Initial revision

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3925 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rexml/attribute.rb

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+require "rexml/namespace"
+require 'rexml/text'
+
+module REXML
+	# Defines an Element Attribute; IE, a attribute=value pair, as in:
+	# <element attribute="value"/>.  Attributes can be in their own
+	# namespaces.  General users of REXML will not interact with the
+	# Attribute class much.
+	class Attribute
+		include Node
+		include Namespace
+
+		# The element to which this attribute belongs
+		attr_reader :element
+		# The normalized value of this attribute.  That is, the attribute with
+		# entities intact.
+		attr_writer :normalized	
+		PATTERN = /\s*(#{NAME_STR})\s*=\s*(["'])(.*?)\2/um
+
+		# Constructor.
+		#
+		#  Attribute.new( attribute_to_clone )
+		#  Attribute.new( source )
+		#  Attribute.new( "attr", "attr_value" )
+		#  Attribute.new( "attr", "attr_value", parent_element )
+		def initialize( first, second=nil, parent=nil )
+			@normalized = @unnormalized = @element = nil
+			if first.kind_of? Attribute
+				self.name = first.expanded_name
+				@value = first.value
+				if second.kind_of? Element
+					@element = second
+				else
+					@element = first.element
+				end
+			elsif first.kind_of? String
+				@element = parent if parent.kind_of? Element
+				self.name = first
+				@value = second
+			else
+				raise "illegal argument #{first.type} to Attribute constructor"
+			end
+		end
+
+		# Returns the namespace of the attribute.
+		# 
+		#  e = Element.new( "elns:myelement" )
+		#  e.add_attribute( "nsa:a", "aval" )
+		#  e.add_attribute( "b", "bval" )
+		#  e.attributes.get_attribute( "a" ).prefix   # -> "nsa"
+		#  e.attributes.get_attribute( "b" ).prefix   # -> "elns"
+		#  a = Attribute.new( "x", "y" )
+		#  a.prefix                                   # -> ""
+		def prefix
+			pf = super
+			if pf == ""
+				pf = @element.prefix if @element
+			end
+			pf
+		end
+
+		# Returns the namespace URL, if defined, or nil otherwise
+		# 
+		#  e = Element.new("el")
+		#  e.add_attributes({"xmlns:ns", "http://url"})
+		#  e.namespace( "ns" )              # -> "http://url"
+		def namespace arg=nil
+			arg = prefix if arg.nil?
+			@element.namespace arg
+		end
+
+		# Returns true if other is an Attribute and has the same name and value,
+		# false otherwise.
+		def ==( other )
+			other.kind_of?(Attribute) and other.name==name and other.value==@value
+		end
+
+		# Creates (and returns) a hash from both the name and value
+		def hash
+			name.hash + value.hash
+		end
+
+		# Returns this attribute out as XML source, expanding the name
+		#
+		#  a = Attribute.new( "x", "y" )
+		#  a.to_string     # -> "x='y'"
+		#  b = Attribute.new( "ns:x", "y" )
+		#  b.to_string     # -> "ns:x='y'"
+		def to_string
+			"#@expanded_name='#{to_s().gsub(/'/, '&apos;')}'"
+		end
+
+		# Returns the attribute value, with entities replaced
+		def to_s
+			return @normalized if @normalized
+
+			doctype = nil
+			if @element
+				doc = @element.document
+				doctype = doc.doctype if doc
+			end
+
+			@unnormalized = nil
+			@value = @normalized = Text::normalize( @value, doctype )
+		end
+
+		# Returns the UNNORMALIZED value of this attribute.  That is, entities
+		# have been expanded to their values
+		def value
+			@unnormalized if @unnormalized
+			doctype = nil
+			if @element
+				doc = @element.document
+				doctype = doc.doctype if doc
+			end
+			@normalized = nil
+			@value = @unnormalized = Text::unnormalize( @value, doctype )
+		end
+
+		# Returns a copy of this attribute
+		def clone
+			Attribute.new self
+		end
+
+		# Sets the element of which this object is an attribute.  Normally, this
+		# is not directly called.
+		#
+		# Returns this attribute
+		def element=( element )
+			@element = element
+			self
+		end
+
+		# Removes this Attribute from the tree, and returns true if successfull
+		# 
+		# This method is usually not called directly.
+		def remove
+			@element.attributes.delete self.name unless @element.nil?
+		end
+
+		# Writes this attribute (EG, puts 'key="value"' to the output)
+		def write( output, indent=-1 )
+			output << to_string
+		end
+
+    def node_type
+      :attribute
+    end
+	end
+end
+#vim:ts=2 sw=2 noexpandtab: