diff --git a/plugins/org.eclipse.wst.common.uriresolver/META-INF/MANIFEST.MF b/plugins/org.eclipse.wst.common.uriresolver/META-INF/MANIFEST.MF
new file mode 100644
index 0000000..ec00e36
--- /dev/null
+++ b/plugins/org.eclipse.wst.common.uriresolver/META-INF/MANIFEST.MF
@@ -0,0 +1,15 @@
+Manifest-Version: 1.0
+Bundle-ManifestVersion: 2
+Bundle-Name: %pluginName
+Bundle-SymbolicName: org.eclipse.wst.common.uriresolver; singleton:=true
+Bundle-Version: 1.1.101.qualifier
+Bundle-Activator: org.eclipse.wst.common.uriresolver.internal.provisional.URIResolverPlugin
+Bundle-Vendor: %providerName
+Bundle-Localization: plugin
+Export-Package: org.eclipse.wst.common.uriresolver.internal,
+ org.eclipse.wst.common.uriresolver.internal.provisional,
+ org.eclipse.wst.common.uriresolver.internal.util
+Require-Bundle: org.eclipse.core.runtime;bundle-version="[3.2.0,4.0.0)",
+ org.eclipse.core.resources;bundle-version="[3.2.0,4.0.0)"
+Eclipse-LazyStart: true
+Bundle-ClassPath: .
diff --git a/plugins/org.eclipse.wst.common.uriresolver/build.properties b/plugins/org.eclipse.wst.common.uriresolver/build.properties
new file mode 100644
index 0000000..a1aa98a
--- /dev/null
+++ b/plugins/org.eclipse.wst.common.uriresolver/build.properties
@@ -0,0 +1,12 @@
+source.. = src/
+output.. = bin/
+bin.includes = plugin.xml,\
+               META-INF/,\
+               about.html,\
+               .,\
+               plugin.properties,\
+               schema/
+bin.excludes = bin/**,\
+               @dot/**,\
+               temp.folder/**
+               
\ No newline at end of file
diff --git a/plugins/org.eclipse.wst.common.uriresolver/src/org/eclipse/wst/common/uriresolver/internal/URI.java b/plugins/org.eclipse.wst.common.uriresolver/src/org/eclipse/wst/common/uriresolver/internal/URI.java
new file mode 100644
index 0000000..044d20b
--- /dev/null
+++ b/plugins/org.eclipse.wst.common.uriresolver/src/org/eclipse/wst/common/uriresolver/internal/URI.java
@@ -0,0 +1,2900 @@
+/*******************************************************************************
+ * Copyright (c) 2004, 2005 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Contributors:
+ *     IBM Corporation - Initial API and implementation
+ *     Jens Lukowski/Innoopract - initial renaming/restructuring
+ *******************************************************************************/
+package org.eclipse.wst.common.uriresolver.internal;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * A representation of a Uniform Resource Identifier (URI), as specified by
+ * <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>, with certain
+ * enhancements.  A <code>URI</code> instance can be created by specifying
+ * values for its components, or by providing a single URI string, which is
+ * parsed into its components.  Static factory methods whose names begin
+ * with "create" are used for both forms of object creation.  No public or
+ * protected constructors are provided; this class can not be subclassed.
+ *
+ * <p>Like <code>String</code>, <code>URI</code> is an immutable class;
+ * a <code>URI</code> instance offers several by-value methods that return a
+ * new <code>URI</code> object based on its current state.  Most useful,
+ * a relative <code>URI</code> can be {@link #resolve(URI) resolve}d against
+ * a base absolute <code>URI</code> -- the latter typically identifies the
+ * document in which the former appears.  The inverse to this is {@link
+ * #deresolve(URI) deresolve}, which answers the question, "what relative
+ * URI will resolve, against the given base, to this absolute URI?"
+ *
+ * <p>In the <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC</a>, much
+ * attention is focused on a hierarchical naming system used widely to
+ * locate resources via common protocols such as HTTP, FTP, and Gopher, and
+ * to identify files on a local file system.  Acordingly, most of this
+ * class's functionality is for handling such URIs, which can be identified
+ * via {@link #isHierarchical isHierarchical}.
+ *
+ * <p><a name="device_explanation">
+ * The primary enhancement beyond the RFC description is an optional
+ * device component.  Instead of treating the device as just another segment
+ * in the path, it can be stored as a separate component (almost a
+ * sub-authority), with the root below it.  For example, resolving
+ * <code>/bar</code> against <code>file:///c:/foo</code> would result in
+ * <code>file:///c:/bar</code> being returned.  Also, you cannot take
+ * the parent of a device, so resolving <code>..</code> against
+ * <code>file:///c:/</code> would not yield <code>file:///</code>, as you
+ * might expect.  This feature is useful when working with file-scheme
+ * URIs, as devices do not typically occur in protocol-based ones.  A
+ * device-enabled <code>URI</code> is created by parsing a string with
+ * {@link #createURI(String) createURI}; if the first segment of the path
+ * ends with the <code>:</code> character, it is stored (including the colon)
+ * as the device, instead.  Alternately, either the {@link
+ * #createHierarchicalURI(String, String, String, String, String) no-path}
+ * or the {@link #createHierarchicalURI(String, String, String, String[],
+ * String, String) absolute-path} form of <code>createHierarchicalURI()</code>
+ * can be used, in which a non-null <code>device</code> parameter can be
+ * specified.
+ *
+ * <p><a name="archive_explanation"> 
+ * The other enhancement provides support for the almost-hierarchical
+ * form used for files within archives, such as the JAR scheme, defined
+ * for the Java Platform in the documentation for {@link
+ * java.net.JarURLConnection}. By default, this support is enabled for
+ * absolute URIs with scheme equal to "jar", "zip", or "archive" (ignoring case), and
+ * is implemented by a hierarchical URI, whose authority includes the
+ * entire URI of the archive, up to and including the <code>!</code>
+ * character.  The URI of the archive must have no fragment.  The whole
+ * archive URI must have no device and an absolute path.  Special handling
+ * is supported for {@link #createURI creating}, {@link
+ * #validArchiveAuthority validating}, {@link #devicePath getting the path}
+ * from, and {@link #toString displaying} archive URIs. In all other
+ * operations, including {@link #resolve(URI) resolving} and {@link
+ * #deresolve(URI) deresolving}, they are handled like any ordinary URI.
+ *
+ * <p>This implementation does not impose the all of the restrictions on
+ * character validity that are specified in the RFC.  Static methods whose
+ * names begin with "valid" are used to test whether a given string is valid
+ * value for the various URI components.  Presently, these tests place no
+ * restrictions beyond what would have been required in order for {@link
+ * createURI(String) createURI} to have parsed them correctly from a single
+ * URI string.  If necessary in the future, these tests may be made more
+ * strict, to better coform to the RFC.
+ * 
+ * <p>Another group of static methods, whose names begin with "encode", use
+ * percent escaping to encode any characters that are not permitted in the
+ * various URI components. Another static method is provided to {@link
+ * #decode decode} encoded strings.  An escaped character is represented as
+ * a percent sybol (<code>%</code>), followed by two hex digits that specify
+ * the character code.  These encoding methods are more strict than the
+ * validation methods described above.  They ensure validity according to the
+ * RFC, with one exception: non-ASCII characters.
+ *
+ * <p>The RFC allows only characters that can be mapped to 7-bit US-ASCII
+ * representations.  Non-ASCII, single-byte characters can be used only via
+ * percent escaping, as described above.  This implementation uses Java's
+ * Unicode <code>char</code> and <code>String</code> representations, and
+ * makes no attempt to encode characters 0xA0 and above.  Characters in the
+ * range 0x80-0x9F are still escaped.  In this respect, this notion of a URI
+ * is actually more like an IRI (Internationalized Resource Identifier), for
+ * which an RFC is now in <href="http://www.w3.org/International/iri-edit/draft-duerst-iri-09.txt">draft
+ * form</a>.
+ *
+ * <p>Finally, note the difference between a <code>null</code> parameter to
+ * the static factory methods and an empty string.  The former signifies the
+ * absense of a given URI component, while the latter simply makes the
+ * component blank.  This can have a significant effect when resolving.  For
+ * example, consider the following two URIs: <code>/bar</code> (with no
+ * authority) and <code>///bar</code> (with a blank authority).  Imagine
+ * resolving them against a base with an authority, such as
+ * <code>http://www.eclipse.org/</code>.  The former case will yield
+ * <code>http://www.eclipse.org/bar</code>, as the base authority will be
+ * preserved.  In the latter case, the empty authority will override the
+ * base authority, resulting in <code>http:///bar</code>!
+ */
+public final class URI
+{
+  // Common to all URI types.
+  private final int hashCode;
+  private final boolean hierarchical;
+  private final String scheme;  // null -> relative URI reference
+  private final String authority;
+  private final String fragment;
+  private URI cachedTrimFragment;
+  private String cachedToString;
+  //private final boolean iri;
+  //private URI cachedASCIIURI;
+
+  // Applicable only to a hierarchical URI.
+  private final String device;
+  private final boolean absolutePath;
+  private final String[] segments; // empty last segment -> trailing separator
+  private final String query;
+
+  // A cache of URIs, keyed by the strings from which they were created.
+  // The fragment of any URI is removed before caching it here, to minimize
+  // the size of the cache in the usual case where most URIs only differ by
+  // the fragment.
+  private static final Map uriCache = Collections.synchronizedMap(new HashMap());
+
+  // The lower-cased schemes that will be used to identify archive URIs.
+  private static final Set archiveSchemes;
+
+  // Identifies a file-type absolute URI.
+  private static final String SCHEME_FILE = "file";
+  private static final String SCHEME_JAR = "jar";
+  private static final String SCHEME_ZIP = "zip";
+  private static final String SCHEME_ARCHIVE = "archive";
+
+  // Special segment values interpreted at resolve and resolve time.
+  private static final String SEGMENT_EMPTY = "";
+  private static final String SEGMENT_SELF = ".";
+  private static final String SEGMENT_PARENT = "..";
+  private static final String[] NO_SEGMENTS = new String[0];
+
+  // Separators for parsing a URI string.
+  private static final char SCHEME_SEPARATOR = ':';
+  private static final String AUTHORITY_SEPARATOR = "//";
+  private static final char DEVICE_IDENTIFIER = ':';
+  private static final char SEGMENT_SEPARATOR = '/';
+  private static final char QUERY_SEPARATOR = '?';
+  private static final char FRAGMENT_SEPARATOR = '#';
+  private static final char USER_INFO_SEPARATOR = '@';
+  private static final char PORT_SEPARATOR = ':';
+  private static final char FILE_EXTENSION_SEPARATOR = '.';
+  private static final char ARCHIVE_IDENTIFIER = '!';
+  private static final String ARCHIVE_SEPARATOR = "!/";
+
+  // Characters to use in escaping.
+  private static final char ESCAPE = '%';
+  private static final char[] HEX_DIGITS = {
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
+
+  // Some character classes, as defined in RFC 2396's BNF for URI.
+  // These are 128-bit bitmasks, stored as two longs, where the Nth bit is set
+  // iff the ASCII character with value N is included in the set.  These are
+  // created with the highBitmask() and lowBitmask() methods defined below,
+  // and a character is tested against them using matches().
+  //
+  private static final long ALPHA_HI = highBitmask('a', 'z') | highBitmask('A', 'Z');
+  private static final long ALPHA_LO = lowBitmask('a', 'z')  | lowBitmask('A', 'Z');
+  private static final long DIGIT_HI = highBitmask('0', '9');
+  private static final long DIGIT_LO = lowBitmask('0', '9');
+  private static final long ALPHANUM_HI = ALPHA_HI | DIGIT_HI;
+  private static final long ALPHANUM_LO = ALPHA_LO | DIGIT_LO;
+  private static final long HEX_HI = DIGIT_HI | highBitmask('A', 'F') | highBitmask('a', 'f');
+  private static final long HEX_LO = DIGIT_LO | lowBitmask('A', 'F')  | lowBitmask('a', 'f');
+  private static final long UNRESERVED_HI = ALPHANUM_HI | highBitmask("-_.!~*'()"); 
+  private static final long UNRESERVED_LO = ALPHANUM_LO | lowBitmask("-_.!~*'()");
+  private static final long RESERVED_HI = highBitmask(";/?:@&=+$,");
+  private static final long RESERVED_LO = lowBitmask(";/?:@&=+$,");
+  private static final long URIC_HI = RESERVED_HI | UNRESERVED_HI;  // | ucschar | escaped
+  private static final long URIC_LO = RESERVED_LO | UNRESERVED_LO;
+
+  // Additional useful character classes, including characters valid in certain
+  // URI components and separators used in parsing them out of a string. 
+  //
+  private static final long SEGMENT_CHAR_HI = UNRESERVED_HI | highBitmask(";:@&=+$,");  // | ucschar | escaped
+  private static final long SEGMENT_CHAR_LO = UNRESERVED_LO | lowBitmask(";:@&=+$,");
+  private static final long PATH_CHAR_HI = SEGMENT_CHAR_HI | highBitmask('/');  // | ucschar | escaped
+  private static final long PATH_CHAR_LO = SEGMENT_CHAR_LO | lowBitmask('/');
+//  private static final long SCHEME_CHAR_HI = ALPHANUM_HI | highBitmask("+-.");
+//  private static final long SCHEME_CHAR_LO = ALPHANUM_LO | lowBitmask("+-.");
+  private static final long MAJOR_SEPARATOR_HI = highBitmask(":/?#");
+  private static final long MAJOR_SEPARATOR_LO = lowBitmask(":/?#");
+  private static final long SEGMENT_END_HI = highBitmask("/?#");
+  private static final long SEGMENT_END_LO = lowBitmask("/?#");
+
+  // Static initializer for archiveSchemes.
+  static
+  {
+    Set set = new HashSet();
+    set.add(SCHEME_JAR);
+    set.add(SCHEME_ZIP);
+    set.add(SCHEME_ARCHIVE);
+    
+    
+    archiveSchemes = Collections.unmodifiableSet(set);
+  }
+
+  // Returns the lower half bitmask for the given ASCII character.
+  private static long lowBitmask(char c)
+  {
+    return c < 64 ? 1L << c : 0L;
+  }
+
+  // Returns the upper half bitmask for the given ACSII character.
+  private static long highBitmask(char c)
+  {
+    return c >= 64 && c < 128 ? 1L << (c - 64) : 0L;
+  }
+
+  // Returns the lower half bitmask for all ASCII characters between the two
+  // given characters, inclusive.
+  private static long lowBitmask(char from, char to)
+  {
+    long result = 0L;
+    if (from < 64 && from <= to)
+    {
+      to = to < 64 ? to : 63;
+      for (char c = from; c <= to; c++)
+      {
+        result |= (1L << c);
+      }
+    }
+    return result;
+  }
+
+  // Returns the upper half bitmask for all AsCII characters between the two
+  // given characters, inclusive.
