awkward but sorta works

src/main.rs

@@ -19,7 +19,7 @@ use anyhow::Result;
 
 fn main() -> Result<()> {
     let mut shell = Shell::new()?;
-    let log_path = shell.expand_path("~/wash.log");
+    let log_path = shell.expand_path("~/clyde.log");
     match Log::file(log_path) {
         Ok(f) => {
             let target = Box::leak(Box::new(f));
@@ -63,7 +63,7 @@ fn main() -> Result<()> {
                     info!("◇ {}", s);
                     let tree = parse::parse(&s)?;
                     debug!("  {:?}", tree);
-                    shell.exec(tree)?;
+                    shell.exec(tree.into())?;
                     // Some commands don't leave the terminal in a clean state, so we use reset
                     // to ensure that our input and output modes are what we expect them to be.
                     shell.reset()?;

src/parse.rs

@@ -1,4 +1,10 @@
 use log::debug;
+use std::{
+    fmt,
+    ops::Deref,
+    cell::RefCell,
+    rc::Rc,
+};
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -104,42 +110,200 @@ impl<'text> Lexer<'text> {
     }
 }
 
-struct Parser {
-    state: Node,
+// struct Parser {
+//     state: Tree,
+// }
+// 
+// impl Parser {
+//     fn new() -> Self {
+//         Self {
+//             state: Tree::new(),
+//         }
+//     }
+// 
+//     fn parse(mut self, tokens: Vec<Token>) -> Result<Node, Error> {
+//         Ok(Node::empty())
+//         // for token in tokens {
+//         //     self.take(token);
+//         // }
+//         // let t = self.state.replace(Node::empty());
+//         // Ok(t.root())
+//     }
+// }
+
+#[derive(PartialEq, Clone)]
+pub enum Element {
+    Empty,
+    Command(String),
+    Literal(String),
 }
 
-impl Parser {
-    fn new() -> Self {
+impl fmt::Debug for Element {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        match self {
+            Element::Empty => write!(f, "()"),
+            Element::Command(cmd) => write!(f, "cmd<{}>", cmd),
+            Element::Literal(lit) => write!(f, "lit<{}>", lit),
+        }
+    }
+}
+
+pub struct Node {
+    pub elem: Element,
+    pub parent: Option<Rc<RefCell<Node>>>,
+    pub children: Vec<Rc<RefCell<Node>>>,
+}
+
+impl Node {
+    pub fn new(elem: Element) -> Self {
+        Self {
+            elem,
+            parent: None,
+            children: Vec::new(),
+        }
+    }
+
+    pub fn empty() -> Self {
+        Self::new(Element::Empty)
+    }
+
+    pub fn child_of(parent: Rc<RefCell<Self>>, elem: Element) -> Self {
         Self {
-            state: Node::Empty,
+            elem,
+            parent: Some(parent),
+            children: Vec::new(),
         }
     }
 
-    fn parse(mut self, tokens: Vec<Token>) -> Result<Node, Error> {
-        for token in tokens {
-            match (self.state, token) {
-                (Node::Empty, Token::Ident(name)) => {
-                    self.state = Node::Command{name, args: vec!()};
-                },
-                (Node::Command{name, mut args}, Token::Ident(s)) => {
-                    args.push(s);
-                    self.state = Node::Command{name, args};
-                },
-                _ => return Err(Error::UnexpectedToken),
+    pub fn visit(self) -> Tree {
+        self.into()
+    }
+}
+
+impl fmt::Debug for Node {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        write!(f, "{:?}", self.elem)?;
+        if self.children.len() > 0 {
+            write!(f, "[")?;
+            for child in self.children.iter() {
+                write!(f, "{:?}", child.borrow())?;
             }
+            write!(f, "]")?;
         }
-        Ok(self.state)
+        Ok(())
     }
+}
 
+pub struct Tree {
+    target: Rc<RefCell<Node>>,
 }
 
-#[derive(Debug)]
-pub enum Node {
-    Empty,
-    Command {
-        name: String,
-        args: Vec<String>,
-    },
+impl Tree {
+    fn new() -> Self {
+        Node::empty().into()
+    }
+
+    /// Adds an element as a node as a child of the current node, then descends the tree to select
+    /// that child node. This is similar to how pushing a value changes the top element of a stack.
+    fn push(self, elem: Element) -> Self {
+        if self.is_empty() {
+            self.target.replace(Node::new(elem));
+            self
+        } else {
+            let child = Node::child_of(Rc::clone(&self.target), elem);
+            Tree{target: Rc::new(RefCell::new(child))}
+        }
+    }
+
+    /// Adds a child node with a given element value to the currently selected node without chaning
+    /// our selection.
+    fn append(self, elem: Element) -> Self {
+        if self.is_empty() {
+            self.target.replace(Node::new(elem));
+        } else {
+            let node = Node::child_of(Rc::clone(&self.target), elem);
+            let child = Rc::new(RefCell::new(node));
+            self.target.borrow_mut().children.push(child);
+        }
+        self
+    }
+
+    /// Tells us whether or not the currently selected node is an empty node
+    fn is_empty(&self) -> bool {
+        self.target.borrow().elem == Element::Empty
+    }
+
+    fn parent(&self) -> Option<Self> {
+        self.target.borrow().parent.as_ref().map(|parent| Self {
+            target: Rc::clone(parent),
+        })
+    }
+
+    fn is_root(&self) -> bool {
+        self.parent().is_none()
+    }
+
+    pub fn root(self) -> Self {
+        match self.parent() {
+            Some(parent) => parent.root(),
+            None => self,
+        }
+    }
+
+    fn peek(&self) -> Element {
+        self.target.borrow().elem.clone()
+    }
+
+    fn into_node(self) -> Node {
+        self.into()
+    }
+
+    fn children(&self) -> ChildIter {
+        ChildIter {
+            parent: Rc::clone(&self.target),
+            idx: 0,
+        }
+    }
+}
+
+impl fmt::Debug for Tree {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        write!(f, "{:?}", self.target.borrow())
+    }
+}
+
+pub struct ChildIter {
+    /// pointer to the node in the tree whose children we are looking at.
+    parent: Rc<RefCell<Node>>,
+    idx: usize,
+}
+
+impl Iterator for ChildIter {
+    type Item = Tree;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.idx >= self.parent.borrow().children.len() {
+            None
+        } else {
+            let child = Rc::clone(&self.parent.borrow().children[self.idx]);
+            self.idx += 1;
+            Some(Tree{target: child})
+        }
+    }
+}
+
+impl From<Tree> for Node {
+    fn from(value: Tree) -> Self {
+        value.target.replace(Node::empty())
+    }
+}
+
+impl From<Node> for Tree {
+    fn from(value: Node) -> Self {
+        Self {
+            target: Rc::new(RefCell::new(value)),
+        }
+    }
 }
 
