aml.py

# node = '(' NAME {attribute} {node} ')'
# attribute = NAME '=' VALUE

import re

class Node(object):
    def __init__(self, name, attributes=None, children=None):
        self.name, self.attributes, self.children = name, attributes or {}, children or []
    
    def __repr__(self):
        return "(%s%s%s%s%s)" % (
            self.name,
            " " if self.attributes else "",
            " ".join("%s=%r" % i for i in self.attributes.items()),
            " " if self.children else "",
            " ".join(repr(c) for c in self.children)
        )

def Scanner(s):
    for m in re.finditer(r'''(\w+)|"([^"]*)"|'([^']*)'|([()=])|#.*?\n|\s+''', s):
        if m.lastindex:
            t = m.group(m.lastindex)
            if m.lastindex == 1: yield "name", t
            elif m.lastindex in (2, 3): yield "value", t
            elif m.lastindex == 4: yield t, t
    yield None, None

class Parser(object):
    def __init__(self, scanner):
        self.scanner = scanner; self.advance()
    
    def advance(self):
        self.t, self.v = self.scanner.next()
    
    def expect(self, t):
        if self.t != t: raise SyntaxError, t + " expected"
        v = self.v; self.advance(); return v
    
    def node(self):
        self.expect('(')
        node = Node(self.expect("name"))
        while self.t == "name": self.attribute(node)
        while self.t == '(': node.children.append(self.node())
        self.expect(')')
        return node
    
    def attribute(self, node):
        name = self.expect("name"); self.expect("=")
        node.attributes[name] = self.expect("value")