First program: Runs Hello World using PRINT

src/basic.rs

@@ -0,0 +1,48 @@
+use nom::{
+    bytes::complete::{tag, take_until},
+    character::complete::u32 as ccu32,
+    combinator::map,
+    sequence::{delimited, terminated, tuple},
+    IResult,
+};
+
+pub type Line<'a> = (u32, Command<'a>);
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum Command<'a> {
+    Print(&'a str),
+    None,
+}
+
+fn read_string(i: &str) -> IResult<&str, &str> {
+    take_until("\"")(i)
+}
+
+fn parse_command(i: &str) -> IResult<&str, Command> {
+    let (i, (command, _)) = tuple((take_until(" "), tag(" ")))(i)?;
+
+    let (i, cmd) = match command {
+        "PRINT" => map(delimited(tag("\""), read_string, tag("\"")), Command::Print)(i)?,
+        _ => (i, Command::None),
+    };
+
+    Ok((i, cmd))
+}
+
+pub fn parse_line(line: &str) -> IResult<&str, Line> {
+    let (i, line_number) = terminated(ccu32, tag(" "))(line)?;
+    let (i, command) = parse_command(i)?;
+    Ok((i, (line_number, command)))
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_parses_a_print_command() {
+        let input = "10 PRINT \"Hello, world\"";
+        let expected = (10, super::Command::Print("Hello, world"));
+
+        let (_, result) = super::parse_line(input).unwrap();
+        assert_eq!(expected, result);
+    }
+}

src/main.rs

@@ -0,0 +1,17 @@
+use std::fs;
+
+mod basic;
+
+fn main() {
+    let file = fs::read_to_string("./inputs/hello_world.bas").unwrap();
+    let lines = file.lines().next().unwrap();
+    let (_, (_, command)) = basic::parse_line(lines).unwrap();
+    match command {
+        basic::Command::Print(input) => {
+            println!("{}", input);
+        }
+        _ => {
+            panic!("Command not recognised");
+        }
+    };
+}