diff --git a/NEWS.md b/NEWS.md
index 51a45cab..7f95d829 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -386,7 +386,7 @@
 
     * Patch by NAITOH Jun.
 
-  * Improved parse performance when an attribute has many `<`s.
+  * Improved parse performance when an attribute has many `>`s.
 
     * GH-126
 
diff --git a/benchmark/parse_cdata.yaml b/benchmark/parse_cdata.yaml
new file mode 100644
index 00000000..cde04306
--- /dev/null
+++ b/benchmark/parse_cdata.yaml
@@ -0,0 +1,50 @@
+loop_count: 100
+contexts:
+  - gems:
+      rexml: 3.2.6
+    require: false
+    prelude: require 'rexml'
+  - name: master
+    prelude: |
+      $LOAD_PATH.unshift(File.expand_path("lib"))
+      require 'rexml'
+  - name: 3.2.6(YJIT)
+    gems:
+      rexml: 3.2.6
+    require: false
+    prelude: |
+      require 'rexml'
+      RubyVM::YJIT.enable
+  - name: master(YJIT)
+    prelude: |
+      $LOAD_PATH.unshift(File.expand_path("lib"))
+      require 'rexml'
+      RubyVM::YJIT.enable
+
+prelude: |
+  require 'rexml/document'
+  require 'rexml/parsers/sax2parser'
+  require 'rexml/parsers/pullparser'
+  require 'rexml/parsers/streamparser'
+  require 'rexml/streamlistener'
+
+  def build_xml(size)
+    xml = "<?xml version=\"1.0\"?>\n" +
+           "<root>Test</root>\n" +
+           "<![CDATA[" + "a" * size + "]]>\n"
+  end
+  xml = build_xml(100000)
+
+  class Listener
+    include REXML::StreamListener
+  end
+
+benchmark:
+  'dom'        : REXML::Document.new(xml)
+  'sax'        : REXML::Parsers::SAX2Parser.new(xml).parse
+  'pull'       : |
+    parser = REXML::Parsers::PullParser.new(xml)
+    while parser.has_next?
+      parser.pull
+    end
+  'stream'     : REXML::Parsers::StreamParser.new(xml, Listener.new).parse
diff --git a/benchmark/parse_comment.yaml b/benchmark/parse_comment.yaml
new file mode 100644
index 00000000..a0a3a771
--- /dev/null
+++ b/benchmark/parse_comment.yaml
@@ -0,0 +1,36 @@
+loop_count: 100
+contexts:
+  - gems:
+      rexml: 3.2.6
+    require: false
+    prelude: require 'rexml'
+  - name: master
+    prelude: |
+      $LOAD_PATH.unshift(File.expand_path("lib"))
+      require 'rexml'
+  - name: 3.2.6(YJIT)
+    gems:
+      rexml: 3.2.6
+    require: false
+    prelude: |
+      require 'rexml'
+      RubyVM::YJIT.enable
+  - name: master(YJIT)
+    prelude: |
+      $LOAD_PATH.unshift(File.expand_path("lib"))
+      require 'rexml'
+      RubyVM::YJIT.enable
+
+prelude: |
+  require 'rexml/document'
+
+  SIZE = 100000
+
+  top_level_xml     = "<!--" + "a" * SIZE + "-->\n"
+  in_doctype_xml    = "<!DOCTYPE foo [<!--" + "a" * SIZE + "-->]>"
+  after_doctype_xml = "<root/><!--" + "a" * SIZE + "-->"
+
+benchmark:
+  'top_level'      : REXML::Document.new(top_level_xml)
+  'in_doctype'     : REXML::Document.new(in_doctype_xml)
+  'after_doctype'  : REXML::Document.new(after_doctype_xml)
diff --git a/benchmark/xpath.yaml b/benchmark/xpath.yaml
new file mode 100644
index 00000000..d6e970eb
--- /dev/null
+++ b/benchmark/xpath.yaml
@@ -0,0 +1,32 @@
+loop_count: 100
+contexts:
+  - gems:
+      rexml: 3.2.6
+    require: false
+    prelude: require 'rexml'
+  - name: master
+    prelude: |
+      $LOAD_PATH.unshift(File.expand_path("lib"))
+      require 'rexml'
+  - name: 3.2.6(YJIT)
+    gems:
+      rexml: 3.2.6
+    require: false
+    prelude: |
+      require 'rexml'
+      RubyVM::YJIT.enable
+  - name: master(YJIT)
+    prelude: |
+      $LOAD_PATH.unshift(File.expand_path("lib"))
+      require 'rexml'
+      RubyVM::YJIT.enable
+
+prelude: |
+  require 'rexml/document'
+
+  DEPTH = 100
+  xml   = '<a>' * DEPTH + '</a>' * DEPTH
+  doc   = REXML::Document.new(xml)
+
+benchmark:
+  "REXML::XPath.match(REXML::Document.new(xml), 'a//a')" : REXML::XPath.match(doc, "a//a")
diff --git a/lib/rexml/attribute.rb b/lib/rexml/attribute.rb
index fe48745c..c5673249 100644
--- a/lib/rexml/attribute.rb
+++ b/lib/rexml/attribute.rb
@@ -130,10 +130,7 @@ def to_string
     end
 
     def doctype
-      if @element
-        doc = @element.document
-        doc.doctype if doc
-      end
+      @element&.document&.doctype
     end
 
     # Returns the attribute value, with entities replaced
@@ -173,7 +170,7 @@ def element=( element )
       @element = element
 
       if @normalized
-        Text.check( @normalized, NEEDS_A_SECOND_CHECK, doctype )
+        Text.check( @normalized, NEEDS_A_SECOND_CHECK )
       end
 
       self
@@ -202,9 +199,11 @@ def inspect
     end
 
     def xpath
-      path = @element.xpath
-      path += "/@#{self.expanded_name}"
-      return path
+      @element.xpath + "/@#{self.expanded_name}"
+    end
+
+    def document
+      @element&.document
     end
   end
 end
diff --git a/lib/rexml/cdata.rb b/lib/rexml/cdata.rb
index 997f5a08..264ad642 100644
--- a/lib/rexml/cdata.rb
+++ b/lib/rexml/cdata.rb
@@ -58,7 +58,7 @@ def value
     #  c = CData.new( " Some text " )
     #  c.write( $stdout )     #->  <![CDATA[ Some text ]]>
     def write( output=$stdout, indent=-1, transitive=false, ie_hack=false )
-      Kernel.warn( "#{self.class.name}.write is deprecated", uplevel: 1)
+      Kernel.warn( "#{self.class.name}#write is deprecated", uplevel: 1)
       indent( output, indent )
       output << START
       output << @string
diff --git a/lib/rexml/child.rb b/lib/rexml/child.rb
index cc6e9a47..40abde87 100644
--- a/lib/rexml/child.rb
+++ b/lib/rexml/child.rb
@@ -83,8 +83,7 @@ def previous_sibling=(other)
     # Returns:: the document this child belongs to, or nil if this child
     # belongs to no document
     def document
-      return parent.document unless parent.nil?
-      nil
+      parent&.document
     end
 
     # This doesn't yet handle encodings
diff --git a/lib/rexml/comment.rb b/lib/rexml/comment.rb
index 52c58b46..e7e104d4 100644
--- a/lib/rexml/comment.rb
+++ b/lib/rexml/comment.rb
@@ -48,7 +48,7 @@ def clone
     # ie_hack::
     #    Needed for conformity to the child API, but not used by this class.
     def write( output, indent=-1, transitive=false, ie_hack=false )
-      Kernel.warn("Comment.write is deprecated.  See REXML::Formatters", uplevel: 1)
+      Kernel.warn("#{self.class.name}#write is deprecated.  See REXML::Formatters", uplevel: 1)
       indent( output, indent )
       output << START
       output << @string
diff --git a/lib/rexml/doctype.rb b/lib/rexml/doctype.rb
index f3590484..a9cf9f7e 100644
--- a/lib/rexml/doctype.rb
+++ b/lib/rexml/doctype.rb
@@ -171,15 +171,11 @@ def write( output, indent=0, transitive=false, ie_hack=false )
     end
 
     def context
-      if @parent
-        @parent.context
-      else
-        nil
-      end
+      @parent&.context
     end
 
     def entity( name )
-      @entities[name].unnormalized if @entities[name]
+      @entities[name]&.unnormalized
     end
 
     def add child
@@ -288,8 +284,7 @@ def initialize name, middle, pub, sys
     end
 
     def to_s
-      context = nil
-      context = parent.context if parent
+      context = parent&.context
       notation = "<!NOTATION #{@name}"
       reference_writer = ReferenceWriter.new(@middle, @public, @system, context)
       reference_writer.write(notation)
diff --git a/lib/rexml/document.rb b/lib/rexml/document.rb
index d1747dd4..96ae5b75 100644
--- a/lib/rexml/document.rb
+++ b/lib/rexml/document.rb
@@ -309,8 +309,8 @@ def stand_alone?
     end
 
