lambdaV: Implement parser

At this point, I have no idea how well it actually works as I have
only performed basic sanity checks on it. But it seems to work.
BodgeMaster 2022-11-05 05:36:57 +01:00
parent eab0d86d7a
commit eeade31e47
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#!/usr/bin/env python3
# Copyright 2022, Jan Danielzick (aka. BodgeMaster)
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, version 3.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied
# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# version 3 along with this program.
# If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
import re
debug_mode = True
cursor_up = 'Λ'
cursor_down = 'V'
cursor_left = '<'
cursor_right = '>'
empty_field = [
" ________________ ",
"| |",
"| |",
"| |",
"| |",
"| |",
"| |",
"| |",
"| |",
" ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ "
]
wall = '#'
apple = 'ó'
goal = '$'
cursor_position = [0, 0]
def debug_message(text):
if debug_mode:
print("DEBUG: ", end="")
print(text)
def condition_in_front_of_wall(inverted):
return False
def condition_goal_reached(inverted):
return False
def condition_on_apple(inverted):
return False
def condition_facing_north(inverted):
return False
def condition_facing_south(inverted):
return False
def condition_facing_east(inverted):
return False
def condition_facing_west(inverted):
return False
# condition prefixed with !
def modifier_not(condition):
return condition(true)
# return value: "" or error message
def command_step():
#TODO
return ""
def command_left():
return ""
def command_right():
return ""
def command_repeat(number, parsed_code):
return ""
def command_while(parsed_condition, parsed_code):
return ""
def command_take():
return ""
def command_if(parsed_condition, parsed_then_code, parsed_else_code):
return ""
# returns -1 for generic error
# returns -2 if end cant be found
def get_length_of_condition(code):
if len(code)==0:
return -1
if code[0] == '<':
length = 0
while length<len(code) and code[length]!='>':
length = length+1
if length==len(code) and code[-1]!='>':
return -2
return length+1
else:
return -1
# returns -1 for generic error
# returns -2 if end cant be found
def get_length_of_contained_code(code):
if len(code)==0:
return -1
if code[0] == '(':
length = 1
nesting_level = 1
while length<len(code) and nesting_level>0:
if code[length] == '(':
nesting_level = nesting_level+1
elif code[length] == ')':
nesting_level = nesting_level-1
length = length+1
if length==len(code) and nesting_level > 0:
return -2
return length
else:
return -1
# clean up whitespace
def format_code(code):
regex_pattern = re.compile(r'\s+')
code = " ".join(re.sub(regex_pattern, ' ', code).lower().split())
code = code.replace(" (", "(")
code = code.replace("( ", "(")
code = code.replace(" )", ")")
code = code.replace(") ", ")")
code = code.replace(" <", "<")
code = code.replace("< ", "<")
code = code.replace(" >", ">")
code = code.replace("< ", "<")
code = code.replace("! ", "!")
# add spaces back after closing parenthesis
code = code.replace(")", ") ")
code = code.replace(") )", "))")
code = code.replace(") )", "))")
if len(code)>0 and code[-1]==' ':
return code[:-1]
return code
# returns [function, inverted?, error message]
def parse_condition(condition_code, allowed_conditions):
inverted = False
condition = None
if len(condition_code)==0:
debug_message(" No condition specified")
return [condition, inverted, "Syntax error: No condition specified"]
if condition_code[0]=='!':
debug_message(" Condition is inverted")
inverted = True
condition_code = condition_code[1:]
if len(condition_code)==0:
debug_message(" No condition specified")
return [condition, inverted, "Syntax error: No condition specified"]
if condition_code == "in front of wall":
condition = condition_in_front_of_wall
elif condition_code == "goal reached":
condition = condition_goal_reached
elif condition_code == "on apple":
condition = condition_on_apple
elif condition_code == "facing north":
condition = condition_facing_north
elif condition_code == "facing south":
condition = condition_facing_south
elif condition_code == "facing east":
condition = condition_facing_east
elif condition_code == "facing west":
condition = condition_facing_west
else:
debug_message(" Unknown condition: "+condition_code)
return [condition, inverted, "Unknown condition: "+condition_code]
return [condition, inverted, ""]
# returns [[functions], [arguments], -1, ""] or [[], [], error_position, "error message"]
def parse_code(code, allowed_commands, allowed_conditions, unformatted_code=True):
if unformatted_code:
code = format_code(code)
debug_message("Formatted code: "+code)
parse_position = 0
parsed_code = [[], [], -1, ""]
while parse_position < len(code):
# find next command
next_space = code.find(' ', parse_position)
next_condition = code.find('<', parse_position)
if next_space == -1:
next_space = len(code)
if next_condition == -1:
next_condition = len(code)
