def parse(filename):
finput = open(filename)
linput = finput.read().decode('utf-8')
char_stream = antlr3.ANTLRStringStream(linput)
lexer = OpenAirLexer(char_stream)
tokens = antlr3.CommonTokenStream(lexer)
parser = OpenAirParser(tokens)
oair = parser.oair_file()
tree = oair.tree
nodes = antlr3.tree.CommonTreeNodeStream(tree)
nodes.setTokenStream(tokens)
walker = OpenAirWalker(nodes)
walker.debug = False
res = walker.oair_file()
return res
