text: # -*- coding: utf-8 -*-
  """
  Parser's execution context (a.k.a. state) object and handling. The state includes:
  
    - language, retrieved from C{@xml:lang} or C{@lang}
    - URI base, determined by C{<base>} or set explicitly. This is a little bit superfluous, because the current RDFa syntax does not make use of C{@xml:base}; i.e., this could be a global value.  But the structure is prepared to add C{@xml:base} easily, if needed.
    - options, in the form of an L{options<pyRdfa.options>} instance
    - a separate vocabulary/CURIE handling resource, in the form of an L{termorcurie<pyRdfa.TermOrCurie>} instance
  
  The execution context object is also used to handle URI-s, CURIE-s, terms, etc.
  
  @summary: RDFa parser execution context
  @organization: U{World Wide Web Consortium<http://www.w3.org>}
  @author: U{Ivan Herman<a href="http://www.w3.org/People/Ivan/">}
  @license: This software is available for use under the
  U{W3C® SOFTWARE NOTICE AND LICENSE<href="http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231">}
  """
  
  """
  $Id: state.py,v 1.23 2013-10-16 11:48:54 ivan Exp $
  $Date: 2013-10-16 11:48:54 $
  """
  import sys
  (py_v_major, py_v_minor, py_v_micro, py_v_final, py_v_serial) = sys.version_info
  
  import rdflib
  from rdflib	import URIRef
  from rdflib	import Literal
  from rdflib	import BNode
  from rdflib	import Namespace
  if rdflib.__version__ >= "3.0.0" :
  	from rdflib	import RDF  as ns_rdf
  	from rdflib	import RDFS as ns_rdfs
  else :
  	from rdflib.RDFS	import RDFSNS as ns_rdfs
  	from rdflib.RDF		import RDFNS  as ns_rdf
  
  from .options	import Options
  from .utils 	import quote_URI
  from .host 		import HostLanguage, accept_xml_base, accept_xml_lang, beautifying_prefixes
  
  from .termorcurie	import TermOrCurie
  from .				import UnresolvablePrefix, UnresolvableTerm
  
  from . import err_lang
  from . import err_URI_scheme
  from . import err_illegal_safe_CURIE
  from . import err_no_CURIE_in_safe_CURIE
  from . import err_undefined_terms
  from . import err_non_legal_CURIE_ref
  from . import err_undefined_CURIE
  
  if py_v_major >= 3 :
  	from urllib.parse import urlparse, urlunparse, urlsplit, urljoin
  else :
  	from urlparse import urlparse, urlunparse, urlsplit, urljoin
  
  class ListStructure :
  	"""Special class to handle the C{@inlist} type structures in RDFa 1.1; stores the "origin", i.e,
  	where the list will be attached to, and the mappings as defined in the spec.
  	"""
  	def __init__(self) :
  		self.mapping = {}
  		self.origin	  = None
  
  #### Core Class definition
  class ExecutionContext :
  	"""State at a specific node, including the current set of namespaces in the RDFLib sense, current language,
  	the base, vocabularies, etc. The class is also used to interpret URI-s and CURIE-s to produce
  	URI references for RDFLib.
  
  	@ivar options: reference to the overall options
  	@type options: L{Options}
  	@ivar base: the 'base' URI
  	@ivar parsedBase: the parsed version of base, as produced by urlparse.urlsplit
  	@ivar defaultNS: default namespace (if defined via @xmlns) to be used for XML Literals
  	@ivar lang: language tag (possibly None)
  	@ivar term_or_curie: vocabulary management class instance
  	@type term_or_curie: L{termorcurie.TermOrCurie}
  	@ivar list_mapping: dictionary of arrays, containing a list of URIs key-ed via properties for lists
  	@ivar node: the node to which this state belongs
  	@type node: DOM node instance
  	@ivar rdfa_version: RDFa version of the content
  	@type rdfa_version: String
  	@ivar supress_lang: in some cases, the effect of the lang attribute should be supressed for the given node, although it should be inherited down below (example: @value attribute of the data element in HTML5)
  	@type supress_lang: Boolean
  	@cvar _list: list of attributes that allow for lists of values and should be treated as such
  	@cvar _resource_type: dictionary; mapping table from attribute name to the exact method to retrieve the URI(s). Is initialized at first instantiation.
  	"""
  
