smolBASIC.py

# A first text-based programming language for children by Giles Booth.
# It targets the BBC micro:bit using a serial console.
# See https://github.com/blogmywiki/smolBASIC/ for more information.

from microbit import *
import music
from random import *
program_list = []
program_counter = -1
variables = [None]*26
operators = '+-/*'
delay = 500
repeat_count = 0
return_address = 0

def run():
    global program_counter
    global delay
    global program_list
    program_counter = -1
    while program_counter < len(program_list):
        program_counter += 1
        if program_counter == len(program_list):
            break
        else:
            parse(program_list[program_counter])
            sleep(delay)

def load():
    global program_list
    with open('data') as f:
        joined_list = f.read()
        program_list = joined_list.split(',')
    for i in range(len(program_list)):
        print(i,program_list[i])


def help():
    print('smolBASIC')
    print('Type image names and then \'run\' to display them.')
    print('\'scroll hello\' scrolls hello on LED display.')
    print('\'beep A\' plays the note A')
    print('\'stop\' stops the program')
    print('\'input a\' prompts user input of a variable')
    print('\'a=23\' assigns 23 to variable a')
    print('\'random a 99\' assigns a random number between 1 and 99 to a')
    print('\'if a>b goto 3\' jumps to line 3 if a>b.')
    print('\'goto 0\' will go back to line 0 in a program.')
    print('You can also use < and = as comparisons.')
    print('Loop with \'repeat 5\' ... \'again\'')
    print('\'list\' to list your program.')
    print('\'new\' to create a new program.')
    print('\'save\' stores your program in non-volatile memory.')
    print('\'load\' to load your program from non-volatile memory.')
    print('\'del 3\' deletes line 3.')    
    print('Edit line 3 by typing \'3 happy\'')

