Not a long time ago, I got into Rust and I made a simple Brainfuck Interpreter. Now I want to get back to Rust and I would like some comments on my code:
Just in case it's hard to read code from post:
https://github.com/DimChtz/brainfuck/tree/master/rust-brainpreter
lib.rs
mod core;
use core::parser::Parser;
use core::program::Program;
use core::instruction::Instruction;
use core::error::Error;
use core::memory::Memory;
use std::io;
use std::io::prelude::*;
use std::path::Path;
// Struct for the bf Interpreter (brainpreter)
pub struct Inter {
tape:Memory,
program:Program,
parser:Parser,
}
impl Inter {
// Function to create and return a new Interpreter
pub fn new() -> Inter {
Inter {
tape: Memory::new(),
program: Program::new(),
parser: Parser::new(),
}
}
// Function to load code into the parser (text)
pub fn load<S: Into<String>>(&mut self, p:S) -> Result<(), Error> {
self.parser.load(p)
}
// Function to load code into the parser (file)
pub fn load_from_file<P: AsRef<Path>>(&mut self, src:P) -> Result<(), Error> {
self.parser.load_from_file(src)
}
// Function to compile the code
pub fn parse(&mut self) -> Result<(), Error> {
// Call the parser
match self.parser.parse() {
Ok(p) => {
self.program = p;
Ok(())
}
Err(e) => Result::Err(e),
}
}
// Function to execute bf program
pub fn run(&mut self) -> Result<(), Error> {
// Check if a program is properly loaded
if self.program.get_size() == 0 {
return Result::Err(Error::EmptyProgram);
}
// Execute instructions
while let Some(instr) = self.program.get() {
match instr {
Instruction::IncPtr => { match self.inc_ptr() { Ok(_) => { } Err(e) => return Result::Err(e), } }
Instruction::DecPtr => { match self.dec_ptr() { Ok(_) => { } Err(e) => return Result::Err(e), } }
Instruction::IncVal => { match self.inc_val() { Ok(_) => { } Err(e) => return Result::Err(e), } }
Instruction::DecVal => { match self.dec_val() { Ok(_) => { } Err(e) => return Result::Err(e), } }
Instruction::Input => { self.input(); }
Instruction::Output => { self.output(); }
Instruction::OpenBracket(n) => { self.open_bracket(n); }
Instruction::CloseBracket(n) => { self.close_bracket(n); }
};
// If this was the last instruction
if !self.program.inc_ptr() {
break;
}
};
return Result::Ok(());
}
// Function to increase the value on the memory (tape)
fn inc_val(&mut self) -> Result<(), Error> {
self.tape.inc_val()
}
// Function to decrease the value on the memory (tape)
fn dec_val(&mut self) -> Result<(), Error> {
self.tape.dec_val()
}
// Function to increase the pointer on the memory (tape)
fn inc_ptr(&mut self) -> Result<(), Error> {
self.tape.inc_ptr()
}
// Function to decrease the pointer on the memory (tape)
fn dec_ptr(&mut self) -> Result<(), Error> {
self.tape.dec_ptr()
}
// Function to read into the memory (tape)
fn input(&mut self) {
match io::stdin().bytes().next() {
Some(v) => self.tape.set_val(v.unwrap()),
None => { }
}
}
// Function to print a char from memory (tape)
fn output(&mut self) {
print!("{}", self.tape.get_val() as char);
}
// Function to handle the open bracket
fn open_bracket(&mut self, pos:usize) {
if self.tape.get_val() == 0 {
self.program.set_ptr(pos);
}
}
// Function to handle the close bracket
fn close_bracket(&mut self, pos:usize) {
if self.tape.get_val() != 0 {
self.program.set_ptr(pos);
}
}
}
core/mod.rs
pub mod instruction;
pub mod program;
pub mod parser;
pub mod error;
pub mod memory;
core/error.rs
use std::error;
use std::fmt;
#[derive(Debug)]
pub enum Error {
NoSuchFile,
EmptyProgram,
MissingOpenBracket,
MissingCloseBracket,
PtrOverflow,
PtrUnderflow,
ValOverflow,
ValUnderflow,
}
impl error::Error for Error {
fn description(&self) -> &str {
match *self {
Error::NoSuchFile => "Failed to open file",
Error::EmptyProgram => "The program is empty",
Error::MissingOpenBracket => "Missing open bracket(s)",
Error::MissingCloseBracket => "Missing close bracket(s)",
Error::PtrOverflow => "Memory pointer overflow",
Error::PtrUnderflow => "Memory pointer underflow",
Error::ValOverflow => "Memory value overflow",
Error::ValUnderflow => "Memory value underflow",
}
}
}
impl fmt::Display for Error {
fn fmt(&self, f:&mut fmt::Formatter) -> fmt::Result {
match *self {
Error::NoSuchFile => write!(f, "Couldn't open file."),
Error::EmptyProgram => write!(f, "The program is empty."),