+  private static long highBitmask(char from, char to)
+  {
+    return to < 64 ? 0 : lowBitmask((char)(from < 64 ? 0 : from - 64), (char)(to - 64));
+  }
+
+  // Returns the lower half bitmask for all the ASCII characters in the given
+  // string.
+  private static long lowBitmask(String chars)
+  {
+    long result = 0L;
+    for (int i = 0, len = chars.length(); i < len; i++)
+    {
+      char c = chars.charAt(i);
+      if (c < 64) result |= (1L << c);
+    }
+    return result;
+  }
+
+  // Returns the upper half bitmask for all the ASCII characters in the given
+  // string.
+  private static long highBitmask(String chars)
+  {
+    long result = 0L;
+    for (int i = 0, len = chars.length(); i < len; i++)
+    {
+      char c = chars.charAt(i);
+      if (c >= 64 && c < 128) result |= (1L << (c - 64));
+    }
+    return result;
+  }
+
+  // Returns whether the given character is in the set specified by the given
+  // bitmask.
+  private static boolean matches(char c, long highBitmask, long lowBitmask)
+  {
+    if (c >= 128) return false;
+    return c < 64 ?
+      ((1L << c) & lowBitmask) != 0 :
+      ((1L << (c - 64)) & highBitmask) != 0;
+  }
+
+  // Debugging method: converts the given long to a string of binary digits.
+/*
+  private static String toBits(long l)
+  {
+    StringBuffer result = new StringBuffer();
+    for (int i = 0; i < 64; i++)
+    {
+      boolean b = (l & 1L) != 0;
+      result.insert(0, b ? '1' : '0');
+      l >>= 1;
+    }
+    return result.toString();
+  }
+*/
+
+  /**
+   * Static factory method for a generic, non-hierarchical URI.  There is no
+   * concept of a relative non-hierarchical URI; such an object cannot be
+   * created.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>scheme</code> is
+   * null, if <code>scheme</code> is an <a href="#archive_explanation">archive
+   * URI</a> scheme, or if <code>scheme</code>, <code>opaquePart</code>, or
+   * <code>fragment</code> is not valid according to {@link #validScheme
+   * validScheme}, {@link #validOpaquePart validOpaquePart}, or {@link
+   * #validFragment validFragment}, respectively.
+   */
+  public static URI createGenericURI(String scheme, String opaquePart,
+                                     String fragment)
+  {
+    if (scheme == null)
+    {
+      throw new IllegalArgumentException("relative non-hierarchical URI");
+    }
+
+    if (isArchiveScheme(scheme))
+    {
+      throw new IllegalArgumentException("non-hierarchical archive URI");
+    }
+
+    validateURI(false, scheme, opaquePart, null, false, NO_SEGMENTS, null, fragment);
+    return new URI(false, scheme, opaquePart, null, false, NO_SEGMENTS, null, fragment);
+  }
+
+  /**
+   * Static factory method for a hierarchical URI with no path.  The
+   * URI will be relative if <code>scheme</code> is non-null, and absolute
+   * otherwise.  An absolute URI with no path requires a non-null
+   * <code>authority</code> and/or <code>device</code>.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>scheme</code> is
+   * non-null while <code>authority</code> and <code>device</code> are null,
+   * if <code>scheme</code> is an <a href="#archive_explanation">archive
+   * URI</a> scheme, or if <code>scheme</code>, <code>authority</code>,
+   * <code>device</code>, <code>query</code>, or <code>fragment</code> is not
+   * valid according to {@link #validScheme validSheme}, {@link
+   * #validAuthority validAuthority}, {@link #validDevice validDevice},
+   * {@link #validQuery validQuery}, or {@link #validFragment validFragment},
+   * respectively.
+   */
+  public static URI createHierarchicalURI(String scheme, String authority,
+                                          String device, String query,
+                                          String fragment)
+  {
+    if (scheme != null && authority == null && device == null)
+    {
+      throw new IllegalArgumentException(
+        "absolute hierarchical URI without authority, device, path");
+    }
+
+    if (isArchiveScheme(scheme))
+    {
+      throw new IllegalArgumentException("archive URI with no path");
+    }
+
+    validateURI(true, scheme, authority, device, false, NO_SEGMENTS, query, fragment);
+    return new URI(true, scheme, authority, device, false, NO_SEGMENTS, query, fragment);
+  }
+
+  /**
+   * Static factory method for a hierarchical URI with absolute path.
+   * The URI will be relative if <code>scheme</code> is non-null, and
+   * absolute otherwise. 
+   *
+   * @param segments an array of non-null strings, each representing one
+   * segment of the path.  As an absolute path, it is automatically
+   * preceeded by a <code>/</code> separator.  If desired, a trailing
+   * separator should be represented by an empty-string segment as the last
+   * element of the array. 
+   *
+   * @exception java.lang.IllegalArgumentException if <code>scheme</code> is
+   * an <a href="#archive_explanation">archive URI</a> scheme and 
+   * <code>device</code> is non-null, or if <code>scheme</code>,
+   * <code>authority</code>, <code>device</code>, <code>segments</code>,
+   * <code>query</code>, or <code>fragment</code> is not valid according to
+   * {@link #validScheme validScheme}, {@link #validAuthority validAuthority}
+   * or {@link #validArchiveAuthority validArchiveAuthority}, {@link
+   * #validDevice validDevice}, {@link #validSegments validSegments}, {@link
+   * #validQuery validQuery}, or {@link #validFragment validFragment}, as
+   * appropriate.
+   */
+  public static URI createHierarchicalURI(String scheme, String authority,
+                                          String device, String[] segments,
+                                          String query, String fragment)
+  {
+    if (isArchiveScheme(scheme) && device != null)
+    {
+      throw new IllegalArgumentException("archive URI with device");
+    }
+
+    segments = fix(segments);
+    validateURI(true, scheme, authority, device, true, segments, query, fragment);
+    return new URI(true, scheme, authority, device, true, segments, query, fragment);
+  }
+
+  /**
+   * Static factory method for a relative hierarchical URI with relative
+   * path.
+   *
+   * @param segments an array of non-null strings, each representing one
+   * segment of the path.  A trailing separator is represented by an
+   * empty-string segment at the end of the array.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>segments</code>,
+   * <code>query</code>, or <code>fragment</code> is not valid according to 
+   * {@link #validSegments validSegments}, {@link #validQuery validQuery}, or
+   * {@link #validFragment validFragment}, respectively.
+   */
+  public static URI createHierarchicalURI(String[] segments, String query,
+                                          String fragment)
+  {
+    segments = fix(segments);
+    validateURI(true, null, null, null, false, segments, query, fragment);
+    return new URI(true, null, null, null, false, segments, query, fragment);
+  }
+
+  // Converts null to length-zero array, and clones array to ensure
+  // immutability.
+  private static String[] fix(String[] segments)
+  {
+    return segments == null ? NO_SEGMENTS : (String[])segments.clone();
+  }
+  
+  /**
+   * Static factory method based on parsing a URI string, with 
+   * <a href="#device_explanation">explicit device support</a> and handling
+   * for <a href="#archive_explanation">archive URIs</a> enabled. The
+   * specified string is parsed as described in <a
+   * href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>, and an
+   * appropriate <code>URI</code> is created and returned.  Note that
+   * validity testing is not as strict as in the RFC; essentially, only
+   * separator characters are considered.  So, for example, non-Latin
+   * alphabet characters appearing in the scheme would not be considered an
+   * error.
+   *
+   * @exception java.lang.IllegalArgumentException if any component parsed
+   * from <code>uri</code> is not valid according to {@link #validScheme
+   * validScheme}, {@link #validOpaquePart validOpaquePart}, {@link
+   * #validAuthority validAuthority}, {@link #validArchiveAuthority
+   * validArchiveAuthority}, {@link #validDevice validDevice}, {@link
+   * #validSegments validSegments}, {@link #validQuery validQuery}, or {@link
+   * #validFragment validFragment}, as appropriate.
+   */
+  public static URI createURI(String uri)
+  {
+    return createURIWithCache(uri); 
+  }
+
+  /**
+   * Static factory method that encodes and parses the given URI string.
+   * Appropriate encoding is performed for each component of the URI.
+   * If more than one <code>#</code> is in the string, the last one is
+   * assumed to be the fragment's separator, and any others are encoded.
+   *  
+   * @param ignoreEscaped <code>true</code> to leave <code>%</code> characters
+   * unescaped if they already begin a valid three-character escape sequence;
+   * <code>false</code> to encode all <code>%</code> characters.  Note that
+   * if a <code>%</code> is not followed by 2 hex digits, it will always be
+   * escaped. 
+   *
+   * @exception java.lang.IllegalArgumentException if any component parsed
+   * from <code>uri</code> is not valid according to {@link #validScheme
+   * validScheme}, {@link #validOpaquePart validOpaquePart}, {@link
+   * #validAuthority validAuthority}, {@link #validArchiveAuthority
+   * validArchiveAuthority}, {@link #validDevice validDevice}, {@link
+   * #validSegments validSegments}, {@link #validQuery validQuery}, or {@link
+   * #validFragment validFragment}, as appropriate.
+   */
+  public static URI createURI(String uri, boolean ignoreEscaped)
+  {
+    return createURIWithCache(encodeURI(uri, ignoreEscaped));
+  }
+
+  /**
+   * Static factory method based on parsing a URI string, with 
+   * <a href="#device_explanation">explicit device support</a> enabled.  
+   * Note that validity testing is not a strict as in the RFC; essentially,
+   * only separator characters are considered.  So, for example, non-Latin
+   * alphabet characters appearing in the scheme would not be considered an
+   * error.
+   *
+   * @exception java.lang.IllegalArgumentException if any component parsed
+   * from <code>uri</code> is not valid according to {@link #validScheme
+   * validScheme}, {@link #validOpaquePart validOpaquePart}, {@link
+   * #validAuthority validAuthority}, {@link #validArchiveAuthority
+   * validArchiveAuthority}, {@link #validDevice validDevice}, {@link
+   * #validSegments validSegments}, {@link #validQuery validQuery}, or {@link
+   * #validFragment validFragment}, as appropriate.
+   *
+   * @deprecated Use {@link #createURI createURI}, which now has explicit
+   * device support enabled. The two methods now operate identically.
+   */
+  public static URI createDeviceURI(String uri)
+  {
+    return createURIWithCache(uri);
+  }
+
+  // Uses a cache to speed up creation of a URI from a string.  The cache
+  // is consulted to see if the URI, less any fragment, has already been
+  // created.  If needed, the fragment is re-appended to the cached URI,
+  // which is considerably more efficient than creating the whole URI from
+  // scratch.  If the URI wasn't found in the cache, it is created using
+  // parseIntoURI() and then cached.  This method should always be used
+  // by string-parsing factory methods, instead of parseIntoURI() directly.
+  /**
+   * This method was included in the public API by mistake.
+   * 
+   * @deprecated Please use {@link #createURI createURI} instead.
+   */
+  public static URI createURIWithCache(String uri)
+  {
+    int i = uri.indexOf(FRAGMENT_SEPARATOR);
+    String base = i == -1 ? uri : uri.substring(0, i);
+    String fragment = i == -1 ? null : uri.substring(i + 1);
+
+    URI result = (URI)uriCache.get(base);
+
+    if (result == null)
+    {
+      result = parseIntoURI(base);
+      uriCache.put(base, result);
+    }
+
+    if (fragment != null)
+    {
+      result = result.appendFragment(fragment);
+    }
+    return result;
+  }
+
+  // String-parsing implementation.
+  private static URI parseIntoURI(String uri)
+  {
+    boolean hierarchical = true;
+    String scheme = null;
+    String authority = null;
+    String device = null;
+    boolean absolutePath = false;
+    String[] segments = NO_SEGMENTS;
+    String query = null;
+    String fragment = null;
+
+    int i = 0;
+    int j = find(uri, i, MAJOR_SEPARATOR_HI, MAJOR_SEPARATOR_LO);
+
+    if (j < uri.length() && uri.charAt(j) == SCHEME_SEPARATOR)
+    {
+      scheme = uri.substring(i, j);
+      i = j + 1;
+    }
+
+    boolean archiveScheme = isArchiveScheme(scheme);
+    if (archiveScheme)
+    {
+      j = uri.lastIndexOf(ARCHIVE_SEPARATOR);
+      if (j == -1)
+      {
+        throw new IllegalArgumentException("no archive separator");
+      }
+      hierarchical = true;
+      authority = uri.substring(i, ++j);
+      i = j;
+    }
+    else if (uri.startsWith(AUTHORITY_SEPARATOR, i))
+    {
+      i += AUTHORITY_SEPARATOR.length();
+      j = find(uri, i, SEGMENT_END_HI, SEGMENT_END_LO);
+      authority = uri.substring(i, j);
+      i = j;
+    }
+    else if (scheme != null &&
+             (i == uri.length() || uri.charAt(i) != SEGMENT_SEPARATOR))
+    {
+      hierarchical = false;
+      j = uri.indexOf(FRAGMENT_SEPARATOR, i);
+      if (j == -1) j = uri.length();
+      authority = uri.substring(i, j);
+      i = j;
+    }
+
+    if (!archiveScheme && i < uri.length() && uri.charAt(i) == SEGMENT_SEPARATOR)
+    {
+      j = find(uri, i + 1, SEGMENT_END_HI, SEGMENT_END_LO);
+      String s = uri.substring(i + 1, j);
+      
+      if (s.length() > 0 && s.charAt(s.length() - 1) == DEVICE_IDENTIFIER)
+      {
+        device = s;
+        i = j;
+      }
+    }
+
+    if (i < uri.length() && uri.charAt(i) == SEGMENT_SEPARATOR)
+    {
+      i++;
+      absolutePath = true;
+    }
+
+    if (segmentsRemain(uri, i))
+    {
+      List segmentList = new ArrayList();
+
+      while (segmentsRemain(uri, i))
+      {
+        j = find(uri, i, SEGMENT_END_HI, SEGMENT_END_LO);
+        segmentList.add(uri.substring(i, j));
+        i = j;
+
+        if (i < uri.length() && uri.charAt(i) == SEGMENT_SEPARATOR)
+        {
+          if (!segmentsRemain(uri, ++i)) segmentList.add(SEGMENT_EMPTY);
+        }
+      }
+      segments = new String[segmentList.size()];
+      segmentList.toArray(segments);
+    }
+
+    if (i < uri.length() && uri.charAt(i) == QUERY_SEPARATOR)
+    {
+      j = uri.indexOf(FRAGMENT_SEPARATOR, ++i);
+      if (j == -1) j = uri.length();
+      query = uri.substring(i, j);
+      i = j;
+    }
+
+    if (i < uri.length()) // && uri.charAt(i) == FRAGMENT_SEPARATOR (implied)
+    {
+      fragment = uri.substring(++i);
+    }
+
+    validateURI(hierarchical, scheme, authority, device, absolutePath, segments, query, fragment);
+    return new URI(hierarchical, scheme, authority, device, absolutePath, segments, query, fragment);
+  }
+
+  // Checks whether the string contains any more segments after the one that
+  // starts at position i.
