shell expansion

2 files changed, 197 insertions, 114 deletions

diff --git a/src/parse.rs b/src/parse.rs
index c30206a..2ed0dbf 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -19,10 +19,10 @@ impl Stage for PostExpansion {
 
 type Res<T, E> = std::result::Result<T, E>;
 
-trait Expander {
+pub trait Expander {
     type Error;
-    fn expand_var(&mut self, v: VarName) -> Res<BString, Self::Error>;
-    fn expand_cmd(&mut self, c: Ast<PreExpansion>) -> Res<BString, Self::Error>;
+    fn expand_var(&mut self, v: BString) -> Res<BString, Self::Error>;
+    fn expand_cmd(&mut self, c: Ast<PostExpansion>) -> Res<BString, Self::Error>;
 }
 
 #[derive(Debug, Clone)]
@@ -80,7 +80,7 @@ impl StringPart {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 /// `"hi ${var} $(cmd) "` gets mapped to `[Boring("hi "), Var("var"), String(" "), Cmd(...), Boring(" ")]`
 pub struct ExpString {
     parts: Vec<StringPart>,
@@ -92,8 +92,11 @@ impl ExpString {
         for part in self.parts.into_iter() {
             let mut x = match part {
                 StringPart::Boring(items) => items,
-                StringPart::Var(v) => e.expand_var(v)?,
-                StringPart::Cmd(ast) => e.expand_cmd(ast)?,
+                StringPart::Var(v) => e.expand_var(v.name)?,
+                StringPart::Cmd(ast) => {
+                    let exp = ast.expand(e)?;
+                    e.expand_cmd(exp)?
+                }
             };
             out.append(&mut x);
         }
diff --git a/src/run/mod.rs b/src/run/mod.rs
index 5cc8149..40f4927 100644
--- a/src/run/mod.rs
+++ b/src/run/mod.rs
@@ -1,150 +1,230 @@
 use std::collections::HashMap;
 use std::path::PathBuf;
+use std::sync::{Arc, Mutex};
 
-use crate::parse::Ast;
+use crate::parse::{Ast, PreExpansion};
 use crate::*;
 
 mod builtin;
 
-pub fn run(se: &mut Session, cmd: Vec<u8>) {
-    let parsed = parse::do_parse(&cmd);
+enum ExecError {
+    UnknownVariable,
+    ExecError(i32),
+}
 
-    let parsed = match parsed {
-        Ok(p) => p,
-        Err(err) => {
-            println!("{cmd:?}");
-            print!("{err:?}\r\n{}", se.prompt());
-            return;
-        }
-    };
+struct Executor<'a> {
+    se: &'a mut Session,
+}
 
-    let Ast::Pipes(pipes) = parsed else {
-        todo!("can only handle pipes");
-    };
+#[derive(Clone)]
+struct ArcWriter {
+    inner: Arc<Mutex<Vec<u8>>>,
+}
 
-    let mut children = Vec::new();
-    let mut threads = Vec::new();
-    let mut prev_reader = None;
-    let mut spawn_error = false;
+impl ArcWriter {
+    pub fn new() -> Self {
+        Self {
+            inner: Arc::new(Mutex::new(Vec::new())),
+        }
+    }
+    pub fn into_inner(self) -> Vec<u8> {
+        self.inner.lock().unwrap().clone()
+    }
+}
 
-    se.raw.disable();
+impl std::io::Write for ArcWriter {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.lock().unwrap().extend_from_slice(buf);
+        Ok(buf.len())
+    }
 
-    let pipelen = pipes.cmds.len();
-    for (i, cmd) in pipes.cmds.into_iter().enumerate() {
-        let last = i == pipelen - 1;
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
 
-        let (reader, writer) = if !last {
-            let (r, w) = io::pipe().unwrap();
-            (Some(r), Some(w))
-        } else {
-            (None, None)
+impl<'a> Executor<'a> {
+    fn execute(
+        &mut self,
+        ast: Ast<parse::PostExpansion>,
+        stdin: Box<dyn io::Read + Send>,
+        stdout: Box<dyn io::Write + Send>,
+    ) -> Result<(), ExecError> {
+        let Ast::Pipes(pipes) = ast else {
+            todo!("can only handle pipes");
         };
 
-        let dc = se.dispatch.get(&cmd.cmd[..]);
+        let mut stdin = Some(stdin);
+        let mut stdout = Some(stdout);
 
