view env/lib/python3.9/site-packages/bleach/_vendor/html5lib/treewalkers/__init__.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

"""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
implement a tree walker object (called TreeWalker by convention) that
implements a 'serialize' method which takes a tree as sole argument and
returns an iterator which generates tokens.
"""

from __future__ import absolute_import, division, unicode_literals

from .. import constants
from .._utils import default_etree

__all__ = ["getTreeWalker", "pprint"]

treeWalkerCache = {}


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

    :arg str treeType: the name of the tree type required (case-insensitive).
        Supported values are:

        * "dom": The xml.dom.minidom DOM implementation
        * "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

    :arg implementation: A module implementing the tree type e.g.
        xml.etree.ElementTree or cElementTree (Currently applies to the "etree"
        tree type only).

    :arg kwargs: keyword arguments passed to the etree walker--for other
        walkers, this has no effect

    :returns: a TreeWalker class

    """

    treeType = treeType.lower()
    if treeType not in treeWalkerCache:
        if treeType == "dom":
            from . import dom
            treeWalkerCache[treeType] = dom.TreeWalker
        elif treeType == "genshi":
            from . import genshi
            treeWalkerCache[treeType] = genshi.TreeWalker
        elif treeType == "lxml":
            from . import etree_lxml
            treeWalkerCache[treeType] = etree_lxml.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)


def concatenateCharacterTokens(tokens):
    pendingCharacters = []
    for token in tokens:
        type = token["type"]
        if type in ("Characters", "SpaceCharacters"):
            pendingCharacters.append(token["data"])
        else:
            if pendingCharacters:
                yield {"type": "Characters", "data": "".join(pendingCharacters)}
                pendingCharacters = []
            yield token
    if pendingCharacters:
        yield {"type": "Characters", "data": "".join(pendingCharacters)}


def pprint(walker):
    """Pretty printer for tree walkers

    Takes a TreeWalker instance and pretty prints the output of walking the tree.

    :arg walker: a TreeWalker instance

    """
    output = []
    indent = 0
    for token in concatenateCharacterTokens(walker):
        type = token["type"]
        if type in ("StartTag", "EmptyTag"):
            # tag name
            if token["namespace"] and token["namespace"] != constants.namespaces["html"]:
                if token["namespace"] in constants.prefixes:
                    ns = constants.prefixes[token["namespace"]]
                else:
                    ns = token["namespace"]
                name = "%s %s" % (ns, token["name"])
            else:
                name = token["name"]
            output.append("%s<%s>" % (" " * indent, name))
            indent += 2
            # attributes (sorted for consistent ordering)
            attrs = token["data"]
            for (namespace, localname), value in sorted(attrs.items()):
                if namespace:
                    if namespace in constants.prefixes:
                        ns = constants.prefixes[namespace]
                    else:
                        ns = namespace
                    name = "%s %s" % (ns, localname)
                else:
                    name = localname
                output.append("%s%s=\"%s\"" % (" " * indent, name, value))
            # self-closing
            if type == "EmptyTag":
                indent -= 2

        elif type == "EndTag":
            indent -= 2

        elif type == "Comment":
            output.append("%s<!-- %s -->" % (" " * indent, token["data"]))

        elif type == "Doctype":
            if token["name"]:
                if token["publicId"]:
                    output.append("""%s<!DOCTYPE %s "%s" "%s">""" %
                                  (" " * indent,
                                   token["name"],
                                   token["publicId"],
                                   token["systemId"] if token["systemId"] else ""))
                elif token["systemId"]:
                    output.append("""%s<!DOCTYPE %s "" "%s">""" %
                                  (" " * indent,
                                   token["name"],
                                   token["systemId"]))
                else:
                    output.append("%s<!DOCTYPE %s>" % (" " * indent,
                                                       token["name"]))
            else:
                output.append("%s<!DOCTYPE >" % (" " * indent,))

        elif type == "Characters":
            output.append("%s\"%s\"" % (" " * indent, token["data"]))

        elif type == "SpaceCharacters":
            assert False, "concatenateCharacterTokens should have got rid of all Space tokens"

        else:
            raise ValueError("Unknown token type, %s" % type)

    return "\n".join(output)