+  private static boolean segmentsRemain(String uri, int i)
+  {
+    return i < uri.length() && uri.charAt(i) != QUERY_SEPARATOR &&
+      uri.charAt(i) != FRAGMENT_SEPARATOR;
+  }
+
+  // Finds the next occurance of one of the characters in the set represented
+  // by the given bitmask in the given string, beginning at index i. The index
+  // of the first found character, or s.length() if there is none, is
+  // returned.  Before searching, i is limited to the range [0, s.length()].
+  //
+  private static int find(String s, int i, long highBitmask, long lowBitmask)
+  {
+    int len = s.length();
+    if (i >= len) return len;
+
+    for (i = i > 0 ? i : 0; i < len; i++)
+    {
+      if (matches(s.charAt(i), highBitmask, lowBitmask)) break;
+    }
+    return i;
+  }
+
+  /**
+   * Static factory method based on parsing a {@link java.io.File} path
+   * string.  The <code>pathName</code> is converted into an appropriate
+   * form, as follows: platform specific path separators are converted to
+   * <code>/<code>; the path is encoded; and a "file" scheme and, if missing,
+   * a leading <code>/</code>, are added to an absolute path.  The result
+   * is then parsed using {@link #createURI(String) createURI}.
+   *
+   * <p>The encoding step escapes all spaces, <code>#</code> characters, and
+   * other characters disallowed in URIs, as well as <code>?</code>, which
+   * would delimit a path from a query.  Decoding is automatically performed
+   * by {@link #toFileString toFileString}, and can be applied to the values
+   * returned by other accessors by via the static {@link #decode(String)
+   * decode} method.
+   *
+   * <p>A relative path with a specified device (something like
+   * <code>C:myfile.txt</code>) cannot be expressed as a valid URI.
+   * 
+   * @exception java.lang.IllegalArgumentException if <code>pathName</code>
+   * specifies a device and a relative path, or if any component of the path
+   * is not valid according to {@link #validAuthority validAuthority}, {@link
+   * #validDevice validDevice}, or {@link #validSegments validSegments},
+   * {@link #validQuery validQuery}, or {@link #validFragment validFragment}.
+   */
+  public static URI createFileURI(String pathName)
+  {
+    File file = new File(pathName);
+    String uri = File.separatorChar != '/' ? pathName.replace(File.separatorChar, SEGMENT_SEPARATOR) : pathName;
+    uri = encode(uri, PATH_CHAR_HI, PATH_CHAR_LO, false);
+    if (file.isAbsolute())
+    {
+      URI result = createURI((uri.charAt(0) == SEGMENT_SEPARATOR ? "file:" : "file:/") + uri);
+      return result;
+    }
+    else
+    {
+      URI result = createURI(uri);
+      if (result.scheme() != null)
+      {
+        throw new IllegalArgumentException("invalid relative pathName: " + pathName);
+      }
+      return result;
+    }
+  }
+
+  /**
+   * Static factory method based on parsing a platform-relative path string.
+   *
+   * <p>The <code>pathName</code> must be of the form:
+   * <pre>
+   *   /project-name/path</pre>
+   *
+   * <p>Platform-specific path separators will be converterted to slashes.
+   * If not included, the leading path separator will be added.  The
+   * result will be of this form, which is parsed using {@link #createURI
+   * createURI}:
+   * <pre>
+   *   platform:/resource/project-name/path</pre>
+   *
+   * 
+   * @exception java.lang.IllegalArgumentException if any component parsed
+   * from the path is not valid according to {@link #validDevice validDevice},
+   * {@link #validSegments validSegments}, {@link #validQuery validQuery}, or
+   * {@link #validFragment validFragment}.
+   *
+   * @see org.eclipse.core.runtime.Platform#resolve
+   * @see #createPlatformResourceURI(String, boolean)
+   */
+  public static URI createPlatformResourceURI(String pathName)
+  {
+    return createPlatformResourceURI(pathName, false);
+  }
+
+  /**
+   * Static factory method based on parsing a platform-relative path string,
+   * with an option to encode the created URI.
+   *
+   * <p>The <code>pathName</code> must be of the form:
+   * <pre>
+   *   /project-name/path</pre>
+   *
+   * <p>Platform-specific path separators will be converterted to slashes.
+   * If not included, the leading path separator will be added.  The
+   * result will be of this form, which is parsed using {@link #createURI
+   * createURI}:
+   * <pre>
+   *   platform:/resource/project-name/path</pre>
+   *
+   * <p>This scheme supports relocatable projects in Eclipse and in
+   * stand-alone .
+   *
+   * <p>Depending on the <code>encode</code> argument, the path may be
+   * automatically encoded to escape all spaces, <code>#</code> characters,
+   * and other characters disallowed in URIs, as well as <code>?</code>,
+   * which would delimit a path from a query.  Decoding can be performed with
+   * the static {@link #decode(String) decode} method.
+   * 
+   * @exception java.lang.IllegalArgumentException if any component parsed
+   * from the path is not valid according to {@link #validDevice validDevice},
+   * {@link #validSegments validSegments}, {@link #validQuery validQuery}, or
+   * {@link #validFragment validFragment}.
+   *
+   * @see org.eclipse.core.runtime.Platform#resolve
+   */
+  public static URI createPlatformResourceURI(String pathName, boolean encode)
+  {
+    if (File.separatorChar != SEGMENT_SEPARATOR)
+    {
+      pathName = pathName.replace(File.separatorChar, SEGMENT_SEPARATOR);
+    }
+
+    if (encode)
+    {
+      pathName = encode(pathName, PATH_CHAR_HI, PATH_CHAR_LO, false);
+    }
+    URI result = createURI((pathName.charAt(0) == SEGMENT_SEPARATOR ? "platform:/resource" : "platform:/resource/") + pathName);
+    return result;
+  }
+  
+  // Private constructor for use of static factory methods.
+  private URI(boolean hierarchical, String scheme, String authority,
+              String device, boolean absolutePath, String[] segments,
+              String query, String fragment)
+  {
+    int hashCode = 0;
+    //boolean iri = false;
+
+    if (hierarchical)
+    {
+      ++hashCode;
+    }
+    if (absolutePath)
+    {
+      hashCode += 2;
+    }
+    if (scheme != null)
+    {
+      hashCode ^= scheme.toLowerCase().hashCode();
+    }
+    if (authority != null)
+    {
+      hashCode ^= authority.hashCode();
+      //iri = iri || containsNonASCII(authority);
+    }
+    if (device != null)
+    {
+      hashCode ^= device.hashCode();
+      //iri = iri || containsNonASCII(device);
+    }
+    if (query != null)
+    {
+      hashCode ^= query.hashCode();
+      //iri = iri || containsNonASCII(query);
+    }
+    if (fragment != null)
+    {
+      hashCode ^= fragment.hashCode();
+      //iri = iri || containsNonASCII(fragment);
+    }
+
+    for (int i = 0, len = segments.length; i < len; i++)
+    {
+      hashCode ^= segments[i].hashCode();
+      //iri = iri || containsNonASCII(segments[i]);
+    }
+
+    this.hashCode = hashCode;
+    //this.iri = iri;
+    this.hierarchical = hierarchical;
+    this.scheme = scheme == null ? null : scheme.intern();
+    this.authority = authority;
+    this.device = device;
+    this.absolutePath = absolutePath;
+    this.segments = segments;
+    this.query = query;
+    this.fragment = fragment;
+  }
+  
+  // Validates all of the URI components.  Factory methods should call this
+  // before using the constructor, though they must ensure that the
+  // inter-component requirements described in their own Javadocs are all
+  // satisfied, themselves.  If a new URI is being constructed out of
+  // an existing URI, this need not be called.  Instead, just the new
+  // components may be validated individually.
+  private static void validateURI(boolean hierarchical, String scheme,
+                                    String authority, String device,
+                                    boolean absolutePath, String[] segments,
+                                    String query, String fragment)
+  {
+    if (!validScheme(scheme))
+    {
+      throw new IllegalArgumentException("invalid scheme: " + scheme);
+    }
+    if (!hierarchical && !validOpaquePart(authority))
+    {
+      throw new IllegalArgumentException("invalid opaquePart: " + authority);
+    }
+    if (hierarchical && !isArchiveScheme(scheme) && !validAuthority(authority))
+    {
+      throw new IllegalArgumentException("invalid authority: " + authority);
+    }
+    if (hierarchical && isArchiveScheme(scheme) && !validArchiveAuthority(authority))
+    {
+      throw new IllegalArgumentException("invalid authority: " + authority);
+    }
+    if (!validDevice(device))
+    {
+      throw new IllegalArgumentException("invalid device: " + device);
+    }
+    if (!validSegments(segments))
+    {
+      String s = segments == null ? "invalid segments: " + segments :
+        "invalid segment: " + firstInvalidSegment(segments);
+      throw new IllegalArgumentException(s);
+    }
+    if (!validQuery(query))
+    {
+      throw new IllegalArgumentException("invalid query: " + query);
+    }
+    if (!validFragment(fragment))
+    {
+      throw new IllegalArgumentException("invalid fragment: " + fragment);
+    }
+  }
+
+  // Alternate, stricter implementations of the following validation methods
+  // are provided, commented out, for possible future use...
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the scheme component of a URI; <code>false</code> otherwise.
+   *
+   * <p>A valid scheme may be null or contain any characters except for the
+   * following: <code>: / ? #</code>
+   */
+  public static boolean validScheme(String value)
+  {
+    return value == null || !contains(value, MAJOR_SEPARATOR_HI, MAJOR_SEPARATOR_LO);  
+
+  // <p>A valid scheme may be null, or consist of a single letter followed
+  // by any number of letters, numbers, and the following characters:
+  // <code>+ - .</code>
+
+    //if (value == null) return true;
+    //return value.length() != 0 &&
+    //  matches(value.charAt(0), ALPHA_HI, ALPHA_LO) &&
+    //  validate(value, SCHEME_CHAR_HI, SCHEME_CHAR_LO, false, false);
+  }
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the opaque part component of a URI; <code>false</code>
+   * otherwise.
+   *
+   * <p>A valid opaque part must be non-null, non-empty, and not contain the
+   * <code>#</code> character.  In addition, its first character must not be
+   * <code>/</code>
+   */
+  public static boolean validOpaquePart(String value)
+  {
+    return value != null && value.indexOf(FRAGMENT_SEPARATOR) == -1 &&
+    value.length() > 0 && value.charAt(0) != SEGMENT_SEPARATOR;
+
+  // <p>A valid opaque part must be non-null and non-empty. It may contain
+  // any allowed URI characters, but its first character may not be
+  // <code>/</code> 
+
+    //return value != null && value.length() != 0 &&
+    //  value.charAt(0) != SEGMENT_SEPARATOR &&
+    //  validate(value, URIC_HI, URIC_LO, true, true);
+  }
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the authority component of a URI; <code>false</code> otherwise.
+   *
+   * <p>A valid authority may be null or contain any characters except for
+   * the following: <code>/ ? #</code>
+   */
+  public static boolean validAuthority(String value)
+  {
+    return value == null || !contains(value, SEGMENT_END_HI, SEGMENT_END_LO);
+
+  // A valid authority may be null or contain any allowed URI characters except
+  // for the following: <code>/ ?</code>
+
+    //return value == null || validate(value, SEGMENT_CHAR_HI, SEGMENT_CHAR_LO, true, true);
+  }
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the authority component of an <a
+   * href="#archive_explanation">archive URI</a>; <code>false</code>
+   * otherwise.
+   *
+   * <p>To be valid, the authority, itself, must be a URI with no fragment,
+   * followed by the character <code>!</code>.
+   */
+  public static boolean validArchiveAuthority(String value)
+  {
+    if (value != null && value.length() > 0 &&
+        value.charAt(value.length() - 1) == ARCHIVE_IDENTIFIER)
+    {
+      try
+      {
+        URI archiveURI = createURI(value.substring(0, value.length() - 1));
+        return !archiveURI.hasFragment();
+      }
+      catch (IllegalArgumentException e)
+      {
+      }
+    }
+    return false;
+  }
+
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the device component of a URI; <code>false</code> otherwise.
+   *
+   * <p>A valid device may be null or non-empty, containing any characters
+   * except for the following: <code>/ ? #</code>  In addition, its last
+   * character must be <code>:</code>
+   */
+  public static boolean validDevice(String value)
+  {    
+    if (value == null) return true;
+    int len = value.length();
+    return len > 0 && value.charAt(len - 1) == DEVICE_IDENTIFIER &&
+      !contains(value, SEGMENT_END_HI, SEGMENT_END_LO);
+
+  // <p>A valid device may be null or non-empty, containing any allowed URI
+  // characters except for the following: <code>/ ?</code>  In addition, its
+  // last character must be <code>:</code>
+
+    //if (value == null) return true;
+    //int len = value.length();
+    //return len > 0 && validate(value, SEGMENT_CHAR_HI, SEGMENT_CHAR_LO, true, true) &&
+    //  value.charAt(len - 1) == DEVICE_IDENTIFIER;
+  }
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * a valid path segment of a URI; <code>false</code> otherwise.
+   *
+   * <p>A valid path segment must be non-null and not contain any of the
+   * following characters: <code>/ ? #</code>
+   */
+  public static boolean validSegment(String value)
+  {
+    return value != null && !contains(value, SEGMENT_END_HI, SEGMENT_END_LO);
+
+  // <p>A valid path segment must be non-null and may contain any allowed URI
+  // characters except for the following: <code>/ ?</code> 
+
+    //return value != null && validate(value, SEGMENT_CHAR_HI, SEGMENT_CHAR_LO, true, true);
+  }
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * a valid path segment array of a URI; <code>false</code> otherwise.
+   *
+   * <p>A valid path segment array must be non-null and contain only path
+   * segements that are valid according to {@link #validSegment validSegment}.
+   */
+  public static boolean validSegments(String[] value)
+  {
+    if (value == null) return false;
+    for (int i = 0, len = value.length; i < len; i++)
+    {
+      if (!validSegment(value[i])) return false;
+    }
+    return true;
+  }
+
+  // Returns null if the specicied value is null or would be a valid path
+  // segment array of a URI; otherwise, the value of the first invalid
+  // segment. 
+  private static String firstInvalidSegment(String[] value)
+  {
+    if (value == null) return null;
+    for (int i = 0, len = value.length; i < len; i++)
+    {
+      if (!validSegment(value[i])) return value[i];
+    }
+    return null;
+  }
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the query component of a URI; <code>false</code> otherwise.
+   *
+   * <p>A valid query may be null or contain any characters except for
+   * <code>#</code>
+   */
+  public static boolean validQuery(String value)
+  {
+    return value == null || value.indexOf(FRAGMENT_SEPARATOR) == -1;
+
+  // <p>A valid query may be null or contain any allowed URI characters.