 // I don't know how to write a parser lol
@@ -167,11 +331,20 @@ pub enum Node {
 //     ]
 //   }
 
-pub fn parse<S: AsRef<str>>(text: S) -> Result<Node, Error> {
-    let tokens = lex(text)?;
-    let parser = Parser::new();
-    debug!("  {:?}", tokens);
-    parser.parse(tokens)
+pub fn parse<S: AsRef<str>>(text: S) -> Result<Tree, Error> {
+    let mut tree = Tree::new();
+    for token in lex(text)? {
+        match (tree.peek(), token) {
+            (Element::Empty, Token::Ident(cmd)) => {
+                tree = tree.push(Element::Command(cmd));
+            }
+            (Element::Command(_), Token::Ident(arg)) => {
+                tree = tree.append(Element::Literal(arg));
+            }
+            _ => todo!(),
+        }
+    }
+    Ok(tree.root())
 }
 
 #[cfg(test)]
@@ -210,8 +383,8 @@ mod tests {
         ident("one");
 
     two_tokens:
-        "one two"
-        ident("one") ident("two");
+        "ls one two"
+        ident("ls") ident("one") ident("two");
 
     leading_whitespace:
         "    one"
@@ -241,4 +414,50 @@ mod tests {
         "one |two"
         ident("one") Pipe ident("two");
     }
+
+    #[test]
+    fn empty_tree() {
+        let root = Tree::new().root();
+        assert!(root.is_root());
+        assert_eq!(root.peek(), Element::Empty);
+        assert_eq!(root.children().count(), 0);
+    }
+
+    #[test]
+    fn tree_root() {
+        let root = Tree::new()
+            .push(Element::Command(String::from("ls")))
+            .root();
+        assert!(root.is_root());
+        assert_eq!(root.children().count(), 0);
+        assert_eq!(root.into_node().elem, Element::Command(String::from("ls")));
+    }
+
+    #[test]
+    fn tree_push() {
+        let tree = Tree::new()
+            .push(Element::Command(String::from("ls")));
+        assert_eq!(tree.peek(), Element::Command(String::from("ls")));
+
+        let tree = Tree::new()
+            .push(Element::Command(String::from("ls")))
+            .append(Element::Command(String::from("one")));
+        assert_eq!(tree.peek(), Element::Command(String::from("ls")));
+    }
+
+    #[test]
+    fn parse_args() {
+        let res = parse("ls one two three");
+        assert!(res.is_ok());
+
+        let tree = res.unwrap();
+        assert_eq!(tree.peek(), Element::Command(String::from("ls")));
+        assert_eq!(tree.children().count(), 3);
+
+        let mut args = tree.children();
+        assert_eq!(args.next().unwrap().peek(), Element::Literal(String::from("one")));
+        assert_eq!(args.next().unwrap().peek(), Element::Literal(String::from("two")));
+        assert_eq!(args.next().unwrap().peek(), Element::Literal(String::from("three")));
+        assert!(args.next().is_none());
+    }
 }

src/shell.rs

@@ -2,13 +2,14 @@ use crate::{
     ext::{Command, Echo, Printenv, Tail, Which},
     input,
     line::Line,
-    parse::Node,
     log::*,
     output,
     // parse::parse,
+    parse::{Element, Node},
 };
 
 use std::path::{Path, PathBuf};
+use std::rc::Rc;
 
 use anyhow::Result;
 use dirs;
@@ -97,17 +98,25 @@ impl Shell {
         }
     }
 
-    pub fn exec(&mut self, mut node: Node) -> Result<bool> {
-        loop {
-            match node {
-                Node::Empty => break,
-                Node::Command{name, args} => {
-                    self.eval(name, args.iter().map(|s| s.as_str()).collect())?;
-                    node = Node::Empty;
-                },
+    pub fn exec(&mut self, root: Node) -> Result<bool> {
+        match root.elem {
+            Element::Empty => Ok(true),
+            Element::Command(cmd) => {
+                let args: Vec<String> = root
+                    .children
+                    .iter()
+                    .map(|node| match &node.borrow().elem {
+                        Element::Literal(v) => v.clone(),
+                        _ => todo!(),
+                    })
+                    .collect();
+                self.eval(
+                    cmd.to_string(),
+                    args.iter().map(|arg| arg.as_str()).collect(),
+                )
             }
+            Element::Literal(_) => todo!(),
         }
-        Ok(true)
     }
 
     pub fn eval(&mut self, cmd: String, args: Vec<&str>) -> Result<bool> {