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"""
Turtle DSL
==========
Implements a LOGO-like toy language for Python’s turtle, with interpreter.
"""
try:
input = raw_input # For Python2 compatibility
except NameError:
pass
import turtle
from lark import Lark
turtle_grammar = """
start: instruction+
instruction: MOVEMENT NUMBER -> movement
| "c" COLOR [COLOR] -> change_color
| "fill" code_block -> fill
| "repeat" NUMBER code_block -> repeat
code_block: "{" instruction+ "}"
MOVEMENT: "f"|"b"|"l"|"r"
COLOR: LETTER+
%import common.LETTER
%import common.INT -> NUMBER
%import common.WS
%ignore WS
"""
parser = Lark(turtle_grammar)
def run_instruction(t):
if t.data == 'change_color':
turtle.color(*t.children) # We just pass the color names as-is
elif t.data == 'movement':
name, number = t.children
{ 'f': turtle.fd,
'b': turtle.bk,
'l': turtle.lt,
'r': turtle.rt, }[name](int(number))
elif t.data == 'repeat':
count, block = t.children
for i in range(int(count)):
run_instruction(block)
elif t.data == 'fill':
turtle.begin_fill()
run_instruction(t.children[0])
turtle.end_fill()
elif t.data == 'code_block':
for cmd in t.children:
run_instruction(cmd)
else:
raise SyntaxError('Unknown instruction: %s' % t.data)
def run_turtle(program):
parse_tree = parser.parse(program)
for inst in parse_tree.children:
run_instruction(inst)
def main():
while True:
code = input('> ')
try:
run_turtle(code)
except Exception as e:
print(e)
def test():
text = """
c red yellow
fill { repeat 36 {
f200 l170
}}
"""
run_turtle(text)
if __name__ == '__main__':
# test()
main()
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