def main():
"""check right amount of the command line arguments and start the lexcial analyzer"""
if len(argv) == 2:
# 2 command line arguments (sys.argv[1]: program file)
# interpret the program file supplied by user
# check whether the file exists in the file system
if os.path.exists(argv[1]):
# check suffix of the file
Tools.check_suffix(argv[1])
# create lexer
lexer = Lexer()
# get the raw program string
raw_program_string = Tools.get_raw_program_string(argv[1])
# lexical analyze the program given, break it down to token stream
token_stream = lexer.lex(raw_program_string)
# replica of token stream for checking the length
# since token stream can only be looped once, we have to replicate it
token_stream_replica = lexer.lex(raw_program_string)
# find the length of the token stream
Tools.check_token_length(token_stream_replica)
# create parser
parser = Parser()
# parse the lexical token stream to AST (abstract syntax tree)
parsed_AST = parser.parse(token_stream)
print(parsed_AST)
else:
Tools.print_error("file \"" + argv[1] +
"\" does not exists in the file system.\n")
else:
# other number of command line arguments
# print usage message
Tools.print_warning("Usage: python main.py <program-to-run>\n")
def interpret(raw_program_string):
"""start the interpretation of the program"""
# create the Lexer
lexer = Lexer()
token_stream = lexer.lex(raw_program_string)
# replica of token stream for checking the length
# since token stream can only be looped once, we have to replicate it
token_stream_replica = lexer.lex(raw_program_string)
# find the length of the token stream
Tools.check_token_length(token_stream_replica)
# create parser
parser = Parser()
parsed_AST = parser.parse(token_stream)
# start the type checking process
parsed_AST.typecheck(AST.Type_Context.get_empty_context())
# start the evaluation process
parsed_AST.eval(AST.Eval_Context.get_empty_context())