def parse(instruction):
    global program_counter
    global repeat_count
    global return_address
    global variables
    try:
        if instruction.startswith('goto '):
            split = instruction.find(' ') + 1
            line_number = int(instruction[split:])
            if line_number > -1 and line_number < len(program_list) + 1:
                program_counter = line_number - 1
            else:
                print('Goto error: line doesn\'t exist.')
        elif instruction.startswith('wait '):
            split = instruction.find(' ') + 1
            wait_time = int(instruction[split:])
            sleep(wait_time)
            print('sleep')
        elif instruction.startswith('repeat '):
            split = instruction.find(' ') + 1
            repeat_count = int(instruction[split:])
            return_address = program_counter
        elif instruction == 'again':
            repeat_count -= 1
            if repeat_count != 0:
                program_counter = return_address
        elif instruction == 'clear':
            display.clear()
        elif instruction == 'stop':
            program_counter = len(program_list)
        elif instruction.startswith('beep '):
            music.play(instruction[5])
        elif instruction.startswith('random '):
            var_rnd = instruction[7]
            var_index = ord(var_rnd) - 97
            rnd_range = int(instruction[9:])
            variables[var_index] = randint(0,rnd_range)
        elif instruction.startswith('if '):
            var1 = ord(instruction[3]) - 97
            operator = instruction[4]
            var2 = ord(instruction[5]) - 97
            goto = int(instruction[12:])
            if goto  < 0 or goto > len(program_list):
                print('Goto error: line doesn\'t exist.')
            else:
                if operator == '=':
                    if variables[var1] == variables[var2]:
                        program_counter = goto - 1
                elif operator == '>':
                    if variables[var1] > variables[var2]:
                        program_counter = goto - 1
                elif operator == '<':
                    if variables[var1] < variables[var2]:
                        program_counter = goto - 1
                else:
                    print('If error: comparsion operators must be =, < or >')
        elif instruction.startswith('scroll '):
            split = instruction.find(' ') + 1
            display.scroll(instruction[split:])
        elif instruction.startswith('input ') and len(instruction) == 7:
            var_input = instruction[6]
            var_index = ord(var_input) - 97
            if var_index >= 0 and var_index <= 26:
                input_text = input()
                try:
                    variables[var_index] = int(input_text)
                except ValueError:
                    variables[var_index] = input_text
            else:
                print('Variable names must be letter a-z.')
        elif instruction.startswith('print '):
            if len(instruction) == 7 and instruction[6].isalpha():
                var_print = instruction[6]
                var_index = ord(var_print) - 97            
                print(variables[var_index])
            else:
                split = instruction.find(' ') + 1
                print(instruction[split:])
        elif len(instruction) == 5 and instruction[3] in operators and instruction[1] == '=' and ord(instruction[0]) > 96 and ord(instruction[0]) < 123 and ord(instruction[2]) > 96 and ord(instruction[2]) < 123 and ord(instruction[4]) > 96 and ord(instruction[4]) < 123:
            var1 = instruction[0]
            var2 = instruction[2]
            var3 = instruction[4]
            operator = instruction[3]
            if operator == '+':
                variables[ord(var1)-97] = variables[ord(var2)-97] + variables[ord(var3)-97]
            elif operator == '-':
                variables[ord(var1)-97] = variables[ord(var2)-97] - variables[ord(var3)-97]
            if operator == '/':
                variables[ord(var1)-97] = variables[ord(var2)-97] / variables[ord(var3)-97]
            if operator == '*':
                variables[ord(var1)-97] = variables[ord(var2)-97] * variables[ord(var3)-97]            
        elif '=' in instruction:
            split = instruction.find('=') + 1
            var_name = instruction[:split-1]
            var_contents = instruction[split:]
            if len(var_name) == 1 and var_name.isalpha():
                if var_contents == 'light':
                    variables[ord(var_name)-97] = display.read_light_level()
                elif var_contents == 'temp':
                    variables[ord(var_name)-97] = temperature()
                elif var_contents == 'sound':
                    variables[ord(var_name)-97] = microphone.sound_level()
                elif var_contents == 'button a':
                    if button_a.was_pressed():
                        variables[ord(var_name)-97] = 1
                    else:
                        variables[ord(var_name)-97] = 0
                elif var_contents == 'button b':
                    if button_b.was_pressed():
                        variables[ord(var_name)-97] = 1
                    else:
                        variables[ord(var_name)-97] = 0
                else:
                    try:
                        variables[ord(var_name)-97] = int(var_contents)
                    except ValueError:
                        variables[ord(var_name)-97] = var_contents
            else:
                print('Variable names must be one letter a-z.')
        elif instruction == 'heart':
            display.show(Image.HEART)
        elif instruction == 'happy':
            display.show(Image.HAPPY)
        elif instruction == 'sad':
            display.show(Image.SAD)
        elif instruction == 'meh':
            display.show(Image.MEH)
        elif instruction == 'confused':
            display.show(Image.CONFUSED)
        elif instruction == 'angry':
            display.show(Image.ANGRY)
        elif instruction == 'asleep':
            display.show(Image.ASLEEP)
        elif instruction == 'yes':
            display.show(Image.YES)
        elif instruction == 'no':
            display.show(Image.NO)
        elif instruction == 'duck':
            display.show(Image.DUCK)
        elif instruction == 'small heart':
            display.show(Image.HEART_SMALL)
        elif instruction == 'pacman':
            display.show(Image.PACMAN)
        elif instruction == 'ghost':
            display.show(Image.GHOST)
        elif instruction == 'skull':
            display.show(Image.SKULL)
        elif instruction == 'rabbit':
            display.show(Image.RABBIT)
        elif instruction == 'diamond':
            display.show(Image.DIAMOND)
        elif instruction == 'small diamond':
            display.show(Image.DIAMOND_SMALL)
        elif instruction == 'star':
            display.show(Image('00300:'
                               '03630:'
                               '36963:'
                               '03630:'
                               '00300'))
        else:
            display.show('?')
    except:
        print('There\'s a mistake in your program.')

try:
    load()
    run()
except:
    pass

print('smolBASIC')
print('Type \'help\' for a list of commands.')
    
while True:
    new_line = input('> ')
    if new_line.startswith('del '):
        if ' ' in new_line:
            split = new_line.find(' ') + 1
            line_number = int(new_line[split:])
            if line_number > -1 and line_number < len(program_list):
                del program_list[line_number]
                print('deleted line ' + str(line_number))
            else:
                print('That line doesn\'t exist.')
        else:
            print('You need to tell me which line to delete.')
    elif new_line[:1].isdigit():
        split = new_line.find(' ') + 1
        line_number = int(new_line[:split])
        if line_number >= 0 and line_number < len(program_list):
            program_list[line_number] = new_line[split:]
        else:
            print('Line', line_number, 'doesn\'t exist.')
    elif new_line == 'list':
        for i in range(len(program_list)):
            print(i,program_list[i])
    elif new_line == 'new':
        program_list = []
    elif new_line == 'help':
        help()
    elif new_line == 'save':
        my_file = open('data', 'w')
        joined_list = ",".join(program_list)
        my_file.write(joined_list)
        my_file.close()
        print('Program saved.')
    elif new_line == 'load':
        try:
            load()
        except:
            print('No file to load.')
    elif new_line == 'fast':
        delay = 0
    elif new_line == 'slow':
        delay = 500
    elif new_line == 'run':
        run()
    else:
        if new_line != '':
            program_list.append(new_line)