  	# list of attributes that allow for lists of values and should be treated as such
  	_list = [ "rel", "rev", "property", "typeof", "role" ]
  	# mapping table from attribute name to the exact method to retrieve the URI(s).
  	_resource_type = {}
  
  	def __init__(self, node, graph, inherited_state=None, base="", options=None, rdfa_version = None) :
  		"""
  		@param node: the current DOM Node
  		@param graph: the RDFLib Graph
  		@keyword inherited_state: the state as inherited
  		from upper layers. This inherited_state is mixed with the state information
  		retrieved from the current node.
  		@type inherited_state: L{state.ExecutionContext}
  		@keyword base: string denoting the base URI for the specific node. This overrides the possible
  		base inherited from the upper layers. The
  		current XHTML+RDFa syntax does not allow the usage of C{@xml:base}, but SVG1.2 does, so this is
  		necessary for SVG (and other possible XML dialects that accept C{@xml:base})
  		@keyword options: invocation options, and references to warning graphs
  		@type options: L{Options<pyRdfa.options>}
  		"""
  		def remove_frag_id(uri) :
  			"""
  			The fragment ID for self.base must be removed
  			"""
  			try :
  				# To be on the safe side:-)
  				t = urlparse(uri)
  				return urlunparse((t[0],t[1],t[2],t[3],t[4],""))
  			except :
  				return uri
  
  		# This is, conceptually, an additional class initialization, but it must be done run time, otherwise import errors show up
  		if len(	ExecutionContext._resource_type ) == 0 :
  			ExecutionContext._resource_type = {
  				"href"		:	ExecutionContext._URI,
  				"src"		:	ExecutionContext._URI,
  				"vocab"	    :   ExecutionContext._URI,
  
  				"about"		:	ExecutionContext._CURIEorURI,
  				"resource"	:	ExecutionContext._CURIEorURI,
  
  				"rel"		:	ExecutionContext._TERMorCURIEorAbsURI,
  				"rev"		:	ExecutionContext._TERMorCURIEorAbsURI,
  				"datatype"	:	ExecutionContext._TERMorCURIEorAbsURI,
  				"typeof"	:	ExecutionContext._TERMorCURIEorAbsURI,
  				"property"	:	ExecutionContext._TERMorCURIEorAbsURI,
  				"role"		:	ExecutionContext._TERMorCURIEorAbsURI,
  			}
  		#-----------------------------------------------------------------
  		self.node = node
  
  		#-----------------------------------------------------------------
  		# Settling the base. In a generic XML, xml:base should be accepted at all levels (though this is not the
  		# case in, say, XHTML...)
  		# At the moment, it is invoked with a 'None' at the top level of parsing, that is
  		# when the <base> element is looked for (for the HTML cases, that is)
  		if inherited_state :
  			self.rdfa_version		= inherited_state.rdfa_version
  			self.base				= inherited_state.base
  			self.options			= inherited_state.options
  
  			self.list_mapping 		= inherited_state.list_mapping
  			self.new_list			= False
  
  			# for generic XML versions the xml:base attribute should be handled
  			if self.options.host_language in accept_xml_base and node.hasAttribute("xml:base") :
  				self.base = remove_frag_id(node.getAttribute("xml:base"))
  		else :
  			# this is the branch called from the very top
  			self.list_mapping = ListStructure()
  			self.new_list	  = True
  
  			if rdfa_version is not None :
  				self.rdfa_version = rdfa_version
  			else :
  				from . import rdfa_current_version
  				self.rdfa_version = rdfa_current_version
  
  			# This value can be overwritten by a @version attribute
  			if node.hasAttribute("version") :
  				top_version = node.getAttribute("version")
  				if top_version.find("RDFa 1.0") != -1 or top_version.find("RDFa1.0") != -1 :
  					self.rdfa_version = "1.0"
  				elif top_version.find("RDFa 1.1") != -1 or top_version.find("RDFa1.1") != -1 :
  					self.rdfa_version = "1.1"
  
  			# this is just to play safe. I believe this should actually not happen...
  			if options == None :
  				from . import Options
  				self.options = Options()
  			else :
  				self.options = options
  
  			self.base = ""
  			# handle the base element case for HTML
  			if self.options.host_language in [ HostLanguage.xhtml, HostLanguage.html5, HostLanguage.xhtml5  ] :
  				for bases in node.getElementsByTagName("base") :
  					if bases.hasAttribute("href") :
  						self.base = remove_frag_id(bases.getAttribute("href"))
  						continue
  			elif self.options.host_language in accept_xml_base and node.hasAttribute("xml:base") :
  				self.base = remove_frag_id(node.getAttribute("xml:base"))
  
