library/rdf/xoRDF.xotcl

# $Id: xoRDF.xotcl,v 1.4 2005/09/09 21:09:01 neumann Exp $
package provide xotcl::rdf::parser 1.0

package require XOTcl
package require xotcl::xml::parser
#package require xotcl::pattern::link
package require xotcl::trace

namespace eval ::xotcl::rdf::parser {
  namespace import ::xotcl::*

  ##############################################################################
  #
  #  RDF Parse Type Handling for RDF Node Class and RDF Parser class
  #  to be used as mixin. Here, we have decomposed the parse type handling
  #
  ##############################################################################

  #
  #  Nodes just call "isParseLiteral", "isParseResource", and "handleParseType"
  #  by their template methods -> mixins concretizes implementation
  #
  Class RDFNodeParseTypeHandling

  #
  # parseType=literal nodes are not parsed, but handled as literals
  # -> the XML parser should parse these nodes -> we have cut them off
  # if we encounter "parseType = literal" nextParsedLiterals searches the
  # parseLiterals array and returns the content
  #
  RDFNodeParseTypeHandling instproc nextParsedLiterals {} {
    set parser [my set parser]
    $parser set parseLiterals([$parser incr parseLiteralsCount])
  }

  #
  # handle attributes that determine the parse type
  #
  RDFNodeParseTypeHandling instproc handleParseType value {
    if {$value eq "Resource"} {
      my set parseResource 1
    } else {
      # with RDF 1.0 all values other than Resource are treated
      # as parseType = literal
      my set pcdata [list "" [my nextParsedLiterals]]
      my set parseLiteral 1
    }
  }

  #
  # two convinience methods that tell us whether the parse type is literal/resource
  #
  RDFNodeParseTypeHandling instproc isParseLiteral {} {
    #
    # if the parse literal var is set -> one child
    # is of type ParseTypeLiteral !
    #
    my exists parseLiteral
  }
  RDFNodeParseTypeHandling instproc isParseResource {} {
    #
    # if the parseResource var is set -> one child
    # is of type ParseTypeResource !
    #
    my exists parseResource
  }

  #
  # and we overload the Parser's parse method in order to cut off
  # all parseType = "Literal", because we have to hinder the XML
  # parser to parse RDF text that is marked as parseType = literal
  # we store the result in an array "parseLiterals" that is used
  # by the RDFNodeParseTypeHandling Mixin
  #
  Class RDFParserParseTypeHandling
  RDFParserParseTypeHandling instproc parse data {
    my array set parseLiterals {}
    my set parseLiteralsCount 0
    set count 0

    set dt $data

    while {[set pt [string first "parseType" $dt]] != -1} {
      # we cut the string off manually, because a regexp is slower
      if {$::tcl_version > 8.0} {
	set last [string first "=" $dt $pt]
      } else {
	set last [string first "=" [string range $dt $pt end]]
	incr last $pt
      }
      set ptStart [expr {[string last "<" [string range $dt 0 $pt]] + 1}]
      set propName [string range $dt $ptStart $pt]
      set blank [string first " " $propName]
      if {$blank != -1} {
	set propName [string range $propName 0 [expr {$blank -1}]]
      }
      set dt [string range $dt $last end]
      # All parse types != Resource treated as literals
      if {![regexp {^= *[\"']Resource} $dt]} {
	regexp -indices ">" $dt idx
	set start [lindex $idx 1]
	if {[regexp -indices "</$propName>" $dt idx]} {
	  set endTagLeft [lindex $idx 0]
	  set literal [string range $dt [expr {$start + 1}] [expr {$endTagLeft - 1}]]
	  set dt [string range $dt $endTagLeft end]
	  my set parseLiterals([incr count]) $literal
	} else {
	  error "end tag for $propName missing"
	}
      }
    }
    next $data
  }

  ##############################################################################
  #
  #  RDFNode Node Class
  #
  ##############################################################################