# Are we working with a simple command?
if next_condition>next_space or next_condition==next_space:
next_command = code[parse_position:next_space]
debug_message("Next command is: "+next_command)
parsed_code[1].append(())
#TODO: add function to to the function list
if next_command == "step":
parsed_code[0].append(command_step)
elif next_command == "left":
parsed_code[0].append(command_left)
elif next_command == "right":
parsed_code[0].append(command_right)
elif next_command == "take":
parsed_code[0].append(command_take)
elif next_command == "repeat":
return [[], [], next_space, "Syntax error: Condition missing"]
elif next_command == "while":
return [[], [], next_space, "Syntax error: Condition missing"]
elif next_command == "if":
return [[], [], next_space, "Syntax error: Condition missing"]
elif next_command == "else":
return [[], [], parse_position, "Syntax error: Else without if statement"]
else:
#TODO: better error message (especially when special chars are detected inside next_command or a known command)
return [[], [], parse_position, "Unknown command: "+next_command]
parse_position = next_space+1
else:
debug_message("Found control structure...")
control_structure = code[parse_position:next_condition]
if control_structure == "repeat":
debug_message(" Type: repeat loop")
parse_position = next_condition
repetitions_length = get_length_of_condition(code[parse_position:])
if repetitions_length == -2:
debug_message(" Mismatched <>")
return [[], [], parse_position, "Syntax error: Cannot not find matching '>' for this '<'"]
repetitions = code[parse_position:parse_position+repetitions_length]
debug_message(" Number of repetitions: "+repetitions)
repetitions_int = 0
try:
repetitions_int = int(repetitions[1:-1])
except ValueError:
return [[], [], parse_position, "Not a valid number: "+repetitions[1:-1]]
parse_position = parse_position+len(repetitions)
contained_code_length = get_length_of_contained_code(code[parse_position:])
if contained_code_length == -1:
debug_message(" Missing (")
return [[], [], parse_position, "Syntax error: Cannot not find '(' for contained code"]
if contained_code_length == -2:
debug_message(" Mismatched ()")
return [[], [], parse_position, "Syntax error: Cannot not find matching ')' for this '('"]
contained_code = code[parse_position:parse_position+contained_code_length]
debug_message(" Contained code: "+contained_code)
parsed_contained_code = parse_code(contained_code[1:-1], allowed_commands, allowed_conditions, unformatted_code=False)
if not parsed_contained_code[2]==-1:
debug_message(" Error while parsing contained code")
return [[], [], parse_position+1+parsed_contained_code[2], parsed_contained_code[3]]
parse_position = parse_position+contained_code_length+1
parsed_code[1].append((repetitions_int, parsed_contained_code))
parsed_code[0].append(command_repeat)
continue
elif control_structure == "if":
debug_message(" Type: if statement")
parse_position = next_condition
condition_length = get_length_of_condition(code[parse_position:])
if condition_length == -2:
debug_message(" Mismatched <>")
return [[], [], parse_position, "Syntax error: Cannot not find matching '>' for this '<'"]
condition = code[parse_position:parse_position+condition_length]
debug_message(" Condition is: "+condition)
parsed_condition = parse_condition(condition[1:-1], allowed_conditions)
if not parsed_condition[2]=="":
return [[], [], parse_position, parsed_condition[2]]
parse_position = parse_position+len(condition)
then_code_length = get_length_of_contained_code(code[parse_position:])
if then_code_length == -1:
debug_message(" Missing (")