  			# If no local setting for base occurs, the input argument has it
  			if self.base == "" :
  				self.base = base
  
  			# Perform an extra beautification in RDFLib
  			if self.options.host_language in beautifying_prefixes :
  				dict = beautifying_prefixes[self.options.host_language]
  				for key in dict :
  					graph.bind(key,dict[key])
  
  			input_info = "Input Host Language:%s, RDFa version:%s, base:%s" % (self.options.host_language, self.rdfa_version, self.base)
  			self.options.add_info(input_info)
  
  
  		#-----------------------------------------------------------------
  		# this will be used repeatedly, better store it once and for all...
  		self.parsedBase = urlsplit(self.base)
  
  		#-----------------------------------------------------------------
  		# generate and store the local CURIE handling class instance
  		self.term_or_curie = TermOrCurie(self, graph, inherited_state)
  
  		#-----------------------------------------------------------------
  		# Settling the language tags
  		# @lang has priority over @xml:lang
  		# it is a bit messy: the three fundamental modes (xhtml, html, or xml) are all slightly different:-(
  		# first get the inherited state's language, if any
  		if inherited_state :
  			self.lang = inherited_state.lang
  		else :
  			self.lang = None
  
  		self.supress_lang = False
  
  
  		if self.options.host_language in [ HostLanguage.xhtml, HostLanguage.xhtml5, HostLanguage.html5 ] :
  			# we may have lang and xml:lang
  			if node.hasAttribute("lang") :
  				lang = node.getAttribute("lang").lower()
  			else :
  				lang = None
  			if node.hasAttribute("xml:lang") :
  				xmllang = node.getAttribute("xml:lang").lower()
  			else :
  				xmllang = None
  			# First of all, set the value, if any
  			if xmllang != None :
  				# this has priority
  				if len(xmllang) != 0 :
  					self.lang = xmllang
  				else :
  					self.lang = None
  			elif lang != None :
  				if len(lang) != 0 :
  					self.lang = lang
  				else :
  					self.lang = None
  			# Ideally, a warning should be generated if lang and xmllang are both present with different values. But
  			# the HTML5 Parser does its magic by overriding a lang value if xmllang is present, so the potential
  			# error situations are simply swallowed...
  
  		elif self.options.host_language in accept_xml_lang and node.hasAttribute("xml:lang") :
  				self.lang = node.getAttribute("xml:lang").lower()
  				if len(self.lang) == 0 : self.lang = None
  
  		#-----------------------------------------------------------------
  		# Set the default namespace. Used when generating XML Literals
  		if node.hasAttribute("xmlns") :
  			self.defaultNS = node.getAttribute("xmlns")
  		elif inherited_state and inherited_state.defaultNS != None :
  			self.defaultNS = inherited_state.defaultNS
  		else :
  			self.defaultNS = None
  	# end __init__
  
  	def _URI(self, val) :
  		"""Returns a URI for a 'pure' URI (ie, not a CURIE). The method resolves possible relative URI-s. It also
  		checks whether the URI uses an unusual URI scheme (and issues a warning); this may be the result of an
  		uninterpreted CURIE...
  		@param val: attribute value to be interpreted
  		@type val: string
  		@return: an RDFLib URIRef instance
  		"""
  		def create_URIRef(uri, check = True) :
  			"""
  			Mini helping function: it checks whether a uri is using a usual scheme before a URIRef is created. In case
  			there is something unusual, a warning is generated (though the URIRef is created nevertheless)
  			@param uri: (absolute) URI string
  			@return: an RDFLib URIRef instance
  			"""
  			from .	import uri_schemes
  			val = uri.strip()
  			if check and urlsplit(val)[0] not in uri_schemes :
  				self.options.add_warning(err_URI_scheme % val.strip(), node=self.node.nodeName)
  			return URIRef(val)
  
  		def join(base, v, check = True) :
  			"""
  			Mini helping function: it makes a urljoin for the paths. Based on the python library, but
  			that one has a bug: in some cases it
  			swallows the '#' or '?' character at the end. This is clearly a problem with
  			Semantic Web URI-s, so this is checked, too
  			@param base: base URI string
  			@param v: local part
  			@param check: whether the URI should be checked against the list of 'existing' URI schemes
  			@return: an RDFLib URIRef instance
  			"""
  			# UGLY!!! There is a bug for a corner case in python version <= 2.5.X
  			if len(v) > 0 and v[0] == '?' and (py_v_major < 3 and py_v_minor <= 5) :
  				return create_URIRef(base+v, check)
  			####
  
  			joined = urljoin(base, v)
  			try :
  				if v[-1] != joined[-1] and (v[-1] == "#" or v[-1] == "?") :
  					return create_URIRef(joined + v[-1], check)
  				else :
  					return create_URIRef(joined, check)
  			except :
  				return create_URIRef(joined, check)
  
  		if val == "" :
  			# The fragment ID must be removed...
  			return URIRef(self.base)
  
