def test_parser(expr):
parser = parser2.Parser() # tree type is parser wrapper
parser.lex.newtext(expr) # subtrees evaluate when clicked
tree = parser.analyse() # input line parses new expr
entry.delete(0, END) # vars set in wrapper dictionary
entry.insert(0, expr) # see lang/text chapter for parser
if tree: viewer.drawTree(tree)
def onInputLine(self, line, viewer): # on input line
p = parser2.Parser() # parse expr text
p.lex.newtext(line) # draw resulting tree
t = p.analyse()
if t: viewer.drawTree(t)