     # :call-seq:
-    #    doc.write(output=$stdout, indent=-1, transtive=false, ie_hack=false, encoding=nil)
-    #    doc.write(options={:output => $stdout, :indent => -1, :transtive => false, :ie_hack => false, :encoding => nil})
+    #    doc.write(output=$stdout, indent=-1, transitive=false, ie_hack=false, encoding=nil)
+    #    doc.write(options={:output => $stdout, :indent => -1, :transitive => false, :ie_hack => false, :encoding => nil})
     #
     # Write the XML tree out, optionally with indent.  This writes out the
     # entire XML document, including XML declarations, doctype declarations,
@@ -415,7 +415,7 @@ def Document::entity_expansion_limit=( val )
     #
     # Deprecated. Use REXML::Security.entity_expansion_limit= instead.
     def Document::entity_expansion_limit
-      return Security.entity_expansion_limit
+      Security.entity_expansion_limit
     end
 
     # Set the entity expansion limit. By default the limit is set to 10240.
@@ -429,7 +429,7 @@ def Document::entity_expansion_text_limit=( val )
     #
     # Deprecated. Use REXML::Security.entity_expansion_text_limit instead.
     def Document::entity_expansion_text_limit
-      return Security.entity_expansion_text_limit
+      Security.entity_expansion_text_limit
     end
 
     attr_reader :entity_expansion_count
@@ -448,6 +448,20 @@ def document
     end
 
     private
+
+    attr_accessor :namespaces_cache
+
+    # New document level cache is created and available in this block.
+    # This API is thread unsafe. Users can't change this document in this block.
+    def enable_cache
+      @namespaces_cache = {}
+      begin
+        yield
+      ensure
+        @namespaces_cache = nil
+      end
+    end
+
     def build( source )
       Parsers::TreeParser.new( source, self ).parse
     end
diff --git a/lib/rexml/element.rb b/lib/rexml/element.rb
index 4e3a60b9..0d74811e 100644
--- a/lib/rexml/element.rb
+++ b/lib/rexml/element.rb
@@ -473,8 +473,7 @@ def root
     # Related: #root, #root_node.
     #
     def document
-      rt = root
-      rt.parent if rt
+      root&.parent
     end
 
     # :call-seq:
@@ -566,7 +565,7 @@ def prefixes
       prefixes = []
       prefixes = parent.prefixes if parent
       prefixes |= attributes.prefixes
-      return prefixes
+      prefixes
     end
 
     # :call-seq:
@@ -589,10 +588,12 @@ def prefixes
     #   d.elements['//c'].namespaces # => {"x"=>"1", "y"=>"2", "z"=>"3"}
     #
     def namespaces
-      namespaces = {}
-      namespaces = parent.namespaces if parent
-      namespaces = namespaces.merge( attributes.namespaces )
-      return namespaces
+      namespaces_cache = document&.__send__(:namespaces_cache)
+      if namespaces_cache
+        namespaces_cache[self] ||= calculate_namespaces
+      else
+        calculate_namespaces
+      end
     end
 
     # :call-seq:
@@ -619,19 +620,11 @@ def namespace(prefix=nil)
       if prefix.nil?
         prefix = prefix()
       end
-      if prefix == ''
-        prefix = "xmlns"
-      else
-        prefix = "xmlns:#{prefix}" unless prefix[0,5] == 'xmlns'
-      end
-      ns = nil
-      target = self
-      while ns.nil? and target
-        ns = target.attributes[prefix]
-        target = target.parent
-      end
+      prefix = (prefix == '') ? 'xmlns' : prefix.delete_prefix("xmlns:")
+      ns = namespaces[prefix]
+
       ns = '' if ns.nil? and prefix == 'xmlns'
-      return ns
+      ns
     end
 
     # :call-seq:
@@ -963,7 +956,7 @@ def get_elements( xpath )
     def next_element
       element = next_sibling
       element = element.next_sibling until element.nil? or element.kind_of? Element
-      return element
+      element
     end
 
     # :call-seq:
@@ -979,7 +972,7 @@ def next_element
     def previous_element
       element = previous_sibling
       element = element.previous_sibling until element.nil? or element.kind_of? Element
-      return element
+      element
     end
 
 
@@ -1029,8 +1022,7 @@ def has_text?
     #
     def text( path = nil )
       rv = get_text(path)
-      return rv.value unless rv.nil?
-      nil
+      rv&.value
     end
 
     # :call-seq:
@@ -1058,7 +1050,7 @@ def get_text path = nil
       else
         rv = @children.find { |node| node.kind_of? Text }
       end
-      return rv
+      rv
     end
 
     # :call-seq:
@@ -1102,7 +1094,7 @@ def text=( text )
           old_text.replace_with( text )
         end
       end
-      return self
+      self
     end
 
     # :call-seq:
@@ -1153,7 +1145,7 @@ def add_text( text )
         text = Text.new( text, whitespace(), nil, raw() )
       end
       self << text unless text.nil?
-      return self
+      self
     end
 
     # :call-seq:
@@ -1197,7 +1189,7 @@ def xpath
         cur = cur.parent
         path_elements << __to_xpath_helper( cur )
       end
-      return path_elements.reverse.join( "/" )
+      path_elements.reverse.join( "/" )
     end
 
     #################################################
@@ -1299,7 +1291,6 @@ def attribute( name, namespace=nil )
       return nil unless ( namespaces[ prefix ] == namespaces[ 'xmlns' ] )
 
       attributes.get_attribute( name )
-
     end
 
     # :call-seq:
@@ -1313,7 +1304,7 @@ def attribute( name, namespace=nil )
     #   b.has_attributes? # => false
     #
     def has_attributes?
-      return !@attributes.empty?
+      !@attributes.empty?
     end
 
     # :call-seq:
@@ -1502,7 +1493,7 @@ def texts
     #  doc.write( out )     #-> doc is written to the string 'out'
     #  doc.write( $stdout ) #-> doc written to the console
     def write(output=$stdout, indent=-1, transitive=false, ie_hack=false)
-      Kernel.warn("#{self.class.name}.write is deprecated.  See REXML::Formatters", uplevel: 1)
+      Kernel.warn("#{self.class.name}#write is deprecated.  See REXML::Formatters", uplevel: 1)
       formatter = if indent > -1
           if transitive
             require_relative "formatters/transitive"
@@ -1516,8 +1507,15 @@ def write(output=$stdout, indent=-1, transitive=false, ie_hack=false)
       formatter.write( self, output )
     end
 
-
     private
+    def calculate_namespaces
+      if parent
+        parent.namespaces.merge(attributes.namespaces)
+      else
+        attributes.namespaces
+      end
+    end
+
     def __to_xpath_helper node
       rv = node.expanded_name.clone
       if node.parent
@@ -1684,11 +1682,7 @@ def []( index, name=nil)
           (num += 1) == index
         }
       else
-        return XPath::first( @element, index )
-        #{ |element|
-        #       return element if element.kind_of? Element
-        #}
-        #return nil
+        XPath::first( @element, index )
       end
     end
 
@@ -1735,7 +1729,7 @@ def []=( index, element )
       else
         previous.replace_with element
       end
-      return previous
+      previous
     end
 
     # :call-seq:
@@ -1774,7 +1768,7 @@ def index element
         child == element
       end
       return rv if found == element
-      return -1
+      -1
     end
 
     # :call-seq:
@@ -1853,7 +1847,7 @@ def delete_all( xpath )
         @element.delete element
         element.remove
       end
-      return rv
+      rv
     end
 
     # :call-seq:
@@ -2180,8 +2174,7 @@ def initialize element
     #
     def [](name)
       attr = get_attribute(name)
-      return attr.value unless attr.nil?
-      return nil
+      attr&.value
     end
 
