index - numDigits - 1;
                  return (back >= start) ? back : (back+1);
              }
              return -1;
          }
          // There can be at most 4 hex digits per group.
          else if (++numDigits > 4) {
              return -1;
          }
        }
        return (numDigits > 0 && ++counter[0] <= 8) ? end : -1;
    }
  
  
   /**
    * Determine whether a char is a digit.
    *
    * @return true if the char is betweeen '0' and '9', false otherwise
    */
    private static boolean isDigit(char p_char) {
      return p_char >= '0' && p_char <= '9';
    }
  
   /**
    * Determine whether a character is a hexadecimal character.
    *
    * @return true if the char is betweeen '0' and '9', 'a' and 'f'
    *         or 'A' and 'F', false otherwise
    */
    private static boolean isHex(char p_char) {
      return (p_char <= 'f' && (fgLookupTable[p_char] & ASCII_HEX_CHARACTERS) != 0);
    }
  
   /**
    * Determine whether a char is an alphabetic character: a-z or A-Z
    *
    * @return true if the char is alphabetic, false otherwise
    */
    private static boolean isAlpha(char p_char) {
        return ((p_char >= 'a' && p_char <= 'z') || (p_char >= 'A' && p_char <= 'Z' ));
    }
  
   /**
    * Determine whether a char is an alphanumeric: 0-9, a-z or A-Z
    *
    * @return true if the char is alphanumeric, false otherwise
    */
    private static boolean isAlphanum(char p_char) {
       return (p_char <= 'z' && (fgLookupTable[p_char] & MASK_ALPHA_NUMERIC) != 0);
    }
  
   /**
    * Determine whether a character is a reserved character:
    * ';', '/', '?', ':', '@', '&', '=', '+', '$', ',', '[', or ']'
    *
    * @return true if the string contains any reserved characters
    */
    private static boolean isReservedCharacter(char p_char) {
       return (p_char <= ']' && (fgLookupTable[p_char] & RESERVED_CHARACTERS) != 0);
    }
  
   /**
    * Determine whether a char is an unreserved character.
    *
    * @return true if the char is unreserved, false otherwise
    */
    private static boolean isUnreservedCharacter(char p_char) {
       return (p_char <= '~' && (fgLookupTable[p_char] & MASK_UNRESERVED_MASK) != 0);
    }
  
   /**
    * Determine whether a char is a URI character (reserved or
    * unreserved, not including '%' for escaped octets).
    *
    * @return true if the char is a URI character, false otherwise
    */
    private static boolean isURICharacter (char p_char) {
        return (p_char <= '~' && (fgLookupTable[p_char] & MASK_URI_CHARACTER) != 0);
    }
  
   /**
    * Determine whether a char is a scheme character.
    *
    * @return true if the char is a scheme character, false otherwise
    */
    private static boolean isSchemeCharacter (char p_char) {
        return (p_char <= 'z' && (fgLookupTable[p_char] & MASK_SCHEME_CHARACTER) != 0);
    }
  
   /**
    * Determine whether a char is a userinfo character.
    *
    * @return true if the char is a userinfo character, false otherwise
    */
    private static boolean isUserinfoCharacter (char p_char) {
        return (p_char <= 'z' && (fgLookupTable[p_char] & MASK_USERINFO_CHARACTER) != 0);
    }
  
   /**
    * Determine whether a char is a path character.
    *
    * @return true if the char is a path character, false otherwise
    */
    private static boolean isPathCharacter (char p_char) {
        return (p_char <= '~' && (fgLookupTable[p_char] & MASK_PATH_CHARACTER) != 0);
    }
  
  
   /**
    * Determine whether a given string contains only URI characters (also
    * called "uric" in RFC 2396). uric consist of all reserved
    * characters, unreserved characters and escaped characters.
    *
    * @return true if the string is comprised of uric, false otherwise
    */
    private static boolean isURIString(String p_uric) {
      if (p_uric == null) {
        return false;
      }
      int end = p_uric.length();
      char testChar = '\0';
      for (int i = 0; i < end; i++) {
        testChar = p_uric.charAt(i);
        if (testChar == '%') {
          if (i+2 >= end ||
              !isHex(p_uric.charAt(i+1)) ||
              !isHex(p_uric.charAt(i+2))) {
            return false;
          }
          else {
            i += 2;
            continue;
          }
        }
        if (isURICharacter(testChar)) {
            continue;
        }
        else {
          return false;
        }
      }
      return true;
    }
  }
  