Added DCMeta - EAV based application to represent document meta-data. Started to...

[redakcja.git] / apps / dcmeta / utils.py

diff --git a/apps/dcmeta/utils.py b/apps/dcmeta/utils.py
new file mode 100644 (file)
index 0000000..60a2482
--- /dev/null
+++ b/apps/dcmeta/utils.py
@@ -0,0 +1,90 @@
+class XMLNamespace(object):
+    '''A handy structure to represent names in an XML namespace.'''
+
+    def __init__(self, uri):
+        self.uri = uri
+
+    def __call__(self, tag):
+        return '{%s}%s' % (self.uri, tag)
+
+    def __contains__(self, tag):
+        return tag.startswith('{' + self.uri + '}')
+
+    def __repr__(self):
+        return 'XMLNamespace(%r)' % self.uri
+
+    def __str__(self):
+        return '%s' % self.uri
+
+    def strip(self, qtag):
+        if qtag not in self:
+            raise ValueError("Tag %s not in namespace %s" % (qtag, self.uri))
+        return qtag[len(self.uri) + 2:]
+
+    @classmethod
+    def split_tag(cls, tag):
+        if '{' != tag[0]:
+            raise ValueError
+        end = tag.find('}')
+        if end < 0:
+            raise ValueError
+        return cls(tag[1:end]), tag[end + 1:]
+
+    @classmethod
+    def tagname(cls, tag):
+        return cls.split_tag(tag)[1]
+
+
+class EmptyNamespace(XMLNamespace):
+    def __init__(self):
+        super(EmptyNamespace, self).__init__('')
+
+    def __call__(self, tag):
+        return tag
+
+# some common namespaces we use
+RDFNS = XMLNamespace('http://www.w3.org/1999/02/22-rdf-syntax-ns#')
+DCNS = XMLNamespace('http://purl.org/dc/elements/1.1/')
+MARCRELNS = XMLNamespace('http://www.loc.gov/loc.terms/relators/')
+
+XINS = XMLNamespace("http://www.w3.org/2001/XInclude")
+XHTMLNS = XMLNamespace("http://www.w3.org/1999/xhtml")
+
+common_uris = {
+    RDFNS.uri: 'rdf',
+    DCNS.uri: 'dc',
+    MARCRELNS.uri: 'marcrel',
+}
+
+common_prefixes = dict((i[1], i[0]) for i in common_uris.items())
+
+class NamespaceProxy(object):
+
+    def __init__(self, desc, uri):
+        object.__setattr__(self, 'uri', uri)
+        object.__setattr__(self, 'desc', desc)
+
+    def __getattr__(self, key):
+        return object.__getattribute__(self, 'desc')[self.uri, key]
+
+    def __setattr__(self, key, value):
+        object.__getattribute__(self, 'desc')[self.uri, key] = value
+
+    def __iter__(self):
+        return ((XMLNamespace.tagname(attr.schema.name), attr.value) for attr in object.__getattribute__(self, 'desc').attrs.filter(schema__name__startswith="{%s}" % self.uri))
+
+class NamespaceDescriptor(object):
+
+    def __init__(self, nsuri):
+        self.nsuri = nsuri
+
+    def __get__(self, instance, owner):
+        if instance is None:
+            return self
+        return NamespaceProxy(instance, self.nsuri)
+
+    def __set__(self, instance, value):
+        raise ValueError
+
+
+