+
+    //return value == null || validate(value, URIC_HI, URIC_LO, true, true);
+}
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the fragment component of a URI; <code>false</code> otherwise.
+   *
+   * <p>A fragment is taken to be unconditionally valid.
+   */
+  public static boolean validFragment(String value)
+  {
+    return true;
+
+  // <p>A valid fragment may be null or contain any allowed URI characters.
+
+    //return value == null || validate(value, URIC_HI, URIC_LO, true, true);
+  }
+
+  // Searches the specified string for any characters in the set represnted
+  // by the 128-bit bitmask.  Returns true if any occur, or false otherwise.
+  private static boolean contains(String s, long highBitmask, long lowBitmask)
+  {
+    for (int i = 0, len = s.length(); i < len; i++)
+    {
+      if (matches(s.charAt(i), highBitmask, lowBitmask)) return true;
+    }
+    return false;
+  }
+
+  // Tests the non-null string value to see if it contains only ASCII
+  // characters in the set represented by the specified 128-bit bitmask,
+  // as well as, optionally, non-ASCII characters 0xA0 and above, and,
+  // also optionally, escape sequences of % followed by two hex digits.
+  // This method is used for the new, strict URI validation that is not
+  // not currently in place.
+/*
+  private static boolean validate(String value, long highBitmask, long lowBitmask,
+                                     boolean allowNonASCII, boolean allowEscaped)
+  {
+    for (int i = 0, len = value.length(); i < len; i++)
+    { 
+      char c = value.charAt(i);
+
+      if (matches(c, highBitmask, lowBitmask)) continue;
+      if (allowNonASCII && c >= 160) continue;
+      if (allowEscaped && isEscaped(value, i))
+      {
+        i += 2;
+        continue;
+      }
+      return false;
+    }
+    return true;
+  }
+*/
+
+  /**
+   * Returns <code>true</code> if this is a relative URI, or
+   * <code>false</code> if it is an absolute URI.
+   */
+  public boolean isRelative()
+  {
+    return scheme == null;
+  }
+
+  /**
+   * Returns <code>true</code> if this a a hierarchical URI, or
+   * <code>false</code> if it is of the generic form.
+   */
+  public boolean isHierarchical()
+  {
+    return hierarchical;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarcical URI with an authority
+   * component; <code>false</code> otherwise. 
+   */
+  public boolean hasAuthority()
+  {
+    return hierarchical && authority != null;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a non-hierarchical URI with an
+   * opaque part component; <code>false</code> otherwise.
+   */
+  public boolean hasOpaquePart()
+  {
+    // note: hierarchical -> authority != null
+    return !hierarchical;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI with a device
+   * component; <code>false</code> otherwise.
+   */
+  public boolean hasDevice()
+  {
+    // note: device != null -> hierarchical
+    return device != null;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI with an
+   * absolute or relative path; <code>false</code> otherwise.
+   */
+  public boolean hasPath()
+  {
+    // note: (absolutePath || authority == null) -> hierarchical
+    // (authority == null && device == null && !absolutePath) -> scheme == null
+    return absolutePath || (authority == null && device == null);
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI with an
+   * absolute path, or <code>false</code> if it is non-hierarchical, has no
+   * path, or has a relative path.
+   */
+  public boolean hasAbsolutePath()
+  {
+    // note: absolutePath -> hierarchical
+    return absolutePath;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI with a relative
+   * path, or <code>false</code> if it is non-hierarchical, has no path, or
+   * has an absolute path.
+   */
+  public boolean hasRelativePath()
+  {
+    // note: authority == null -> hierarchical
+    // (authority == null && device == null && !absolutePath) -> scheme == null
+    return authority == null && device == null && !absolutePath;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI with an empty
+   * relative path; <code>false</code> otherwise.  
+   *
+   * <p>Note that <code>!hasEmpty()</code> does <em>not</em> imply that this
+   * URI has any path segments; however, <code>hasRelativePath &&
+   * !hasEmptyPath()</code> does.
+   */
+  public boolean hasEmptyPath()
+  {
+    // note: authority == null -> hierarchical
+    // (authority == null && device == null && !absolutePath) -> scheme == null
+    return authority == null && device == null && !absolutePath &&
+      segments.length == 0;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI with a query
+   * component; <code>false</code> otherwise.
+   */
+  public boolean hasQuery()
+  {
+    // note: query != null -> hierarchical
+    return query != null;
+  }
+
+  /**
+   * Returns <code>true</code> if this URI has a fragment component;
+   * <code>false</code> otherwise.
+   */
+  public boolean hasFragment()
+  {
+    return fragment != null;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a current document reference; that
+   * is, if it is a relative hierarchical URI with no authority, device or
+   * query components, and no path segments; <code>false</code> is returned
+   * otherwise.
+   */
+  public boolean isCurrentDocumentReference()
+  {
+    // note: authority == null -> hierarchical
+    // (authority == null && device == null && !absolutePath) -> scheme == null
+    return authority == null && device == null && !absolutePath &&
+      segments.length == 0 && query == null;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a {@link
+   * #isCurrentDocumentReference() current document reference} with no
+   * fragment component; <code>false</code> otherwise.
+   *
+   * @see #isCurrentDocumentReference()
+   */
+  public boolean isEmpty()
+  {
+    // note: authority == null -> hierarchical
+    // (authority == null && device == null && !absolutePath) -> scheme == null
+    return authority == null && device == null && !absolutePath &&
+      segments.length == 0 && query == null && fragment == null;
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI that may refer
+   * directly to a locally accessible file.  This is considered to be the
+   * case for a file-scheme absolute URI, or for a relative URI with no query;
+   * <code>false</code> is returned otherwise.
+   */
+  public boolean isFile()
+  {
+    return isHierarchical() &&
+      ((isRelative() && !hasQuery()) || SCHEME_FILE.equalsIgnoreCase(scheme));
+  }
+
+  // Returns true if this is an archive URI.  If so, we should expect that
+  // it is also hierarchical, with an authority (consisting of an absolute
+  // URI followed by "!"), no device, and an absolute path.
+  private boolean isArchive()
+  {
+    return isArchiveScheme(scheme);
+  }
+
+  /**
+   * Returns <code>true</code> if the specified <code>value</code> would be
+   * valid as the scheme of an <a
+   * href="#archive_explanation">archive URI</a>; <code>false</code>
+   * otherwise.
+   */
+  public static boolean isArchiveScheme(String value)
+  {
+    return value != null && archiveSchemes.contains(value.toLowerCase());
+  }
+  
+  /**
+   * Returns the hash code.
+   */
+  public int hashCode()
+  {
+    return hashCode;
+  }
+
+  /**
+   * Returns <code>true</code> if <code>obj</code> is an instance of
+   * <code>URI</code> equal to this one; <code>false</code> otherwise.
+   *
+   * <p>Equality is determined strictly by comparing components, not by
+   * attempting to interpret what resource is being identified.  The
+   * comparison of schemes is case-insensitive.
+   */
+  public boolean equals(Object obj)
+  {
+    if (this == obj) return true;
+    if (!(obj instanceof URI)) return false;
+    URI uri = (URI) obj;
+
+    return hashCode == uri.hashCode() &&
+      hierarchical == uri.isHierarchical() &&
+      absolutePath == uri.hasAbsolutePath() &&
+      equals(scheme, uri.scheme(), true) &&
+      equals(authority, hierarchical ? uri.authority() : uri.opaquePart()) &&
+      equals(device, uri.device()) &&
+      equals(query, uri.query()) && 
+      equals(fragment, uri.fragment()) &&
+      segmentsEqual(uri);
+  }
+
+  // Tests whether this URI's path segment array is equal to that of the
+  // given uri.
+  private boolean segmentsEqual(URI uri)
+  {
+    if (segments.length != uri.segmentCount()) return false;
+    for (int i = 0, len = segments.length; i < len; i++)
+    {
+      if (!segments[i].equals(uri.segment(i))) return false;
+    }
+    return true;
+  }
+
+  // Tests two objects for equality, tolerating nulls; null is considered
+  // to be a valid value that is only equal to itself.
+  private static boolean equals(Object o1, Object o2)
+  {
+    return o1 == null ? o2 == null : o1.equals(o2);
+  }
+
+  // Tests two strings for equality, tolerating nulls and optionally
+  // ignoring case.
+  private static boolean equals(String s1, String s2, boolean ignoreCase)
+  {
+    return s1 == null ? s2 == null :
+      ignoreCase ? s1.equalsIgnoreCase(s2) : s1.equals(s2);
+  }
+
+  /**
+   * If this is an absolute URI, returns the scheme component;
+   * <code>null</code> otherwise.
+   */
+  public String scheme()
+  {
+    return scheme;
+  }
+
+  /**
+   * If this is a non-hierarchical URI, returns the opaque part component;
+   * <code>null</code> otherwise.
+   */
+  public String opaquePart()
+  {
+    return isHierarchical() ? null : authority;
+  }
+
+  /**
+   * If this is a hierarchical URI with an authority component, returns it;
+   * <code>null</code> otherwise.
+   */
+  public String authority()
+  {
+    return isHierarchical() ? authority : null;
+  }
+
+  /**
+   * If this is a hierarchical URI with an authority component that has a
+   * user info portion, returns it; <code>null</code> otherwise.
+   */
+  public String userInfo()
+  { 
+    if (!hasAuthority()) return null;
+   
+    int i = authority.indexOf(USER_INFO_SEPARATOR);
+    return i < 0 ? null : authority.substring(0, i);
+  }
+
+  /**
+   * If this is a hierarchical URI with an authority component that has a
+   * host portion, returns it; <code>null</code> otherwise.
+   */
+  public String host()
+  {
+    if (!hasAuthority()) return null;
+    
+    int i = authority.indexOf(USER_INFO_SEPARATOR);
+    int j = authority.indexOf(PORT_SEPARATOR);
+    return j < 0 ? authority.substring(i + 1) : authority.substring(i + 1, j);
+  }
+
+  /**
+   * If this is a hierarchical URI with an authority component that has a
+   * port portion, returns it; <code>null</code> otherwise.
+   */
+  public String port()
+  {
+    if (!hasAuthority()) return null;
+
+    int i = authority.indexOf(PORT_SEPARATOR);
+    return i < 0 ? null : authority.substring(i + 1);
+  }
+
+  /**
+   * If this is a hierarchical URI with a device component, returns it;
+   * <code>null</code> otherwise.
+   */
+  public String device()
+  {
+    return device;
+  }
+
+  /**
+   * If this is a hierarchical URI with a path, returns an array containing
+   * the segments of the path; an empty array otherwise.  The leading
+   * separator in an absolute path is not represented in this array, but a
+   * trailing separator is represented by an empty-string segment as the
+   * final element.
+   */
+  public String[] segments()
+  {
+    return (String[])segments.clone();
+  }
+
+  /**
+   * Returns an unmodifiable list containing the same segments as the array
+   * returned by {@link #segments segments}.
+   */
+  public List segmentsList()
+  {
+    return Collections.unmodifiableList(Arrays.asList(segments));
+  }
+
+  /**
+   * Returns the number of elements in the segment array that would be
+   * returned by {@link #segments segments}.
+   */
+  public int segmentCount()
+  {
+    return segments.length;
+  }
+
+  /**
+   * Provides fast, indexed access to individual segments in the path
+   * segment array.
+   *
+   * @exception java.lang.IndexOutOfBoundsException if <code>i < 0</code> or
+   * <code>i >= segmentCount()</code>.
+   */
+  public String segment(int i)
+  {
+    return segments[i];
+  }
+
+  /**
+   * Returns the last segment in the segment array, or <code>null</code>.
+   */
+  public String lastSegment()
+  {
+    int len = segments.length;
+    if (len == 0) return null;
+    return segments[len - 1];
+  }
+
+  /**
+   * If this is a hierarchical URI with a path, returns a string
+   * representation of the path; <code>null</code> otherwise.  The path
+   * consists of a leading segment separator character (a slash), if the
+   * path is absolute, followed by the slash-separated path segments.  If
+   * this URI has a separate <a href="#device_explanation">device
+   * component</a>, it is <em>not</em> included in the path.
+   */
+  public String path()
+  {
+    if (!hasPath()) return null;
+
+    StringBuffer result = new StringBuffer();
+    if (hasAbsolutePath()) result.append(SEGMENT_SEPARATOR);
+
+    for (int i = 0, len = segments.length; i < len; i++)
+    {
+      if (i != 0) result.append(SEGMENT_SEPARATOR);
+      result.append(segments[i]);
+    }
+    return result.toString();
+  }
+
+  /**
+   * If this is a hierarchical URI with a path, returns a string
+   * representation of the path, including the authority and the 
+   * <a href="#device_explanation">device component</a>; 
+   * <code>null</code> otherwise.  
+   *
+   * <p>If there is no authority, the format of this string is:
+   * <pre>
+   *   device/pathSegment1/pathSegment2...</pre>
+   *
+   * <p>If there is an authority, it is:
+   * <pre>
+   *   //authority/device/pathSegment1/pathSegment2...</pre>
+   *
+   * <p>For an <a href="#archive_explanation">archive URI</a>, it's just:
+   * <pre>
+   *   authority/pathSegment1/pathSegment2...</pre>
+   */
+  public String devicePath()
+  {
+    if (!hasPath()) return null;
+
+    StringBuffer result = new StringBuffer();
+
+    if (hasAuthority())
+    {
+      if (!isArchive()) result.append(AUTHORITY_SEPARATOR);
+      result.append(authority);
+
+      if (hasDevice()) result.append(SEGMENT_SEPARATOR);
+    }
+
+    if (hasDevice()) result.append(device);
+    if (hasAbsolutePath()) result.append(SEGMENT_SEPARATOR);
+
+    for (int i = 0, len = segments.length; i < len; i++)
+    {
+      if (i != 0) result.append(SEGMENT_SEPARATOR);
+      result.append(segments[i]);
+    }
+    return result.toString();
+  }
+
+  /**
+   * If this is a hierarchical URI with a query component, returns it;
+   * <code>null</code> otherwise.
+   */
+  public String query()
+  {
+    return query;
+  }
+
+
+  /**
+   * Returns the URI formed from this URI and the given query.
+   *
+   * @exception java.lang.IllegalArgumentException if
+   * <code>query</code> is not a valid query (portion) according
+   * to {@link #validQuery validQuery}.
+   */
+  public URI appendQuery(String query)
+  {
+    if (!validQuery(query))
+    {
+      throw new IllegalArgumentException(
+        "invalid query portion: " + query);
+    }
+    return new URI(hierarchical, scheme, authority, device, absolutePath, segments, query, fragment); 
+  }
+
+  /**
+   * If this URI has a non-null {@link #query query}, returns the URI
+   * formed by removing it; this URI unchanged, otherwise.