     # :call-seq:
@@ -2324,11 +2317,11 @@ def get_attribute( name )
             return attr
           end
         end
-        element_document = @element.document
-        if element_document and element_document.doctype
+        doctype = @element.document&.doctype
+        if doctype
           expn = @element.expanded_name
-          expn = element_document.doctype.name if expn.size == 0
-          attr_val = element_document.doctype.attribute_of(expn, name)
+          expn = doctype.name if expn.size == 0
+          attr_val = doctype.attribute_of(expn, name)
           return Attribute.new( name, attr_val ) if attr_val
         end
         return nil
@@ -2336,7 +2329,7 @@ def get_attribute( name )
       if attr.kind_of? Hash
         attr = attr[ @element.prefix ]
       end
-      return attr
+      attr
     end
 
     # :call-seq:
@@ -2370,8 +2363,9 @@ def []=( name, value )
       end
 
       unless value.kind_of? Attribute
-        if @element.document and @element.document.doctype
-          value = Text::normalize( value, @element.document.doctype )
+        doctype = @element.document&.doctype
+        if doctype
+          value = Text::normalize( value, doctype )
         else
           value = Text::normalize( value, nil )
         end
@@ -2389,7 +2383,7 @@ def []=( name, value )
       else
         store value.name, value
       end
-      return @element
+      @element
     end
 
     # :call-seq:
@@ -2408,10 +2402,11 @@ def prefixes
       each_attribute do |attribute|
         ns << attribute.name if attribute.prefix == 'xmlns'
       end
-      if @element.document and @element.document.doctype
+      doctype = @element.document&.doctype
+      if doctype
         expn = @element.expanded_name
-        expn = @element.document.doctype.name if expn.size == 0
-        @element.document.doctype.attributes_of(expn).each {
+        expn = doctype.name if expn.size == 0
+        doctype.attributes_of(expn).each {
           |attribute|
           ns << attribute.name if attribute.prefix == 'xmlns'
         }
@@ -2433,10 +2428,11 @@ def namespaces
       each_attribute do |attribute|
         namespaces[attribute.name] = attribute.value if attribute.prefix == 'xmlns' or attribute.name == 'xmlns'
       end
-      if @element.document and @element.document.doctype
+      doctype = @element.document&.doctype
+      if doctype
         expn = @element.expanded_name
-        expn = @element.document.doctype.name if expn.size == 0
-        @element.document.doctype.attributes_of(expn).each {
+        expn = doctype.name if expn.size == 0
+        doctype.attributes_of(expn).each {
           |attribute|
           namespaces[attribute.name] = attribute.value if attribute.prefix == 'xmlns' or attribute.name == 'xmlns'
         }
@@ -2491,9 +2487,7 @@ def delete( attribute )
           old.each_value{|v| repl = v}
           store name, repl
         end
-      elsif old.nil?
-        return @element
-      else # the supplied attribute is a top-level one
+      elsif old # the supplied attribute is a top-level one
         super(name)
       end
       @element
@@ -2547,7 +2541,7 @@ def delete_all( name )
         rv << attribute if attribute.expanded_name == name
       }
       rv.each{ |attr| attr.remove }
-      return rv
+      rv
     end
 
     # :call-seq:
diff --git a/lib/rexml/encoding.rb b/lib/rexml/encoding.rb
index da2d70d6..7eb05f4d 100644
--- a/lib/rexml/encoding.rb
+++ b/lib/rexml/encoding.rb
@@ -5,7 +5,7 @@ module Encoding
     # ID ---> Encoding name
     attr_reader :encoding
     def encoding=(encoding)
-      encoding = encoding.name if encoding.is_a?(Encoding)
+      encoding = encoding.name if encoding.is_a?(::Encoding)
       if encoding.is_a?(String)
         original_encoding = encoding
         encoding = find_encoding(encoding)
@@ -13,12 +13,9 @@ def encoding=(encoding)
           raise ArgumentError, "Bad encoding name #{original_encoding}"
         end
       end
+      encoding = encoding.upcase if encoding
       return false if defined?(@encoding) and encoding == @encoding
-      if encoding
-        @encoding = encoding.upcase
-      else
-        @encoding = 'UTF-8'
-      end
+      @encoding = encoding || "UTF-8"
       true
     end
 
diff --git a/lib/rexml/functions.rb b/lib/rexml/functions.rb
index 4c114616..60ae34e7 100644
--- a/lib/rexml/functions.rb
+++ b/lib/rexml/functions.rb
@@ -39,11 +39,11 @@ def Functions::context=(value); @@context = value; end
 
     def Functions::text( )
       if @@context[:node].node_type == :element
-        return @@context[:node].find_all{|n| n.node_type == :text}.collect{|n| n.value}
+        @@context[:node].find_all{|n| n.node_type == :text}.collect{|n| n.value}
       elsif @@context[:node].node_type == :text
-        return @@context[:node].value
+        @@context[:node].value
       else
-        return false
+        false
       end
     end
 
diff --git a/lib/rexml/instruction.rb b/lib/rexml/instruction.rb
index 318741f0..a3dfbbec 100644
--- a/lib/rexml/instruction.rb
+++ b/lib/rexml/instruction.rb
@@ -49,7 +49,7 @@ def clone
     # See the rexml/formatters package
     #
     def write writer, indent=-1, transitive=false, ie_hack=false
-      Kernel.warn( "#{self.class.name}.write is deprecated", uplevel: 1)
+      Kernel.warn( "#{self.class.name}#write is deprecated", uplevel: 1)
       indent(writer, indent)
       writer << START
       writer << @target
diff --git a/lib/rexml/namespace.rb b/lib/rexml/namespace.rb
index 2e67252a..232b7ca4 100644
--- a/lib/rexml/namespace.rb
+++ b/lib/rexml/namespace.rb
@@ -42,11 +42,11 @@ def name=( name )
     # Compares names optionally WITH namespaces
     def has_name?( other, ns=nil )
       if ns
-        return (namespace() == ns and name() == other)
+        namespace() == ns and name() == other
       elsif other.include? ":"
-        return fully_expanded_name == other
+        fully_expanded_name == other
       else
-        return name == other
+        name == other
       end
     end
 
@@ -57,7 +57,7 @@ def has_name?( other, ns=nil )
     def fully_expanded_name
       ns = prefix
       return "#{ns}:#@name" if ns.size > 0
-      return @name
+      @name
     end
   end
 end
diff --git a/lib/rexml/node.rb b/lib/rexml/node.rb
index c771db70..bccacc51 100644
--- a/lib/rexml/node.rb
+++ b/lib/rexml/node.rb
@@ -26,7 +26,7 @@ def previous_sibling_node
     #   REXML::Formatters package for changing the output style.
     def to_s indent=nil
       unless indent.nil?
-        Kernel.warn( "#{self.class.name}.to_s(indent) parameter is deprecated", uplevel: 1)
+        Kernel.warn( "#{self.class.name}#to_s(indent) parameter is deprecated", uplevel: 1)
         f = REXML::Formatters::Pretty.new( indent )
         f.write( self, rv = "" )
       else
@@ -68,7 +68,7 @@ def find_first_recursive(&block) # :yields: node
       each_recursive {|node|
         return node if block.call(node)
       }
-      return nil
+      nil
     end
 
     # Returns the position that +self+ holds in its parent's array, indexed
diff --git a/lib/rexml/parsers/baseparser.rb b/lib/rexml/parsers/baseparser.rb
index 44aacfa2..a87657b5 100644
--- a/lib/rexml/parsers/baseparser.rb
+++ b/lib/rexml/parsers/baseparser.rb
@@ -206,12 +206,12 @@ def position
 
       # Returns true if there are no more events
       def empty?
-        return (@source.empty? and @stack.empty?)
+        (@source.empty? and @stack.empty?)
       end
 
       # Returns true if there are more events.  Synonymous with !empty?
       def has_next?
-        return !(@source.empty? and @stack.empty?)
+        !(@source.empty? and @stack.empty?)
       end
 
