rforth/rforth.py

#!/usr/bin/python3
import argparse
stack = []
heap = [0] * 100
next_heap = 0
compiling = False
reading_string = False
words = {}
word_name = ""

def get_next(input_string):
    if len(input_string) > 1:
        return input_string[1:len(input_string)]
    else:
        return []
def get_input():
    i = input()
    return i

def parse_input(input_string, say_ok=True):
    while len(input_string) > 0:
        string = str(input_string[0])
        if not compiling and not reading_string:
            if string.isnumeric():
                add_to_stack(string)
            elif string == "stack":
                show_stack()
            elif string == "+":
                add()
            elif string == "-":
                subtract()
            elif string == ".":
                output()
            elif string == "bye":
                exit()
            elif string == "emit":
                emit()
            elif string == ":":
                start_compiling()
            elif string in words:
                parse_input(words[string].split(" "), False)
            elif string == "words":
                show_words()
            elif string == ">":
                greater_than()
            elif string == "<":
                less_than()
            elif string == "=":
                equals()
            elif string == "if":
                input_string = _if(input_string)
            elif string == "dup":
                dup()
            elif string == "swap":
                swap()
            elif string == "rot":
                rot()
            elif string == "and":
                _and()
            elif string == "or":
                _or()
            elif string == "!":
                store()
            elif string == "@":
                fetch()
            elif string == "heap":
                dump_heap()
            elif string == "alloc":
                alloc()
            elif string == 's"':
                start_reading_string()
        elif reading_string:
            if string == '"':
                stop_reading_string()
            else: 
                add_new_word_to_string(string)
        elif compiling and not reading_string:
            if string == ";":
                stop_compiling()
            else:
                add_to_new_word(string)
        input_string = get_next(input_string)
    if say_ok:
        print("ok.")
def add_new_word_to_string(string):
    for char in string[::-1]:
        stack.insert(0, ord(char))
def dump_heap():
    print(heap)

def alloc():
    global next_heap
    heap[next_heap] = 0
    stack.insert(0, next_heap)
    next_heap += 1

def store():
    k = stack.pop(0)
    v = stack.pop(0)
    heap[k] = v

def fetch():
    k = stack.pop(0)
    v = heap[k]
    stack.insert(0, v)

def rot():
    a = stack.pop(0)
    b = stack.pop(0)
    c = stack.pop(0)
    stack.insert(0,b)
    stack.insert(0,a)
    stack.insert(0,c)

def swap():
    a = stack.pop(0)
    b = stack.pop(0)
    stack.insert(0,a)
    stack.insert(0,b)

def _if(input_string):
    a = stack.pop(0)
    if int(a) == -1:
        then_index = scan_for_then(input_string)
        else_index = scan_for_else(input_string[0:then_index], then_index)
        if else_index == -1:
            return input_string[0:then_index]
        else:
            return input_string[0: else_index] + input_string[then_index : len(input_string)]
    else:
        then_index = scan_for_then(input_string)
        else_index = scan_for_else(input_string[0:then_index], then_index)
        
        if else_index == -1:
            return input_string[then_index: len(input_string)]
        else:
            return input_string[else_index : len(input_string)]
    return input_string

def scan_for_else(input_string, then_index):
    for index in reversed(range(0, then_index)):
        if input_string[index] == "else":
            return index
    return -1

def scan_for_then(input_string):
    for index in reversed(range(0, len(input_string))):
        if input_string[index] == "then":
            return index
    return -1

def dup():
    a = stack.pop(0)
    stack.insert(0,a)
    stack.insert(0,a)

def greater_than():
    a = stack.pop(0)
    b = stack.pop(0)
    if a > b:
        stack.insert(0,-1)
    else:
        stack.insert(0,0)

def less_than():
    a = stack.pop(0)
    b = stack.pop(0)
    if a < b:
        stack.insert(0,-1)
    else:
        stack.insert(0,0)

def equals():
    a = stack.pop(0)
    b = stack.pop(0)
    if a == b:
        stack.insert(0,-1)
    else:
        stack.insert(0,0)

def show_words():
    print(words)

def add_to_new_word(value):
    global word_name
    if word_name == "":
        word_name = value
        words[word_name] = ""
    else:
        words[word_name] = words[word_name] + value + " "

def start_reading_string():
    global reading_string
    reading_string = True

def stop_reading_string():
    global reading_string
    reading_string = False

def start_compiling():
    global compiling
    compiling = True

def stop_compiling():
    global compiling
    global word_name
    compiling = False
    words[word_name] = words[word_name].strip()
    word_name = ""

def emit():
    a = stack.pop(0)
    print(chr(a),end='')

def exit():
    print("l8r sk8r")
    quit()

def output():
    a = stack.pop(0)
    print(a)

def subtract():
    a = stack.pop(0)
    b = stack.pop(0)
    stack.insert(0, a-b)

def add():
    a = stack.pop(0)
    b = stack.pop(0)
    stack.insert(0, a+b)

def _and():
    a = stack.pop(0)
    b = stack.pop(0)
    if a == -1 and b == -1:
        stack.insert(0, -1)
    else:
        stack.insert(0,0)

def _or():
    a = stack.pop(0)
    b = stack.pop(0)
    if a == -1 or b == -1:
        stack.insert(0, -1)
    else:
        stack.insert(0,0)

def show_stack():
    print(stack)

def add_to_stack(value):
    stack.insert(0, int(value))


def main(args):
    if args.preload != None:
        f = open(args.preload, "r")
        file_data = f.readlines()
        preload = []
        for line in file_data:
            split_line = line.split(' ')
            for word in split_line:
                preload.append(word)
        parse_input(preload, False)
        f.close()
    print("Welcome to rforth!")
    while True:
        i = get_input()
        parse_input(i.split(' '))

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='A weird little Forth implementation')
    parser.add_argument('-p', '--preload', default="standard-library.f", type=str, help='A file to preload')
    args = parser.parse_args()
    main(args)