import string,re

TOKEN_RE = re.compile(r"(?P<space>\s+)|[*]?\s*(?P<cond>(=|>=|=<)\s*(\w|[._/+-])+)|(?P<var>\w+[ \t]*(?=[=]))|(?P<comment>#.*)")
VALUE_RE = re.compile(r"=[ \t]*(\"(?P<val1>(\\.|[^\"])*)\"|(?P<val2>[^ \t\n\r\f\v\#]+))")

def parse(filename):
	file = open(filename)
	text = file.read()
	file.close()
	index = index0 = 0
	line = 1
	length = len(text)
	hunks = []
	current_hunk = None
	state = 'preamble'
	def signal_error(msg):
		raise "%s (file: %s, line: %s, column: %s)" \
		      % (msg,filename,line,index-index0)
	def read_result():
		for key,val in res.groupdict().items():
			if val is not None:
				return key,val
	while index<length:
		res = TOKEN_RE.match(text,index)
		if not res:
			signal_error("syntax error")
		type,value = read_result()
		line = line + string.count(text,'\n',index,res.end())
		nlidx = string.rfind(text,'\n',index,res.end())
		if nlidx>0:
			index0 = nlidx + 1
		index = res.end()
		if   type=='space'  : pass
		elif type=='comment': pass
		elif type=='cond'   :
			if state != 'conds':
				current_hunk = {'conds':[],'env':{}}
				hunks.append(current_hunk)
				state = 'conds'
			current_hunk['conds'].append(value)
		elif type=='var'    :
			res = VALUE_RE.match(text,index)
			if not res:
				signal_error("syntax error for assignment to %s" % value)
			if state != 'env':
				if state != 'conds':
					current_hunk = {'conds':[],'env':{}}
					hunks.append(current_hunk)
				state = 'env'
			var = value
			type,value = read_result()
			line = line + string.count(text,'\n',index,res.end())
			nlidx = string.rfind(text,'\n',index,res.end())
			if nlidx>0:
				index0 = nlidx + 1
			index = res.end()
			current_hunk['env'][var] = value
		else:
			signal_error("this should never happen")
	return hunks