  		# fall back on good old traditional URI-s.
  		# To be on the safe side, let us use the Python libraries
  		if self.parsedBase[0] == "" :
  			# base is, in fact, a local file name
  			# The following call is just to be sure that some pathological cases when
  			# the ':' _does_ appear in the URI but not in a scheme position is taken
  			# care of properly...
  
  			key = urlsplit(val)[0]
  			if key == "" :
  				# relative URI, to be combined with local file name:
  				return join(self.base, val, check = False)
  			else :
  				return create_URIRef(val)
  		else :
  			# Trust the python library...
  			# Well, not quite:-) there is what is, in my view, a bug in the urljoin; in some cases it
  			# swallows the '#' or '?' character at the end. This is clearly a problem with
  			# Semantic Web URI-s
  			return join(self.base, val)
  	# end _URI
  
  	def _CURIEorURI(self, val) :
  		"""Returns a URI for a (safe or not safe) CURIE. In case it is a safe CURIE but the CURIE itself
  		is not defined, an error message is issued. Otherwise, if it is not a CURIE, it is taken to be a URI
  		@param val: attribute value to be interpreted
  		@type val: string
  		@return: an RDFLib URIRef instance or None
  		"""
  		if val == "" :
  			return URIRef(self.base)
  
  		safe_curie = False
  		if val[0] == '[' :
  			# If a safe CURIE is asked for, a pure URI is not acceptable.
  			# Is checked below, and that is why the safe_curie flag is necessary
  			if val[-1] != ']' :
  				# that is certainly forbidden: an incomplete safe CURIE
  				self.options.add_warning(err_illegal_safe_CURIE % val, UnresolvablePrefix, node=self.node.nodeName)
  				return None
  			else :
  				val = val[1:-1]
  				safe_curie = True
  		# There is a branch here depending on whether we are in 1.1 or 1.0 mode
  		if self.rdfa_version >= "1.1" :
  			retval = self.term_or_curie.CURIE_to_URI(val)
  			if retval == None :
  				# the value could not be interpreted as a CURIE, ie, it did not produce any valid URI.
  				# The rule says that then the whole value should be considered as a URI
  				# except if it was part of a safe CURIE. In that case it should be ignored...
  				if safe_curie :
  					self.options.add_warning(err_no_CURIE_in_safe_CURIE % val, UnresolvablePrefix, node=self.node.nodeName)
  					return None
  				else :
  					return self._URI(val)
  			else :
  				# there is an unlikely case where the retval is actually a URIRef with a relative URI. Better filter that one out
  				if isinstance(retval, BNode) == False and urlsplit(str(retval))[0] == "" :
  					# yep, there is something wrong, a new URIRef has to be created:
  					return URIRef(self.base+str(retval))
  				else :
  					return retval
  		else :
  			# in 1.0 mode a CURIE can be considered only in case of a safe CURIE
  			if safe_curie :
  				return self.term_or_curie.CURIE_to_URI(val)
  			else :
  				return self._URI(val)
  	# end _CURIEorURI
  
  	def _TERMorCURIEorAbsURI(self, val) :
  		"""Returns a URI either for a term or for a CURIE. The value must be an NCNAME to be handled as a term; otherwise
  		the method falls back on a CURIE or an absolute URI.
  		@param val: attribute value to be interpreted
  		@type val: string
  		@return: an RDFLib URIRef instance or None
  		"""
  		from . import uri_schemes
  		# This case excludes the pure base, ie, the empty value
  		if val == "" :
  			return None
  
  		from .termorcurie import ncname, termname
  		if termname.match(val) :
  			# This is a term, must be handled as such...
  			retval = self.term_or_curie.term_to_URI(val)
  			if not retval :
  				self.options.add_warning(err_undefined_terms % val, UnresolvableTerm, node=self.node.nodeName, buggy_value = val)
  				return None
  			else :
  				return retval
  		else :
  			# try a CURIE
  			retval = self.term_or_curie.CURIE_to_URI(val)
  			if retval :
  				return retval
  			elif self.rdfa_version >= "1.1" :
  				# See if it is an absolute URI
  				scheme = urlsplit(val)[0]
  				if scheme == "" :
  					# bug; there should be no relative URIs here
  					self.options.add_warning(err_non_legal_CURIE_ref % val, UnresolvablePrefix, node=self.node.nodeName)
  					return None
  				else :
  					if scheme not in uri_schemes :
  						self.options.add_warning(err_URI_scheme % val.strip(), node=self.node.nodeName)
  					return URIRef(val)
  			else :
  				# rdfa 1.0 case
  				self.options.add_warning(err_undefined_CURIE % val.strip(), UnresolvablePrefix, node=self.node.nodeName)
  				return None
  	# end _TERMorCURIEorAbsURI
  
