breakpoints and lots of things

Cargo.lock

@@ -3,5 +3,5 @@
 version = 3
 
 [[package]]
-name = "m8ni-rs"
+name = "m8db"
 version = "0.1.0"

Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "m8ni-rs"
+name = "m8db"
 version = "0.1.0"
 edition = "2018"
 

src/db.rs

@@ -0,0 +1,179 @@
+use crate::stmt::Stmt;
+use std::io::Write;
+
+#[derive(Debug, Clone)]
+struct Vm {
+    stmts: Vec<Stmt>,
+    pc: usize,
+    registers: Vec<usize>,
+    breakpoints: Vec<usize>,
+}
+
+#[derive(Debug, Copy, Clone)]
+enum VmState {
+    Run,
+    Break,
+    Stop,
+}
+
+impl Vm {
+    fn step(&mut self) -> VmState {
+        let pc = self.pc;
+        self.pc += 1;
+        match self.stmts[pc] {
+            Stmt::Inc(r) => self.registers[r] += 1,
+            Stmt::Dec(r) => self.registers[r] -= 1,
+            Stmt::IsZero(r, line) => {
+                if self.registers[r] == 0 {
+                    self.pc = line;
+                }
+            }
+            Stmt::Jump(line) => self.pc = line,
+            Stmt::Stop => return VmState::Stop,
+        }
+        if self.breakpoints.contains(&self.pc) {
+            VmState::Break
+        } else {
+            VmState::Run
+        }
+    }
+
+    fn run(&mut self) -> VmState {
+        while let VmState::Run = self.step() {}
+        VmState::Break
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+enum VmInstruction {
+    Step,
+    Run,
+    Break(usize),
+}
+
+pub fn run(stmts: Vec<Stmt>) {
+    let max_register = max_register(&stmts);
+    let mut vm = Vm {
+        stmts,
+        pc: 0,
+        registers: vec![0; max_register],
+        breakpoints: vec![],
+    };
+
+    loop {
+        match debug_input(&mut vm) {
+            VmInstruction::Run => match vm.run() {
+                VmState::Stop => break,
+                VmState::Run => unreachable!(),
+                _ => {}
+            },
+            VmInstruction::Step => match vm.step() {
+                VmState::Stop => break,
+                _ => {}
+            },
+            VmInstruction::Break(line) => {
+                let position = vm.breakpoints.iter().position(|point| *point == line);
+                match position {
+                    None => vm.breakpoints.push(line),
+                    Some(pos) => {
+                        vm.breakpoints.remove(pos);
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn debug_input(vm: &Vm) -> VmInstruction {
+    loop {
+        let mut input_buf = String::new();
+        print!("(m8db) ");
+        std::io::stdout().flush().unwrap();
+        std::io::stdin().read_line(&mut input_buf).unwrap();
+        let input = input_buf.trim();
+        let mut iter = input.split_ascii_whitespace();
+        match iter.next() {
+            Some(str) => match str {
+                "r" | "register" => print_registers(vm),
+                "p" | "program" => print_program(vm),
+                "h" | "?" | "help" => print_help(),
+                "b" | "break" => match iter.next() {
+                    Some(num) => match num.parse() {
+                        Ok(num) => return VmInstruction::Break(num),
+                        Err(_) => println!("Invalid argument provided"),
+                    },
+                    None => print_breakpoints(vm),
+                },
+                "c" | "continue" => return VmInstruction::Run,
+                "s" | "step" => return VmInstruction::Step,
+                _ => {}
+            },
+            None => {}
+        }
+    }
+}
+
+fn max_register(stmts: &[Stmt]) -> usize {
+    stmts
+        .iter()
+        .map(|stmt| match stmt {
+            Stmt::Inc(r) => *r,
+            Stmt::Dec(r) => *r,
+            Stmt::IsZero(r, _) => *r,
+            Stmt::Jump(_) => 0,
+            Stmt::Stop => 0,
+        })
+        .max()
+        .unwrap_or(0)
+}
+
+fn print_registers(vm: &Vm) {
+    println!("Registers:");
+    for (i, r) in vm.registers.iter().enumerate() {
+        println!("{: >4} : {}", i, r);
+    }
+}
+
+fn print_program(vm: &Vm) {
+    use std::cmp::{max, min};
+
+    println!("Program:");
+    let lower = max(vm.pc, 5) - 5;
+    let higher = min(vm.pc, vm.stmts.len() - 6) + 5;
+
+    for i in lower..higher {
+        let stmt = vm.stmts[i];
+        if i == vm.pc {
+            println!("> {}  {}", i, stmt)
+        } else {
+            println!("{}  {}", i, stmt);
+        }
+    }
+}
+
+fn print_breakpoints(vm: &Vm) {
+    println!(
+        "Breakpoints:
+    {}
+    ",
+        vm.breakpoints
+            .iter()
+            .map(|p| p.to_string())
+            .collect::<Vec<String>>()
+            .join(", ")
+    );
+}
+
+fn print_help() {
+    println!(
+        "List of commands and their aliases:
+
+    step (s) -- Steps the program forward by one step
+    break <line> (b) -- Set a breakpoint to a line, use again to toggle
+    continue (c) -- Run the program until the next breakpoint
+    register (r) -- Shows the contents of the registers
+    program (p) -- Shows where the program currently is
+    help (h, ?) -- Shows this help page
+    "
+    );
+}

