Added REPL.

src/backend.rs

@@ -156,7 +156,7 @@ impl<'a> Vm {
 			    let expr = unwrap!();
 			    let mut content = String::new();
 			    let mut next = parser.inner_next();
-			    while next != Some("THEN") && next != None {
+			    while !matches!(next, Some("THEN")|Some("then")|None) {
 				content.push_str(next.unwrap());
 				content.push_str(" ");
 				next = parser.inner_next();
@@ -168,6 +168,30 @@ impl<'a> Vm {
 				self.vmrun(&mut Parser::new(content.as_str()));
 			    }
 			},
+			"(" => {
+			    let mut next = parser.inner_next();
+			    while next != Some(")") && next != None {
+				next = parser.inner_next();
+			    }
+			},
+			"DO"|"do" => {
+			    let start = unwrap!();
+			    let limit = unwrap!();
+			    let mut action = String::new();
+
+			    let mut next = parser.inner_next();
+			    while !matches!(next, Some("LOOP")|Some("loop")|None) {
+				action.push_str(next.unwrap());
+				action.push_str(" ");
+				next = parser.inner_next();
+			    }
+
+			    for i in start..limit {
+				self.dictionary.words.insert("I".to_string(), i.to_string());
+				self.vmrun(&mut Parser::new(action.as_str()));
+			    }
+			    self.dictionary.words.remove("I");
+			},
 			":" => {
 			    let mut word_content = String::new();
 			    let Some(Word(word_name)) = parser.next() else { println!("ERROR: Word name not given."); std::process::exit(1); };
@@ -180,6 +204,9 @@ impl<'a> Vm {
 
 			    self.dictionary.words.insert(word_name.to_string(), word_content);
 			},
+			"BYE"|"bye" => {
+			    std::process::exit(0);
+			}
 			word => {
 			    let words = self.dictionary.words.clone();
 			    let Some(word_content) = words.get(word) else {

src/main.rs

@@ -1,19 +1,38 @@
+use std::io::Write;
 use std::fs::read_to_string;
 pub mod parse;
 pub mod backend;
 use parse::Parser;
 use backend::Vm;
 
+fn repl() {
+    println!("Fourth REPL:");
+    println!("To exit, use the `bye` command");
+    let mut code = String::new();
+    loop {
+	print!("> ");
+	std::io::stdout().flush().unwrap();
+	let mut line = String::new();
+	let _ = std::io::stdin().read_line(&mut line);
+	code.push_str(line.as_str());
+	if !matches!(line.as_str(), "bye"|"BYE") {
+	    Vm::new().vmrun(&mut Parser::new(format!("{} trace stack\n", code).as_str()));
+	} else {
+	    println!("Bye bye and have a good day!");
+	    std::io::stdout().flush().unwrap();
+	    std::process::exit(1);
+	}
+    }
+}
 fn main() -> std::io::Result<()> {
     let mut args = std::env::args();
-    let command = args.next().unwrap();
+    let _command = args.next().unwrap();
     if let Some(filename) = args.next() {
 	let contents = read_to_string(filename)?;
 	let contents = contents.as_str();
 	Vm::new().vmrun(&mut Parser::new(contents));
     } else {
-	eprintln!("Usage: {} filename", command);
-	std::process::exit(1);
+	repl();
     }
     Ok(())
 }