Initial Commit

lib/html5lib/treebuilders/__init__.py

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+"""A collection of modules for building different kinds of tree from
+HTML documents.
+
+To create a treebuilder for a new type of tree, you need to do
+implement several things:
+
+1) A set of classes for various types of elements: Document, Doctype,
+Comment, Element. These must implement the interface of
+_base.treebuilders.Node (although comment nodes have a different
+signature for their constructor, see treebuilders.etree.Comment)
+Textual content may also be implemented as another node type, or not, as
+your tree implementation requires.
+
+2) A treebuilder object (called TreeBuilder by convention) that
+inherits from treebuilders._base.TreeBuilder. This has 4 required attributes:
+documentClass - the class to use for the bottommost node of a document
+elementClass - the class to use for HTML Elements
+commentClass - the class to use for comments
+doctypeClass - the class to use for doctypes
+It also has one required method:
+getDocument - Returns the root node of the complete document tree
+
+3) If you wish to run the unit tests, you must also create a
+testSerializer method on your treebuilder which accepts a node and
+returns a string containing Node and its children serialized according
+to the format used in the unittests
+"""
+
+from __future__ import absolute_import, division, unicode_literals
+
+from ..utils import default_etree
+
+treeBuilderCache = {}
+
+
+def getTreeBuilder(treeType, implementation=None, **kwargs):
+    """Get a TreeBuilder class for various types of tree with built-in support
+
+    treeType - the name of the tree type required (case-insensitive). Supported
+               values are:
+
+               "dom" - A generic builder for DOM implementations, defaulting to
+                       a xml.dom.minidom based implementation.
+               "etree" - A generic builder for tree implementations exposing an
+                         ElementTree-like interface, defaulting to
+                         xml.etree.cElementTree if available and
+                         xml.etree.ElementTree if not.
+               "lxml" - A etree-based builder for lxml.etree, handling
+                        limitations of lxml's implementation.
+
+    implementation - (Currently applies to the "etree" and "dom" tree types). A
+                      module implementing the tree type e.g.
+                      xml.etree.ElementTree or xml.etree.cElementTree."""
+
+    treeType = treeType.lower()
+    if treeType not in treeBuilderCache:
+        if treeType == "dom":
+            from . import dom
+            # Come up with a sane default (pref. from the stdlib)
+            if implementation is None:
+                from xml.dom import minidom
+                implementation = minidom
+            # NEVER cache here, caching is done in the dom submodule
+            return dom.getDomModule(implementation, **kwargs).TreeBuilder
+        elif treeType == "lxml":
+            from . import etree_lxml
+            treeBuilderCache[treeType] = etree_lxml.TreeBuilder
+        elif treeType == "etree":
+            from . import etree
+            if implementation is None:
+                implementation = default_etree
+            # NEVER cache here, caching is done in the etree submodule
+            return etree.getETreeModule(implementation, **kwargs).TreeBuilder
+        else:
+            raise ValueError("""Unrecognised treebuilder "%s" """ % treeType)
+    return treeBuilderCache.get(treeType)