  Class RDFNode -superclass XMLNode -parameter {
    subject
    {rdfNSPrefix ""}
  }
  @ Class RDFNode -superclass XMLNode {
    description {
      general superclass for RDF nodes
      common properties
    }
  }

  #
  # add mixins for parse type handling
  #
  RDFNode instproc init args {
    next
    my mixin add RDFNodeParseTypeHandling
    set p [my info parent]
    if {[$p exists rdfNSPrefix]} {
      my set rdfNSPrefix [$p set rdfNSPrefix]
      #puts stderr "RDF Prefix defined in [self]->init to [$p set rdfNSPrefix]"
    }
  }

  RDFNode instproc parseData {text} {
    if {[my isParseLiteral]} {return}
    next
  }

  #
  # try to find the "subject" of the RDF statement ->
  # if it not found on the actual node search the parents
  #
  # per default subject is ""; subclasses add subjects,
  # when they encounter ID, about, ... attrs
  #
  RDFNode instproc getSubject {} {
    for {set o [self]} {![$o istype RDFTag]} {set o [$o info parent]} {
      if {[$o exists subject]} {return [$o set subject]}
    }
    return ""
  }


  #
  # lets the parser construct an unique ID in the parser
  #
  RDFNode instproc makeID {} {
    [my set parser] makeID
  }

  #
  # abstract methods that have to be concretized with parse type handling
  # by a parse type mixin (or in subclass)
  #
  RDFNode abstract instproc isParseLiteral {}
  RDFNode abstract instproc isParseResource {}
  RDFNode abstract instproc handleParseType value

  RDFNode instproc appendRDFType t {
    set t [[my resolveNS] getFullName $t]
    my set rdfTypes($t) 1
  }

  #
  # get a typed node abbreviation -> convert it to
  # a description + a nested rdf:type property
  #
  RDFNode instproc getTypedNode {name attrList} {
    set r [my getNestingNode RDFDescription \
	       [my qualifyWithRdfNsPrefix Description] $attrList]
    $r appendRDFType $name
    set r
  }

  #
  # try to parse children corresponding to parse type or if none is given
  # try to parse a child of type obj -> Description or Container
  #
  RDFNode instproc parseNestedChild {name attrList} {
    if {[my isParseResource]} {
      if {![my exists resourceDescription]} {
	my set resourceDescription \
	    [my getNestingNode RDFDescription \
		 [my qualifyWithRdfNsPrefix Description] {}]
	# we have resolved parseType="resource" with a description
	# -> remove parse type attribute info ... it is not correct anymore,
	# but remember parseResource flag
	if {[my exists attributes(parseType)]} {
	  my unset attributes(parseType)
	}
	if {[my exists attributes([set parseType [my qualifyWithRdfNsPrefix parseType]])]} {
	  my unset attributes($parseType)
	}
      }

      set r [[my set resourceDescription] getPropertyNodeChild $name $attrList]
    } elseif {[my isParseLiteral]} {
      set r [self]
      # literal -> do nothing
    } else {
      if {[set node [my isNestingNode $name]] ne ""} {
	set r [my getNestingNode $node $name $attrList]
      } else {
	set r [my getTypedNode $name $attrList]
      }
    }
    return $r
  }

  #
  # step forward in the attrList
  #
  RDFNode instproc nextAttrNode {node attrList index} {
    upvar [self callinglevel] $index i $attrList a
    if {$node ne ""} {
      set a [lreplace $a $i [expr {$i + 1}]]
    } else {
      incr i 2
    }
  }