  	# -----------------------------------------------------------------------------------------------
  
  	def getURI(self, attr) :
  		"""Get the URI(s) for the attribute. The name of the attribute determines whether the value should be
  		a pure URI, a CURIE, etc, and whether the return is a single element of a list of those. This is done
  		using the L{ExecutionContext._resource_type} table.
  		@param attr: attribute name
  		@type attr: string
  		@return: an RDFLib URIRef instance (or None) or a list of those
  		"""
  		if self.node.hasAttribute(attr) :
  			val = self.node.getAttribute(attr)
  		else :
  			if attr in ExecutionContext._list :
  				return []
  			else :
  				return None
  
  		# This may raise an exception if the attr has no key. This, actually,
  		# should not happen if the code is correct, but it does not harm having it here...
  		try :
  			func = ExecutionContext._resource_type[attr]
  		except :
  			# Actually, this should not happen...
  			func = ExecutionContext._URI
  
  		if attr in ExecutionContext._list :
  			# Allows for a list
  			resources = [ func(self, v.strip()) for v in val.strip().split() if v != None ]
  			retval = [ r for r in resources if r != None ]
  		else :
  			retval = func(self, val.strip())
  		return retval
  	# end getURI
  
  	def getResource(self, *args) :
  		"""Get single resources from several different attributes. The first one that returns a valid URI wins.
  		@param args: variable list of attribute names, or a single attribute being a list itself.
  		@return: an RDFLib URIRef instance (or None) :
  		"""
  		if len(args) == 0 :
  			return None
  		if isinstance(args[0], tuple) or isinstance(args[0], list) :
  			rargs = args[0]
  		else :
  			rargs = args
  
  		for resource in rargs :
  			uri = self.getURI(resource)
  			if uri != None : return uri
  		return None
  
  	# -----------------------------------------------------------------------------------------------
  	def reset_list_mapping(self, origin=None) :
  		"""
  		Reset, ie, create a new empty dictionary for the list mapping.
  		"""
  		self.list_mapping = ListStructure()
  		if origin: self.set_list_origin(origin)
  		self.new_list = True
  
  	def list_empty(self) :
  		"""
  		Checks whether the list is empty.
  		@return: Boolean
  		"""
  		return len(self.list_mapping.mapping) == 0
  
  	def get_list_props(self) :
  		"""
  		Return the list of property values in the list structure
  		@return: list of URIRef
  		"""
  		return list(self.list_mapping.mapping.keys())
  
  	def get_list_value(self,prop) :
  		"""
  		Return the list of values in the list structure for a specific property
  		@return: list of RDF nodes
  		"""
  		return self.list_mapping.mapping[prop]
  
  	def set_list_origin(self, origin) :
  		"""
  		Set the origin of the list, ie, the subject to attach the final list(s) to
  		@param origin: URIRef
  		"""
  		self.list_mapping.origin = origin
  
  	def get_list_origin(self) :
  		"""
  		Return the origin of the list, ie, the subject to attach the final list(s) to
  		@return: URIRef
  		"""
  		return self.list_mapping.origin
  
  	def add_to_list_mapping(self, property, resource) :
  		"""Add a new property-resource on the list mapping structure. The latter is a dictionary of arrays;
  		if the array does not exist yet, it will be created on the fly.
  
  		@param property: the property URI, used as a key in the dictionary
  		@param resource: the resource to be added to the relevant array in the dictionary. Can be None; this is a dummy
  		placeholder for C{<span rel="property" inlist>...</span>} constructions that may be filled in by children or siblings; if not
  		an empty list has to be generated.
  		"""
  		if property in self.list_mapping.mapping :
  			if resource != None :
  				# indeed, if it is None, than it should not override anything
  				if self.list_mapping.mapping[property] == None :
  					# replacing a dummy with real content
  					self.list_mapping.mapping[property] = [ resource ]
  				else :
  					self.list_mapping.mapping[property].append(resource)
  		else :
  			if resource != None :
  				self.list_mapping.mapping[property] = [ resource ]
  			else :
  				self.list_mapping.mapping[property] = None
  
  
  ####################
  