return [[], [], parse_position, "Syntax error: Cannot not find '(' for then-code"]
if then_code_length == -2:
debug_message(" Mismatched ()")
return [[], [], parse_position, "Syntax error: Cannot not find matching ')' for this '('"]
then_code = code[parse_position:parse_position+then_code_length]
debug_message(" Then-code: "+then_code)
parsed_then_code = parse_code(then_code[1:-1], allowed_commands, allowed_conditions, unformatted_code=False)
if not parsed_then_code[2]==-1:
debug_message(" Error while parsing then-code")
return [[], [], parse_position+1+parsed_then_code[2], parsed_then_code[3]]
parse_position = parse_position+then_code_length+1
parsed_else_code = None
if parse_position<len(code)+4 and code[parse_position:parse_position+4]=="else":
parse_position = parse_position+4
else_code_length = get_length_of_contained_code(code[parse_position:])
if else_code_length == -1:
debug_message(" Missing (")
return [[], [], parse_position, "Syntax error: Cannot not find '(' for else-code"]
if else_code_length == -2:
debug_message(" Mismatched ()")
return [[], [], parse_position, "Syntax error: Cannot not find matching ')' for this '('"]
else_code = code[parse_position:parse_position+else_code_length]
debug_message(" Else-code: "+else_code)
parsed_else_code = parse_code(else_code[1:-1], allowed_commands, allowed_conditions, unformatted_code=False)
parse_position = parse_position+else_code_length+1
parsed_code[1].append((parsed_condition, parsed_then_code, parsed_else_code))
parsed_code[0].append(command_if)
continue
elif control_structure == "while":
debug_message(" Type: while loop")
parse_position = next_condition
condition_length = get_length_of_condition(code[parse_position:])
if condition_length == -2:
debug_message(" Mismatched <>")
return [[], [], parse_position, "Syntax error: Cannot not find matching '>' for this '<'"]
condition = code[parse_position:parse_position+condition_length]
debug_message(" Condition is: "+condition)
parsed_condition = parse_condition(condition[1:-1], allowed_conditions)
if not parsed_condition[2]=="":
return [[], [], parse_position, parsed_condition[2]]
parse_position = parse_position+len(condition)
contained_code_length = get_length_of_contained_code(code[parse_position:])
if contained_code_length == -1:
debug_message(" Missing (")
return [[], [], parse_position, "Syntax error: Cannot not find '(' for contained code"]
if contained_code_length == -2:
debug_message(" Mismatched ()")
return [[], [], parse_position, "Syntax error: Cannot not find matching ')' for this '('"]
contained_code = code[parse_position:parse_position+contained_code_length]
debug_message(" Contained code: "+contained_code)
parsed_contained_code = parse_code(contained_code[1:-1], allowed_commands, allowed_conditions, unformatted_code=False)
if not parsed_contained_code[2]==-1:
debug_message(" Error while parsing contained code")
return [[], [], parse_position+1+parsed_contained_code[2], parsed_contained_code[3]]
parse_position = parse_position+contained_code_length+1
parsed_code[1].append((parsed_condition, parsed_contained_code))
parsed_code[0].append(command_while)
else:
debug_message(" Type: unknown control structure: "+control_structure)
#TODO: better error message (especially when special chars are detected inside control_structure or a known command)
return [[], [], parse_position, "Syntax error: Unknown control structure: "+control_structure]
return parsed_code
# returns success or error message
# Parsed code is the result of running the parser.
def run_code(parsed_code):
return ""
if __name__ == "__main__":
pass