clean up command interface

programs/adder.mbl

@@ -1,5 +1,4 @@
-(print sum of 123 and 45)
+(print sum of 2 numbers)
-
   o
   > 1230  B
  vo      A-+
@@ -17,8 +16,7 @@ v> * 1    o  ^
  F -R0  * 4 B
 *| # <  -A8 v
  |      # <
-#|
+#-|            v   <
- -|            v   <
   |         *-|
   F           +B * ^
  #<         \F----

src/main.rs

@@ -1,4 +1,4 @@
-use std::{env, fs, io::stdin, process::exit};
+use std::{env, fs, io::{stdin, stdout, Write}, process::exit};
 
 use owo_colors::OwoColorize;
 
@@ -15,7 +15,6 @@ struct Machine {
 	input: Vec<u8>,
 	input_index: usize,
 	output: Vec<u8>,
-	state: State,
 	steps: usize,
 }
 
@@ -79,13 +78,6 @@ enum Direction {
 	Right,
 }
 
-#[derive(Debug, Default, PartialEq)]
-enum State {
-	#[default]
-	Running,
-	EndOfProgram,
-}
-
 fn main() {
 	let args: Vec<_> = env::args().collect();
 	if args.len() <= 1 {
@@ -109,9 +101,11 @@ fn main() {
 
 	let mut interpreter = Machine::new(&source, input_data);
 	print!("\x1B[2J"); // clear screen
+	interpreter.show();
 
 	loop {
-		interpreter.show();
+		print!(":> ");
+		stdout().flush().unwrap();
 		let mut input_text = String::new();
 		stdin().read_line(&mut input_text).unwrap();
 		let action: Vec<_> = input_text.trim().split_ascii_whitespace().collect();
@@ -122,18 +116,35 @@ fn main() {
 					.unwrap_or(&input_text)
 					.as_bytes()[6..],
 			);
+			interpreter.print_input();
 			continue;
 		}
+
+		const HELP_TEXT:&str = r#"\n | step
+  - step once
+step [n]
+  - step n times
+input [text]
+  - append text to the input buffer
+dbg | debug
+  - debug print interpreter state
+q | quit | exit
+  - exit to terminal
+"#;
 		match action.as_slice() {
-			[] | ["step"] => interpreter.step_once(),
+			[] | ["step"] => {
+				interpreter.step_once();
+				interpreter.show();
+			}
 			["dbg" | "debug"] => {
 				dbg!(&interpreter);
 			}
 			["step", num] => _ = num.parse().map(|n| interpreter.step(n)),
-			["run"] => interpreter.run(),
 			["q" | "exit" | "quit"] => break,
-
+			["h" | "help" | "?"] => {
-			_ => println!("{}", "unrecognised command".red()),
+				println!("{}", HELP_TEXT.green());
+			}
+			_ => println!("{}", "unrecognised command (try 'help')".red()),
 		}
 	}
 }
@@ -148,23 +159,12 @@ impl Machine {
 			input,
 			input_index: 0,
 			output: Vec::new(),
-			state: State::default(),
 			steps: 0,
 		}
 	}
 
-	fn run(&mut self) {
-		while self.state == State::Running {
-			self.step_once();
-			self.show();
-		}
-	}
-
 	fn step(&mut self, n: usize) {
 		for _ in 0..n {
-			if self.state != State::Running {
-				break;
-			}
 			self.step_once();
 		}
 	}
@@ -230,7 +230,7 @@ impl Machine {
 					print!("{}", c.cyan());
 				}
 			}
-			print!(" :: ");
+			print!(".");
 			for (val, dir) in marbles_on_row {
 				print!("{}", format!("{}{} ", dir.char(), val).magenta())
 			}
@@ -239,10 +239,14 @@ impl Machine {
 		if !self.output.is_empty() {
 			println!("output: '{}'", String::from_utf8_lossy(&self.output));
 		}
+		self.print_input();
+		println!("steps: {}", self.steps);
+	}
+
+	fn print_input(&self){
 		if !self.input.is_empty() {
 			println!("input: '{}'", String::from_utf8_lossy(&self.input));
 		}
-		println!("steps: {}", self.steps);
 	}
 
 	fn step_once(&mut self) {