       # Push an event back on the head of the stream.  This method
@@ -277,14 +277,7 @@ def pull_event
             return process_instruction
           elsif @source.match?("<!", true)
             if @source.match?("--", true)
-              md = @source.match(/(.*?)-->/um, true)
-              if md.nil?
-                raise REXML::ParseException.new("Unclosed comment", @source)
-              end
-              if /--|-\z/.match?(md[1])
-                raise REXML::ParseException.new("Malformed comment", @source)
-              end
-              return [ :comment, md[1] ]
+              return [ :comment, process_comment ]
             elsif @source.match?("DOCTYPE", true)
               base_error_message = "Malformed DOCTYPE"
               unless @source.match?(/\s+/um, true)
@@ -417,20 +410,17 @@ def pull_event
                 raise REXML::ParseException.new(message, @source)
               end
               return [:notationdecl, name, *id]
-            elsif md = @source.match(/--(.*?)-->/um, true)
-              case md[1]
-              when /--/, /-\z/
-                raise REXML::ParseException.new("Malformed comment", @source)
-              end
-              return [ :comment, md[1] ] if md
+            elsif @source.match?("--", true)
+              return [ :comment, process_comment ]
+            else
+              raise REXML::ParseException.new("Malformed node: Started with '<!' but not a comment nor ELEMENT,ENTITY,ATTLIST,NOTATION", @source)
             end
           elsif match = @source.match(/(%.*?;)\s*/um, true)
             return [ :externalentity, match[1] ]
           elsif @source.match?(/\]\s*>/um, true)
             @document_status = :after_doctype
             return [ :end_doctype ]
-          end
-          if @document_status == :in_doctype
+          else
             raise ParseException.new("Malformed DOCTYPE: invalid declaration", @source)
           end
         end
@@ -460,23 +450,19 @@ def pull_event
               end
               return [ :end_element, last_tag ]
             elsif @source.match?("!", true)
-              md = @source.match(/([^>]*>)/um)
               #STDERR.puts "SOURCE BUFFER = #{source.buffer}, #{source.buffer.size}"
-              raise REXML::ParseException.new("Malformed node", @source) unless md
-              if md[0][0] == ?-
-                md = @source.match(/--(.*?)-->/um, true)
-
-                if md.nil? || /--|-\z/.match?(md[1])
-                  raise REXML::ParseException.new("Malformed comment", @source)
+              if @source.match?("--", true)
+                return [ :comment, process_comment ]
+              elsif @source.match?("[CDATA[", true)
+                text = @source.read_until("]]>")
+                if text.chomp!("]]>")
+                  return [ :cdata, text ]
+                else
+                  raise REXML::ParseException.new("Malformed CDATA: Missing end ']]>'", @source)
                 end
-
-                return [ :comment, md[1] ]
               else
-                md = @source.match(/\[CDATA\[(.*?)\]\]>/um, true)
-                return [ :cdata, md[1] ] if md
+                raise REXML::ParseException.new("Malformed node: Started with '<!' but not a comment nor CDATA", @source)
               end
-              raise REXML::ParseException.new( "Declarations can only occur "+
-                "in the doctype declaration.", @source)
             elsif @source.match?("?", true)
               return process_instruction
             else
@@ -536,7 +522,8 @@ def pull_event
           raise REXML::ParseException.new( "Exception parsing",
             @source, self, (error ? error : $!) )
         end
-        return [ :dummy ]
+        # NOTE: The end of the method never runs, because it is unreachable.
+        #       All branches of code above have explicit unconditional return or raise statements.
       end
       private :pull_event
 
@@ -734,6 +721,18 @@ def parse_id_invalid_details(accept_external_id:,
         end
       end
 
+      def process_comment
+        text = @source.read_until("-->")
+        unless text.chomp!("-->")
+          raise REXML::ParseException.new("Unclosed comment: Missing end '-->'", @source)
+        end
+
+        if text.include? "--" or text.end_with?("-")
+          raise REXML::ParseException.new("Malformed comment", @source)
+        end
+        text
+      end
+
       def process_instruction
         name = parse_name("Malformed XML: Invalid processing instruction node")
         if @source.match?(/\s+/um, true)
diff --git a/lib/rexml/parsers/xpathparser.rb b/lib/rexml/parsers/xpathparser.rb
index bd3b6856..a6d76fdc 100644
--- a/lib/rexml/parsers/xpathparser.rb
+++ b/lib/rexml/parsers/xpathparser.rb
@@ -215,7 +215,7 @@ def predicate_to_path(parsed, &block)
         else
           path << yield( parsed )
         end
-        return path.squeeze(" ")
+        path.squeeze(" ")
       end
       # For backward compatibility
       alias_method :preciate_to_string, :predicate_to_path
@@ -252,7 +252,7 @@ def LocationPath path, parsed
             path = path[1..-1]
           end
         end
-        return RelativeLocationPath( path, parsed ) if path.size > 0
+        RelativeLocationPath( path, parsed ) if path.size > 0
       end
 
       #RelativeLocationPath
@@ -388,7 +388,7 @@ def NodeTest path, parsed
         else
           path = original_path
         end
-        return path
+        path
       end
 
       # Filters the supplied nodeset on the predicate(s)
@@ -600,7 +600,7 @@ def PathExpr path, parsed
         end
         rest = LocationPath(rest, n) if rest =~ /\A[\/\.\@\[\w*]/
         parsed.concat(n)
-        return rest
+        rest
       end
 
       #| FilterExpr Predicate
diff --git a/lib/rexml/quickpath.rb b/lib/rexml/quickpath.rb
index a0466b25..cded06f5 100644
--- a/lib/rexml/quickpath.rb
+++ b/lib/rexml/quickpath.rb
@@ -41,7 +41,7 @@ def QuickPath::match element, path, namespaces=EMPTY_HASH
       else
         results = filter([element], path)
       end
-      return results
+      results
     end
 
     # Given an array of nodes it filters the array based on the path. The
@@ -51,18 +51,18 @@ def QuickPath::filter elements, path
       return elements if path.nil? or path == '' or elements.size == 0
       case path
       when /^\/\//u                                                                                     # Descendant
-        return axe( elements, "descendant-or-self", $' )
+        axe( elements, "descendant-or-self", $' )
       when /^\/?\b(\w[-\w]*)\b::/u                                                      # Axe
-        return axe( elements, $1, $' )
+        axe( elements, $1, $' )
       when /^\/(?=\b([:!\w][-\.\w]*:)?[-!\*\.\w]*\b([^:(]|$)|\*)/u      # Child
         rest = $'
         results = []
         elements.each do |element|
           results |= filter( element.to_a, rest )
         end
-        return results
+        results
       when /^\/?(\w[-\w]*)\(/u                                                  # / Function
-        return function( elements, $1, $' )
+        function( elements, $1, $' )
       when Namespace::NAMESPLIT         # Element name
         name = $2
         ns = $1
@@ -73,21 +73,21 @@ def QuickPath::filter elements, path
              (element.name == name and
               element.namespace == Functions.namespace_context[ns])))
         end
-        return filter( elements, rest )
+        filter( elements, rest )
       when /^\/\[/u
         matches = []
         elements.each do |element|
           matches |= predicate( element.to_a, path[1..-1] ) if element.kind_of? Element
         end
-        return matches
+        matches
       when /^\[/u                                                                                               # Predicate
-        return predicate( elements, path )
+        predicate( elements, path )
       when /^\/?\.\.\./u                                                                                # Ancestor
-        return axe( elements, "ancestor", $' )
+        axe( elements, "ancestor", $' )
       when /^\/?\.\./u                                                                                  # Parent
-        return filter( elements.collect{|e|e.parent}, $' )
+        filter( elements.collect{|e|e.parent}, $' )
       when /^\/?\./u                                                                                            # Self
-        return filter( elements, $' )
+        filter( elements, $' )
       when /^\*/u                                                                                                       # Any
         results = []
         elements.each do |element|
@@ -98,9 +98,10 @@ def QuickPath::filter elements, path
           #     results |= filter( children, $' )
           #end
         end
-        return results
+        results
+      else
+        []
       end
-      return []
     end
 
     def QuickPath::axe( elements, axe_name, rest )
@@ -138,7 +139,7 @@ def QuickPath::axe( elements, axe_name, rest )
         matches = filter(elements.collect{|element|
           element.previous_sibling}.uniq, rest )
       end
-      return matches.uniq
+      matches.uniq
     end
 
     OPERAND_ = '((?=(?:(?!and|or).)*[^\s<>=])[^\s<>=]+)'
@@ -200,15 +201,15 @@ def QuickPath::predicate( elements, path )
           results << element
         end
       end
-      return filter( results, rest )
+      filter( results, rest )
     end
 
     def QuickPath::attribute( name )
-      return Functions.node.attributes[name] if Functions.node.kind_of? Element
+      Functions.node.attributes[name] if Functions.node.kind_of? Element
     end
 
     def QuickPath::name()
-      return Functions.node.name if Functions.node.kind_of? Element
+      Functions.node.name if Functions.node.kind_of? Element
     end
 
     def QuickPath::method_missing( id, *args )
@@ -234,7 +235,7 @@ def QuickPath::function( elements, fname, rest )
           results << element if Functions.pair[0] == res
         end
       end
-      return results
+      results
     end
 
     def QuickPath::parse_args( element, string )
diff --git a/lib/rexml/rexml.rb b/lib/rexml/rexml.rb
index a653f028..bf3c0d32 100644
--- a/lib/rexml/rexml.rb
+++ b/lib/rexml/rexml.rb
@@ -31,7 +31,7 @@
 module REXML
   COPYRIGHT = "Copyright © 2001-2008 Sean Russell <ser@germane-software.com>"
   DATE = "2008/019"
-  VERSION = "3.4.1"
+  VERSION = "3.4.2"
   REVISION = ""
 
