def init_state():
    return {
           'tokens':   [],
           'pos':      0,
           'codes':    [],
           'branch':   [],
           'words':    {},
           'vars':     {},
           'end':      False
           }

def compile(state, tokens):
    state['tokens'].extend(tokens)
    if state['codes'] and state['codes'][-1] == 'END':
        state['codes'].pop()
    state['end'] = False

    while not state['end']:
        run(state)

    after_last_ret = max(i for i, v in enumerate((';', *state['codes'])) if v == ';')
    return state['codes'], after_last_ret, len(state['vars'])

def run(state):
    if state['pos'] == len(state['tokens']):
        state['codes'].append('END')
        state['end'] = True
        return

    token = state['tokens'][state['pos']]

    if is_int(token):
        run_int(state, token)
    elif token in primitives:
        run_primitive(state, token)
    elif token in state['words']:
        run_word(state, token)
    elif token in state['vars']:
        run_var(state, token)

    state['pos'] += 1


def is_int(s):
    try:
        int(s)
    except ValueError:
        return False
    return True

def run_int(state, token):
    state['codes'].extend(('PUSH', int(token)))


def run_if(state):
    state['branch'].append(len(state['codes']) + 1)
    state['codes'].extend(('IF', None))

def run_else(state):
    if_jump = state['branch'].pop()
    code_len = len(state['codes'])
    state['codes'][if_jump] = code_len + 2
    state['branch'].append(code_len + 1)
    state['codes'].extend(('ELSE', None))

def run_then(state):
    else_jump = state['branch'].pop()
    code_len = len(state['codes'])
    state['codes'][else_jump] = code_len + 1
    state['codes'].append('THEN')

def run_do(state):
    state['branch'].append(len(state['codes']) + 1)
    state['codes'].append('DO')

def run_loop(state):
    do_pos = state['branch'].pop()
    state['codes'].extend(('LOOP', do_pos))

def run_def(state):
    word = state['tokens'][state['pos'] + 1]
    state['words'][word] = len(state['codes'])
    state['tokens'][state['pos'] + 1] = ''

def run_variable(state):
    var = state['tokens'][state['pos'] + 1]
    if var not in state['vars']:
        state['vars'][var] = len(state['vars'])
        state['tokens'][state['pos'] + 1] = ''

primitives = {
        'IF': run_if,
        'ELSE': run_else,
        'THEN': run_then,
        'DO': run_do,
        'LOOP': run_loop,
        'VARIABLE': run_variable,
        ':': run_def,
        ';': lambda s: s['codes'].append(';'),
        '+': lambda s: s['codes'].append('+'),
        '.': lambda s: s['codes'].append('.'),
        'I': lambda s: s['codes'].append('I'),
        'CR': lambda s: s['codes'].append('CR'),
        '@': lambda s: s['codes'].append('@'),
        '!': lambda s: s['codes'].append('!'),
        }

def run_primitive(state, token):
    primitives[token](state)

def run_word(state, token):
    state['codes'].extend(('CALL', state['words'][token]))

def run_var(state, token):
    state['codes'].extend(('PUSH', state['vars'][token]))