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f8de21c51b
Add support for the DOM Level 3 (draft) DOMImplementationSource interface to the xml.dom and xml.dom.minidom modules. Note API issue: the draft spec says to return null when there is no suitable implementation, while the Python getDOMImplementation() function raises ImportError (minor).
99 lines
3.4 KiB
Python
99 lines
3.4 KiB
Python
"""Registration facilities for DOM. This module should not be used
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directly. Instead, the functions getDOMImplementation and
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registerDOMImplementation should be imported from xml.dom."""
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from xml.dom.minicompat import * # isinstance, StringTypes
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# This is a list of well-known implementations. Well-known names
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# should be published by posting to xml-sig@python.org, and are
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# subsequently recorded in this file.
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well_known_implementations = {
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'minidom':'xml.dom.minidom',
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'4DOM': 'xml.dom.DOMImplementation',
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}
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# DOM implementations not officially registered should register
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# themselves with their
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registered = {}
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def registerDOMImplementation(name, factory):
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"""registerDOMImplementation(name, factory)
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Register the factory function with the name. The factory function
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should return an object which implements the DOMImplementation
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interface. The factory function can either return the same object,
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or a new one (e.g. if that implementation supports some
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customization)."""
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registered[name] = factory
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def _good_enough(dom, features):
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"_good_enough(dom, features) -> Return 1 if the dom offers the features"
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for f,v in features:
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if not dom.hasFeature(f,v):
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return 0
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return 1
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def getDOMImplementation(name = None, features = ()):
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"""getDOMImplementation(name = None, features = ()) -> DOM implementation.
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Return a suitable DOM implementation. The name is either
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well-known, the module name of a DOM implementation, or None. If
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it is not None, imports the corresponding module and returns
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DOMImplementation object if the import succeeds.
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If name is not given, consider the available implementations to
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find one with the required feature set. If no implementation can
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be found, raise an ImportError. The features list must be a sequence
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of (feature, version) pairs which are passed to hasFeature."""
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import os
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creator = None
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mod = well_known_implementations.get(name)
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if mod:
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mod = __import__(mod, {}, {}, ['getDOMImplementation'])
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return mod.getDOMImplementation()
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elif name:
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return registered[name]()
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elif os.environ.has_key("PYTHON_DOM"):
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return getDOMImplementation(name = os.environ["PYTHON_DOM"])
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# User did not specify a name, try implementations in arbitrary
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# order, returning the one that has the required features
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if isinstance(features, StringTypes):
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features = _parse_feature_string(features)
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for creator in registered.values():
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dom = creator()
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if _good_enough(dom, features):
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return dom
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for creator in well_known_implementations.keys():
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try:
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dom = getDOMImplementation(name = creator)
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except StandardError: # typically ImportError, or AttributeError
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continue
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if _good_enough(dom, features):
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return dom
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raise ImportError,"no suitable DOM implementation found"
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def _parse_feature_string(s):
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features = []
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parts = s.split()
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i = 0
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length = len(parts)
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while i < length:
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feature = parts[i]
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if feature[0] in "0123456789":
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raise ValueError, "bad feature name: " + `feature`
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i = i + 1
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version = None
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if i < length:
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v = parts[i]
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if v[0] in "0123456789":
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i = i + 1
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version = v
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features.append((feature, version))
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return tuple(features)
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