   Copyright = COPYRIGHT
diff --git a/lib/rexml/security.rb b/lib/rexml/security.rb
index 99b74607..e8e8c6b4 100644
--- a/lib/rexml/security.rb
+++ b/lib/rexml/security.rb
@@ -10,7 +10,7 @@ def self.entity_expansion_limit=( val )
 
     # Get the entity expansion limit. By default the limit is set to 10000.
     def self.entity_expansion_limit
-      return @@entity_expansion_limit
+      @@entity_expansion_limit
     end
 
     @@entity_expansion_text_limit = 10_240
@@ -22,7 +22,7 @@ def self.entity_expansion_text_limit=( val )
 
     # Get the entity expansion limit. By default the limit is set to 10240.
     def self.entity_expansion_text_limit
-      return @@entity_expansion_text_limit
+      @@entity_expansion_text_limit
     end
   end
 end
diff --git a/lib/rexml/source.rb b/lib/rexml/source.rb
index 5ba5ab12..3ec1141e 100644
--- a/lib/rexml/source.rb
+++ b/lib/rexml/source.rb
@@ -67,7 +67,7 @@ class Source
     module Private
       SCANNER_RESET_SIZE = 100000
       PRE_DEFINED_TERM_PATTERNS = {}
-      pre_defined_terms = ["'", '"', "<"]
+      pre_defined_terms = ["'", '"', "<", "]]>"]
       if StringScanner::Version < "3.1.1"
         pre_defined_terms.each do |term|
           PRE_DEFINED_TERM_PATTERNS[term] = /#{Regexp.escape(term)}/
diff --git a/lib/rexml/text.rb b/lib/rexml/text.rb
index 2bf480fb..8799d89d 100644
--- a/lib/rexml/text.rb
+++ b/lib/rexml/text.rb
@@ -104,16 +104,16 @@ def initialize(arg, respect_whitespace=false, parent=nil, raw=nil,
       @entity_filter = entity_filter if entity_filter
       clear_cache
 
-      Text.check(@string, illegal, doctype) if @raw
+      Text.check(@string, illegal) if @raw
     end
 
     def parent= parent
       super(parent)
-      Text.check(@string, NEEDS_A_SECOND_CHECK, doctype) if @raw and @parent
+      Text.check(@string, NEEDS_A_SECOND_CHECK) if @raw and @parent
     end
 
     # check for illegal characters
-    def Text.check string, pattern, doctype
+    def Text.check string, pattern, doctype = nil
 
       # illegal anywhere
       if !string.match?(VALID_XML_CHARS)
@@ -177,7 +177,7 @@ def empty?
 
 
     def clone
-      return Text.new(self, true)
+      Text.new(self, true)
     end
 
 
@@ -200,10 +200,7 @@ def <=>( other )
     end
 
     def doctype
-      if @parent
-        doc = @parent.document
-        doc.doctype if doc
-      end
+      @parent&.document&.doctype
     end
 
     REFERENCE = /#{Entity::REFERENCE}/
@@ -264,10 +261,10 @@ def wrap(string, width, addnewline=false)
       # Recursively wrap string at width.
       return string if string.length <= width
       place = string.rindex(' ', width) # Position in string with last ' ' before cutoff
-      if addnewline then
-        return "\n" + string[0,place] + "\n" + wrap(string[place+1..-1], width)
+      if addnewline
+        "\n" + string[0,place] + "\n" + wrap(string[place+1..-1], width)
       else
-        return string[0,place] + "\n" + wrap(string[place+1..-1], width)
+        string[0,place] + "\n" + wrap(string[place+1..-1], width)
       end
     end
 
@@ -280,14 +277,14 @@ def indent_text(string, level=1, style="\t", indentfirstline=true)
         new_string << new_line
       }
       new_string.strip! unless indentfirstline
-      return new_string
+      new_string
     end
 
     # == DEPRECATED
     # See REXML::Formatters
     #
     def write( writer, indent=-1, transitive=false, ie_hack=false )
-      Kernel.warn("#{self.class.name}.write is deprecated.  See REXML::Formatters", uplevel: 1)
+      Kernel.warn("#{self.class.name}#write is deprecated.  See REXML::Formatters", uplevel: 1)
       formatter = if indent > -1
           REXML::Formatters::Pretty.new( indent )
         else
@@ -299,9 +296,7 @@ def write( writer, indent=-1, transitive=false, ie_hack=false )
     # FIXME
     # This probably won't work properly
     def xpath
-      path = @parent.xpath
-      path += "/text()"
-      return path
+      @parent.xpath + "/text()"
     end
 
     # Writes out text, substituting special characters beforehand.
diff --git a/lib/rexml/validation/relaxng.rb b/lib/rexml/validation/relaxng.rb
index f29a2c05..c6894dcb 100644
--- a/lib/rexml/validation/relaxng.rb
+++ b/lib/rexml/validation/relaxng.rb
@@ -157,16 +157,16 @@ def next( event )
         if ( @events[@current].matches?(event) )
           @current += 1
           if @events[@current].nil?
-            return @previous.pop
+            @previous.pop
           elsif @events[@current].kind_of? State
             @current += 1
             @events[@current-1].previous = self
-            return @events[@current-1]
+            @events[@current-1]
           else
-            return self
+            self
           end
         else
-          return nil
+          nil
         end
       end
 
@@ -186,7 +186,7 @@ def inspect
       end
 
       def expected
-        return [@events[@current]]
+        [@events[@current]]
       end
 
       def <<( event )
@@ -244,7 +244,7 @@ def generate_event( event )
             evt = :end_attribute
           end
         end
-        return Event.new( evt, arg )
+        Event.new( evt, arg )
       end
     end
 
@@ -262,9 +262,10 @@ def next( event )
           rv = super
           return rv if rv
           @prior = @previous.pop
-          return @prior.next( event )
+          @prior.next( event )
+        else
+          super
         end
-        super
       end
 
       def matches?(event)
@@ -274,7 +275,7 @@ def matches?(event)
 
       def expected
         return [ @prior.expected, @events[0] ].flatten if @current == 0
-        return [@events[@current]]
+        [@events[@current]]
       end
     end
 
@@ -286,24 +287,24 @@ def next( event )
           @current += 1
           if @events[@current].nil?
             @current = 0
-            return self
+            self
           elsif @events[@current].kind_of? State
             @current += 1
             @events[@current-1].previous = self
-            return @events[@current-1]
+            @events[@current-1]
           else
-            return self
+            self
           end
         else
           @prior = @previous.pop
           return @prior.next( event ) if @current == 0
-          return nil
+          nil
         end
       end
 
       def expected
         return [ @prior.expected, @events[0] ].flatten if @current == 0
-        return [@events[@current]]
+        [@events[@current]]
       end
     end
 
@@ -326,17 +327,17 @@ def next( event )
           @ord += 1
           if @events[@current].nil?
             @current = 0
-            return self
+            self
           elsif @events[@current].kind_of? State
             @current += 1
             @events[@current-1].previous = self
-            return @events[@current-1]
+            @events[@current-1]
           else
-            return self
+            self
           end
         else
           return @previous.pop.next( event ) if @current == 0 and @ord > 0
-          return nil
+          nil
         end
       end
 
@@ -347,9 +348,9 @@ def matches?( event )
 
       def expected
         if @current == 0 and @ord > 0
-          return [@previous[-1].expected, @events[0]].flatten
+          [@previous[-1].expected, @events[0]].flatten
         else
-          return [@events[@current]]
+          [@events[@current]]
         end
       end
     end
@@ -403,7 +404,7 @@ def matches?( event )
 
       def expected
         return [@events[@current]] if @events.size > 0
-        return @choices.collect do |x|
+        @choices.collect do |x|
           if x[0].kind_of? State
             x[0].expected
           else
@@ -490,16 +491,16 @@ def next( event )
           @current += 1
           if @events[@current].nil?
             return self unless @choices[@choice].nil?
-            return @previous.pop
+            @previous.pop
           elsif @events[@current].kind_of? State
             @current += 1
             @events[@current-1].previous = self
-            return @events[@current-1]
+            @events[@current-1]
           else
-            return self
+            self
           end
         else
-          return nil
+          nil
         end
       end
 