+   */
+  public URI trimQuery()
+  {
+    if (query == null)
+    {
+      return this;
+    }
+    else
+    {
+      return new URI(hierarchical, scheme, authority, device, absolutePath, segments, null, fragment); 
+    }
+  }
+
+  /**
+   * If this URI has a fragment component, returns it; <code>null</code>
+   * otherwise.
+   */
+  public String fragment()
+  {
+    return fragment;
+  }
+
+  /**
+   * Returns the URI formed from this URI and the given fragment.
+   *
+   * @exception java.lang.IllegalArgumentException if
+   * <code>fragment</code> is not a valid fragment (portion) according
+   * to {@link #validFragment validFragment}.
+   */
+  public URI appendFragment(String fragment)
+  {
+    if (!validFragment(fragment))
+    {
+      throw new IllegalArgumentException(
+        "invalid fragment portion: " + fragment);
+    }
+    URI result = new URI(hierarchical, scheme, authority, device, absolutePath, segments, query, fragment); 
+
+    if (!hasFragment())
+    {
+      result.cachedTrimFragment = this;
+    }
+    return result;
+  }
+
+  /**
+   * If this URI has a non-null {@link #fragment fragment}, returns the URI
+   * formed by removing it; this URI unchanged, otherwise.
+   */
+  public URI trimFragment()
+  {
+    if (fragment == null)
+    {
+      return this;
+    }
+    else if (cachedTrimFragment == null)
+    {
+      cachedTrimFragment = new URI(hierarchical, scheme, authority, device, absolutePath, segments, query, null); 
+    }
+
+    return cachedTrimFragment;
+  }
+
+  /**
+   * Resolves this URI reference against a <code>base</code> absolute
+   * hierarchical URI, returning the resulting absolute URI.  If already
+   * absolute, the URI itself is returned.  URI resolution is described in
+   * detail in section 5.2 of <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC
+   * 2396</a>, "Resolving Relative References to Absolute Form."
+   *
+   * <p>During resolution, empty segments, self references ("."), and parent
+   * references ("..") are interpreted, so that they can be removed from the
+   * path.  Step 6(g) gives a choice of how to handle the case where parent
+   * references point to a path above the root: the offending segments can
+   * be preserved or discarded.  This method preserves them.  To have them
+   * discarded, please use the two-parameter form of {@link
+   * #resolve(URI, boolean) resolve}.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>base</code> is
+   * non-hierarchical or is relative.
+   */
+  public URI resolve(URI base)
+  {
+    return resolve(base, true);
+  }
+
+  /**
+   * Resolves this URI reference against a <code>base</code> absolute
+   * hierarchical URI, returning the resulting absolute URI.  If already
+   * absolute, the URI itself is returned.  URI resolution is described in
+   * detail in section 5.2 of <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC
+   * 2396</a>, "Resolving Relative References to Absolute Form."
+   *
+   * <p>During resultion, empty segments, self references ("."), and parent
+   * references ("..") are interpreted, so that they can be removed from the
+   * path.  Step 6(g) gives a choice of how to handle the case where parent
+   * references point to a path above the root: the offending segments can
+   * be preserved or discarded.  This method can do either.
+   *
+   * @param preserveRootParents <code>true</code> if segments refering to the
+   * parent of the root path are to be preserved; <code>false</code> if they
+   * are to be discarded.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>base</code> is
+   * non-hierarchical or is relative.
+   */
+  public URI resolve(URI base, boolean preserveRootParents)
+  {
+    if (!base.isHierarchical() || base.isRelative())
+    {
+      throw new IllegalArgumentException(
+        "resolve against non-hierarchical or relative base");
+    }
+
+    // an absolute URI needs no resolving
+    if (!isRelative()) return this;
+
+    // note: isRelative() -> hierarchical
+
+    String newAuthority = authority;
+    String newDevice = device;
+    boolean newAbsolutePath = absolutePath;
+    String[] newSegments = segments;
+    String newQuery = query;
+    // note: it's okay for two URIs to share a segments array, since
+    // neither will ever modify it
+    
+    if (authority == null)
+    {
+      // no authority: use base's
+      newAuthority = base.authority();
+
+      if (device == null)
+      {
+        // no device: use base's
+        newDevice = base.device();
+
+        if (hasEmptyPath() && query == null)
+        {
+          // current document reference: use base path and query
+          newAbsolutePath = base.hasAbsolutePath();
+          newSegments = base.segments();
+          newQuery = base.query();
+        }
+        else if (hasRelativePath())
+        {
+          // relative path: merge with base and keep query (note: if the
+          // base has no path and this a non-empty relative path, there is
+          // an implied root in the resulting path) 
+          newAbsolutePath = base.hasAbsolutePath() || !hasEmptyPath();
+          newSegments = newAbsolutePath ? mergePath(base, preserveRootParents)
+            : NO_SEGMENTS;
+        }
+        // else absolute path: keep it and query
+      }
+      // else keep device, path, and query
+    }
+    // else keep authority, device, path, and query
+    
+    // always keep fragment, even if null, and use scheme from base;
+    // no validation needed since all components are from existing URIs
+    return new URI(true, base.scheme(), newAuthority, newDevice,
+                   newAbsolutePath, newSegments, newQuery, fragment);
+  }
+
+  // Merges this URI's relative path with the base non-relative path.  If
+  // base has no path, treat it as the root absolute path, unless this has
+  // no path either.
+  private String[] mergePath(URI base, boolean preserveRootParents)
+  {
+    if (base.hasRelativePath())
+    {
+      throw new IllegalArgumentException("merge against relative path");
+    }
+    if (!hasRelativePath())
+    {
+      throw new IllegalStateException("merge non-relative path");
+    }
+
+    int baseSegmentCount = base.segmentCount();
+    int segmentCount = segments.length;
+    String[] stack = new String[baseSegmentCount + segmentCount];
+    int sp = 0;
+
+    // use a stack to accumulate segments of base, except for the last
+    // (i.e. skip trailing separator and anything following it), and of
+    // relative path
+    for (int i = 0; i < baseSegmentCount - 1; i++)
+    {
+      sp = accumulate(stack, sp, base.segment(i), preserveRootParents);
+    }
+
+    for (int i = 0; i < segmentCount; i++)
+    {
+      sp = accumulate(stack, sp, segments[i], preserveRootParents);
+    }
+
+    // if the relative path is empty or ends in an empty segment, a parent 
+    // reference, or a self referenfce, add a trailing separator to a
+    // non-empty path
+    if (sp > 0 &&  (segmentCount == 0 ||
+                    SEGMENT_EMPTY.equals(segments[segmentCount - 1]) ||
+                    SEGMENT_PARENT.equals(segments[segmentCount - 1]) ||
+                    SEGMENT_SELF.equals(segments[segmentCount - 1])))
+    {
+      stack[sp++] = SEGMENT_EMPTY;
+    }
+
+    // return a correctly sized result
+    String[] result = new String[sp];
+    System.arraycopy(stack, 0, result, 0, sp);
+    return result;
+  }
+
+  // Adds a segment to a stack, skipping empty segments and self references,
+  // and interpreting parent references.
+  private static int accumulate(String[] stack, int sp, String segment,
+                                boolean preserveRootParents)
+  {
+    if (SEGMENT_PARENT.equals(segment))
+    {
+      if (sp == 0)
+      {
+        // special care must be taken for a root's parent reference: it is
+        // either ignored or the symbolic reference itself is pushed
+        if (preserveRootParents) stack[sp++] = segment;
+      }
+      else
+      {
+        // unless we're already accumulating root parent references,
+        // parent references simply pop the last segment descended
+        if (SEGMENT_PARENT.equals(stack[sp - 1])) stack[sp++] = segment;
+        else sp--;
+      }
+    }
+    else if (!SEGMENT_EMPTY.equals(segment) && !SEGMENT_SELF.equals(segment))
+    {
+      // skip empty segments and self references; push everything else
+      stack[sp++] = segment;
+    }
+    return sp;
+  }
+
+  /**
+   * Finds the shortest relative or, if necessary, the absolute URI that,
+   * when resolved against the given <code>base</code> absolute hierarchical
+   * URI using {@link #resolve(URI) resolve}, will yield this absolute URI.  
+   *
+   * @exception java.lang.IllegalArgumentException if <code>base</code> is
+   * non-hierarchical or is relative.
+   * @exception java.lang.IllegalStateException if <code>this</code> is
+   * relative.
+   */
+  public URI deresolve(URI base)
+  {
+    return deresolve(base, true, false, true);
+  }
+
+  /**
+   * Finds an absolute URI that, when resolved against the given
+   * <code>base</code> absolute hierarchical URI using {@link
+   * #resolve(URI, boolean) resolve}, will yield this absolute URI.
+   *
+   * @param preserveRootParents the boolean argument to <code>resolve(URI,
+   * boolean)</code> for which the returned URI should resolve to this URI.
+   * @param anyRelPath if <code>true</code>, the returned URI's path (if
+   * any) will be relative, if possible.  If <code>false</code>, the form of
+   * the result's path will depend upon the next parameter.
+   * @param shorterRelPath if <code>anyRelPath</code> is <code>false</code>
+   * and this parameter is <code>true</code>, the returned URI's path (if
+   * any) will be relative, if one can be found that is no longer (by number
+   * of segments) than the absolute path.  If both <code>anyRelPath</code>
+   * and this parameter are <code>false</code>, it will be absolute.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>base</code> is
+   * non-hierarchical or is relative.
+   * @exception java.lang.IllegalStateException if <code>this</code> is
+   * relative.
+   */
+  public URI deresolve(URI base, boolean preserveRootParents,
+                       boolean anyRelPath, boolean shorterRelPath)
+  {
+    if (!base.isHierarchical() || base.isRelative())
+    {
+      throw new IllegalArgumentException(
+        "deresolve against non-hierarchical or relative base");
+    }
+    if (isRelative())
+    {
+      throw new IllegalStateException("deresolve relative URI");
+    }
+
+    // note: these assertions imply that neither this nor the base URI has a
+    // relative path; thus, both have either an absolute path or no path
+    
+    // different scheme: need complete, absolute URI
+    if (!scheme.equalsIgnoreCase(base.scheme())) return this;
+
+    // since base must be hierarchical, and since a non-hierarchical URI
+    // must have both scheme and opaque part, the complete absolute URI is
+    // needed to resolve to a non-hierarchical URI
+    if (!isHierarchical()) return this;
+
+    String newAuthority = authority;
+    String newDevice = device;
+    boolean newAbsolutePath = absolutePath;
+    String[] newSegments = segments;
+    String newQuery = query;
+
+    if (equals(authority, base.authority()) &&
+        (hasDevice() || hasPath() || (!base.hasDevice() && !base.hasPath())))
+    {
+      // matching authorities and no device or path removal
+      newAuthority = null;
+
+      if (equals(device, base.device()) && (hasPath() || !base.hasPath()))
+      {
+        // matching devices and no path removal
+        newDevice = null;
+
+        // exception if (!hasPath() && base.hasPath())
+
+        if (!anyRelPath && !shorterRelPath)
+        {
+          // user rejects a relative path: keep absolute or no path
+        }
+        else if (hasPath() == base.hasPath() && segmentsEqual(base) &&
+                 equals(query, base.query()))
+        {
+          // current document reference: keep no path or query
+          newAbsolutePath = false;
+          newSegments = NO_SEGMENTS;
+          newQuery = null;
+        }
+        else if (!hasPath() && !base.hasPath())
+        {
+          // no paths: keep query only
+          newAbsolutePath = false;
+          newSegments = NO_SEGMENTS;
+        }
+        // exception if (!hasAbsolutePath())
+        else if (hasCollapsableSegments(preserveRootParents))
+        {
+          // path form demands an absolute path: keep it and query
+        }
+        else
+        {
+          // keep query and select relative or absolute path based on length
+          String[] rel = findRelativePath(base, preserveRootParents);
+          if (anyRelPath || segments.length > rel.length)
+          {
+            // user demands a relative path or the absolute path is longer
+            newAbsolutePath = false;
+            newSegments = rel;
+          }
+          // else keep shorter absolute path
+        }
+      }
+      // else keep device, path, and query
+    }
+    // else keep authority, device, path, and query
+
+    // always include fragment, even if null;
+    // no validation needed since all components are from existing URIs
+    return new URI(true, null, newAuthority, newDevice, newAbsolutePath,
+                   newSegments, newQuery, fragment);
+  }
+
+  // Returns true if the non-relative path includes segments that would be
+  // collapsed when resolving; false otherwise.  If preserveRootParents is
+  // true, collapsable segments include any empty segments, except for the
+  // last segment, as well as and parent and self references.  If
+  // preserveRootsParents is false, parent references are not collapsable if
+  // they are the first segment or preceeded only by other parent
+  // references.
+  private boolean hasCollapsableSegments(boolean preserveRootParents)
+  {
+    if (hasRelativePath())
+    {
+      throw new IllegalStateException("test collapsability of relative path");
+    }
+
+    for (int i = 0, len = segments.length; i < len; i++)
+    {
+      String segment = segments[i];
+      if ((i < len - 1 && SEGMENT_EMPTY.equals(segment)) ||
+          SEGMENT_SELF.equals(segment) ||
+          SEGMENT_PARENT.equals(segment) && (
+            !preserveRootParents || (
+              i != 0 && !SEGMENT_PARENT.equals(segments[i - 1]))))
+      {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  // Returns the shortest relative path between the the non-relative path of
+  // the given base and this absolute path.  If the base has no path, it is
+  // treated as the root absolute path.
+  private String[] findRelativePath(URI base, boolean preserveRootParents)
+  {
+    if (base.hasRelativePath())
+    {
+      throw new IllegalArgumentException(
+        "find relative path against base with relative path");
+    }
+    if (!hasAbsolutePath())
+    {
+      throw new IllegalArgumentException(
+        "find relative path of non-absolute path");
+    }
+
+    // treat an empty base path as the root absolute path
+    String[] startPath = base.collapseSegments(preserveRootParents);
+    String[] endPath = segments;
+
+    // drop last segment from base, as in resolving
+    int startCount = startPath.length > 0 ? startPath.length - 1 : 0;
+    int endCount = endPath.length;
+
+    // index of first segment that is different between endPath and startPath
+    int diff = 0;
+
+    // if endPath is shorter than startPath, the last segment of endPath may
+    // not be compared: because startPath has been collapsed and had its
+    // last segment removed, all preceeding segments can be considered non-
+    // empty and followed by a separator, while the last segment of endPath
+    // will either be non-empty and not followed by a separator, or just empty
+    for (int count = startCount < endCount ? startCount : endCount - 1;
+         diff < count && startPath[diff].equals(endPath[diff]); diff++);
+
+    int upCount = startCount - diff;
+    int downCount = endCount - diff;
+
+    // a single separator, possibly preceeded by some parent reference
+    // segments, is redundant
+    if (downCount == 1 && SEGMENT_EMPTY.equals(endPath[endCount - 1]))
+    {
+      downCount = 0;
+    }
+
+    // an empty path needs to be replaced by a single "." if there is no
+    // query, to distinguish it from a current document reference
+    if (upCount + downCount == 0)
+    {
+      if (query == null) return new String[] { SEGMENT_SELF };
+      return NO_SEGMENTS;
+    }
+
+    // return a correctly sized result
+    String[] result = new String[upCount + downCount];
+    Arrays.fill(result, 0, upCount, SEGMENT_PARENT);
+    System.arraycopy(endPath, diff, result, upCount, downCount);
+    return result;
+  }
+
+  // Collapses non-ending empty segments, parent references, and self
+  // references in a non-relative path, returning the same path that would
+  // be produced from the base hierarchical URI as part of a resolve.
