pyRdfa.transform

  1# -*- coding: utf-8 -*-
  2"""
  3Transformer sub-package for the pyRdfa package. It contains modules with transformer functions; each may be
  4invoked by pyRdfa to transform the dom tree before the "real" RDfa processing.
  5
  6@summary: RDFa Transformer package
  7@requires: U{RDFLib package<http://rdflib.net>}
  8@organization: U{World Wide Web Consortium<http://www.w3.org>}
  9@author: U{Ivan Herman<a href="http://www.w3.org/People/Ivan/">}
 10@license: This software is available for use under the
 11U{W3C® SOFTWARE NOTICE AND LICENSE<href="http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231">}
 12"""
 13
 14"""
 15$Id: __init__.py,v 1.8 2012/06/12 11:47:19 ivan Exp $
 16$Date: 2012/06/12 11:47:19 $
 17"""
 18__version__ = "3.0"
 19
 20# Here are the transfomer functions that are to be performed for all RDFa files, no matter what
 21
 22def top_about(root, options, state):
 23    """
 24    @param root: a DOM node for the top level element
 25    @param options: invocation options
 26    @type options: L{Options<pyRdfa.options>}
 27    @param state: top level execution state
 28    @type state: L{State<pyRdfa.state>}
 29    """
 30    def set_about(node):
 31        if has_one_of_attributes(node, "rel", "rev"):
 32            if not has_one_of_attributes(top, "about", "src"):
 33                node.setAttribute("about","")
 34        else:
 35            if not has_one_of_attributes(node, "href", "resource", "about", "src"):
 36                node.setAttribute("about","")
 37    
 38    from ..host import HostLanguage
 39    from ..utils import has_one_of_attributes
 40        
 41    if not has_one_of_attributes(root, "about"):
 42        # The situation is a bit complicated: if a @resource is present without anything else, then it sets
 43        # the subject, ie, should be accepted...
 44        if has_one_of_attributes(root, "resource", "href", "src"):
 45            if has_one_of_attributes(root, "rel", "rev","property"):
 46                root.setAttribute("about","")
 47        else:
 48            root.setAttribute("about","")
 49        
 50    if options.host_language in [ HostLanguage.xhtml, HostLanguage.html5, HostLanguage.xhtml5 ]:
 51        if state.rdfa_version >= "1.1":
 52            pass
 53        else:
 54            for top in root.getElementsByTagName("head"):
 55                if not has_one_of_attributes(top, "href", "resource", "about", "src"):
 56                    set_about(top)
 57            for top in root.getElementsByTagName("body"):
 58                if not has_one_of_attributes(top, "href", "resource", "about", "src"):
 59                    set_about(top)
 60
 61
 62def empty_safe_curie(node, options, state):
 63    """
 64    Remove the attributes whose value is an empty safe curie. It also adds an 'artificial' flag, ie, an
 65    attribute (called 'emptysc') into the node to signal that there _is_ an attribute with an ignored
 66    safe curie value. The name of the attribute is 'about_pruned' or 'resource_pruned'.
 67    
 68    @param node: a DOM node for the top level element
 69    @param options: invocation options
 70    @type options: L{Options<pyRdfa.options>}
 71    @param state: top level execution state
 72    @type state: L{State<pyRdfa.state>}
 73    """
 74    def prune_safe_curie(node,name):
 75        if node.hasAttribute(name):
 76            av = node.getAttribute(name)
 77            if av == '[]':
 78                node.removeAttribute(name)
 79                node.setAttribute(name+'_pruned','')
 80                msg = "Attribute @%s uses an empty safe CURIE; the attribute is ignored" % name
 81                options.add_warning(msg, node=node)
 82                
 83    prune_safe_curie(node, "about")
 84    prune_safe_curie(node, "resource")
 85    for n in node.childNodes:
 86        if n.nodeType == node.ELEMENT_NODE:
 87            empty_safe_curie(n, options, state)
 88
 89def vocab_for_role(node, options, state):
 90    """
 91    The value of the @role attribute (defined separately in the U{Role Attribute Specification Lite<http://www.w3.org/TR/role-attribute/#using-role-in-conjunction-with-rdfa>}) should be as if a @vocab value to the
 92    XHTML vocabulary was defined for it. This method turns all terms in role attributes into full URI-s, so that
 93    this would not be an issue for the run-time.
 94    
 95    @param node: a DOM node for the top level element
 96    @param options: invocation options
 97    @type options: L{Options<pyRdfa.options>}
 98    @param state: top level execution state
 99    @type state: L{State<pyRdfa.state>}
100    """
101    from ..termorcurie import termname, XHTML_URI
102
103    def handle_role(node):
104        if node.hasAttribute("role"):
105            old_values = node.getAttribute("role").strip().split()
106            new_values = ""
107            for val in old_values:
108                if termname.match(val):
109                    new_values += XHTML_URI + val + ' '
110                else:
111                    new_values += val + ' '
112            node.setAttribute("role", new_values.strip())
113
114    handle_role(node)
115    for n in node.childNodes:
116        if n.nodeType == node.ELEMENT_NODE:
117            vocab_for_role(n, options, state)