  #
  # create a child node of Property type and return it
  #
  # don't build a node for "type" properties, but append them to
  # the list
  #
  RDFNode instproc getPropertyNodeChild {name attrList} {
    regexp "^[my set rdfNSPrefix]:(.*)" $name _ name
    set parser [my set parser]
    if {$name eq "type" && [my istype RDFResource]} {
      # seek for resource attribute and append type to list
      set rp [my prependRDFPrefix resource]
      set rdfns [$parser set rdfNamespace]
      foreach {n v} $attrList {
	if {![my istype RDFContainerNodeClass]} {
	  if {$n eq $rp || $n eq "resource"} {
	    foreach c {Bag Alt Seq} {
	      if {$v eq "$rdfns$c"} {
		my class RDF$c
		my set memberNr 0
		my set ID [my set bagID]
		my unset bagID
		my set content [my prependRDFPrefix $c]
		# reclass existing li props to member
		set li [my prependRDFPrefix li]
		foreach child [lsort [my info children]] {
		  if {[namespace tail [$child info class]] eq "RDFProperty"} {
		    if {[$child set content] eq $li ||
			[$child set content] eq "li"} {
		      $child class RDFMember
		      my giveMemberNr $child
		      $child set content $li
		    }
		  }
		}
	      }
	    }
	  }
	}
	my appendRDFType $v
      }
      return [self]
    } else {
      set nf [$parser set nodeFactory]
      set r [$nf getNode RDFProperty [self]::[my nextChild prop] $parser]
      $r set content $name
      $r parseAttributes $name $attrList
      set r
    }
  }

  #
  # property in abbr syntax (as attribute)
  #
  RDFNode instproc propertyAttribute {n v} {
    set r [my getPropertyNodeChild $n ""]
    $r parseData $v
    set r
  }

  #
  # check whether an attribute name matches an attributed RDFNode
  # of this class or not
  # return the corresponding node class
  #
  RDFNode instproc isAttribute {n} {
    regexp "^[my set rdfNSPrefix]:(.*)" $n _ n
    if {[lsearch [[my info class] set attributeList] $n] != -1} {
      return $n
    } elseif {$n eq "xml:lang"} {
      # we create attribute for xml_lang (for recreation purposes)
      return $n
    }
    return ""
  }

  #
  # check if name matches an node class that may be nested in [self]
  #
  RDFNode instproc isNestingNode {n} {
    regexp "^[my set rdfNSPrefix]:(.*)" $n _ n
    set cl [my info class]
    if {[$cl exists nestingList($n)]} {
      return [$cl set nestingList($n)]
    }
    return ""
  }

  RDFNode instproc getNestingNode {node name attrList} {
    set parser [my set parser]
    set nf [$parser set nodeFactory]
    switch [namespace tail $node] {
      "RDFMember" - "RDFProperty" {set objName prop}
      default {set objName res}
    }
    set r [$nf getNode $node [self]::[my nextChild $objName] $parser]
    $r set content $name
    $r parseAttributes $name $attrList
    set r
  }

  #
  # check whether the RDF namespace is redefined to another prefix
  #
  RDFNode instproc makeIndividualNSEntry {prefix entry} {
    if {$entry eq [[my set parser] rdfNamespace]} {
      if {[my set rdfNSPrefix] eq "" || $prefix ne "xmlns"} {
	my set rdfNSPrefix $prefix
      }
      #puts stderr "RDF Prefix redefined in [self] to $prefix"
    }
    next
  }

  RDFNode instproc qualifyWithRdfNsPrefix t {
    set ns [my set rdfNSPrefix]
    if {$ns eq "xmlns"} {return $t}
    return $ns:$t
  }

  #
  # checks whether a given attribute is part of the attributes array
  # and returns the varname, otherwise ""
  #
  RDFNode instproc getAttribute {n nsFullName} {
    set ns [my resolveNS]
    set xmlns [$ns searchPrefix xmlns]
    if {$xmlns eq $nsFullName && [my exists attributes($n)]} {
      return attributes($n)
    }
    set prefix [$ns searchFullName $nsFullName]
    if {$prefix ne "" &&
	[my exists attributes($prefix:$n)]} {
      return attributes($prefix:$n)
    }
    return ""
  }

