[Zope3-checkins] CVS: Zope3/src/zope/app/dublincore - xmlmetadata.py:1.4

[Fred L. Drake, Jr.]

Update of /cvs-repository/Zope3/src/zope/app/dublincore
In directory cvs.zope.org:/tmp/cvs-serv2402

Modified Files:
	xmlmetadata.py 
Log Message:
refactor to move some namespace handling to be less intrusive in the
dumpString() function; it might be somewhat reusable as well


=== Zope3/src/zope/app/dublincore/xmlmetadata.py 1.3 => 1.4 ===
--- Zope3/src/zope/app/dublincore/xmlmetadata.py:1.3	Wed Aug 27 00:43:55 2003
+++ Zope3/src/zope/app/dublincore/xmlmetadata.py	Thu Aug 28 19:27:32 2003
@@ -32,14 +32,45 @@
 dublin_core_namespaces = dcterms.DC_NS, dcterms.DCTERMS_NS
 
 
+DEFAULT_NAMESPACE_PREFIXES = {
+    # uri:              prefix,
+    dcterms.DC_NS:      "dc",
+    dcterms.DCTERMS_NS: "dcterms",
+    dcterms.XSI_NS:     "xsi",
+    }
+
+class NamespaceTracker:
+    def __init__(self, mapping=None):
+        self._mapping = {}
+        self._used = {}
+        if mapping:
+            self._mapping.update(mapping)
+        self._counter = 0
+
+    def encode(self, (uri, localname)):
+        if not uri:
+            return localname
+        if uri not in self._mapping:
+            self._counter += 1
+            prefix = "ns%d" % self._counter
+            self._mapping[uri] = prefix
+            self._used[prefix] = uri
+        else:
+            prefix = self._mapping[uri]
+            if prefix not in self._used:
+                self._used[prefix] = uri
+        if prefix:
+            return "%s:%s" % (prefix, localname)
+        else:
+            return localname
+
+    def getPrefixMappings(self):
+        return self._used.items()
+
+
 def dumpString(mapping):
     sio = StringIO()
-    nsmap = {
-        # prefix: [uri, used],
-        dcterms.DC_NS:      ("dc", False),
-        dcterms.DCTERMS_NS: ("dcterms", False),
-        dcterms.XSI_NS:     ("xsi", False),
-        }
+    nsmap = NamespaceTracker(DEFAULT_NAMESPACE_PREFIXES)
     items = mapping.items()
     items.sort()
     prev = None
@@ -51,20 +82,12 @@
             prev = group
         if name in dcterms.name_to_element:
             element, t = dcterms.name_to_element[name]
-            nsuri, localname = element
-            if nsuri not in nsmap:
-                prefix = "ns%d" % (len(nsmap) - 2)
-                nsmap[nsuri] = prefix, True
-            else:
-                prefix, used = nsmap[nsuri]
-                if not used:
-                    nsmap[nsuri] = prefix, True
-            qname = "%s:%s" % (prefix, localname)
+            qname = nsmap.encode(element)
             if not type:
                 type = t
             if type:
-                type = " xsi:type=" + quoteattr(type)
-                nsmap[dcterms.XSI_NS] = "xsi", True
+                type = " %s=%s" % (nsmap.encode((dcterms.XSI_NS, "type")),
+                                   quoteattr(type))
             for value in values:
                 sio.write("  <%s%s>\n    %s\n  </%s>\n"
                           % (qname, type, _encode_string(value), qname))
@@ -75,9 +98,8 @@
     sio = StringIO()
     sio.write("<?xml version='1.0' encoding='utf-8'?>\n"
               "<metadata")
-    for uri, (prefix, used) in nsmap.iteritems():
-        if used:
-            sio.write("\n  xmlns:%s=%s" % (prefix, quoteattr(uri)))
+    for prefix, uri in nsmap.getPrefixMappings():
+        sio.write("\n  xmlns:%s=%s" % (prefix, quoteattr(uri)))
     sio.write(">\n")
     sio.write(content)
     sio.write("</metadata>\n")