public String[] knownNamespaces() {
final PsiElement parentElement = getParent();
BidirectionalMap<String, String> map = initNamespaceMaps(parentElement);
Set<String> known = Collections.emptySet();
if (map != null) {
known = new HashSet<String>(map.values());
}
if (parentElement instanceof XmlTag) {
if (known.isEmpty()) return ((XmlTag) parentElement).knownNamespaces();
ContainerUtil.addAll(known, ((XmlTag) parentElement).knownNamespaces());
} else {
XmlExtension xmlExtension = XmlExtension.getExtensionByElement(this);
if (xmlExtension != null) {
final XmlFile xmlFile = xmlExtension.getContainingFile(this);
if (xmlFile != null) {
final XmlTag rootTag = xmlFile.getRootTag();
if (rootTag != null && rootTag != this) {
if (known.isEmpty()) return rootTag.knownNamespaces();
ContainerUtil.addAll(known, rootTag.knownNamespaces());
}
}
}
}
return ArrayUtil.toStringArray(known);
}
@Nullable
private BidirectionalMap<String, String> computeNamespaceMap(PsiElement parent) {
BidirectionalMap<String, String> map = null;
if (hasNamespaceDeclarations()) {
map = new BidirectionalMap<String, String>();
final XmlAttribute[] attributes = getAttributes();
for (final XmlAttribute attribute : attributes) {
if (attribute.isNamespaceDeclaration()) {
final String name = attribute.getName();
int splitIndex = name.indexOf(':');
final String value = getRealNs(attribute.getValue());
if (value != null) {
if (splitIndex < 0) {
map.put("", value);
} else {
map.put(XmlUtil.findLocalNameByQualifiedName(name), value);
}
}
}
}
}
if (parent instanceof XmlDocument) {
final XmlExtension extension = XmlExtension.getExtensionByElement(parent);
if (extension != null) {
final String[][] defaultNamespace =
extension.getNamespacesFromDocument((XmlDocument) parent, map != null);
if (defaultNamespace != null) {
if (map == null) {
map = new BidirectionalMap<String, String>();
}
for (final String[] prefix2ns : defaultNamespace) {
map.put(prefix2ns[0], getRealNs(prefix2ns[1]));
}
}
}
}
return map;
}