xmltools.py

   1 from xml.dom import Node, minidom
   2
   3 XMLNS_INTERFACE = "http://zero-install.sourceforge.net/2004/injector/interface"
   4
   5 def data(node):
   6         """Return all the text directly inside this DOM Node."""
   7         return ''.join([text.nodeValue for text in node.childNodes
   8                         if text.nodeType == Node.TEXT_NODE])
   9
  10 def set_data(elem, value):
  11         """Replace all children of 'elem' with a single text node containing 'value'"""
  12         for node in elem.childNodes:
  13                 elem.removeChild(node)
  14         if value:
  15                 text = elem.ownerDocument.createTextNode(value)
  16                 elem.appendChild(text)
  17
  18 def indent_of(x):
  19         """If x's previous sibling is whitespace, return its length. Otherwise, return 0."""
  20         indent = x.previousSibling
  21         if indent and indent.nodeType == Node.TEXT_NODE:
  22                 spaces = indent.nodeValue.split('\n')[-1]
  23                 if spaces.strip() == '':
  24                         return len(spaces)
  25         return 0
  26
  27 def insert_before(new, next):
  28         indent_depth = indent_of(next)
  29         new_parent = next.parentNode
  30
  31         prev = next.previousSibling
  32         if prev and prev.nodeType == Node.TEXT_NODE:
  33                 next = prev
  34
  35         new_parent.insertBefore(new, next)
  36         if indent_depth:
  37                 text = new_parent.ownerDocument.createTextNode('\n' + (' ' * indent_depth))
  38                 new_parent.insertBefore(text, new)
  39
  40 def insert_element(new, parent, before = []):
  41         indent = indent_of(parent) + 2  # Default indent
  42         last_element = None
  43         for x in parent.childNodes:
  44                 if x.nodeType == Node.ELEMENT_NODE:
  45                         indent = indent or indent_of(x)
  46                         if x.localName in before:
  47                                 parent.insertBefore(new, last_element.nextSibling)
  48                                 break
  49                         last_element = x
  50         else:
  51                 if last_element:
  52                         parent.insertBefore(new, last_element.nextSibling)
  53                 else:
  54                         had_children = bool(list(child_elements(parent)))
  55                         parent.appendChild(new)
  56                         if not had_children:
  57                                 final_indent = '\n' + (' ' * indent_of(parent))
  58                                 parent.appendChild(parent.ownerDocument.createTextNode(final_indent))
  59         if indent:
  60                 indent_text = parent.ownerDocument.createTextNode('\n' + (' ' * indent))
  61                 parent.insertBefore(indent_text, new)
  62
  63 def create_element(parent, name, uri = XMLNS_INTERFACE, before = []):
  64         """Create a new child element with the given name.
  65         Add it as far down the list of children as possible, but before
  66         any element in the 'before' set. Indent it sensibly."""
  67         new = parent.ownerDocument.createElementNS(uri, name)
  68         insert_element(new, parent, before)
  69         return new
  70
  71 def remove_element(elem):
  72         """Remove 'elem' and any whitespace before it."""
  73         parent = elem.parentNode
  74         prev = elem.previousSibling
  75         if prev and prev.nodeType == Node.TEXT_NODE:
  76                 if prev.nodeValue.strip() == '':
  77                         parent.removeChild(prev)
  78         parent.removeChild(elem)
  79
  80         whitespace = []
  81         for x in parent.childNodes:
  82                 if x.nodeType != Node.TEXT_NODE: return
  83                 if x.nodeValue.strip(): return
  84                 whitespace.append(x)
  85
  86         # Nothing but white-space left
  87         for w in whitespace:
  88                 parent.removeChild(w)
  89
  90 def format_para(para):
  91         """Turn new-lines into spaces, removing any blank lines."""
  92         lines = [l.strip() for l in para.split('\n')]
  93         return ' '.join(filter(None, lines))
  94
  95 def attrs_match(elem, attrs):
  96         for x in attrs:
  97                 if not elem.hasAttribute(x): return False
  98                 if elem.getAttribute(x) != attrs[x]: return False
  99         return True
 100
 101 def child_elements(parent):
 102         """Yield all direct child elements."""
 103         for x in parent.childNodes:
 104                 if x.nodeType == Node.ELEMENT_NODE:
 105                         yield x
 106
 107 def children(parent, localName, uri = XMLNS_INTERFACE, attrs = {}):
 108         """Yield all direct child elements with this name and attributes."""
 109         for x in parent.childNodes:
 110                 if x.nodeType == Node.ELEMENT_NODE:
 111                         if x.nodeName == localName and x.namespaceURI == uri and attrs_match(x, attrs):
 112                                 yield x
 113
 114 def singleton_text(parent, localName, uri = XMLNS_INTERFACE):
 115         """Return the text of the first child element with this name, or None
 116         if there aren't any."""
 117         elements = list(children(parent, localName, uri))
 118         if elements:
 119                 return data(elements[0])
 120
 121 def set_or_remove(element, attr_name, value):
 122         if value:
 123                 element.setAttribute(attr_name, value)
 124         elif element.hasAttribute(attr_name):
 125                 element.removeAttribute(attr_name)