+  String[] collapseSegments(boolean preserveRootParents)
+  {
+    if (hasRelativePath())
+    {
+      throw new IllegalStateException("collapse relative path");
+    }
+
+    if (!hasCollapsableSegments(preserveRootParents)) return segments();
+
+    // use a stack to accumulate segments
+    int segmentCount = segments.length;
+    String[] stack = new String[segmentCount];
+    int sp = 0;
+
+    for (int i = 0; i < segmentCount; i++)
+    {
+      sp = accumulate(stack, sp, segments[i], preserveRootParents);
+    }
+
+    // if the path is non-empty and originally ended in an empty segment, a
+    // parent reference, or a self reference, add a trailing separator
+    if (sp > 0 && (SEGMENT_EMPTY.equals(segments[segmentCount - 1]) ||
+                   SEGMENT_PARENT.equals(segments[segmentCount - 1]) ||
+                   SEGMENT_SELF.equals(segments[segmentCount - 1])))
+    {                   
+      stack[sp++] = SEGMENT_EMPTY;
+    }
+
+    // return a correctly sized result
+    String[] result = new String[sp];
+    System.arraycopy(stack, 0, result, 0, sp);
+    return result;
+  }
+
+  /**
+   * Returns the string representation of this URI.  For a generic,
+   * non-hierarchical URI, this looks like:
+   * <pre>
+   *   scheme:opaquePart#fragment</pre>
+   * 
+   * <p>For a hierarchical URI, it looks like:
+   * <pre>
+   *   scheme://authority/device/pathSegment1/pathSegment2...?query#fragment</pre>
+   *
+   * <p>For an <a href="#archive_explanation">archive URI</a>, it's just:
+   * <pre>
+   *   scheme:authority/pathSegment1/pathSegment2...?query#fragment</pre>
+   * <p>Of course, absent components and their separators will be omitted.
+   */
+  public String toString()
+  {
+    if (cachedToString == null)
+    {
+      StringBuffer result = new StringBuffer();
+      if (!isRelative())
+      {
+        result.append(scheme);
+        result.append(SCHEME_SEPARATOR);
+      }
+
+      if (isHierarchical())
+      {
+        if (hasAuthority())
+        {
+          if (!isArchive()) result.append(AUTHORITY_SEPARATOR);
+          result.append(authority);
+        }
+
+        if (hasDevice())
+        {
+          result.append(SEGMENT_SEPARATOR);
+          result.append(device);
+        }
+
+        if (hasAbsolutePath()) result.append(SEGMENT_SEPARATOR);
+
+        for (int i = 0, len = segments.length; i < len; i++)
+        {
+          if (i != 0) result.append(SEGMENT_SEPARATOR);
+          result.append(segments[i]);
+        }
+
+        if (hasQuery())
+        {
+          result.append(QUERY_SEPARATOR);
+          result.append(query);
+        }
+      }
+      else
+      {
+        result.append(authority);
+      }
+
+      if (hasFragment())
+      {
+        result.append(FRAGMENT_SEPARATOR);
+        result.append(fragment);
+      }
+      cachedToString = result.toString();
+    }
+    return cachedToString;
+  }
+
+  // Returns a string representation of this URI for debugging, explicitly
+  // showing each of the components.
+  String toString(boolean includeSimpleForm)
+  {
+    StringBuffer result = new StringBuffer();
+    if (includeSimpleForm) result.append(toString());
+    result.append("\n hierarchical: ");
+    result.append(hierarchical);
+    result.append("\n       scheme: ");
+    result.append(scheme);
+    result.append("\n    authority: ");
+    result.append(authority);
+    result.append("\n       device: ");
+    result.append(device);
+    result.append("\n absolutePath: ");
+    result.append(absolutePath);
+    result.append("\n     segments: ");
+    if (segments.length == 0) result.append("<empty>");
+    for (int i = 0, len = segments.length; i < len; i++)
+    {
+      if (i > 0) result.append("\n               ");
+      result.append(segments[i]);
+    }
+    result.append("\n        query: ");
+    result.append(query);
+    result.append("\n     fragment: ");
+    result.append(fragment);
+    return result.toString();
+  }
+
+  /**
+   * If this URI may refer directly to a locally accessible file, as
+   * determined by {@link #isFile isFile}, {@link decode decodes} and formats  
+   * the URI as a pathname to that file; returns null otherwise.
+   *
+   * <p>If there is no authority, the format of this string is:
+   * <pre>
+   *   device/pathSegment1/pathSegment2...</pre>
+   *
+   * <p>If there is an authority, it is:
+   * <pre>
+   *   //authority/device/pathSegment1/pathSegment2...</pre>
+   * 
+   * <p>However, the character used as a separator is system-dependant and
+   * obtained from {@link java.io.File#separatorChar}.
+   */
+  public String toFileString()
+  {
+    if (!isFile()) return null;
+
+    StringBuffer result = new StringBuffer();
+    char separator = File.separatorChar;
+
+    if (hasAuthority())
+    {
+      result.append(separator);
+      result.append(separator);
+      result.append(authority);
+
+      if (hasDevice()) result.append(separator);
+    }
+
+    if (hasDevice()) result.append(device);
+    if (hasAbsolutePath()) result.append(separator);
+
+    for (int i = 0, len = segments.length; i < len; i++)
+    {
+      if (i != 0) result.append(separator);
+      result.append(segments[i]);
+    }
+
+    return decode(result.toString());
+  }
+
+  /**
+   * Returns the URI formed by appending the specified segment on to the end
+   * of the path of this URI, if hierarchical; this URI unchanged,
+   * otherwise.  If this URI has an authority and/or device, but no path,
+   * the segment becomes the first under the root in an absolute path.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>segment</code>
+   * is not a valid segment according to {@link #validSegment}.
+   */
+  public URI appendSegment(String segment)
+  {
+    if (!validSegment(segment))
+    {
+      throw new IllegalArgumentException("invalid segment: " + segment);
+    }
+
+    if (!isHierarchical()) return this;
+
+    // absolute path or no path -> absolute path
+    boolean newAbsolutePath = !hasRelativePath();
+
+    int len = segments.length;
+    String[] newSegments = new String[len + 1];
+    System.arraycopy(segments, 0, newSegments, 0, len);
+    newSegments[len] = segment;
+
+    return new URI(true, scheme, authority, device, newAbsolutePath,
+                   newSegments, query, fragment);
+  }
+
+  /**
+   * Returns the URI formed by appending the specified segments on to the
+   * end of the path of this URI, if hierarchical; this URI unchanged,
+   * otherwise.  If this URI has an authority and/or device, but no path,
+   * the segments are made to form an absolute path.
+   *
+   * @param segments an array of non-null strings, each representing one
+   * segment of the path.  If desired, a trailing separator should be
+   * represented by an empty-string segment as the last element of the
+   * array.
+   *
+   * @exception java.lang.IllegalArgumentException if <code>segments</code>
+   * is not a valid segment array according to {@link #validSegments}.
+   */
+  public URI appendSegments(String[] segments)
+  {
+    if (!validSegments(segments))
+    {
+      String s = segments == null ? "invalid segments: " + segments :
+        "invalid segment: " + firstInvalidSegment(segments);
+      throw new IllegalArgumentException(s);
+    }
+
+    if (!isHierarchical()) return this;
+
+    // absolute path or no path -> absolute path
+    boolean newAbsolutePath = !hasRelativePath(); 
+
+    int len = this.segments.length;
+    int segmentsCount = segments.length;
+    String[] newSegments = new String[len + segmentsCount];
+    System.arraycopy(this.segments, 0, newSegments, 0, len);
+    System.arraycopy(segments, 0, newSegments, len, segmentsCount);
+    
+    return new URI(true, scheme, authority, device, newAbsolutePath,
+                   newSegments, query, fragment);
+  }
+
+  /**
+   * Returns the URI formed by trimming the specified number of segments
+   * (including empty segments, such as one representing a trailing
+   * separator) from the end of the path of this URI, if hierarchical;
+   * otherwise, this URI is returned unchanged.
+   *
+   * <p>Note that if all segments are trimmed from an absolute path, the
+   * root absolute path remains.
+   * 
+   * @param i the number of segments to be trimmed in the returned URI.  If
+   * less than 1, this URI is returned unchanged; if equal to or greater
+   * than the number of segments in this URI's path, all segments are
+   * trimmed.  
+   */
+  public URI trimSegments(int i)
+  {
+    if (!isHierarchical() || i < 1) return this;
+
+    String[] newSegments = NO_SEGMENTS;
+    int len = segments.length - i;
+    if (len > 0)
+    {
+      newSegments = new String[len];
+      System.arraycopy(segments, 0, newSegments, 0, len);
+    }
+    return new URI(true, scheme, authority, device, absolutePath,
+                   newSegments, query, fragment);
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI that has a path
+   * that ends with a trailing separator; <code>false</code> otherwise.
+   *
+   * <p>A trailing separator is represented as an empty segment as the
+   * last segment in the path; note that this definition does <em>not</em>
+   * include the lone separator in the root absolute path.
+   */
+  public boolean hasTrailingPathSeparator()
+  {
+    return segments.length > 0 && 
+      SEGMENT_EMPTY.equals(segments[segments.length - 1]);
+  }
+
+  /**
+   * If this is a hierarchical URI whose path includes a file extension,
+   * that file extension is returned; null otherwise.  We define a file
+   * extension as any string following the last period (".") in the final
+   * path segment.  If there is no path, the path ends in a trailing
+   * separator, or the final segment contains no period, then we consider
+   * there to be no file extension.  If the final segment ends in a period,
+   * then the file extension is an empty string.
+   */
+  public String fileExtension()
+  {
+    int len = segments.length;
+    if (len == 0) return null;
+
+    String lastSegment = segments[len - 1];
+    int i = lastSegment.lastIndexOf(FILE_EXTENSION_SEPARATOR);
+    return i < 0 ? null : lastSegment.substring(i + 1);
+  }
+
+  /**
+   * Returns the URI formed by appending a period (".") followed by the
+   * specified file extension to the last path segment of this URI, if it is
+   * hierarchical with a non-empty path ending in a non-empty segment;
+   * otherwise, this URI is returned unchanged.
+
+   * <p>The extension is appended regardless of whether the segment already
+   * contains an extension.
+   *
+   * @exception java.lang.IllegalArgumentException if
+   * <code>fileExtension</code> is not a valid segment (portion) according
+   * to {@link #validSegment}.
+   */
+  public URI appendFileExtension(String fileExtension)
+  {
+    if (!validSegment(fileExtension))
+    {
+      throw new IllegalArgumentException(
+        "invalid segment portion: " + fileExtension);
+    }
+
+    int len = segments.length;
+    if (len == 0) return this;
+
+    String lastSegment = segments[len - 1];
+    if (SEGMENT_EMPTY.equals(lastSegment)) return this;
+    StringBuffer newLastSegment = new StringBuffer(lastSegment);
+    newLastSegment.append(FILE_EXTENSION_SEPARATOR);
+    newLastSegment.append(fileExtension);
+
+    String[] newSegments = new String[len];
+    System.arraycopy(segments, 0, newSegments, 0, len - 1);
+    newSegments[len - 1] = newLastSegment.toString();
+    
+    // note: segments.length > 0 -> hierarchical
+    return new URI(true, scheme, authority, device, absolutePath,
+                   newSegments, query, fragment); 
+  }
+
+  /**
+   * If this URI has a non-null {@link #fileExtension fileExtension},
+   * returns the URI formed by removing it; this URI unchanged, otherwise.
+   */
+  public URI trimFileExtension()
+  {
+    int len = segments.length;
+    if (len == 0) return this;
+
+    String lastSegment = segments[len - 1];
+    int i = lastSegment.lastIndexOf(FILE_EXTENSION_SEPARATOR);
+    if (i < 0) return this;
+
+    String newLastSegment = lastSegment.substring(0, i);
+    String[] newSegments = new String[len];
+    System.arraycopy(segments, 0, newSegments, 0, len - 1);
+    newSegments[len - 1] = newLastSegment;
+
+    // note: segments.length > 0 -> hierarchical
+    return new URI(true, scheme, authority, device, absolutePath,
+                   newSegments, query, fragment); 
+  }
+
+  /**
+   * Returns <code>true</code> if this is a hierarchical URI that ends in a
+   * slash; that is, it has a trailing path separator or is the root
+   * absolute path, and has no query and no fragment; <code>false</code>
+   * is returned otherwise.
+   */
+  public boolean isPrefix()
+  {
+    return hierarchical && query == null && fragment == null &&
+      (hasTrailingPathSeparator() || (absolutePath && segments.length == 0));
+  }
+
+  /**
+   * If this is a hierarchical URI reference and <code>oldPrefix</code> is a
+   * prefix of it, this returns the URI formed by replacing it by
+   * <code>newPrefix</code>; <code>null</code> otherwise.
+   *
+   * <p>In order to be a prefix, the <code>oldPrefix</code>'s
+   * {@link #isPrefix isPrefix} must return <code>true</code>, and it must
+   * match this URI's scheme, authority, and device.  Also, the paths must
+   * match, up to prefix's end.
+   *
+   * @exception java.lang.IllegalArgumentException if either
+   * <code>oldPrefix</code> or <code>newPrefix</code> is not a prefix URI
+   * according to {@link #isPrefix}.
+   */
+  public URI replacePrefix(URI oldPrefix, URI newPrefix)
+  {
+    if (!oldPrefix.isPrefix() || !newPrefix.isPrefix())
+    {
+      String which = oldPrefix.isPrefix() ? "new" : "old";
+      throw new IllegalArgumentException("non-prefix " + which + " value");
+    }
+
+    // Get what's left of the segments after trimming the prefix.
+    String[] tailSegments = getTailSegments(oldPrefix);
+    if (tailSegments == null) return null;
+
+    // If the new prefix has segments, it is not the root absolute path,
+    // and we need to drop the trailing empty segment and append the tail
+    // segments.