  #
  # searches for attribute "n" with rdf namespace prefix
  #
  RDFNode instproc getRDFAttribute {n} {
    if {[my exists attributes($n)]} {
      return [my set attributes($n)]
    }
    set rdfNSPrefix [my set rdfNSPrefix]
    if {$rdfNSPrefix ne "xmlns"} {
      set n $rdfNSPrefix:$n
      if {[my exists attributes($n)]} {
	return [my set attributes($n)]
      }
    }
    return ""
  }

  RDFNode instproc prependRDFPrefix ts {
    set rdfNSPrefix [my set rdfNSPrefix]
    if {$rdfNSPrefix ne "xmlns"} {set ts $rdfNSPrefix:$ts}
    return $ts
  }

  ##############################################################################
  #
  # superclass for all resources (like Description, Alt, Seq, Beg)
  # used directly in the parse tree ... resource nodes are mixed in
  #
  ##############################################################################

  Class RDFResource -superclass RDFNode

  RDFResource instproc print {} {
    set t [my array names rdfTypes]
    if {$t eq ""} {return [next]} else {return "[next]\nTYPES: $t"}
  }


  ##############################################################################
  #
  # superclasses for container node classes (alt seq bag)
  #
  ##############################################################################
  Class RDFContainerNodeClass -superclass RDFResource

  RDFContainerNodeClass instproc init args {
    # cache the member number
    # 0 inidicates, there is currently no member
    next

    my set memberNr 0
    my set ID [my makeID]
    my appendRDFType [my qualifyWithRdfNsPrefix \
			  [[my info class] set content]]
  }

  RDFContainerNodeClass instproc parseAttributes {name attrList} {
    #set index 0
    foreach {n v} $attrList {
      if {[set an [my isAttribute $n]] ne ""} {
	my set attributes($n) $v
	if {$an eq "ID"} {
	  my set subject $v
	  my set ID [[my set parser] set baseURL]\#$v
	}
      }
      #set attrList [my nextAttrNode $an attrList index]
    }
  }

  RDFContainerNodeClass instproc giveMemberNr {member} {
    set pf [my getContentPrefix]
    if {$pf ne ""} {append pf ":"}
    $member set memberIndex "${pf}_[my incr memberNr]"
  }

  RDFContainerNodeClass instproc parseStart {name attrList} {
    set r [self]
    next
    if {[set node [my isNestingNode $name]] ne ""} {
      set r [my getNestingNode $node $name $attrList]
      if {[namespace tail [$r info class]] eq "RDFMember"} {
	my giveMemberNr $r
      }
    } else {
      set r [my getPropertyNodeChild $name $attrList]
    }
    return $r
  }

  ##############################################################################
  #
  # Concrete Factory for creating RDF-style nodes
  #
  ##############################################################################
  Class RDFNodeClassFactory -superclass XMLNodeClassFactory
  RDFNodeClassFactory instproc content content {
    my set content $content
  }
  RDFNodeClassFactory instproc attributeList attributeList {
    my set attributeList $attributeList
  }
  RDFNodeClassFactory instproc nestingTo nestingTo {
    set name [string trimleft [self] :]
    foreach cl $nestingTo {
      $cl set nestingList([my set content]) $name
    }
  }

  RDFNodeClassFactory proc create args {
    # create the class
    set name [next]
    switch -exact $name {
      RDFDescription - RDFProperty - RDFMember {
	my array set attributeList {}
      }
      RDFMember - RDFProperty {
	my array set nestingList {}
      }
    }
  }
  ##########################################################################
  #
  # now create a factory and build all the node classes
  # needed for the RDF Parser/Interpreter
  #
  ##########################################################################
  RDFNodeClassFactory proc createFactories {} {
    foreach {name superclasses content attributeList} {
      RDFTag 	  RDFNode		        RDF     {}
      RDFBag 	  RDFContainerNodeClass 	Bag     {ID}
      RDFSeq 	  RDFContainerNodeClass 	Seq     {ID}
      RDFAlt 	  RDFContainerNodeClass 	Alt     {ID}
      RDFProperty RDFNode	    	""      {bagID ID resource parseType}
      RDFMember   RDFProperty           li      {resource parseType}
      RDFDescription  RDFResource	Description {ID bagID about type aboutEach aboutEachPrefix}
    } {
      #puts "Create class: $name -superclass $superclasses"
      RDFNodeClassFactory create $name -superclass $superclasses \
	  -content $content \
	  -attributeList $attributeList
    }
  }
  RDFNodeClassFactory createFactories

