def _create_parser(self):
def xo_yo(fo1, fo2):
if not fo1:
return fo2
return fo1[1](fo1[0], fo2[0]), fo2[1]
def xo_x(fo1, fo2):
if not fo1:
return fo2
return fo1[1](fo1[0], fo2)
fnumber = Regex(
re.compile(r"[+-]?\d+(?:\.\d*)?(?:[eE][+-]?\d+)?")).value(float)
plus, minus, mult, div = map(Terminal, '+-*/')
addop = (plus | minus).value(lambda o: self._opn[o])
multop = (mult | div).value(lambda o: self._opn[o])
expr = Forward()
sub_expr = Terminal('(').then(expr).skip(')')
factor = Terminal('-').repeat(0, 1).then(fnumber | sub_expr,
lambda x, y: -y if x else y)
term = factor.then(multop, lambda f, o:
(f, o)).repeat(0, None, xo_yo).then(factor, xo_x)
expr.is_(
term.then(addop, lambda f, o:
(f, o)).repeat(0, None, xo_yo).then(term, xo_x))
self.parser = expr
def setUp(self):
# Translated from https://github.com/gvanrossum/pegen/blob/ec2b354f64f6dbfcb46133757fe4c0e07880f526/test/test_pegen.py#L232
ident = Alpha + Alnum.repeat()
atom = (ident.value(lambda v: ast.Name(id=v, ctx=ast.Load()))
| Digit.repeat(1).value(
lambda v: ast.Constant(value=ast.literal_eval(v))))
expr = Forward()
factor = (Terminal('(').then(expr).skip(')') | atom)
term = Forward()
term.is_(
term.skip('*').then(
factor, lambda l, r: ast.BinOp(l, ast.Mult(), r)) ^ term.skip(
'/').then(factor, lambda l, r: ast.BinOp(l, ast.Div(), r))
^ factor)
expr.is_(
expr.skip('+').then(term, lambda l, r: ast.BinOp(l, ast.Add(), r))
^ expr.skip('-').then(
term, lambda l, r: ast.BinOp(l, ast.Sub(), r)) ^ term)
start = expr.skip(Terminal('\n').repeat(0, 1)).filter(
lambda r: not r.remain).value(lambda v: ast.fix_missing_locations(
ast.Expression(v, lineno=1, col_offset=0)))
self.parser = start
