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Mini Shell
Mini Shell
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 import Add, Basic, Symbol, S
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(0, 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(0, 0, Basic(0, 0))
def _test_stop_on_non_basics(trav):
def add_one_if_can(expr):
try:
return expr + 1
except TypeError:
return expr
expr = Basic(1, 'a', Basic(2, 'b'))
expected = Basic(2, 'a', Basic(3, 'b'))
rl = trav(add_one_if_can)
assert rl(expr) == expected
class Basic2(Basic):
pass
rl = lambda x: Basic2(*x.args) if isinstance(x, Basic) else x
def test_top_down_once():
top_rl = top_down_once(rl)
assert top_rl(Basic(1, 2, Basic(3, 4))) == Basic2(1, 2, Basic(3, 4))
def test_bottom_up_once():
bottom_rl = bottom_up_once(rl)
assert bottom_rl(Basic(1, 2, Basic(3, 4))) == Basic(1, 2, Basic2(3, 4))
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
Zerion Mini Shell 1.0