@@ -510,7 +511,7 @@ def matches?( event )
 
       def expected
         return [@events[@current]] if @events[@current]
-        return @choices[@choice..-1].collect do |x|
+        @choices[@choice..-1].collect do |x|
           if x[0].kind_of? State
             x[0].expected
           else
diff --git a/lib/rexml/validation/validation.rb b/lib/rexml/validation/validation.rb
index 0ad6ada4..6475c628 100644
--- a/lib/rexml/validation/validation.rb
+++ b/lib/rexml/validation/validation.rb
@@ -80,26 +80,26 @@ def done?
       end
 
       def single?
-        return (@event_type != :start_element and @event_type != :start_attribute)
+        (@event_type != :start_element and @event_type != :start_attribute)
       end
 
       def matches?( event )
         return false unless event[0] == @event_type
         case event[0]
         when nil
-          return true
+          true
         when :start_element
-          return true if event[1] == @event_arg
+          event[1] == @event_arg
         when :end_element
-          return true
+          true
         when :start_attribute
-          return true if event[1] == @event_arg
+          event[1] == @event_arg
         when :end_attribute
-          return true
+          true
         when :end_document
-          return true
+          true
         when :text
-          return (@event_arg.nil? or @event_arg == event[1])
+          @event_arg.nil? || @event_arg == event[1]
 =begin
         when :processing_instruction
           false
diff --git a/lib/rexml/xpath.rb b/lib/rexml/xpath.rb
index a0921bd8..eed0300c 100644
--- a/lib/rexml/xpath.rb
+++ b/lib/rexml/xpath.rb
@@ -31,12 +31,7 @@ class XPath
     def XPath::first(element, path=nil, namespaces=nil, variables={}, options={})
       raise "The namespaces argument, if supplied, must be a hash object." unless namespaces.nil? or namespaces.kind_of?(Hash)
       raise "The variables argument, if supplied, must be a hash object." unless variables.kind_of?(Hash)
-      parser = XPathParser.new(**options)
-      parser.namespaces = namespaces
-      parser.variables = variables
-      path = "*" unless path
-      element = [element] unless element.kind_of? Array
-      parser.parse(path, element).flatten[0]
+      match(element, path, namespaces, variables, options).flatten[0]
     end
 
     # Iterates over nodes that match the given path, calling the supplied
@@ -60,12 +55,7 @@ def XPath::first(element, path=nil, namespaces=nil, variables={}, options={})
     def XPath::each(element, path=nil, namespaces=nil, variables={}, options={}, &block)
       raise "The namespaces argument, if supplied, must be a hash object." unless namespaces.nil? or namespaces.kind_of?(Hash)
       raise "The variables argument, if supplied, must be a hash object." unless variables.kind_of?(Hash)
-      parser = XPathParser.new(**options)
-      parser.namespaces = namespaces
-      parser.variables = variables
-      path = "*" unless path
-      element = [element] unless element.kind_of? Array
-      parser.parse(path, element).each( &block )
+      match(element, path, namespaces, variables, options).each( &block )
     end
 
     # Returns an array of nodes matching a given XPath.
@@ -74,7 +64,6 @@ def XPath::match(element, path=nil, namespaces=nil, variables={}, options={})
       parser.namespaces = namespaces
       parser.variables = variables
       path = "*" unless path
-      element = [element] unless element.kind_of? Array
       parser.parse(path,element)
     end
   end
diff --git a/lib/rexml/xpath_parser.rb b/lib/rexml/xpath_parser.rb
index 5eb1e5a9..64c8846a 100644
--- a/lib/rexml/xpath_parser.rb
+++ b/lib/rexml/xpath_parser.rb
@@ -76,19 +76,32 @@ def variables=( vars={} )
       @variables = vars
     end
 
-    def parse path, nodeset
+    def parse path, node
       path_stack = @parser.parse( path )
-      match( path_stack, nodeset )
+      if node.is_a?(Array)
+        Kernel.warn("REXML::XPath.each, REXML::XPath.first, REXML::XPath.match dropped support for nodeset...", uplevel: 1)
+        return [] if node.empty?
+        node = node.first
+      end
+
+      document = node.document
+      if document
+        document.__send__(:enable_cache) do
+          match( path_stack, node )
+        end
+      else
+        match( path_stack, node )
+      end
     end
 
-    def get_first path, nodeset
+    def get_first path, node
       path_stack = @parser.parse( path )
-      first( path_stack, nodeset )
+      first( path_stack, node )
     end
 
-    def predicate path, nodeset
+    def predicate path, node
       path_stack = @parser.parse( path )
-      match( path_stack, nodeset )
+      match( path_stack, node )
     end
 
     def []=( variable_name, value )
@@ -106,7 +119,7 @@ def first( path_stack, node )
       case path[0]
       when :document
         # do nothing
-        return first( path[1..-1], node )
+        first( path[1..-1], node )
       when :child
         for c in node.children
           r = first( path[1..-1], c )
@@ -116,9 +129,9 @@ def first( path_stack, node )
         name = path[2]
         if node.name == name
           return node if path.size == 3
-          return first( path[3..-1], node )
+          first( path[3..-1], node )
         else
-          return nil
+          nil
         end
       when :descendant_or_self
         r = first( path[1..-1], node )
@@ -128,23 +141,21 @@ def first( path_stack, node )
           return r if r
         end
       when :node
-        return first( path[1..-1], node )
+        first( path[1..-1], node )
       when :any
-        return first( path[1..-1], node )
+        first( path[1..-1], node )
+      else
+        nil
       end
-      return nil
     end
 
 
-    def match(path_stack, nodeset)
-      nodeset = nodeset.collect.with_index do |node, i|
-        position = i + 1
-        XPathNode.new(node, position: position)
-      end
+    def match(path_stack, node)
+      nodeset = [XPathNode.new(node, position: 1)]
       result = expr(path_stack, nodeset)
       case result
       when Array # nodeset
-        unnode(result)
+        unnode(result).uniq
       else
         [result]
       end
@@ -162,10 +173,10 @@ def strict?
     #  2. If no mapping was supplied, use the context node to look up the namespace
     def get_namespace( node, prefix )
       if @namespaces
-        return @namespaces[prefix] || ''
+        @namespaces[prefix] || ''
       else
         return node.namespace( prefix ) if node.node_type == :element
-        return ''
+        ''
       end
     end
 
@@ -492,14 +503,10 @@ def node_test(path_stack, nodesets, any_type: :element)
                 if strict?
                   raw_node.name == name and raw_node.namespace == ""
                 else
-                  # FIXME: This DOUBLES the time XPath searches take
-                  ns = get_namespace(raw_node, prefix)
-                  raw_node.name == name and raw_node.namespace == ns
+                  raw_node.name == name and raw_node.namespace == get_namespace(raw_node, prefix)
                 end
               else
-                # FIXME: This DOUBLES the time XPath searches take
-                ns = get_namespace(raw_node, prefix)
-                raw_node.name == name and raw_node.namespace == ns
+                raw_node.name == name and raw_node.namespace == get_namespace(raw_node, prefix)
               end
             when :attribute
               if prefix.nil?
@@ -507,9 +514,7 @@ def node_test(path_stack, nodesets, any_type: :element)
               elsif prefix.empty?
                 raw_node.name == name and raw_node.namespace == ""
               else
-                # FIXME: This DOUBLES the time XPath searches take
-                ns = get_namespace(raw_node.element, prefix)
-                raw_node.name == name and raw_node.namespace == ns
+                raw_node.name == name and raw_node.namespace == get_namespace(raw_node.element, prefix)
               end
             else
               false
@@ -671,7 +676,7 @@ def sort(array_of_nodes, order)
         if order == :forward
           index
         else
-          -index
+          index.map(&:-@)
         end
       end
       ordered.collect do |_index, node|
@@ -758,22 +763,19 @@ def following(node)
     end
 
     def following_node_of( node )
-      if node.kind_of? Element and node.children.size > 0
-        return node.children[0]
-      end
-      return next_sibling_node(node)
+      return node.children[0] if node.kind_of?(Element) and node.children.size > 0
+
+      next_sibling_node(node)
     end
 
     def next_sibling_node(node)
       psn = node.next_sibling_node
       while psn.nil?
-        if node.parent.nil? or node.parent.class == Document
-          return nil
-        end
+        return nil if node.parent.nil? or node.parent.class == Document
         node = node.parent
         psn = node.next_sibling_node
       end
-      return psn
+      psn
     end
 
     def child(nodeset)
@@ -806,13 +808,13 @@ def child(nodeset)
     def norm b
       case b
       when true, false
-        return b
+        b
       when 'true', 'false'
-        return Functions::boolean( b )
+        Functions::boolean( b )
       when /^\d+(\.\d+)?$/, Numeric
-        return Functions::number( b )
+        Functions::number( b )
       else
-        return Functions::string( b )
+        Functions::string( b )
       end
     end
 
diff --git a/test/parse/test_cdata.rb b/test/parse/test_cdata.rb
index b5f1a3bc..c742d6a1 100644
--- a/test/parse/test_cdata.rb
+++ b/test/parse/test_cdata.rb
@@ -7,10 +7,28 @@ module REXMLTests
   class TestParseCData < Test::Unit::TestCase
     include Test::Unit::CoreAssertions
 
