Get a TreeBuilder class for various types of trees with built-in support

    :arg 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.

    :arg 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.

    :arg kwargs: Any additional options to pass to the TreeBuilder when
        creating it.

    Example:

    >>> from html5lib.treebuilders import getTreeBuilder
    >>> builder = getTreeBuilder('etree')

def getTreeBuilder(treeType, implementation=None, **kwargs):
    """Get a TreeBuilder class for various types of trees with built-in support

    :arg 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.

    :arg 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.

    :arg kwargs: Any additional options to pass to the TreeBuilder when
        creating it.

    Example:

    >>> from html5lib.treebuilders import getTreeBuilder
    >>> builder = getTreeBuilder('etree')

    """

    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)