Coverage for /usr/lib/python3/dist-packages/sympy/strategies/traverse.py: 39%

1"""Strategies to Traverse a Tree.""" 

2from sympy.strategies.util import basic_fns 

3from sympy.strategies.core import chain, do_one 

4 

5 

6def top_down(rule, fns=basic_fns): 

7 """Apply a rule down a tree running it on the top nodes first.""" 

8 return chain(rule, lambda expr: sall(top_down(rule, fns), fns)(expr)) 

9 

10 

11def bottom_up(rule, fns=basic_fns): 

12 """Apply a rule down a tree running it on the bottom nodes first.""" 

13 return chain(lambda expr: sall(bottom_up(rule, fns), fns)(expr), rule) 

14 

15 

16def top_down_once(rule, fns=basic_fns): 

17 """Apply a rule down a tree - stop on success.""" 

18 return do_one(rule, lambda expr: sall(top_down(rule, fns), fns)(expr)) 

19 

20 

21def bottom_up_once(rule, fns=basic_fns): 

22 """Apply a rule up a tree - stop on success.""" 

23 return do_one(lambda expr: sall(bottom_up(rule, fns), fns)(expr), rule) 

24 

25 

26def sall(rule, fns=basic_fns): 

27 """Strategic all - apply rule to args.""" 

28 op, new, children, leaf = map(fns.get, ('op', 'new', 'children', 'leaf')) 

29 

30 def all_rl(expr): 

31 if leaf(expr): 

32 return expr 

33 else: 

34 args = map(rule, children(expr)) 

35 return new(op(expr), *args) 

36 

37 return all_rl