| """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. |
| """ |
| |
| 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 "simpletree", "dom", "etree" and "beautifulsoup" |
| |
| "simpletree" - a built-in DOM-ish tree type with support for some |
| more pythonic idioms. |
| "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 |
| "beautifulsoup" - Beautiful soup (if installed) |
| "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", "simpletree"): |
| mod = __import__(treeType, globals()) |
| treeWalkerCache[treeType] = mod.TreeWalker |
| elif treeType == "genshi": |
| import genshistream |
| treeWalkerCache[treeType] = genshistream.TreeWalker |
| elif treeType == "beautifulsoup": |
| import soup |
| treeWalkerCache[treeType] = soup.TreeWalker |
| elif treeType == "lxml": |
| import lxmletree |
| treeWalkerCache[treeType] = lxmletree.TreeWalker |
| elif treeType == "etree": |
| import etree |
| # XXX: NEVER cache here, caching is done in the etree submodule |
| return etree.getETreeModule(implementation, **kwargs).TreeWalker |
| return treeWalkerCache.get(treeType) |
