魅力的なPython: DOMの動的性

                
"""Convert a valid HTML document to XML
   USAGE: python try_dom1.py < infile.html > outfile.xml
"""
import sys
from xml.dom import core
from xml.dom.html_builder import HtmlBuilder

# Construct an HtmlBuilder object and feed the data to it
b = HtmlBuilder()
b.feed(sys.stdin.read())

# Get the newly-constructed document object
doc = b.document

# Output it as XML
print doc.toxml()

                
"""Build a DOM instance from scratch, write it to XML
   USAGE: python try_dom2.py > outfile.xml
"""
import types
from xml.dom import core
from xml.dom.builder import Builder

# Recursive function to build DOM instance from Python instance
def
                 object_convert(builder, inst):    
     # Put entire object inside an elem w/ same name as the class.
     builder.startElement(inst.__class__.__name__)
    
     for attr in inst.__dict__.keys():        
          if attr[0] == '_':      # Skip internal attributes
               continue
          value = getattr(inst, attr)        
          if type(value) == types.InstanceType:
               # Recursively process subobjects
               object_convert(builder, value)        
          else:            
               # Convert anything else to string, put it in an element
               builder.startElement(attr)
               builder.text(str(value))
               builder.endElement(attr)

     builder.endElement(inst.__class__.__name__)

if __name__ == '__main__':
     # Create container classes    
     class
                 quotations: pass
                

     
class
                 quotation: pass

     # Create an instance, fill it with hierarchy of attributes
     inst = quotations()
     inst.title = "Quotations file (not quotations.dtd conformant)"
     inst.quot1 = quot1 = quotation()
     quot1.text = """'"is not a quine" is not a quine' is a quine"""
     quot1.source = "Joshua Shagam, kuro5hin.org"
     inst.quot2 = quot2 = quotation()
     quot2.text = "Python is not a democracy. Voting doesn't help. "+\
                

                  
"Crying may..."
     quot2.source = "Guido van Rossum, comp.lang.python"
    
     # Create the DOM Builder
     builder = Builder()
     object_convert(builder, inst)    
     print builder.document.toxml()

                
"""Read in a DOM instance, convert it to a Python object
"""
from xml.dom.utils import FileReader

class
                 PyObject: pass
                

                def
                 pyobj_printer(py_obj, level=0):
     """Return a "deep" string description of a Python object"""
                

     
from string import join, split    
     import types
     descript = ''  
     for membname in dir(py_obj):
          member = getattr(py_obj,membname)
          if type(member) == types.InstanceType:
               descript = descript + (' '*level) + '{'+membname+'}\n'
               descript = descript + pyobj_printer(member, level+3)
          elif type(member) == types.ListType:
               descript = descript + (' '*level) + '['+membname+']\n'
               for i in range(len(member)):
               descript = descript+(' '*level)+str(i+1)+': '+ \
                           pyobj_printer(member[i],level+3)
          else:
               descript = descript + membname+'='
               descript = descript + join(split(str(member)[:50]))+'...\n'    
     return descript

def
                pyobj_from_dom(dom_node):
     """Converts a DOM tree to a "native" Python object"""
     py_obj = PyObject()
     py_obj.PCDATA = ''
     for node in dom_node.get_childNodes():
          if node.name == '#text':
               py_obj.PCDATA = py_obj.PCDATA + node.value
          elif hasattr(py_obj, node.name):
               getattr(py_obj, node.name).append(pyobj_from_dom(node))
          else:
               setattr(py_obj, node.name, [pyobj_from_dom(node)])
     return py_obj

# Main test
dom_obj = FileReader("quotes.xml").document
py_obj = pyobj_from_dom(dom_obj)
if __name__ == "__main__":
     print pyobj_printer(py_obj)

                
>>> from try_dom3 import *
>>> py_obj.quotations[0].quotation[3].source[0].PCDATA
'Guido van Rossum, '
            

                
"""Manipulate the arrangement of nodes in a DOM object
"""
from try_dom3 import *

#-- Var 'doc' will hold the single <quotations> "trunk"
doc = dom_obj.get_childNodes()[0]

#-- Pull off all the nodes into a Python list
# (each node is a <quotation> block, or a whitespace text node)
nodes = []
while 1:
     try: node = doc.removeChild(doc.get_childNodes()[0])
     except: break
     nodes.append(node)

#-- Reverse the order of the quotations using a list method
# (we could also perform more complicated operations on the list:
# delete elements, add new ones, sort on complex criteria, etc.)
nodes.reverse()

#-- Fill 'doc' back up with our rearranged nodes
for node in nodes:    
     # if second arg is None, insert is to end of list
     doc.insertBefore(node, None)

#-- Output the manipulated DOM
print
 dom_obj.toxml()