Error::MissingOpenBracket => write!(f, "Missing open bracket(s)."),
Error::MissingCloseBracket => write!(f, "Missing close bracket(s)."),
Error::PtrOverflow => write!(f,"Memory pointer overflow."),
Error::PtrUnderflow => write!(f,"Memory pointer underflow."),
Error::ValOverflow => write!(f,"Memory value overflow."),
Error::ValUnderflow => write!(f,"Memory value underflow."),
}
}
}
core/instruction.rs
use std::fmt::{self, Display};
#[derive(Copy, Clone)]
pub enum Instruction {
IncPtr,
DecPtr,
IncVal,
DecVal,
Input,
Output,
OpenBracket(usize),
CloseBracket(usize),
}
impl Display for Instruction {
fn fmt(&self, f:&mut fmt::Formatter) -> fmt::Result {
match *self {
Instruction::IncPtr => write!(f, ">"),
Instruction::DecPtr => write!(f, "<"),
Instruction::IncVal => write!(f, "+"),
Instruction::DecVal => write!(f, "-"),
Instruction::Input => write!(f, ","),
Instruction::Output => write!(f, "."),
Instruction::OpenBracket(_) => write!(f, "["),
Instruction::CloseBracket(_) => write!(f, "]"),
}
}
}
pub mod mapper {
use super::Instruction;
pub fn get_instr(c:char) -> Option<super::Instruction> {
match c {
'>' => Option::Some(Instruction::IncPtr),
'<' => Option::Some(Instruction::DecPtr),
'+' => Option::Some(Instruction::IncVal),
'-' => Option::Some(Instruction::DecVal),
',' => Option::Some(Instruction::Input),
'.' => Option::Some(Instruction::Output),
'[' => Option::Some(Instruction::OpenBracket(0usize)),
']' => Option::Some(Instruction::CloseBracket(0usize)),
_ => Option::None,
}
}
#[allow(unused)]
pub fn get_char(instr:Instruction) -> char {
match instr {
Instruction::IncPtr => '>',
Instruction::DecPtr => '<',
Instruction::IncVal => '+',
Instruction::DecVal => '-',
Instruction::Input => ',',
Instruction::Output => '.',
Instruction::OpenBracket(_) => '[',
Instruction::CloseBracket(_) => ']',
}
}
}
core/memory.rs
use super::error::Error;
pub const MEMORY_SIZE:usize = 30000;
// Memory tape
#[derive(Debug)]
pub struct Memory {
cells: Vec<u8>,
ptr:usize,
}
impl Memory {
// Function to create and return a new Memory tape
pub fn new() -> Memory {
let mut v = Vec::<u8>::new();
v.push(0);
Memory {
cells: v,
ptr:0,
}
}
// Function to move the pointer to the right
pub fn inc_ptr(&mut self) -> Result<(), Error> {
self.ptr += 1;
match self.ptr {
n if n >= MEMORY_SIZE => {
Result::Err(Error::PtrOverflow)
}
_ => {
if self.ptr >= self.cells.len() {
self.cells.push(0);
}
Result::Ok(())
}
}
}
// Function to move the poiner to the left
pub fn dec_ptr(&mut self) -> Result<(), Error> {
match self.ptr {
n if n == 0 => {
Result::Err(Error::PtrUnderflow)
}
_ => {
self.ptr -= 1;
Result::Ok(())
}
}
}
// Function to increase the value
pub fn inc_val(&mut self) -> Result<(), Error> {
match self.cells[self.ptr].checked_add(1) {
Some(v) => {
self.cells[self.ptr] = v;
Result::Ok(())
}
None => Result::Err(Error::ValOverflow),
}
}
// Function to decrease the value
pub fn dec_val(&mut self) -> Result<(), Error> {
match self.cells[self.ptr].checked_sub(1) {
Some(v) => {
self.cells[self.ptr] = v;
Result::Ok(())
}
None => Result::Err(Error::ValUnderflow),
}
}
// Function to get the current value
pub fn get_val(&self) -> u8 {
self.cells[self.ptr]
}
// Function to set the current value
pub fn set_val(&mut self, v:u8) {
self.cells[self.ptr] = v;
}
}
core/parser.rs
use super::instruction::{mapper, Instruction};
use super::program::Program;
use super::error::Error;
use std::io::prelude::*;
use std::fs::File;
use std::path::Path;
use std::convert::AsRef;
pub struct Parser {
code_buffer:Vec<u8>,
}
impl Parser {
// Function to create and return a new Parser
pub fn new() -> Parser {
Parser {
code_buffer:Vec::<u8>::new(),
}
}
// Function to load code from simple text
pub fn load<S: Into<String>>(&mut self, buffer:S) -> Result<(), Error> {
self.code_buffer = buffer.into().into_bytes();
match self.code_buffer.len() {
l if l > 0 => Result::Ok(()),
_ => Result::Err(Error::EmptyProgram),
}
}
// Function to load code from a file
pub fn load_from_file<P: AsRef<Path>>(&mut self, src:P) -> Result<(), Error> {
match File::open(src) {
Ok(mut file) => {
let mut content = String::new();
match file.read_to_string(&mut content) {
_ => self.load(content)
}
}
Err(_) => Result::Err(Error::NoSuchFile),
}
}
// Function to compile the code into intermidiate code (program)
pub fn parse(&mut self) -> Result<Program, Error> {