+    String[] mergedSegments = tailSegments;
+    if (newPrefix.segmentCount() != 0)
+    {
+      int segmentsToKeep = newPrefix.segmentCount() - 1;
+      mergedSegments = new String[segmentsToKeep + tailSegments.length];
+      System.arraycopy(newPrefix.segments(), 0, mergedSegments, 0,
+                       segmentsToKeep);
+
+      if (tailSegments.length != 0)
+      {
+        System.arraycopy(tailSegments, 0, mergedSegments, segmentsToKeep,
+                         tailSegments.length);
+      }
+    }
+
+    // no validation needed since all components are from existing URIs
+    return new URI(true, newPrefix.scheme(), newPrefix.authority(),
+                   newPrefix.device(), newPrefix.hasAbsolutePath(),
+                   mergedSegments, query, fragment);
+  }
+
+  // If this is a hierarchical URI reference and prefix is a prefix of it,
+  // returns the portion of the path remaining after that prefix has been
+  // trimmed; null otherwise.
+  private String[] getTailSegments(URI prefix)
+  {
+    if (!prefix.isPrefix())
+    {
+      throw new IllegalArgumentException("non-prefix trim");
+    }
+
+    // Don't even consider it unless this is hierarchical and has scheme,
+    // authority, device and path absoluteness equal to those of the prefix.
+    if (!hierarchical ||
+        !equals(scheme, prefix.scheme(), true) ||
+        !equals(authority, prefix.authority()) ||
+        !equals(device, prefix.device()) ||
+        absolutePath != prefix.hasAbsolutePath())
+    {
+      return null;
+    }
+
+    // If the prefix has no segments, then it is the root absolute path, and
+    // we know this is an absolute path, too.
+    if (prefix.segmentCount() == 0) return segments;
+
+    // This must have no fewer segments than the prefix.  Since the prefix
+    // is not the root absolute path, its last segment is empty; all others
+    // must match.
+    int i = 0;
+    int segmentsToCompare = prefix.segmentCount() - 1;
+    if (segments.length <= segmentsToCompare) return null;
+
+    for (; i < segmentsToCompare; i++)
+    {
+      if (!segments[i].equals(prefix.segment(i))) return null;
+    }
+
+    // The prefix really is a prefix of this.  If this has just one more,
+    // empty segment, the paths are the same.
+    if (i == segments.length - 1 && SEGMENT_EMPTY.equals(segments[i]))
+    {
+      return NO_SEGMENTS;
+    }
+    
+    // Otherwise, the path needs only the remaining segments.
+    String[] newSegments = new String[segments.length - i];
+    System.arraycopy(segments, i, newSegments, 0, newSegments.length);
+    return newSegments;
+  }
+
+  /**
+   * Encodes a string so as to produce a valid opaque part value, as defined
+   * by the RFC.  All excluded characters, such as space and <code>#</code>,
+   * are escaped, as is <code>/</code> if it is the first character.
+   * 
+   * @param ignoreEscaped <code>true</code> to leave <code>%</code> characters
+   * unescaped if they already begin a valid three-character escape sequence;
+   * <code>false</code> to encode all <code>%</code> characters.  Note that
+   * if a <code>%</code> is not followed by 2 hex digits, it will always be
+   * escaped. 
+   */
+  public static String encodeOpaquePart(String value, boolean ignoreEscaped)
+  {
+    String result = encode(value, URIC_HI, URIC_LO, ignoreEscaped);
+    return result != null && result.length() > 0 && result.charAt(0) == SEGMENT_SEPARATOR ?
+      "%2F" + result.substring(1) :
+      result;
+  }
+
+  /**
+   * Encodes a string so as to produce a valid authority, as defined by the
+   * RFC.  All excluded characters, such as space and <code>#</code>,
+   * are escaped, as are <code>/</code> and <code>?</code>
+   * 
+   * @param ignoreEscaped <code>true</code> to leave <code>%</code> characters
+   * unescaped if they already begin a valid three-character escape sequence;
+   * <code>false</code> to encode all <code>%</code> characters.  Note that
+   * if a <code>%</code> is not followed by 2 hex digits, it will always be
+   * escaped. 
+   */
+  public static String encodeAuthority(String value, boolean ignoreEscaped)
+  {
+    return encode(value, SEGMENT_CHAR_HI, SEGMENT_CHAR_LO, ignoreEscaped);
+  }
+
+  /**
+   * Encodes a string so as to produce a valid segment, as defined by the
+   * RFC.  All excluded characters, such as space and <code>#</code>,
+   * are escaped, as are <code>/</code> and <code>?</code>
+   * 
+   * @param ignoreEscaped <code>true</code> to leave <code>%</code> characters
+   * unescaped if they already begin a valid three-character escape sequence;
+   * <code>false</code> to encode all <code>%</code> characters.  Note that
+   * if a <code>%</code> is not followed by 2 hex digits, it will always be
+   * escaped. 
+   */
+  public static String encodeSegment(String value, boolean ignoreEscaped)
+  {
+    return encode(value, SEGMENT_CHAR_HI, SEGMENT_CHAR_LO, ignoreEscaped);
+  }
+
+  /**
+   * Encodes a string so as to produce a valid query, as defined by the RFC.
+   * Only excluded characters, such as space and <code>#</code>, are escaped.
+   * 
+   * @param ignoreEscaped <code>true</code> to leave <code>%</code> characters
+   * unescaped if they already begin a valid three-character escape sequence;
+   * <code>false</code> to encode all <code>%</code> characters.  Note that
+   * if a <code>%</code> is not followed by 2 hex digits, it will always be
+   * escaped. 
+   */
+  public static String encodeQuery(String value, boolean ignoreEscaped)
+  {
+    return encode(value, URIC_HI, URIC_LO, ignoreEscaped);
+  }
+
+  /**
+   * Encodes a string so as to produce a valid fragment, as defined by the
+   * RFC.  Only excluded characters, such as space and <code>#</code>, are
+   * escaped.
+   * 
+   * @param ignoreEscaped <code>true</code> to leave <code>%</code> characters
+   * unescaped if they already begin a valid three-character escape sequence;
+   * <code>false</code> to encode all <code>%</code> characters.  Note that
+   * if a <code>%</code> is not followed by 2 hex digits, it will always be
+   * escaped. 
+   */
+  public static String encodeFragment(String value, boolean ignoreEscaped)
+  {
+    return encode(value, URIC_HI, URIC_LO, ignoreEscaped);
+  }
+
+  // Encodes a complete URI, optionally leaving % characters unescaped when
+  // beginning a valid three-character escape sequence.  We assume that the
+  // last # begins the fragment.
+  private static String encodeURI(String uri, boolean ignoreEscaped)
+  {
+    if (uri == null) return null;
+
+    StringBuffer result = new StringBuffer();
+
+    int i = uri.indexOf(SCHEME_SEPARATOR);
+    if (i != -1)
+    {
+      String scheme = uri.substring(0, i);
+      result.append(scheme);
+      result.append(SCHEME_SEPARATOR);
+    }
+    
+    int j = uri.lastIndexOf(FRAGMENT_SEPARATOR);
+    if (j != -1)
+    {
+      String sspart = uri.substring(++i, j);
+      result.append(encode(sspart, URIC_HI, URIC_LO, ignoreEscaped));
+      result.append(FRAGMENT_SEPARATOR);
+
+      String fragment = uri.substring(++j);
+      result.append(encode(fragment, URIC_HI, URIC_LO, ignoreEscaped));
+    }
+    else
+    {
+      String sspart = uri.substring(++i);
+      result.append(encode(sspart, URIC_HI, URIC_LO, ignoreEscaped));
+    }
+    
+    return result.toString();
+  }
+
+  // Encodes the given string, replacing each ASCII character that is not in
+  // the set specified by the 128-bit bitmask and each non-ASCII character
+  // below 0xA0 by an escape sequence of % followed by two hex digits.  If
+  // % is not in the set but ignoreEscaped is true, then % will not be encoded
+  // iff it already begins a valid escape sequence.
+  private static String encode(String value, long highBitmask, long lowBitmask, boolean ignoreEscaped)
+  {
+    if (value == null) return null;
+
+    StringBuffer result = null;
+
+    for (int i = 0, len = value.length(); i < len; i++)
+    {
+      char c = value.charAt(i);
+
+      if (!matches(c, highBitmask, lowBitmask) && c < 160 &&
+          (!ignoreEscaped || !isEscaped(value, i)))
+      {
+        if (result == null)
+        {
+          result = new StringBuffer(value.substring(0, i));
+        }
+        appendEscaped(result, (byte)c);
+      }
+      else if (result != null)
+      {
+        result.append(c);
+      }
+    }
+    return result == null ? value : result.toString();
+  }
+
+  // Tests whether an escape occurs in the given string, starting at index i.
+  // An escape sequence is a % followed by two hex digits.
+  private static boolean isEscaped(String s, int i)
+  {
+    return s.charAt(i) == ESCAPE && s.length() > i + 2 &&
+      matches(s.charAt(i + 1), HEX_HI, HEX_LO) &&
+      matches(s.charAt(i + 2), HEX_HI, HEX_LO);
+  }
+
+  // Computes a three-character escape sequence for the byte, appending
+  // it to the StringBuffer.  Only characters up to 0xFF should be escaped;
+  // all but the least significant byte will be ignored.
+  private static void appendEscaped(StringBuffer result, byte b)
+  {
+    result.append(ESCAPE);
+
+    // The byte is automatically widened into an int, with sign extension,
+    // for shifting.  This can introduce 1's to the left of the byte, which
+    // must be cleared by masking before looking up the hex digit.
+    //
+    result.append(HEX_DIGITS[(b >> 4) & 0x0F]);
+    result.append(HEX_DIGITS[b & 0x0F]);
+  }
+
+  /**
+   * Decodes the given string, replacing each three-digit escape sequence by
+   * the character that it represents.  Incomplete escape sequences are
+   * ignored.
+   */
+  public static String decode(String value)
+  {
+    if (value == null) return null;
+
+    StringBuffer result = null;
+
+    for (int i = 0, len = value.length(); i < len; i++)
+    {
+      if (isEscaped(value, i)) 
+      {
+        if (result == null)
+        {
+          result = new StringBuffer(value.substring(0, i));
+        }
+        result.append(unescape(value.charAt(i + 1), value.charAt(i + 2)));
+        i += 2;
+      }
+      else if (result != null)
+      {
+        result.append(value.charAt(i));
+      }
+    }
+    return result == null ? value : result.toString();
+  }
+
+  // Returns the character encoded by % followed by the two given hex digits,
+  // which is always 0xFF or less, so can safely be casted to a byte.  If
+  // either character is not a hex digit, a bogus result will be returned.
+  private static char unescape(char highHexDigit, char lowHexDigit)
+  {
+    return (char)((valueOf(highHexDigit) << 4) | valueOf(lowHexDigit));
+  }
+
+  // Returns the int value of the given hex digit.
+  private static int valueOf(char hexDigit)
+  {
+    if (hexDigit >= 'A' && hexDigit <= 'F')
+    {
+      return hexDigit - 'A' + 10;
+    }
+    if (hexDigit >= 'a' && hexDigit <= 'f')
+    {
+      return hexDigit - 'a' + 10;
+    }
+    if (hexDigit >= '0' && hexDigit <= '9')
+    {
+      return hexDigit - '0';
+    }
+    return 0;
+  }
+
+  
+  /**
+   * This method takes two URIs, the first one relative, the second absolute. It
+   * tries to resolve the first URI (making it absolute) by using the second one.
+   * If the URI cannot be resolved, the relative one is returned unmodified.
+   * 
+   * @param relativeURI
+   * @param absoluteURI
+   * @return relativeURI resolved (absolute) or relativeURI unmodified if it cannot
+   * be resolved.
+   */
+  public static String resolveRelativeURI(String relativeURI, String absoluteURI) {
+
+	  String result = relativeURI;
+
+	  try {
+      	URI relative = URI.createURI(relativeURI);
+       	URI absolute = URI.createURI(absoluteURI);
+       	URI resolvedRelative = relative.resolve(absolute);
+       	result = resolvedRelative.toString();
+      } catch (Exception e) {}
+      return result;
+  }
+  
+  
+  /*
+   * Returns <code>true</code> if this URI contains non-ASCII characters;
+   * <code>false</code> otherwise.
+   *
+   * This unused code is included for possible future use... 
+   */
+/*
+  public boolean isIRI()
+  {
+    return iri; 
+  }
+
+  // Returns true if the given string contains any non-ASCII characters;
+  // false otherwise.
+  private static boolean containsNonASCII(String value)
+  {
+    for (int i = 0, len = value.length(); i < len; i++)
+    {
+      if (value.charAt(i) > 127) return true;
+    }
+    return false;
+  }
+*/
+
+  /*
+   * If this is an {@link #isIRI IRI}, converts it to a strict ASCII URI,
+   * using the procedure described in Section 3.1 of the
+   * <a href="http://www.w3.org/International/iri-edit/draft-duerst-iri-09.txt">IRI
+   * Draft RFC</a>.  Otherwise, this URI, itself, is returned.
+   *
+   * This unused code is included for possible future use...
+   */
+/*
+  public URI toASCIIURI()
+  {
+    if (!iri) return this;
+
+    if (cachedASCIIURI == null)
+    {
+      String eAuthority = encodeAsASCII(authority);
+      String eDevice = encodeAsASCII(device);
+      String eQuery = encodeAsASCII(query);
+      String eFragment = encodeAsASCII(fragment);
+      String[] eSegments = new String[segments.length];
+      for (int i = 0; i < segments.length; i++)
+      {
+        eSegments[i] = encodeAsASCII(segments[i]);
+      }
+      cachedASCIIURI = new URI(hierarchical, scheme, eAuthority, eDevice, absolutePath, eSegments, eQuery, eFragment); 
+
+    }
+    return cachedASCIIURI;
+  }
+
+  // Returns a strict ASCII encoding of the given value.  Each non-ASCII
+  // character is converted to bytes using UTF-8 encoding, which are then
+  // represnted using % escaping.
+  private String encodeAsASCII(String value)
+  {
+    if (value == null) return null;
+
+    StringBuffer result = null;
+
+    for (int i = 0, len = value.length(); i < len; i++)
+    {
+      char c = value.charAt(i);
+
+      if (c >= 128)
+      {
+        if (result == null)
+        {
+          result = new StringBuffer(value.substring(0, i));
+        }
+
+        try
+        {
+          byte[] encoded = (new String(new char[] { c })).getBytes("UTF-8");
+          for (int j = 0, encLen = encoded.length; j < encLen; j++)
+          {
+            appendEscaped(result, encoded[j]);
+          }
+        }
+        catch (UnsupportedEncodingException e)
+        {
+          throw new WrappedException(e);
+        }
+      }
+      else if (result != null)
+      {
+        result.append(c);
+      }
+
+    }
+    return result == null ? value : result.toString();
+  }
+
+  // Returns the number of valid, consecutive, three-character escape
+  // sequences in the given string, starting at index i.
