def walk(p, q=capture1(an_instance(int))):
return ( nest(one_of('+') + p.star() + end) >> tag('+')
| nest(one_of('-') + p.star() + end) >> tag('-')
| q)
def walk(p, q=capture1(an_instance(int))):
return (nest(one_of('+') + p.star() + end) >> tag('+')
| nest(one_of('-') + p.star() + end) >> tag('-')
| q)
from operator import add, sub
from parson import anyone, capture, delay, nest, one_of, one_that
end = ~anyone
def match(p, x): return (p + end)([x])
def an_instance(type_): return one_that(lambda x: isinstance(x, type_))
def capture1(p): return capture(p) >> (lambda x: x[0]) # Ouch
var = capture1(anyone)
## (var + var)(eg)
#. ('+', 2)
calc = delay(lambda:
nest(one_of('+') + calc + calc + end) >> add
| nest(one_of('-') + calc + calc + end) >> sub
| capture1(an_instance(int)))
eg = ['+', 2, 3]
## match(calc, eg)
#. (5,)
eg2 = ['+', ['-', 2, 4], 3]
## match(calc, eg2)
#. (1,)
# Exercise: transforming trees with generic walks
flatten1 = delay(lambda:
return (p + end)([x])
def an_instance(type_):
return one_that(lambda x: isinstance(x, type_))
def capture1(p):
return capture(p) >> (lambda x: x[0]) # Ouch
var = capture1(anyone)
## (var + var)(eg)
#. ('+', 2)
calc = delay(lambda: nest(one_of('+') + calc + calc + end) >> add
| nest(one_of('-') + calc + calc + end) >> sub
| capture1(an_instance(int)))
eg = ['+', 2, 3]
## match(calc, eg)
#. (5,)
eg2 = ['+', ['-', 2, 4], 3]
## match(calc, eg2)
#. (1,)
# Exercise: transforming trees with generic walks
flatten1 = delay(lambda: nest(one_of('+') + flatten1.star() + end)
| capture1(an_instance(int)))