-        match dc {
-            CommandKind::Path(path) => {
-                let mut command = Command::new(&path);
-                for arg in cmd.args.iter() {
-                    command.arg(OsStr::from_bytes(arg));
-                }
+        let mut children = Vec::new();
+        let mut threads = Vec::new();
+        let mut prev_reader = None;
+        let mut spawn_error = false;
 
-                if let Some(r) = prev_reader.take() {
-                    command.stdin(Stdio::from(r));
-                }
+        let pipelen = pipes.cmds.len();
+        for (i, cmd) in pipes.cmds.into_iter().enumerate() {
+            let last = i == pipelen - 1;
 
-                if let Some(w) = writer {
-                    command.stdout(Stdio::from(w));
-                }
+            let (reader, writer) = if !last {
+                let (r, w) = io::pipe().unwrap();
+                (Some(r), Some(w))
+            } else {
+                (None, None)
+            };
 
-                let child = match command.spawn() {
-                    Ok(c) => c,
-                    Err(e) => {
-                        let cmd = path.to_string_lossy();
-                        let msg = match e.kind() {
-                            io::ErrorKind::NotFound => format!("{cmd} not found"),
-                            io::ErrorKind::PermissionDenied => format!("{cmd} is not executable"),
-                            io::ErrorKind::FileTooLarge => format!("{cmd} is too massive"),
-                            io::ErrorKind::ResourceBusy | io::ErrorKind::ExecutableFileBusy => {
-                                format!("{cmd} is busy")
-                            }
-                            io::ErrorKind::TooManyLinks => format!("{cmd} could not be resolved"),
-                            io::ErrorKind::InvalidFilename => {
-                                format!("{cmd} is not a valid file name")
-                            }
-                            io::ErrorKind::ArgumentListTooLong => format!("too many arguments"),
-                            io::ErrorKind::Interrupted => format!("got interrupted"),
-                            io::ErrorKind::Unsupported => format!("{cmd} is not supported"),
-                            e => format!("I am surprised you can get this error here: {e:?}"),
-                        };
-                        println!("pish: {msg}");
-                        spawn_error = true;
-                        break;
+            let dc = self.se.dispatch.get(&cmd.cmd[..]);
+
+            match dc {
+                CommandKind::Path(path) => {
+                    let mut command = Command::new(&path);
+                    for arg in cmd.args.iter() {
+                        command.arg(OsStr::from_bytes(arg));
                     }
-                };
 
-                children.push(child);
-            }
+                    if let Some(r) = prev_reader.take() {
+                        command.stdin(Stdio::from(r));
+                    }
 
-            CommandKind::Builtin(builtin) => {
-                builtin.mod_session(se, &cmd.args);
+                    if let Some(w) = writer {
+                        command.stdout(Stdio::from(w));
+                    }
 
-                let mut input: Box<dyn io::Read + Send> = match prev_reader.take() {
-                    Some(r) => Box::new(r),
-                    None => Box::new(io::stdin()),
-                };
+                    let child = match command.spawn() {
+                        Ok(c) => c,
+                        Err(e) => {
+                            let cmd = path.to_string_lossy();
+                            let msg = match e.kind() {
+                                io::ErrorKind::NotFound => format!("{cmd} not found"),
+                                io::ErrorKind::PermissionDenied => {
+                                    format!("{cmd} is not executable")
+                                }
+                                io::ErrorKind::FileTooLarge => format!("{cmd} is too massive"),
+                                io::ErrorKind::ResourceBusy | io::ErrorKind::ExecutableFileBusy => {
+                                    format!("{cmd} is busy")
+                                }
+                                io::ErrorKind::TooManyLinks => {
+                                    format!("{cmd} could not be resolved")
+                                }
+                                io::ErrorKind::InvalidFilename => {
+                                    format!("{cmd} is not a valid file name")
+                                }
+                                io::ErrorKind::ArgumentListTooLong => format!("too many arguments"),
+                                io::ErrorKind::Interrupted => format!("got interrupted"),
+                                io::ErrorKind::Unsupported => format!("{cmd} is not supported"),
+                                e => format!("I am surprised you can get this error here: {e:?}"),
+                            };
+                            println!("pish: {msg}");
+                            spawn_error = true;
+                            break;
+                        }
+                    };
+
+                    children.push(child);
+                }
 
