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