+    def parse(xml)
+      REXML::Document.new(xml)
+    end
+
     def test_linear_performance_gt
       seq = [10000, 50000, 100000, 150000, 200000]
       assert_linear_performance(seq, rehearsal: 10) do |n|
-        REXML::Document.new('<description><![CDATA[ ' + ">" * n + ' ]]></description>')
+        parse('<description><![CDATA[ ' + ">" * n + ' ]]></description>')
+      end
+    end
+
+    class TestInvalid < self
+      def test_unclosed_cdata
+        exception = assert_raise(REXML::ParseException) do
+          parse("<root><![CDATA[a]></root>")
+        end
+        assert_equal(<<~DETAIL, exception.to_s)
+          Malformed CDATA: Missing end ']]>'
+          Line: 1
+          Position: 25
+          Last 80 unconsumed characters:
+        DETAIL
       end
     end
   end
diff --git a/test/parse/test_comment.rb b/test/parse/test_comment.rb
index 4475dca7..6339835d 100644
--- a/test/parse/test_comment.rb
+++ b/test/parse/test_comment.rb
@@ -17,7 +17,7 @@ def test_toplevel_unclosed_comment
           parse("<!--")
         end
         assert_equal(<<~DETAIL, exception.to_s)
-          Unclosed comment
+          Unclosed comment: Missing end '-->'
           Line: 1
           Position: 4
           Last 80 unconsumed characters:
@@ -48,6 +48,31 @@ def test_toplevel_malformed_comment_end
         DETAIL
       end
 
+      def test_doctype_malformed_node
+        exception = assert_raise(REXML::ParseException) do
+          parse("<!DOCTYPE foo [<!a")
+        end
+        assert_equal(<<~DETAIL.chomp, exception.to_s)
+          Malformed node: Started with '<!' but not a comment nor ELEMENT,ENTITY,ATTLIST,NOTATION
+          Line: 1
+          Position: 18
+          Last 80 unconsumed characters:
+          a
+        DETAIL
+      end
+
+      def test_doctype_unclosed_comment
+        exception = assert_raise(REXML::ParseException) do
+          parse("<!DOCTYPE foo [<!--")
+        end
+        assert_equal(<<~DETAIL, exception.to_s)
+          Unclosed comment: Missing end '-->'
+          Line: 1
+          Position: 19
+          Last 80 unconsumed characters:
+        DETAIL
+      end
+
       def test_doctype_malformed_comment_inner
         exception = assert_raise(REXML::ParseException) do
           parse("<!DOCTYPE foo [<!-- -- -->")
@@ -72,16 +97,28 @@ def test_doctype_malformed_comment_end
         DETAIL
       end
 
-      def test_after_doctype_malformed_comment_short
+      def test_after_doctype_malformed_node
         exception = assert_raise(REXML::ParseException) do
-          parse("<a><!-->")
+          parse("<a><!a")
         end
         assert_equal(<<~DETAIL.chomp, exception.to_s)
-          Malformed comment
+          Malformed node: Started with '<!' but not a comment nor CDATA
+          Line: 1
+          Position: 6
+          Last 80 unconsumed characters:
+          a
+        DETAIL
+      end
+
+      def test_after_doctype_unclosed_comment
+        exception = assert_raise(REXML::ParseException) do
+          parse("<a><!-->")
+        end
+        assert_equal(<<~DETAIL, exception.to_s)
+          Unclosed comment: Missing end '-->'
           Line: 1
           Position: 8
           Last 80 unconsumed characters:
-          -->
         DETAIL
       end
 
diff --git a/test/parser/test_xpath.rb b/test/parser/test_xpath.rb
index 9143d25c..5d62afee 100644
--- a/test/parser/test_xpath.rb
+++ b/test/parser/test_xpath.rb
@@ -4,7 +4,7 @@
 require "rexml/parsers/xpathparser"
 
 module REXMLTests
-  class TestXPathParser < Test::Unit::TestCase
+  class TestParserXPathParser < Test::Unit::TestCase
     sub_test_case("#abbreviate") do
       def abbreviate(xpath)
         parser = REXML::Parsers::XPathParser.new
diff --git a/test/test_core.rb b/test/test_core.rb
index 34fe9e07..651056f2 100644
--- a/test/test_core.rb
+++ b/test/test_core.rb
@@ -653,18 +653,23 @@ def test_namespace
       assert_equal "<sean:blah>Some text</sean:blah>", out
     end
 
-
     def test_add_namespace
       e = Element.new 'a'
+      assert_equal("", e.namespace)
+      assert_nil(e.namespace('foo'))
       e.add_namespace 'someuri'
       e.add_namespace 'foo', 'otheruri'
       e.add_namespace 'xmlns:bar', 'thirduri'
-      assert_equal 'someuri', e.attributes['xmlns']
-      assert_equal 'otheruri', e.attributes['xmlns:foo']
-      assert_equal 'thirduri', e.attributes['xmlns:bar']
+      assert_equal("someuri", e.namespace)
+      assert_equal("otheruri", e.namespace('foo'))
+      assert_equal("otheruri", e.namespace('xmlns:foo'))
+      assert_equal("thirduri", e.namespace('bar'))
+      assert_equal("thirduri", e.namespace('xmlns:bar'))
+      assert_equal('someuri', e.attributes['xmlns'])
+      assert_equal('otheruri', e.attributes['xmlns:foo'])
+      assert_equal('thirduri', e.attributes['xmlns:bar'])
     end
 
-
     def test_big_documentation
       d = File.open(fixture_path("documentation.xml")) {|f| Document.new f }
       assert_equal "Sean Russell", d.elements["documentation/head/author"].text.tr("\n\t", " ").squeeze(" ")
@@ -764,9 +769,15 @@ def test_attributes_each
 
     def test_delete_namespace
       doc = Document.new "<a xmlns='1' xmlns:x='2'/>"
+      assert_equal("1", doc.root.namespace)
+      assert_equal("2", doc.root.namespace('x'))
+      assert_equal("2", doc.root.namespace('xmlns:x'))
       doc.root.delete_namespace
       doc.root.delete_namespace 'x'
-      assert_equal "<a/>", doc.to_s
+      assert_equal("<a/>", doc.to_s)
+      assert_equal("", doc.root.namespace)
+      assert_nil(doc.root.namespace('x'))
+      assert_nil(doc.root.namespace('xmlns:x'))
     end
 
     def test_each_element_with_attribute
diff --git a/test/test_jaxen.rb b/test/test_jaxen.rb
index 6038e88e..548120d6 100644
--- a/test/test_jaxen.rb
+++ b/test/test_jaxen.rb
@@ -56,7 +56,9 @@ def process_test_case(name)
 
     # processes a tests/document/context node
     def process_context(doc, context)
-      test_context = XPath.match(doc, context.attributes["select"])
+      matched = XPath.match(doc, context.attributes["select"])
+      assert_equal(1, matched.size)
+      test_context = matched.first
       namespaces = context.namespaces
       namespaces.delete("var")
       namespaces = nil if namespaces.empty?
@@ -101,10 +103,14 @@ def process_nominal_test(context, variables, namespaces, test)
         assert_equal(Integer(expected, 10),
                      matched.size,
                      user_message(context, xpath, matched))
+      else
+        assert_operator(matched.size, :>, 0, user_message(context, xpath, matched))
       end
 
       XPath.each(test, "valueOf") do |value_of|
-        process_value_of(matched, variables, namespaces, value_of)
+        matched.each do |subcontext|
+          process_value_of(subcontext, variables, namespaces, value_of)
+        end
       end
     end
 
