# After being inspired by...
# craftinginterpreters.com/representing-code.html
# ...I'm implementing the breakfast generator that the author describes
# therein.
import random
import string
# Breakfast
def breakfast():
fn = random.choice([
lambda: " ".join([protein(), "with", breakfast(), "on the side"]),
lambda: protein(),
lambda: bread(),
])
return fn()
def protein():
fn = random.choice([
lambda: " ".join([qualifier(), "crispy", "bacon"]),
lambda: "sausage",
lambda: " ".join([cooking_method(), "sausage"]),
])
return fn()
def qualifier():
fn = random.choice([
lambda: "really",
lambda: "super",
lambda: " ".join(["really", qualifier()]),
])
return fn()
def cooking_method():
return random.choice([
"scrambled",
"poached",
"fried",
])
def bread():
return random.choice([
"toast",
"biscuits",
"English muffin",
])
print(breakfast())
# Expression Language
# Because Python is a strictly evaluated language any functions that are
# mutually recursive won't terminate and will overflow our stack. Therefore, any
# non-terminals expressed in an alternative are wrapped in lambdas as thunks.
def expression():
fn = random.choice([
lambda: literal(),
lambda: binary(),
])
return fn()
def literal():
return str(random.randint(0, 100))
def binary():
return " ".join([expression(), operator(), expression()])
def operator():
return random.choice(["+", "*"])
print(expression())
# Lox
def lox_expression():
fn = random.choice([
lambda: lox_literal(),
lambda: lox_unary(),
lambda: lox_binary(),
lambda: lox_grouping(),
])
return fn()
def lox_literal():
fn = random.choice([
lambda: str(random.randint(0, 100)),
lambda: lox_string(),
lambda: random.choice(["true", "false"]),
lambda: "nil",
])
return fn()
def lox_string():
return "\"{}\"".format(
"".join(random.choice(string.ascii_lowercase)
for _ in range(random.randint(0, 25))))
def lox_grouping():
return "(" + lox_expression() + ")"
def lox_unary():
return random.choice(["-", "!"]) + lox_expression()
def lox_binary():
return lox_expression() + lox_operator() + lox_expression()
def lox_operator():
return random.choice(["==", "!=", "<", "<=", ">", ">=", "+", "-", "*", "/"])
print(lox_expression())