  #
  # define nesting constraints
  #
  RDFTag nestingTo {}
  RDFBag nestingTo {RDFTag RDFProperty}
  RDFSeq nestingTo {RDFTag RDFProperty}
  RDFAlt nestingTo {RDFTag RDFProperty}
  RDFMember nestingTo {RDFContainerNodeClass RDFBag RDFSeq RDFAlt}
  RDFProperty nestingTo {}
  RDFDescription nestingTo {RDFTag RDFMember RDFProperty}

  ##############################################################################
  #
  # add some methods to the property node class
  #
  ##############################################################################

  RDFProperty instproc parseAttributes {name attrList} {
    set r [self]
    #set index 0
    foreach {n v} $attrList {
      if {[my checkForXmlNS $n $v]} {continue}
      if {[set an [my isAttribute $n]] ne ""} {
	my set attributes($n) $v
	if {$an eq "parseType"} {my handleParseType $v}
      } else {
	if {![info exists abbrvPropResource]} {
	  set abbrvPropResource \
	      [my getNestingNode RDFDescription \
		   [my qualifyWithRdfNsPrefix Description] {}]
	}
	$abbrvPropResource propertyAttribute $n $v
      }
      #set attrList [my nextAttrNode $an attrList index]
    }

    if {[info exists abbrvPropResource]} {
      # if resource attribute is given -> use it for abbr property
      # description as about attr
      if {[my exists attributes(resource)]} {
	set about [my set attributes(resource)]
	my unset attributes(resource)
      }
      if  {[my exists attributes([set resource [my qualifyWithRdfNsPrefix resource]])]} {
	set about [my set attributes($resource)]
	my unset attributes($resource)
      }
      if {[info exists about]} {
	$abbrvPropResource set attributes(about) $about
	$abbrvPropResource set subject $about
      }
    }
  }
  RDFProperty instproc parseStart {name attrList} {
    if {[my isParseLiteral]} {return [self]}
    next
    return [my parseNestedChild $name $attrList]
  }

  ##############################################################################
  #
  # add methods to the member class
  #
  ##############################################################################

  RDFMember parameter {
    memberIndex
  }

  RDFMember instproc parseAttributes {name attrList} {
    #set index 0
    foreach {n v} $attrList {
      if {[set an [my isAttribute $n]] ne ""} {
	my set attributes($n) $v
	if {$an eq "parseType"} {my handleParseType $v}
      }
      #set attrList [my nextAttrNode $an attrList index]
    }
  }

  RDFMember instproc print {} {
    return "[next]\nMEMBER-INDEX: [my set memberIndex]"
  }

  ##############################################################################
  #
  # add methods to the description node class
  #
  ##############################################################################

  RDFDescription instproc init {args} {
    next
    set ID [my makeID]
    my set subject $ID
    my set bagID $ID
  }

  RDFDescription instproc parseAttributes {name attrList} {
    set r [self]

    # if the parent is a property with an ID -> use it
    # as description subject
    set ID [my qualifyWithRdfNsPrefix ID]
    set parent [my info parent]
    if {[$parent exists attributes(ID)]} {
      my set subject [$parent set attributes(ID)]
    } elseif {[$parent exists attributes($ID)]} {
      my set subject [$parent set attributes($ID)]
    }

    foreach {n v} $attrList {
      if {[my checkForXmlNS $n $v]} {continue}
      if {[set an [my isAttribute $n]] ne ""} {
	my set attributes($n) $v
	switch -exact $an {
	  about -
	  ID -
	  aboutEach -
	  aboutEachPrefix {
	    my set subject $v
	  }
	  bagID {
	    my set bagID [[my set parser] set baseURL]\#$v
	  }
	  type {
	    my appendRDFType $v
	  }
	}
      } else {
	set r [my propertyAttribute $n $v]
      }
    }
    return $r
  }

