Patch #103885: Add dynamic registration and lookup of DOM implementations.
diff --git a/Doc/lib/xmldom.tex b/Doc/lib/xmldom.tex
index 5e752a0..87070b9 100644
--- a/Doc/lib/xmldom.tex
+++ b/Doc/lib/xmldom.tex
@@ -85,6 +85,36 @@
{This specifies the mapping from OMG IDL to Python.}
\end{seealso}
+\subsection{Module Contents}
+
+The \module{xml.dom} contains the following functions:
+
+\begin{funcdesc}{registerDOMImplementation}{name, factory}
+Register the \var{factory} function with the \var{name}. The factory
+function should return an object which implements the
+\code{DOMImplementation| interface. The factory function can either return
+the same object, or a new one (e.g. if that implementation supports
+some customization).
+\end{funcdesc}
+
+\begin{funcdesc}{getDOMImplementation}{name = None, features = ()}
+Return a suitable DOM implementation. The \var{name} is either
+well-known, the module name of a DOM implementation, or
+\code{None}. If it is not \code{None}, imports the corresponding module and
+returns a \class{DOMImplementation} object if the import succeeds. If
+no name is given, and if the environment variable \code{PYTHON_DOM} is
+set, this variable is used to find the implementation.
+
+If name is not given, consider the available implementations to find
+one with the required feature set. If no implementation can be found,
+raise an \exception{ImportError}. The features list must be a sequence of
+(feature, version) pairs which are passed to hasFeature.
+\end{funcdesc}
+
+% Should the Node documentation go here?
+
+In addition, \module{xml.dom} contains the \class{Node}, and the DOM
+exceptions.
\subsection{Objects in the DOM \label{dom-objects}}
diff --git a/Lib/xml/dom/__init__.py b/Lib/xml/dom/__init__.py
index 2dbb695..aa19ca1 100644
--- a/Lib/xml/dom/__init__.py
+++ b/Lib/xml/dom/__init__.py
@@ -115,3 +115,5 @@
class InvalidAccessErr(DOMException):
code = INVALID_ACCESS_ERR
+
+from domreg import getDOMImplementation,registerDOMImplementation
diff --git a/Lib/xml/dom/domreg.py b/Lib/xml/dom/domreg.py
new file mode 100644
index 0000000..14b87d6
--- /dev/null
+++ b/Lib/xml/dom/domreg.py
@@ -0,0 +1,76 @@
+"""Registration facilities for DOM. This module should not be used
+directly. Instead, the functions getDOMImplementation and
+registerDOMImplementation should be imported from xml.dom."""
+
+# This is a list of well-known implementations. Well-known names
+# should be published by posting to xml-sig@python.org, and are
+# subsequently recorded in this file.
+
+well_known_implementations = {
+ 'minidom':'xml.dom.minidom',
+ '4DOM': 'xml.dom.DOMImplementation',
+ }
+
+# DOM implementations not officially registered should register
+# themselves with their
+
+registered = {}
+
+def registerDOMImplementation(name, factory):
+ """registerDOMImplementation(name, factory)
+
+ Register the factory function with the name. The factory function
+ should return an object which implements the DOMImplementation
+ interface. The factory function can either return the same object,
+ or a new one (e.g. if that implementation supports some
+ customization)."""
+
+ registered[name] = factory
+
+def _good_enough(dom, features):
+ "_good_enough(dom, features) -> Return 1 if the dom offers the features"
+ for f,v in features:
+ if not dom.hasFeature(f,v):
+ return 0
+ return 1
+
+def getDOMImplementation(name = None, features = ()):
+ """getDOMImplementation(name = None, features = ()) -> DOM implementation.
+
+ Return a suitable DOM implementation. The name is either
+ well-known, the module name of a DOM implementation, or None. If
+ it is not None, imports the corresponding module and returns
+ DOMImplementation object if the import succeeds.
+
+ If name is not given, consider the available implementations to
+ find one with the required feature set. If no implementation can
+ be found, raise an ImportError. The features list must be a sequence
+ of (feature, version) pairs which are passed to hasFeature."""
+
+ import os
+ creator = None
+ mod = well_known_implementations.get(name)
+ if mod:
+ mod = __import__(mod, {}, {}, ['getDOMImplementation'])
+ return mod.getDOMImplementation()
+ elif name:
+ return registered[name]()
+ elif os.environ.has_key("PYTHON_DOM"):
+ return getDOMImplementation(name = os.environ["PYTHON_DOM"])
+
+ # User did not specify a name, try implementations in arbitrary
+ # order, returning the one that has the required features
+ for creator in registered.values():
+ dom = creator()
+ if _good_enough(dom, features):
+ return dom
+
+ for creator in well_known_implementations.keys():
+ try:
+ dom = getDOMImplementation(name = creator)
+ except StandardError: # typically ImportError, or AttributeError
+ continue
+ if _good_enough(dom, features):
+ return dom
+
+ raise ImportError,"no suitable DOM implementation found"
diff --git a/Lib/xml/dom/minidom.py b/Lib/xml/dom/minidom.py
index b4ae267..35adfd5 100644
--- a/Lib/xml/dom/minidom.py
+++ b/Lib/xml/dom/minidom.py
@@ -782,3 +782,6 @@
"""Parse a file into a DOM from a string."""
from xml.dom import pulldom
return _doparse(pulldom.parseString, args, kwargs)
+
+def getDOMImplementation():
+ return Document.implementation