-                let mut output: Box<dyn io::Write + Send> = match writer {
-                    Some(w) => Box::new(w),
-                    None => Box::new(io::stdout()),
-                };
+                CommandKind::Builtin(builtin) => {
+                    builtin.mod_session(&mut self.se, &cmd.args);
 
-                let handle =
-                    std::thread::spawn(move || builtin.io(&cmd.args, &mut input, &mut output));
+                    let mut input: Box<dyn io::Read + Send> = match prev_reader.take() {
+                        Some(r) => Box::new(r),
+                        None => stdin.take().unwrap(),
+                    };
 
-                threads.push(handle);
-            }
-        }
+                    let mut output: Box<dyn io::Write + Send> = match writer {
+                        Some(w) => Box::new(w),
+                        None => stdout.take().unwrap(),
+                    };
 
-        prev_reader = reader;
-    }
+                    let handle =
+                        std::thread::spawn(move || builtin.io(&cmd.args, &mut input, &mut output));
 
-    let status_string;
-
-    if spawn_error {
-        for child in children.iter_mut() {
-            if let Err(e) = child.kill() {
-                println!("failed to kill child - {e:?}");
+                    threads.push(handle);
+                }
             }
+
+            prev_reader = reader;
         }
-        status_string = "".into();
-    } else {
-        let mut code = 0;
-        for jh in threads {
-            // TODO do not ignore panics
-            let _ = jh.join();
-        }
-        for mut child in children {
-            match child.wait() {
-                Ok(ec) => {
-                    if let Some(c) = ec.code() {
-                        code = c;
-                    }
+
+        if spawn_error {
+            for child in children.iter_mut() {
+                if let Err(e) = child.kill() {
+                    println!("failed to kill child - {e:?}");
                 }
-                Err(e) => {
-                    println!("failed to wait for child - {e:?}")
+            }
+            Err(ExecError::ExecError(127))
+        } else {
+            let mut code = 0;
+            for jh in threads {
+                // TODO do not ignore panics
+                let _ = jh.join();
+            }
+            for mut child in children {
+                match child.wait() {
+                    Ok(ec) => {
+                        if let Some(c) = ec.code() {
+                            code = c;
+                        }
+                    }
+                    Err(e) => {
+                        println!("failed to wait for child - {e:?}")
+                    }
                 }
             }
+            if code == 0 {
+                Ok(())
+            } else {
+                Err(ExecError::ExecError(code))
+            }
         }
-        if code == 0 {
-            status_string = String::new();
-        } else {
-            status_string = format!("{code}");
+    }
+}
+
+impl<'a> parse::Expander for Executor<'a> {
+    type Error = ExecError;
+
+    fn expand_var(&mut self, var: BString) -> Result<BString, Self::Error> {
+        match std::env::var_os(OsStr::from_bytes(&var)) {
+            Some(val) => Ok(val.as_bytes().to_vec()),
+            None => Err(ExecError::UnknownVariable),
         }
     }
 
+    fn expand_cmd(&mut self, ast: Ast<parse::PostExpansion>) -> Result<BString, Self::Error> {
+        let stdout = Box::new(ArcWriter::new());
+        let stdin = Box::new(std::io::empty());
+        self.execute(ast, stdin, stdout.clone())?;
+        Ok(stdout.into_inner())
+    }
+}
+
+fn exec(se: &mut Session, ast: Ast<PreExpansion>) -> Result<(), ExecError> {
+    let mut exec = Executor { se };
+    let ast = ast.expand(&mut exec)?;
+    exec.execute(ast, Box::new(io::stdin()), Box::new(io::stdout()))
+}
+
+pub fn run(se: &mut Session, cmd: Vec<u8>) {
+    let parsed = parse::do_parse(&cmd);
+    let parsed = match parsed {
+        Ok(p) => p,
+        Err(err) => {
+            println!("{cmd:?}");
+            print!("{err:?}\r\n{}", se.prompt());
+            return;
+        }
+    };
+
+    se.raw.disable();
+    let result = exec(se, parsed);
     se.raw.enable();
 
+    let status_string = match result {
+        Ok(_) => String::new(),
+        Err(ExecError::UnknownVariable) => String::from("unbound variable"),
+        Err(ExecError::ExecError(i)) => i.to_string(),
+    };
+
     print!("\r{status_string}\r\n{}", se.prompt());
     let _ = std::io::stdout().lock().flush();
 }