// Create a new program
let mut prog = Program::new();
// Create a stack for the loop brackets
let mut loop_stack = Vec::<usize>::new();
// Create a code buffer ptr
let mut code_ptr:usize = 0;
// Compile the code buffer and feed the program
if self.code_buffer.len() != 0 {
loop {
match self.code_buffer[code_ptr] as char {
b @ '+' => { prog.push(mapper::get_instr(b).unwrap()); }
b @ '-' => { prog.push(mapper::get_instr(b).unwrap()); }
b @ '>' => { prog.push(mapper::get_instr(b).unwrap()); }
b @ '<' => { prog.push(mapper::get_instr(b).unwrap()); }
b @ ',' => { prog.push(mapper::get_instr(b).unwrap()); }
b @ '.' => { prog.push(mapper::get_instr(b).unwrap()); }
b @ '[' => {
// Add the instruction to the program (leave 0 for now)
prog.push(mapper::get_instr(b).unwrap());
// Update the loop stack
loop_stack.push(prog.get_size() - 1);
}
']' => {
if loop_stack.is_empty() {
// Missmatch `]` bracket found
return Result::Err(Error::MissingOpenBracket);
}
let curr_ptr = prog.get_size();
let last_open_bracket_ptr = loop_stack.pop().unwrap();
prog.update_instr(last_open_bracket_ptr, Instruction::OpenBracket(curr_ptr));
prog.push(Instruction::CloseBracket(last_open_bracket_ptr));
}
_ => { /* IGNORE UNUSED SYMBOLS */ }
};
code_ptr += 1;
if code_ptr >= self.code_buffer.len() {
break;
}
}
// Check if loop_stack is empty or not -> not = error (missmatched brackets)
if !loop_stack.is_empty() {
return Result::Err(Error::MissingCloseBracket);
}
} else {
// The code buffer is empty -> empty code loaded or just never loaded
return Result::Err(Error::EmptyProgram);
}
// Program is empty return Error (code buffer contains only unused symbols)
if prog.get_size() == 0 {
return Result::Err(Error::EmptyProgram);
}
return Result::Ok(prog);
}
}
core/program.rs
use super::instruction::Instruction;
// Struct for the program (a series of instructions)
pub struct Program {
instr:Vec<Instruction>,
ptr:usize,
}
impl Program {
// Function to create and return a new program
pub fn new() -> Program {
Program {
instr:Vec::<Instruction>::new(),
ptr:0,
}
}
// Function to increase the pointer
pub fn inc_ptr(&mut self) -> bool {
if self.ptr < self.instr.len() - 1 {
self.ptr += 1;
return true;
}
false
}
// Function to decrease the pointer
#[allow(unused)]
pub fn dec_ptr(&mut self) -> bool {
if self.ptr > 0 {
self.ptr -= 1;
return true;
}
false
}
// Function to move the pointer
pub fn set_ptr(&mut self, pos:usize) -> bool {
if pos >= self.get_size() {
return false;
}
self.ptr = pos;
true
}
// Function to get the current instruction (if a program is already loaded and the instruction exists)
pub fn get(&self) -> Option<Instruction> {
if self.instr.len() > 0 { Option::Some(self.instr[self.ptr]) } else { Option::None }
}
// Function to increase the pointer and get the instruction
#[allow(unused)]
pub fn get_next(&mut self) -> Option<Instruction> {
if self.inc_ptr() { self.get() } else { Option::None }
}
// Function to decrease the pointer and get the instruction
#[allow(unused)]
pub fn get_prev(&mut self) -> Option<Instruction> {
if self.dec_ptr() { self.get() } else { Option::None }
}
// Function to get an instruction
#[allow(unused)]
pub fn get_at(&self, p:usize) -> Option<Instruction> {
if p >= (0 as usize) && p < self.instr.len() { Option::Some(self.instr[p]) } else { Option::None }
}
// Function to add a new instruction at the end of the program
pub fn push(&mut self, i:Instruction) -> &mut Program {
self.instr.push(i);
self
}
// Function to remove the last instruction from the program (if exists)
#[allow(unused)]
pub fn pop(&mut self) -> bool {
return match self.instr.pop() {
Some(_) => {
if self.ptr >= self.instr.len() {
if self.ptr > 0 {
self.ptr -= 1;
}
}
true
}
None => false
}
}
// Function to clear the program and set pointer to 0
#[allow(unused)]
pub fn clear(&mut self) -> &mut Program {
self.instr.clear();
self.ptr = 0;
self
}
// Function to reset the pointer (set to 0)
#[allow(unused)]
pub fn reset_ptr(&mut self) -> &mut Program {
self.ptr = 0;
self
}
// Function to update a specific instruction
pub fn update_instr(&mut self, pos:usize, new_instr:Instruction) -> bool {
if self.instr.len() == 0 || pos >= self.instr.len() {
return false;
}
self.instr[pos] = new_instr;
return true;
}
// Function to get program's size
pub fn get_size(&self) -> usize {
self.instr.len()
}
}