+  private static int countEscaped(String s, int i)
+  {
+    int result = 0;
+
+    for (int len = s.length(); i < len; i += 3)
+    {
+      if (isEscaped(s, i)) result++;
+    }
+    return result;
+  }
+*/
+}
diff --git a/plugins/org.eclipse.wst.common.uriresolver/src/org/eclipse/wst/common/uriresolver/internal/util/URIHelper.java b/plugins/org.eclipse.wst.common.uriresolver/src/org/eclipse/wst/common/uriresolver/internal/util/URIHelper.java
new file mode 100644
index 0000000..f9540b3
--- /dev/null
+++ b/plugins/org.eclipse.wst.common.uriresolver/src/org/eclipse/wst/common/uriresolver/internal/util/URIHelper.java
@@ -0,0 +1,528 @@
+/*******************************************************************************
+ * Copyright (c) 2004, 2005 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Contributors:
+ *     IBM Corporation - Initial API and implementation
+ *     Jens Lukowski/Innoopract - initial renaming/restructuring
+ *******************************************************************************/
+package org.eclipse.wst.common.uriresolver.internal.util;
+
+import java.io.File;
+import java.io.InputStream;
+import java.io.UnsupportedEncodingException;
+import java.net.URI;
+import java.net.URL;
+
+import org.eclipse.core.resources.IResource;
+import org.eclipse.core.runtime.FileLocator;
+import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.Path;
+
+
+public class URIHelper
+{                       
+  protected static final String FILE_PROTOCOL = "file:";
+  protected static final String PLATFORM_RESOURCE_PROTOCOL = "platform:/resource/";
+  protected static final String PROTOCOL_PATTERN = ":"; 
+  
+  
+  public static String ensureURIProtocolFormat(String uri) {
+	  String protocol = getProtocol(uri);
+	  if (protocol != null) {
+		  if (protocol.equals(FILE_PROTOCOL)) {
+			  return ensureFileURIProtocolFormat(uri);
+		  }
+	  }
+	 return uri;
+  }
+  
+  
+  /**
+   * This method takes a file URI in String format and ensures the protocol is followed by three slashes.
+   * For example, files "file:D:/XXX", "file:/D:/XXX" and "file://D:/XXX" are corrected to:
+   * "file:///D:/XXX".
+   * If the input is not a file URI (does not start with "file:"), the String is returned unmodified.
+   */
+  public static String ensureFileURIProtocolFormat(String uri) {
+      if (uri.startsWith(FILE_PROTOCOL) && !uri.startsWith(FILE_PROTOCOL + "///")) //$NON-NLS-1$
+      {
+      	if (uri.startsWith(FILE_PROTOCOL + "//")) {
+      		uri = FILE_PROTOCOL + "/" + uri.substring(FILE_PROTOCOL.length()); //$NON-NLS-1$
+      	} else if (uri.startsWith(FILE_PROTOCOL + "/")) {
+      		uri = FILE_PROTOCOL + "//" + uri.substring(FILE_PROTOCOL.length()); //$NON-NLS-1$
+      	} else {
+      		uri = FILE_PROTOCOL + "///" + uri.substring(FILE_PROTOCOL.length()); //$NON-NLS-1$
+      	}
+      }
+     return uri;
+  }
+  
+  public static String normalize(String uri)
+  {                           
+    if (uri != null)
+    {                      
+      String protocol = getProtocol(uri);
+      String file = uri;
+           
+      if (protocol != null)
+      {               
+        try
+        {   
+          // 
+          URL url = new URL(uri); 
+          // we use a 'Path' on the 'file' part of the url in order to normalize the '.' and '..' segments
+          IPath path = new Path(url.getFile()); 
+          URL url2 = new URL(url.getProtocol(), url.getHost(), url.getPort(), path.toString());
+          uri = url2.toString();                               
+        }                        
+        catch (Exception e)
+        {  
+        }
+      }   
+      else
+      {      
+        IPath path = new Path(file);
+        uri = path.toString();
+      }
+    }
+    return uri;
+  }
+
+
+  /**
+   * a 'null' rootLocation argument will causes uri that begins with a '/' to be treated as a workspace relative resource
+   * (i.e. the string "platform:/resource" is prepended and the uri is resolved via the Platform object)
+   */
+  public static String normalize(String uri, String resourceLocation, String rootLocation)
+  {
+    String result = null;
+
+    if (uri != null)
+    { 
+      // is the uri a url
+      if (hasProtocol(uri))
+      {                  
+        if (isPlatformResourceProtocol(uri))
+        {
+          result = resolvePlatformUrl(uri);
+        }
+        else
+        {
+          result = uri;
+        }
+      }
+   
+      // is uri absolute
+      //
+      if (result == null)
+      {
+        if (uri.indexOf(":") != -1 || uri.startsWith("/") || uri.startsWith("\\"))
+        {                   
+          result = uri;
+        }
+      }
+  
+      // if uri is relative to the resourceLocation
+      //
+      if (result == null && resourceLocation != null)
+      {          
+        if (resourceLocation.endsWith("/"))
+        {
+			    result = resourceLocation + uri;
+        }
+		    else
+        {
+			    result = resourceLocation + "/../" + uri;
+        }
+      }
+      
+      if (result == null)
+      {
+        result = uri;
+      }
+  
+      result = normalize(result);
+    }
+
+    //System.out.println("normalize(" + uri + ", " + resourceLocation + ", " + rootLocation + ") = " + result);
+    return result;
+  }
+
+
+  public static boolean isURL(String uri)
+  {
+    return uri.indexOf(":/") > 2; // test that the index is > 2 so that C:/ is not considered a protocol
+  }
+
+
+  public static String getLastSegment(String uri)
+  {
+    String result = uri;
+    int index = Math.max(uri.lastIndexOf("/"), uri.lastIndexOf("\\"));
+    if (index != -1)
+    {
+      result = uri.substring(index + 1);
+    }
+    return result;
+  }
+
+
+  public static String getFileExtension(String uri)
+  {
+    String result = null;
+    int dotIndex = getExtensionDotIndex(uri);
+               
+    if (dotIndex != -1)
+    {
+      result = uri.substring(dotIndex + 1);
+    }
+
+    return result;
+  }
+
+
+  public static String removeFileExtension(String uri)
+  {
+    String result = null;
+    int dotIndex = getExtensionDotIndex(uri);
+
+    if (dotIndex != -1)
+    {
+      result = uri.substring(0, dotIndex);
+    }
+
+    return result;
+  }   
+             
+
+  // here we use the Platform to resolve a workspace relative path to an actual url
+  //
+  protected static String resolvePlatformUrl(String urlspec)
+  {
+    String result = null;
+    try
+    {                        
+      urlspec = urlspec.replace('\\', '/'); 
+      URL url = new URL(urlspec);
+      URL resolvedURL = FileLocator.resolve(url);
+      result = resolvedURL.toString();
+    }
+    catch (Exception e)
+    {
+    }
+    return result;
+  }
+
+
+  protected static int getExtensionDotIndex(String uri)
+  {
+    int result = -1;
+    int dotIndex = uri.lastIndexOf(".");
+    int slashIndex = Math.max(uri.lastIndexOf("/"), uri.lastIndexOf("\\"));
+
+    if (dotIndex != -1 && dotIndex > slashIndex)
+    {
+      result = dotIndex;
+    }
+
+    return result;
+  }
+  
+
+  public static boolean isPlatformResourceProtocol(String uri)
+  {                                                     
+    return uri != null && uri.startsWith(PLATFORM_RESOURCE_PROTOCOL);
+  }                                                   
+
+  public static String removePlatformResourceProtocol(String uri)
+  {  
+    if (uri != null && uri.startsWith(PLATFORM_RESOURCE_PROTOCOL))
+    {
+      uri = uri.substring(PLATFORM_RESOURCE_PROTOCOL.length());
+    }                                                          
+    return uri;
+  }            
+
+
+  public static String prependPlatformResourceProtocol(String uri)
+  {  
+    if (uri != null && !uri.startsWith(PLATFORM_RESOURCE_PROTOCOL))
+    {
+      uri = PLATFORM_RESOURCE_PROTOCOL + uri;
+    }                                                          
+    return uri;
+  } 
+  
+
+  public static String prependFileProtocol(String uri)
+  {  
+    if (uri != null && !uri.startsWith(FILE_PROTOCOL))
+    {
+      uri = FILE_PROTOCOL + uri;
+    }                                                          
+    return uri;
+  } 
+            
+  public static boolean hasProtocol(String uri)
+  {
+    boolean result = false;     
+    if (uri != null)
+    {
+      int index = uri.indexOf(PROTOCOL_PATTERN);
+      if (index != -1 && index > 2) // assume protocol with be length 3 so that the'C' in 'C:/' is not interpreted as a protocol
+      {
+        result = true;
+      }
+    }
+    return result;
+  }     
+                      
+
+  public static boolean isAbsolute(String uri)
+  {
+    boolean result = false;     
+    if (uri != null)
+    {
+      int index = uri.indexOf(PROTOCOL_PATTERN);
+      if (index != -1 || uri.startsWith("/") || uri.startsWith("\\"))
+      {
+        result = true;
+      }
+    }
+    return result;
+  }
+
+
+  public static String addImpliedFileProtocol(String uri)
+  {  
+    if (!hasProtocol(uri))
+    {                           
+      String prefix = FILE_PROTOCOL;
+      prefix += uri.startsWith("/") ? "//" : "///";
+      uri = prefix + uri;
+    }
+    return uri;
+  }
+             
+  // todo... need to revisit this before we publicize it
+  // 
+  protected static String getProtocol(String uri)
+  {  
+    String result = null;     
+    if (uri != null)
+    {
+      int index = uri.indexOf(PROTOCOL_PATTERN);
+      if (index > 2) // assume protocol with be length 3 so that the'C' in 'C:/' is not interpreted as a protocol
+      {
+        result = uri.substring(0, index + PROTOCOL_PATTERN.length());
+      }
+    }
+    return result;
+  } 
+ 
+
+  public static String removeProtocol(String uri)
+  {
+    String result = uri;     
+    if (uri != null)
+    {
+      int index = uri.indexOf(PROTOCOL_PATTERN);
+      if (index > 2)
+      {
+        result = result.substring(index + PROTOCOL_PATTERN.length());                 
+      }
+    }
+    return result;
+  } 
+
+
+  protected static boolean isProtocolFileOrNull(String uri)
+  {                                    
+    String protocol = getProtocol(uri);   
+    return protocol == null || protocol.equals(FILE_PROTOCOL);
+  }  
+
+                                           
+  protected static boolean isMatchingProtocol(String uri1, String uri2)
+  { 
+    boolean result = false;  
+
+    String protocol1 = getProtocol(uri1);
+    String protocol2 = getProtocol(uri2);
+
+    if (isProtocolFileOrNull(protocol1) && isProtocolFileOrNull(protocol2))
+    {                                                                      
+      result = true;
+    } 
+    else
+    {
+      result = protocol1 != null && protocol2 != null && protocol1.equals(protocol2);
+    }             
+
+    return result;
+  }
+
+  /**
+   * warning... this method not fully tested yet
+   */
+  public static String getRelativeURI(String uri, String resourceLocation)
+  {                                      
+    String result = uri;  
+    if (isMatchingProtocol(uri, resourceLocation)) 
+    {
+      result = getRelativeURI(new Path(removeProtocol(uri)),
+                              new Path(removeProtocol(resourceLocation)));
+    }            
+
+    return result;
+  }
+
+  /**
+   * warning... this method not fully tested yet
+   */
+  public static String getRelativeURI(IPath uri, IPath resourceLocation)
+  {            
+    String result = null;
+    int nMatchingSegments = 0;       
+    resourceLocation = resourceLocation.removeLastSegments(1);
+    while (true)
+    {                   
+      String a = uri.segment(nMatchingSegments); 
+      String b = resourceLocation.segment(nMatchingSegments); 
+      if (a != null && b != null && a.equals(b))
+      {
+        nMatchingSegments++;
+      }
+      else
+      {
+        break;
+      }
+    }                 
+
+    if (nMatchingSegments == 0)
+    {
+      result = uri.toOSString();
+    }
+    else
+    {    
+      result = "";   
+      boolean isFirst = true;
+      String[] segments = resourceLocation.segments();
+      for (int i = nMatchingSegments; i < segments.length; i++)
+      {  
+        result += isFirst ? ".." : "/..";     
+        if (isFirst)
+        {
+          isFirst = false;
+        }        
+      }
+      // 
+      segments = uri.segments();
+      for (int i = nMatchingSegments; i < segments.length; i++)
+      {                      
+        result += isFirst ? segments[i] : ("/" + segments[i]);     
+        if (isFirst)
+        {
+          isFirst = false;
+        } 
+      }
+    }   
+    return result;
+  }
+
+
+  public static String getPlatformURI(IResource resource)
+  {                            
+    String fullPath = resource.getFullPath().toString();
+    if (fullPath.startsWith("/"))
+    {
+      fullPath = fullPath.substring(1);
+    }
+    return PLATFORM_RESOURCE_PROTOCOL + fullPath;
+  }
+  
+
+  /**
+   * This methods is used as a quick test to see if a uri can be resolved to an existing resource.   
+   */
+  public static boolean isReadableURI(String uri, boolean testRemoteURI)
+  {  
+    boolean result = true;  
+    if (uri != null)
+    {   
+      try
+      {                               
+        uri = normalize(uri, null, null);
+        if (isProtocolFileOrNull(uri))
+        {
+          uri = removeProtocol(uri);                            
+          File file = new File(org.eclipse.wst.common.uriresolver.internal.URI.decode(uri));
+          result = file.exists() && file.isFile();
+        }
+        else if (isPlatformResourceProtocol(uri))
+        {
+          // Note - If we are here, uri has been failed to resolve
+          // relative to the Platform. See normalize() to find why.
+          result = false;
+        }
+        else if (testRemoteURI)
+        {
+          URL url = new URL(uri);
+          InputStream is = url.openConnection().getInputStream();
+          is.close();
+          // the uri is readable if we reach here.
+          result = true;
+        }
+      }
+      catch (Exception e)
+      {
+        result = false;
+      }
+    }
+    else // uri is null
+      result = false;
+
+    return result;
+  }  
+
+  /**
+   * return true if this is a valid uri
+   */
+  public static boolean isValidURI(String uri)
+  {                       
+    boolean result = false;
+    try                                                              
+    {
+      new URI(uri);
+      result = true;
+    }
+    catch (Exception e)
+    {
+    }               
+    return result;
+  }
+
+  /**
+   * returns an acceptable URI for a file path
+   */
+  public static String getURIForFilePath(String filePath)
+  {
+    String result = addImpliedFileProtocol(filePath);
+    if (!isValidURI(result))
+    {
+    	try
+    	{
+        result = URIEncoder.encode(result, "UTF8");
+    	}
+    	catch(UnsupportedEncodingException e)
+    	{
+    		// Do nothing as long as UTF8 is used. This is supported.
+    	}
+    }
+    return result;
+  }
+}