inputs/printing_program.bas

@@ -1,8 +0,0 @@
-10 REM Assign vars
-20 LET a$="Hello"
-30 LET b$="World"
-40 LET c$=a$
-50 REM Print values
-60 PRINT a$
-70 PRINT b$
-80 PRINT c$

inputs/simple_program.bas

@@ -1,4 +0,0 @@
-10 PRINT "Hello World"
-20 LET apple=10
-30 LET b$="Hello"
-40 LET cat=apple

src/basic.rs

@@ -1,173 +1,41 @@
-use std::collections::HashMap;
-
 use nom::{
-    branch::alt, bytes::complete::tag, character::complete::u64 as ccu64, combinator::map,
-    multi::separated_list0, sequence::terminated, IResult,
-};
-
-use crate::parsers::{generic, variables};
-
-pub type Line = (usize, Command);
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub enum Command {
-    Print(PrintOutput),
-    GoTo(usize),
-    Var((String, Primitive)),
-    Comment,
-    None,
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub enum Primitive {
-    Int(i64),
-    String(String),
-    Assignment(String),
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub enum PrintOutput {
-    Value(String),
-    Variable(String),
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub enum Node {
-    None,
-    Link { item: Line, next: Box<Node> },
-}
-
-impl Node {
-    fn push(&mut self, val: Line) {
-        *self = match self {
-            Self::Link { item, next } => {
-                next.push(val);
-                Self::Link {
-                    item: item.clone(),
-                    next: next.clone(),
-                }
-            }
-            Self::None => Self::Link {
-                item: val,
-                next: Box::new(Self::None),
+    branch::alt,
+    bytes::complete::{escaped_transform, tag, take_until},
+    character::{
+        complete::{u32 as ccu32},
+        streaming::none_of,
     },
-        }
-    }
-
-    pub fn find_line(&self, line: usize) -> Option<Node> {
-        if let Self::Link { item, next } = self {
-            if item.0 == line {
-                Some(self.clone())
-            } else {
-                next.find_line(line)
-            }
-        } else {
-            None
-        }
-    }
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub struct Program {
-    nodes: Node,
-    current: Node,
-    vars: HashMap<String, Primitive>,
-}
-
-impl Program {
-    pub fn new(node: Node) -> Self {
-        Program {
-            vars: HashMap::new(),
-            nodes: node.clone(),
-            current: node,
-        }
-    }
-
-    pub fn jump_to_line(&mut self, line: usize) {
-        if let Some(node) = self.nodes.find_line(line) {
-            self.current = node;
-        } else {
-            panic!("Cannot jump to line {}, it does not exist", line);
-        }
-    }
-
-    pub fn execute(&mut self) {
-        let mut iter = self.clone();
-
-        while let Some(node) = iter.next() {
-            if let Node::Link { item, next: _ } = node {
-                match item.1 {
-                    Command::Print(PrintOutput::Value(line)) => println!("{}", line),
-                    Command::Print(PrintOutput::Variable(variable)) => {
-                        println!("{:?}", self.vars.get(&variable).unwrap())
-                    }
-                    Command::GoTo(line) => iter.jump_to_line(line),
-                    Command::Var((id, Primitive::Assignment(variable))) => {
-                        self.vars
-                            .insert(id, self.vars.get(&variable).unwrap().clone());
-                    }
-                    Command::Var((id, var)) => {
-                        self.vars.insert(id, var);
-                    }
-                    Command::Comment => (),
-                    _ => panic!("Unrecognised command"),
-                }
+    combinator::{map, value},
+    sequence::{delimited, terminated, tuple},
+    IResult,
 };
-        }
-    }
+
+pub type Line = (u32, Command);
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum Command {
+    Print(String),
+    None,
 }
 
