interpret.py

"""
Author: Matúš Ďurica (xduric06)
"""


import sys
import argparse as ap
import xml.etree.ElementTree as ET
from libs.utils import *
from libs.factory import Factory


if __name__ == '__main__':
    GF_vars = {}
    TF_vars = {}
    instructions = []
    LF_stack = []
    labels = {}
    call_stack = []
    data_stack = []

    arg_parser = ap.ArgumentParser(
        prog='interpret', description='Interpretting XML file')
    arg_parser.add_argument('--source', metavar='file',
                            nargs='?', help='XML source file')
    arg_parser.add_argument('--input', metavar='file',
                            nargs='?', help='Input file')

    input_file_flag = 0
    TF_created_flag = 0
    args = arg_parser.parse_args()

    if not args.source and not args.input:
        errprint('At least one file has to be specified')
        exit(10)

    if args.input:
        input_file_flag = 1
        args.input = open(args.input)

    # parsing XML
    if args.source:
        try:
            tree = ET.parse(args.source)
        except ET.ParseError:
            errprint('Badly formatted XML file!')
            exit(31)

    else:
        tree = ET.parse(sys.stdin)

    program = tree.getroot()

    for node in program:
        if not re.match(r'^instruction$', node.tag):
            errprint('Bad node tag!')
            exit(32)
        opcode = node.attrib.get('opcode', 'ERR:NotFound')
        if opcode == 'ERR:NotFound':
            errprint('Missing opcode!')
            exit(32)
        try:
            try:
                order = int(node.attrib.get('order'))
            except ValueError:
                errprint('Number as order!')
                exit(32)
        except TypeError:
            errprint('Missing order!')
            exit(32)
        instr = Factory.create(opcode, order)
        instructions.append(instr)

        for arg in node:
            if re.match(r'^arg[\d]+$', arg.tag):
                if arg.attrib.get('type') == 'string':
                    if not arg.text:
                        arg_text = ''
                    else:
                        arg_text = parse_esc_seq(str(arg.text))
                else:
                    arg_text = arg.text
                instr.add_arg(arg.attrib.get('type'),
                              arg_text, arg.tag)
            else:
                errprint('Bad argument tag!')
                exit(32)
        for index, checked in enumerate(instr.get_args()):
            if int(checked.get_order()) != index+1:
                errprint('Bad argument order!')
                exit(32)

    # sorting by order
    instructions = sorted(instructions, key=lambda x: x.get_order())

    # changing order to increments of 1; easier implementation of jumps
    index = 1
    last = 0
    for i in instructions:
        if i.get_order() == last:
            errprint('Duplicit order!')
            exit(32)
        i.set_order(index)
        last = i.get_order()
        index += 1

    # main interpretting loop
    iterator_obj = iter(instructions)
    while True:
        try:
            current_instruction = next(iterator_obj)
        except StopIteration:
            break

        tmp = iterator_obj

        match current_instruction.get_opcode():
            case 'JUMP' | 'JUMPIFEQ' | 'JUMPIFNEQ' | 'CALL' | 'RETURN':
                iterator_obj = current_instruction.execute(GF_vars, TF_vars, LF_stack, instructions,
                                                           labels, input_file_flag, TF_created_flag, args, current_instruction, call_stack, data_stack)
                if not iterator_obj:
                    iterator_obj = tmp
            case 'CREATEFRAME' | 'PUSHFRAME':
                TF_created_flag = current_instruction.execute(GF_vars, TF_vars, LF_stack, instructions,
                                                              labels, input_file_flag, TF_created_flag, args, current_instruction, call_stack, data_stack)
            case _:
                current_instruction.execute(GF_vars, TF_vars, LF_stack, instructions,
                                            labels, input_file_flag, TF_created_flag, args, current_instruction, call_stack, data_stack)