  RDFDescription instproc parseStart {name attrList} {
    next
    return [my getPropertyNodeChild $name $attrList]
  }

  ##############################################################################
  #
  # add some methods to the <RDF> node class
  #
  ##############################################################################

  RDFTag parameter {{startTagOn 0}}

  RDFTag instproc match {c} {
    # the prefix of the topnode determines initially how the RDF
    # namespace is named ... since several examples don't have a
    # namespace definition for this ns, we set here a default, which
    # may be overridden by ns definitions in the XML text
    if {[regexp {^([^:]*):(.*)} $c _ pre c]} {
      my makeIndividualNSEntry $pre [[my set parser] rdfNamespace]
      #puts stderr "Making RDF namespace entry for <$pre>"
    }
    #puts "Match for $c --- Content: [[my info class] set content]"
    expr {$c eq [[my info class] set content]}
  }

  RDFTag instproc parseStart {name attrList} {
    set parsed 0
    if {[set node [my isNestingNode $name]] ne ""} {
      set r [my getNestingNode $node $name $attrList]
    } else {
      set r [my getTypedNode $name $attrList]
    }
    next
    return $r
  }

  RDFTag instproc parseEnd content {
    if {!([my startTagOn] && [my match $content])} {
      [my errorChild $content]
    }
    next
    self ;# return [self]
  }

  ##############################################################################
  #
  # RDF Factory for creating node objects
  #
  ##############################################################################
  Class RDFNodeFactory -superclass XMLNodeFactory
  RDFNodeFactory create rdfNodeFactory -sharedNodes {RDFDescription RDFTag}


  ##############################################################################
  #
  # RDF parser class used to access the xml parser and produce the
  # rdf node tree
  #
  ##############################################################################
  Class RDFParser -superclass XMLParser -parameter {
    {baseURL "rdfdoc"}
    {rdfNamespace "http://www.w3.org/1999/02/22-rdf-syntax-ns#"}
  }

  RDFParser instproc init args {
    my mixin add RDFParserParseTypeHandling

    ### this special parser handles rdf:RDF tags
    my topLevelHandlerPattern {^([^:]*):RDF|RDF} RDFTag

    next
    my set nodeFactory "rdfNodeFactory"
  }

  RDFParser instproc makeID {} {
    my autoname [my baseURL]\#id
  }

  RDFParser instproc reset {} {
    next
    set id [my baseURL]\#id
    my autoname -reset $id
  }

  RDFParser instproc createTopLevelNode {name attrList} {
    set tn [next]
    #$tn makeIndividualNSEntry xmlns [my set rdfNamespace]
    ### toplevel node must be of type RDFTag
    if {![$tn istype RDFTag]} {
      error "Top level node must be of type RDFTag"
    }
    if {[$tn match $name]} {
      $tn set content $name
      $tn startTagOn 1

      ### use default values for rdf/default (xmlns) namespace
      #my makeIndividualNSEntry rdfs "http://www.w3.org/TR/1999/PR-rdf-schema-19990303#"

      foreach {n v} $attrList {
	if {[$tn checkForXmlNS $n $v]} {continue}
      }
    }
    return $tn
  }

  #RDFParser instproc parse data {
  #  next
  #}

  namespace export RDFNodeParseTypeHandling RDFParserParseTypeHandling \
      RDFNode RDFResource RDFContainerNodeClass RDFNodeClassFactory \
      RDFNodeFactory RDFParser rdfNodeFactory \
      RDFTag RDFBag RDFSeq RDFAlt RDFProperty  RDFMember RDFDescription
}

namespace import ::xotcl::rdf::parser::*