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from sympy.strategies.traverse import (
top_down, bottom_up, sall, top_down_once, bottom_up_once, basic_fns)
from sympy.strategies.rl import rebuild
from sympy.strategies.util import expr_fns
from sympy.core.add import Add
from sympy.core.basic import Basic
from sympy.core.numbers import Integer
from sympy.core.singleton import S
from sympy.core.symbol import Str, Symbol
from sympy.abc import x, y, z
def zero_symbols(expression):
return S.Zero if isinstance(expression, Symbol) else expression
def test_sall():
zero_onelevel = sall(zero_symbols)
assert zero_onelevel(Basic(x, y, Basic(x, z))) == \
Basic(S(0), S(0), Basic(x, z))
def test_bottom_up():
_test_global_traversal(bottom_up)
_test_stop_on_non_basics(bottom_up)
def test_top_down():
_test_global_traversal(top_down)
_test_stop_on_non_basics(top_down)
def _test_global_traversal(trav):
zero_all_symbols = trav(zero_symbols)
assert zero_all_symbols(Basic(x, y, Basic(x, z))) == \
Basic(S(0), S(0), Basic(S(0), S(0)))
def _test_stop_on_non_basics(trav):
def add_one_if_can(expr):
try:
return expr + 1
except TypeError:
return expr
expr = Basic(S(1), Str('a'), Basic(S(2), Str('b')))
expected = Basic(S(2), Str('a'), Basic(S(3), Str('b')))
rl = trav(add_one_if_can)
assert rl(expr) == expected
class Basic2(Basic):
pass
def rl(x):
if x.args and not isinstance(x.args[0], Integer):
return Basic2(*x.args)
return x
def test_top_down_once():
top_rl = top_down_once(rl)
assert top_rl(Basic(S(1.0), S(2.0), Basic(S(3), S(4)))) == \
Basic2(S(1.0), S(2.0), Basic(S(3), S(4)))
def test_bottom_up_once():
bottom_rl = bottom_up_once(rl)
assert bottom_rl(Basic(S(1), S(2), Basic(S(3.0), S(4.0)))) == \
Basic(S(1), S(2), Basic2(S(3.0), S(4.0)))
def test_expr_fns():
expr = x + y**3
e = bottom_up(lambda v: v + 1, expr_fns)(expr)
b = bottom_up(lambda v: Basic.__new__(Add, v, S(1)), basic_fns)(expr)
assert rebuild(b) == e
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