-impl From<&str> for Program {
-    fn from(value: &str) -> Self {
-        let (_, program) = read_program(value).unwrap();
-        program
-    }
-}
-
-impl Iterator for Program {
-    type Item = Node;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        let curr = self.current.clone();
-        match &self.current {
-            Node::Link { item: _, next } => {
-                self.current = *next.clone();
-                Some(curr)
-            }
-            Node::None => None,
-        }
-    }
-}
-
-fn match_command(i: &str) -> IResult<&str, &str> {
-    alt((tag("PRINT"), tag("GO TO"), tag("LET"), tag("REM")))(i)
-}
-
-fn parse_print_command(i: &str) -> IResult<&str, PrintOutput> {
-    alt((
-        map(
-            alt((
-                variables::parse_str_variable_name,
-                variables::parse_int_variable_name,
-            )),
-            PrintOutput::Variable,
+fn read_string(i: &str) -> IResult<&str, String> {
+    // take_until("\"")(i)
+    delimited(
+        tag("\""),
+        escaped_transform(
+            none_of("\\\""),
+            '\\',
+            alt((value("\\", tag("\\")), value("\"", tag("\"")))),
         ),
-        map(generic::read_string, PrintOutput::Value),
-    ))(i)
+        tag("\""),
+    )(i)
 }
 
 fn parse_command(i: &str) -> IResult<&str, Command> {
-    let (i, command): (&str, &str) = match_command(i).unwrap_or((i, ""));
-    let (i, _) = tag(" ")(i)?;
+    let (i, (command, _)) = tuple((take_until(" "), tag(" ")))(i)?;
 
     let (i, cmd) = match command {
-        "PRINT" => map(parse_print_command, Command::Print)(i)?,
-        "GO TO" => map(ccu64, |line| Command::GoTo(line as usize))(i)?,
-        "LET" => map(variables::parse_var, Command::Var)(i)?,
-        "REM" => {
-            let (i, _) = generic::consume_line(i)?;
-            (i, Command::Comment)
-        }
+        "PRINT" => map(read_string, Command::Print)(i)?,
         _ => (i, Command::None),
     };
 
@@ -175,222 +43,35 @@ fn parse_command(i: &str) -> IResult<&str, Command> {
 }
 
 pub fn parse_line(line: &str) -> IResult<&str, Line> {
-    let (i, line_number) = map(terminated(ccu64, tag(" ")), |l| l as usize)(line)?;
+    let (i, line_number) = terminated(ccu32, tag(" "))(line)?;
     let (i, command) = parse_command(i)?;
     Ok((i, (line_number, command)))
 }
 
-pub fn read_program(i: &str) -> IResult<&str, Program> {
-    let (i, lines) = separated_list0(tag("\n"), parse_line)(i)?;
-    let mut node = Node::None;
-
-    for line in lines.iter() {
-        node.push(line.clone());
-    }
-
-    Ok((i, Program::new(node)))
-}
-
 #[cfg(test)]
 mod tests {
-    use crate::basic::PrintOutput;
-
-    use super::{parse_line, read_program, Command, Line, Node, Primitive};
-
-    use crate::parsers::generic::read_string;
-
     #[test]
     fn it_parses_a_print_command() {
         let input = "10 PRINT \"Hello, world\"";
-        let expected = (
-            10,
-            Command::Print(PrintOutput::Value(String::from("Hello, world"))),
-        );
+        let expected = (10, super::Command::Print(String::from("Hello, world")));
 
-        let (_, result) = parse_line(input).unwrap();
+        let (_, result) = super::parse_line(input).unwrap();
         assert_eq!(expected, result);
     }
 
     #[test]
     fn it_reads_a_string() {
         let input = r#""Hello, \"World\"""#;
-        let (_, output) = read_string(input).unwrap();
+        let (_, output) = super::read_string(input).unwrap();
         assert_eq!(r#"Hello, "World""#, output);
     }
 
     #[test]
     fn it_parses_a_print_command_with_escaped_quotes() {
         let input = r#"10 PRINT "Hello, \"world\"""#;
-        let expected = (
-            10,
-            Command::Print(PrintOutput::Value(String::from(r#"Hello, "world""#))),
-        );
+        let expected = (10, super::Command::Print(String::from(r#"Hello, "world""#)));
 