@@ -118,10 +124,8 @@ def process_exceptional_test(context, variables, namespaces, test)
 
     def user_message(context, xpath, matched)
       message = ""
-      context.each_with_index do |node, i|
-        message << "Node#{i}:\n"
-        message << "#{node}\n"
-      end
+      message << "Node:\n"
+      message << "#{context}\n"
       message << "XPath: <#{xpath}>\n"
       message << "Matched <#{matched}>"
       message
diff --git a/test/test_source.rb b/test/test_source.rb
new file mode 100644
index 00000000..86755f37
--- /dev/null
+++ b/test/test_source.rb
@@ -0,0 +1,36 @@
+require "rexml/source"
+
+module REXMLTests
+  class TestSource < Test::Unit::TestCase
+    def setup
+      @source = REXML::Source.new(+"<root/>")
+    end
+
+    sub_test_case("#encoding=") do
+      test("String") do
+        @source.encoding = "UTF-8"
+        assert_equal("UTF-8", @source.encoding)
+      end
+
+      test("encoding_updated") do
+        def @source.n_encoding_updated_called
+          @n_encoding_updated_called
+        end
+        def @source.encoding_updated
+          super
+          @n_encoding_updated_called ||= 0
+          @n_encoding_updated_called += 1
+        end
+        @source.encoding = "shift-jis"
+        assert_equal(1, @source.n_encoding_updated_called)
+        @source.encoding = "Shift-JIS"
+        assert_equal(1, @source.n_encoding_updated_called)
+      end
+
+      test("Encoding") do
+        @source.encoding = Encoding::UTF_8
+        assert_equal("UTF-8", @source.encoding)
+      end
+    end
+  end
+end
diff --git a/test/test_text_check.rb b/test/test_text_check.rb
index 11cf65a3..3f2f7864 100644
--- a/test/test_text_check.rb
+++ b/test/test_text_check.rb
@@ -4,7 +4,7 @@ module REXMLTests
   class TextCheckTester < Test::Unit::TestCase
 
     def check(string)
-      REXML::Text.check(string, REXML::Text::NEEDS_A_SECOND_CHECK, nil)
+      REXML::Text.check(string, REXML::Text::NEEDS_A_SECOND_CHECK)
     end
 
     def assert_check(string)
diff --git a/test/test_xpath_parser.rb b/test/test_xpath_parser.rb
new file mode 100644
index 00000000..bcb14c34
--- /dev/null
+++ b/test/test_xpath_parser.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+module REXMLTests
+  class TestXPathParser < Test::Unit::TestCase
+    def setup
+      @root_element = make_service_element(["urn:type1", "urn:type2"], ["http://uri"])
+      @element = @root_element.children[0]
+      @parser = REXML::XPathParser.new
+    end
+
+    def make_service_element(types, uris)
+      root_element = REXML::Element.new
+      element = root_element.add_element("Service")
+      types.each do |type_text|
+        element.add_element("Type").text = type_text
+      end
+      uris.each do |uri_text|
+        element.add_element("URI").text = uri_text
+      end
+      root_element
+    end
+
+    def test_found
+      res = @parser.parse("/Service", @root_element)
+      assert_equal([@element],
+                   res)
+    end
+
+    def test_not_found
+      res = @parser.parse("/nonexistent", @root_element)
+      assert_equal([],
+                   res)
+    end
+  end
+end
diff --git a/test/xpath/test_base.rb b/test/xpath/test_base.rb
index 1dacd69d..764171ab 100644
--- a/test/xpath/test_base.rb
+++ b/test/xpath/test_base.rb
@@ -411,9 +411,107 @@ def test_preceding
 
       s = "<a><b><c id='1'/></b><b><b><c id='2'/><c id='3'/></b><c id='4'/></b><c id='NOMATCH'><c id='5'/></c></a>"
       d = REXML::Document.new(s)
-      c = REXML::XPath.match( d, "//c[@id = '5']")
-      cs = REXML::XPath.match( c, "preceding::c" )
-      assert_equal( 4, cs.length )
+      c = REXML::XPath.match(d, "//c[@id = '5']")
+      assert_equal(1, c.length)
+      cs = REXML::XPath.match(c.first, "preceding::c")
+      assert_equal(4, cs.length)
+    end
+
+    def test_preceding_multiple
+      source = <<-XML
+<a>
+  <b/><c/><d/><d/><e/><f/>
+</a>
+      XML
+      doc = REXML::Document.new(source)
+      matches = REXML::XPath.match(doc, "a/d/preceding::*")
+      assert_equal(["d", "c", "b"], matches.map(&:name))
+    end
+
+    def test_following_multiple
+      source = <<-XML
+<a>
+  <b/><c/><d/><d/><e/><f/>
+</a>
+      XML
+      doc = REXML::Document.new(source)
+      matches = REXML::XPath.match(doc, "a/d/following::*")
+      assert_equal(["d", "e", "f"], matches.map(&:name))
+    end
+
+    def test_following_sibling_across_multiple_nodes
+      source = <<-XML
+<a>
+  <b>
+    <x/><c/><d/>
+  </b>
+  <b>
+    <x/><e/>
+  </b>
+</a>
+      XML
+      doc = REXML::Document.new(source)
+      matches = REXML::XPath.match(doc, "a/b/x/following-sibling::*")
+      assert_equal(["c", "d", "e"], matches.map(&:name))
+    end
+
+    def test_following_sibling_within_single_node
+      source = <<-XML
+<a>
+  <b>
+    <x/><c/><d/><x/><e/>
+  </b>
+</a>
+      XML
+      doc = REXML::Document.new(source)
+      matches = REXML::XPath.match(doc, "a/b/x/following-sibling::*")
+      assert_equal(["c", "d", "x", "e"], matches.map(&:name))
+    end
+
+    def test_following_sibling_predicates
+      source = <<-XML
+<div>
+  <div>
+    <a/><w/>
+  </div>
+  <a/><x/>
+  <a/><y/>
+  <a/><z/>
+</div>
+      XML
+      doc = REXML::Document.new(source)
+      # Finds a node flowing <a/>
+      matches = REXML::XPath.match(doc, "//a/following-sibling::*[1]")
+      assert_equal(["w", "x", "y", "z"], matches.map(&:name))
+    end
+
+    def test_preceding_sibling_across_multiple_nodes
+      source = <<-XML
+<a>
+  <b>
+    <c/><d/><x/>
+  </b>
+  <b>
+    <e/><x/>
+  </b>
+</a>
+      XML
+      doc = REXML::Document.new(source)
+      matches = REXML::XPath.match(doc, "a/b/x/preceding-sibling::*")
+      assert_equal(["e", "d", "c"], matches.map(&:name))
+    end
+
+    def test_preceding_sibling_within_single_node
+      source = <<-XML
+<a>
+  <b>
+    <c/><d/><x/><e/><x/>
+  </b>
+</a>
+      XML
+      doc = REXML::Document.new(source)
+      matches = REXML::XPath.match(doc, "a/b/x/preceding-sibling::*")
+      assert_equal(["e", "x", "d", "c"], matches.map(&:name))
     end
 
     def test_following
@@ -1095,6 +1193,16 @@ def test_namespaces_0
       assert_equal( 1,  XPath.match( d, "//x:*" ).size )
     end
 
+    def test_namespaces_cache
+      doc = Document.new("<a xmlns='1'><b/></a>")
+      assert_equal("<b/>", XPath.first(doc, "//b[namespace-uri()='1']").to_s)
+      assert_nil(XPath.first(doc, "//b[namespace-uri()='']"))
+
+      doc.root.delete_namespace
+      assert_nil(XPath.first(doc, "//b[namespace-uri()='1']"))
+      assert_equal("<b/>", XPath.first(doc, "//b[namespace-uri()='']").to_s)
+    end
+
     def test_ticket_71
       doc = Document.new(%Q{<root xmlns:ns1="xyz" xmlns:ns2="123"><element ns1:attrname="foo" ns2:attrname="bar"/></root>})
       el = doc.root.elements[1]
@@ -1158,5 +1266,15 @@ def test_or_and
       end
       assert_equal(["/"], hrefs, "Bug #3842 [ruby-core:32447]")
     end
+
+    def test_match_with_deprecated_usage
+      verbose, $VERBOSE = $VERBOSE, nil
+      doc = Document.new("<a><b/></a>")
+      assert_equal(['b'], XPath.match([doc, doc], '//b').map(&:name))
+      assert_equal(['b'], XPath.match([doc], '//b').map(&:name))
+      assert_equal([], XPath.match([], '//b').map(&:name))
+    ensure
+      $VERBOSE = verbose
+    end
   end
 end