# XML DOM tree manipulation

from xml.dom import Node

def name_of(node): return node.tagName.lower()

def get_id(node): return node.getAttribute('id')

def set_id(node, id_): node.setAttribute('id', id_)

class NodeElemIter:

    def __init__(self, node): self.child = node.firstChild

    def __iter__(self): return self

    def curr(self):

        while self.child != None:

            if self.child.nodeType == Node.ELEMENT_NODE: return self.child

            self.child = self.child.nextSibling

        raise StopIteration

    def next(self):

        child = self.curr()

        self.child = self.child.nextSibling

        return child

def first_elem(node): return NodeElemIter(node).next()

class NodeElemReverseIter:

    def __init__(self, node): self.child = node.lastChild

    def __iter__(self): return self

    def curr(self):

        while self.child != None:

            if self.child.nodeType == Node.ELEMENT_NODE: return self.child

            self.child = self.child.previousSibling

        raise StopIteration

    def next(self):

        child = self.curr()

        self.child = self.child.previousSibling

        return child

def last_elem(node): return NodeElemReverseIter(node).next()

class NodeParentIter:

    def __init__(self, node): self.node = node

    def __iter__(self): return self

    def curr(self):

        if self.node != None and self.node.nodeType == Node.ELEMENT_NODE:

            return self.node

        raise StopIteration

    def next(self):

        node = self.curr()

        self.node = self.node.parentNode

        return node

def is_text(node):

    for child in NodeElemIter(node): return False # has an element node

    return True

def value(node):

    if node.firstChild != None: return node.firstChild.nodeValue.strip()

    else: return node.nodeValue

def set_value(doc, node, value):

    if node.nodeType == Node.ELEMENT_NODE:

        node.appendChild(doc.createTextNode(value))

    else: node.nodeValue = value

def by_tag_name(node, name, last_only=False):

    # last_only optimization returns last (most recently inserted) matching node

    children = []

    for child in NodeElemReverseIter(node):

        if child.tagName == name:

            children.append(child)

            if last_only: break

    return children