src/main.rs

@@ -1,54 +1,22 @@
-enum Stmt {
-    Inc(usize),
-    Dec(usize),
-    IsZero(usize, usize),
-    Jump(usize),
-    Stop
-}
+mod db;
+mod stmt;
 
 fn main() {
     let filename = match std::env::args().skip(1).next() {
         Some(name) => name,
-        None => eprintln!("error: no file provided.\nUsage: <filename>"),
+        None => {
+            eprintln!("error: no file provided.\nUsage: <filename>");
+            return;
+        }
     };
 
     let program = std::fs::read_to_string(filename).unwrap();
-    let statements = parse(&program);
-}
-
-fn parse(text: &str) -> Result<Vec<Stmt>, String> {
-    text.lines().map(parse_line).collect()
-}
-
-
-fn parse_line(line: &str) -> Result<Stmt, String> {
-    const NO_REGISTER: fn() -> String = || "No register".to_string();
-    const NO_LINE_NUMBER: fn() -> String = || "No line number".to_string();
-    const EMPTY_LINE: fn() -> String = || "Empty line not allowed".to_string();
-
-
-    let mut iter = line.split_ascii_whitespace();
-    let first = iter.next().ok_or_else(EMPTY_LINE)?;
-
-    Ok(match first {
-        "INC" => {
-            let register = iter.next().ok_or_else(NO_REGISTER)?.parse()?;
-            Stmt::Inc(register)
-        }
-        "DEC" => {
-            let register = iter.next().ok_or_else(NO_REGISTER)?.parse()?;
-            Stmt::Dec(register)
-        }
-        "IS_ZERO" => {
-            let register = iter.next().ok_or_else(NO_REGISTER)?.parse()?;
-            let line_number = iter.next().ok_or_else(NO_LINE_NUMBER)?.parse()?;
-            Stmt::IsZero(register, line_number)
-        }
-        "JUMP" => {
-            let line_number = iter.next().ok_or_else(NO_LINE_NUMBER)?.parse()?;
-            Stmt::Jump(line_number)
-        }
-        "STOP" => Stmt::Stop,
-        stmt => return Err(format!("Illegal instruction: '{}'", stmt)),
-    })
+    let statements = match stmt::parse(&program) {
+        Ok(stmts) => stmts,
+        Err(str) => {
+            eprintln!("{}", str);
+            return;
+        }
+    };
+    db::run(statements);
 }

src/stmt.rs

@@ -0,0 +1,80 @@
+use std::fmt::Formatter;
+use std::num::ParseIntError;
+
+#[derive(Debug, Copy, Clone)]
+pub enum Stmt {
+    Inc(usize),
+    Dec(usize),
+    IsZero(usize, usize),
+    Jump(usize),
+    Stop,
+}
+
+pub fn parse(text: &str) -> Result<Vec<Stmt>, String> {
+    text.lines().map(parse_line).collect()
+}
+
+fn parse_line(line: &str) -> Result<Stmt, String> {
+    const NO_REGISTER: fn() -> String = || "No register".to_string();
+    const NO_LINE_NUMBER: fn() -> String = || "No line number".to_string();
+    const EMPTY_LINE: fn() -> String = || "Empty line not allowed".to_string();
+    const DISPLAY_ERR: fn(ParseIntError) -> String = |parse_err| parse_err.to_string();
+
+    let mut iter = line.split_ascii_whitespace();
+    let first = iter.next().ok_or_else(EMPTY_LINE)?;
+
+    Ok(match first {
+        "INC" => {
+            let register = iter
+                .next()
+                .ok_or_else(NO_REGISTER)?
+                .parse()
+                .map_err(DISPLAY_ERR)?;
+            Stmt::Inc(register)
+        }
+        "DEC" => {
+            let register = iter
+                .next()
+                .ok_or_else(NO_REGISTER)?
+                .parse()
+                .map_err(DISPLAY_ERR)?;
+            Stmt::Dec(register)
+        }
+        "IS_ZERO" => {
+            let register = iter
+                .next()
+                .ok_or_else(NO_REGISTER)?
+                .parse()
+                .map_err(DISPLAY_ERR)?;
+            let line_number = iter
+                .next()
+                .ok_or_else(NO_LINE_NUMBER)?
+                .parse()
+                .map_err(DISPLAY_ERR)?;
+            Stmt::IsZero(register, line_number)
+        }
+        "JUMP" => {
+            let line_number = iter
+                .next()
+                .ok_or_else(NO_LINE_NUMBER)?
+                .parse()
+                .map_err(DISPLAY_ERR)?;
+            Stmt::Jump(line_number)
+        }
+        "STOP" => Stmt::Stop,
+        stmt => return Err(format!("Illegal instruction: '{}'", stmt)),
+    })
+}
+
+impl std::fmt::Display for Stmt {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Stmt::Inc(r) => write!(f, "INC {}", r)?,
+            Stmt::Dec(r) => write!(f, "DEC {}", r)?,
+            Stmt::IsZero(r, line) => write!(f, "IS_ZERO {} {}", r, line)?,
+            Stmt::Jump(r) => write!(f, "JUMP {}", r)?,
+            Stmt::Stop => write!(f, "STOP")?,
+        }
+        Ok(())
+    }
+}