-        let (_, result) = parse_line(input).unwrap();
+        let (_, result) = super::parse_line(input).unwrap();
         assert_eq!(expected, result);
     }
-
-    #[test]
-    fn it_parses_a_goto_command() {
-        let input = "20 GO TO 10";
-        let expected = (20, Command::GoTo(10));
-        let (_, result) = parse_line(input).unwrap();
-        assert_eq!(expected, result);
-    }
-
-    #[test]
-    fn it_can_create_a_linked_list_for_a_program() {
-        let mut node = Node::Link {
-            item: (
-                10,
-                Command::Print(PrintOutput::Value(String::from("Hello world"))),
-            ),
-            next: Box::new(Node::None),
-        };
-        node.push((20, Command::GoTo(10)));
-
-        let expected = Node::Link {
-            item: (
-                10,
-                Command::Print(PrintOutput::Value(String::from("Hello world"))),
-            ),
-            next: Box::new(Node::Link {
-                item: (20, Command::GoTo(10)),
-                next: Box::new(Node::None),
-            }),
-        };
-        assert_eq!(node, expected);
-    }
-
-    #[test]
-    fn it_finds_a_node_by_line_number() {
-        let mut node = Node::Link {
-            item: (
-                10,
-                Command::Print(PrintOutput::Value(String::from("Hello world"))),
-            ),
-            next: Box::new(Node::None),
-        };
-        node.push((
-            20,
-            Command::Print(PrintOutput::Value(String::from("I'm a second line"))),
-        ));
-        node.push((
-            30,
-            Command::Print(PrintOutput::Value(String::from("Still printing..."))),
-        ));
-        node.push((40, Command::GoTo(10)));
-
-        let expected: Option<Node> = Some(Node::Link {
-            item: (
-                30,
-                Command::Print(PrintOutput::Value(String::from("Still printing..."))),
-            ),
-            next: Box::new(Node::Link {
-                item: (40, Command::GoTo(10)),
-                next: Box::new(Node::None),
-            }),
-        });
-        let result = node.find_line(30);
-        assert_eq!(expected, result);
-    }
-
-    #[test]
-    fn it_reads_a_program() {
-        let lines = "10 PRINT \"Hello world\"\n20 GO TO 10";
-        let expected_node = Node::Link {
-            item: (
-                10,
-                Command::Print(PrintOutput::Value(String::from("Hello world"))),
-            ),
-            next: Box::new(Node::Link {
-                item: (20, Command::GoTo(10)),
-                next: Box::new(Node::None),
-            }),
-        };
-        let expected = ("", super::Program::new(expected_node));
-        let result = read_program(lines).unwrap();
-        assert_eq!(expected, result);
-    }
-
-    #[test]
-    fn it_parses_an_integer() {
-        let line = "10 LET a=22";
-        let expected: Line = (10, Command::Var((String::from("a"), Primitive::Int(22))));
-        let (_, result) = parse_line(line).unwrap();
-        assert_eq!(expected, result);
-    }
-
-    #[test]
-    fn it_parses_a_many_char_integer() {
-        let line = "10 LET apple=1";
-        let expected: Line = (10, Command::Var((String::from("apple"), Primitive::Int(1))));
-        let (_, result) = parse_line(line).unwrap();
-        assert_eq!(expected, result);
-    }
-
-    #[test]
-    fn it_fails_if_integer_var_name_starts_with_number() {
-        let line = "10 LET 0apple=1";
-        let result = parse_line(line);
-        assert!(result.is_err());
-    }
-
-    #[test]
-    fn it_parses_a_string_variable() {
-        let line = r#"10 LET a$="Hello world""#;
-        let expected: Line = (
-            10,
-            Command::Var((
-                String::from("a$"),
-                Primitive::String(String::from("Hello world")),
-            )),
-        );
-        let (_, result) = parse_line(line).unwrap();
-        assert_eq!(expected, result);
-    }
-
-    #[test]
-    fn it_fails_a_string_var_with_a_multichar_name() {
-        let line = r#"10 LET asd$="Hello world""#;
-        let result = parse_line(line);
-        assert!(result.is_err());
-    }
-
-    #[test]
-    fn it_fails_a_string_var_with_a_numeric_name() {
-        let line = r#"10 LET 0$="Hello world""#;
-        let result = parse_line(line);
-        assert!(result.is_err());
-    }
-
-    #[test]
-    fn it_assigns_one_variable_to_another() {
-        let line = "10 LET a=b$";
-        let (_, result) = parse_line(line).unwrap();
-        let expected: Line = (
-            10,
-            Command::Var((String::from("a"), Primitive::Assignment(String::from("b$")))),
-        );
-        assert_eq!(result, expected);
-    }
-
-    #[test]
-    fn it_parses_a_print_command_with_a_variable_name() {
-        let line = "10 PRINT a$";
-        let (_, result) = parse_line(line).unwrap();
-        let expected: Line = (
-            10,
-            Command::Print(PrintOutput::Variable(String::from("a$"))),
-        );
-        assert_eq!(result, expected);
-    }
-
-    #[test]
-    fn it_parses_a_comment() {
-        let line = "10 REM This is an arbitrary comment";
-        let (_, result) = parse_line(line).unwrap();
-        let expected: Line = (10, Command::Comment);
-        assert_eq!(result, expected);
-    }
 }

