Initial Commit

lib/html5lib/treewalkers/__init__.py

@@ -0,0 +1,57 @@
+"""A collection of modules for iterating through different kinds of
+tree, generating tokens identical to those produced by the tokenizer
+module.
+
+To create a tree walker for a new type of tree, you need to do
+implement a tree walker object (called TreeWalker by convention) that
+implements a 'serialize' method taking a tree as sole argument and
+returning an iterator generating tokens.
+"""
+
+from __future__ import absolute_import, division, unicode_literals
+
+import sys
+
+from ..utils import default_etree
+
+treeWalkerCache = {}
+
+
+def getTreeWalker(treeType, implementation=None, **kwargs):
+    """Get a TreeWalker class for various types of tree with built-in support
+
+    treeType - the name of the tree type required (case-insensitive). Supported
+               values are:
+
+                "dom" - The xml.dom.minidom DOM implementation
+                "pulldom" - The xml.dom.pulldom event stream
+                "etree" - A generic walker for tree implementations exposing an
+                          elementtree-like interface (known to work with
+                          ElementTree, cElementTree and lxml.etree).
+                "lxml" - Optimized walker for lxml.etree
+                "genshi" - a Genshi stream
+
+    implementation - (Currently applies to the "etree" tree type only). A module
+                      implementing the tree type e.g. xml.etree.ElementTree or
+                      cElementTree."""
+
+    treeType = treeType.lower()
+    if treeType not in treeWalkerCache:
+        if treeType in ("dom", "pulldom"):
+            name = "%s.%s" % (__name__, treeType)
+            __import__(name)
+            mod = sys.modules[name]
+            treeWalkerCache[treeType] = mod.TreeWalker
+        elif treeType == "genshi":
+            from . import genshistream
+            treeWalkerCache[treeType] = genshistream.TreeWalker
+        elif treeType == "lxml":
+            from . import lxmletree
+            treeWalkerCache[treeType] = lxmletree.TreeWalker
+        elif treeType == "etree":
+            from . import etree
+            if implementation is None:
+                implementation = default_etree
+            # XXX: NEVER cache here, caching is done in the etree submodule
+            return etree.getETreeModule(implementation, **kwargs).TreeWalker
+    return treeWalkerCache.get(treeType)