| 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) | |