src/main.rs

@@ -1,10 +1,17 @@
 use std::fs;
 
 mod basic;
-mod parsers;
 
 fn main() {
-    let file = fs::read_to_string("./inputs/printing_program.bas").unwrap();
-    let mut program = basic::Program::from(file.as_str());
-    program.execute();
+    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");
+        }
+    };
 }

src/parsers.rs

@@ -1,2 +0,0 @@
-pub mod generic;
-pub mod variables;

src/parsers/generic.rs

@@ -1,25 +0,0 @@
-use nom::{
-    branch::alt,
-    bytes::complete::{escaped_transform, tag, take_while},
-    character::complete::none_of,
-    combinator::value,
-    sequence::delimited,
-    IResult,
-};
-
-// Take everything until it hits a newline, if it does
-pub fn consume_line(i: &str) -> IResult<&str, &str> {
-    take_while(|c| c != '\n')(i)
-}
-
-pub fn read_string(i: &str) -> IResult<&str, String> {
-    delimited(
-        tag("\""),
-        escaped_transform(
-            none_of("\\\""),
-            '\\',
-            alt((value("\\", tag("\\")), value("\"", tag("\"")))),
-        ),
-        tag("\""),
-    )(i)
-}

src/parsers/variables.rs

@@ -1,51 +0,0 @@
-use nom::{
-    branch::alt,
-    bytes::complete::tag,
-    character::complete::{alphanumeric1, anychar, digit1, i64 as cci64},
-    combinator::{map, not, verify},
-    sequence::{preceded, terminated},
-    IResult,
-};
-
-use crate::basic::Primitive;
-
-use super::generic::{consume_line, read_string};
-
-pub fn parse_int_variable_name(i: &str) -> IResult<&str, String> {
-    map(preceded(not(digit1), alphanumeric1), String::from)(i)
-}
-
-pub fn parse_int(i: &str) -> IResult<&str, (String, Primitive)> {
-    let (i, id) = parse_int_variable_name(i)?;
-    let (i, _) = tag("=")(i)?;
-    let (i, var) = map(cci64, Primitive::Int)(i)?;
-
-    Ok((i, (id, var)))
-}
-
-pub fn parse_str_variable_name(i: &str) -> IResult<&str, String> {
-    let (i, id) = terminated(verify(anychar, |c| c.is_alphabetic()), tag("$"))(i)?;
-    let id = format!("{}$", id);
-    Ok((i, id))
-}
-
-pub fn parse_str(i: &str) -> IResult<&str, (String, Primitive)> {
-    let (i, id) = parse_str_variable_name(i)?;
-    let (i, _) = tag("=")(i)?;
-    let (i, var) = map(read_string, Primitive::String)(i)?;
-    Ok((i, (id, var)))
-}
-
-pub fn parse_assignment(i: &str) -> IResult<&str, (String, Primitive)> {
-    let (i, id) = alt((parse_str_variable_name, parse_int_variable_name))(i)?;
-    let (i, _) = tag("=")(i)?;
-    let (i, assigned_variable) = consume_line(i)?;
-    Ok((
-        i,
-        (id, Primitive::Assignment(assigned_variable.to_string())),
-    ))
-}
-
-pub fn parse_var(i: &str) -> IResult<&str, (String, Primitive)> {
-    alt((parse_int, parse_str, parse_assignment))(i)
-}