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from . import rl
from .core import do_one, exhaust, switch
from .traverse import top_down
def subs(d, **kwargs):
""" Full simultaneous exact substitution.
Examples
========
>>> from sympy.strategies.tools import subs
>>> from sympy import Basic, S
>>> mapping = {S(1): S(4), S(4): S(1), Basic(S(5)): Basic(S(6), S(7))}
>>> expr = Basic(S(1), Basic(S(2), S(3)), Basic(S(4), Basic(S(5))))
>>> subs(mapping)(expr)
Basic(4, Basic(2, 3), Basic(1, Basic(6, 7)))
"""
if d:
return top_down(do_one(*map(rl.subs, *zip(*d.items()))), **kwargs)
else:
return lambda x: x
def canon(*rules, **kwargs):
""" Strategy for canonicalization.
Explanation
===========
Apply each rule in a bottom_up fashion through the tree.
Do each one in turn.
Keep doing this until there is no change.
"""
return exhaust(top_down(exhaust(do_one(*rules)), **kwargs))
def typed(ruletypes):
""" Apply rules based on the expression type
inputs:
ruletypes -- a dict mapping {Type: rule}
Examples
========
>>> from sympy.strategies import rm_id, typed
>>> from sympy import Add, Mul
>>> rm_zeros = rm_id(lambda x: x==0)
>>> rm_ones = rm_id(lambda x: x==1)
>>> remove_idents = typed({Add: rm_zeros, Mul: rm_ones})
"""
return switch(type, ruletypes)
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