Implemented the autocmd builtin, which allows you to register hooks for certain shell events.

src/builtin/autocmd.rs

@@ -0,0 +1,91 @@
+use regex::Regex;
+
+use crate::{
+  getopt::{Opt, OptSpec, get_opts_from_tokens}, libsh::error::{ShErr, ShErrKind, ShResult, ShResultExt}, parse::{NdRule, Node, execute::prepare_argv}, state::{self, AutoCmd, AutoCmdKind, write_logic}
+};
+
+pub struct AutoCmdOpts {
+	pattern: Option<Regex>,
+	clear: bool
+}
+fn autocmd_optspec() -> [OptSpec;2] {
+	[
+		OptSpec {
+			opt: Opt::Short('p'),
+			takes_arg: true
+		},
+		OptSpec {
+			opt: Opt::Short('c'),
+			takes_arg: false
+		}
+	]
+}
+
+pub fn get_autocmd_opts(opts: &[Opt]) -> ShResult<AutoCmdOpts> {
+	let mut autocmd_opts = AutoCmdOpts {
+		pattern: None,
+		clear: false
+	};
+
+	let mut opts = opts.iter();
+	while let Some(arg) = opts.next() {
+		match arg {
+			Opt::ShortWithArg('p', arg) => {
+				autocmd_opts.pattern = Some(Regex::new(arg).map_err(|e| ShErr::simple(ShErrKind::ExecFail, format!("invalid regex for -p: {}", e)))?);
+			}
+			Opt::Short('c') => {
+				autocmd_opts.clear = true;
+			}
+			_ => {
+				return Err(ShErr::simple(ShErrKind::ExecFail, format!("unexpected option: {}", arg)));
+			}
+		}
+	}
+
+	Ok(autocmd_opts)
+}
+
+pub fn autocmd(node: Node) -> ShResult<()> {
+  let span = node.get_span();
+  let NdRule::Command {
+    assignments: _,
+    argv,
+  } = node.class
+  else {
+    unreachable!()
+  };
+
+	let (argv,opts) = get_opts_from_tokens(argv, &autocmd_optspec()).promote_err(span.clone())?;
+	let autocmd_opts = get_autocmd_opts(&opts).promote_err(span.clone())?;
+  let mut argv = prepare_argv(argv)?;
+  if !argv.is_empty() { argv.remove(0); }
+	let mut args = argv.iter();
+
+	let Some(autocmd_kind) = args.next() else {
+		return Err(ShErr::at(ShErrKind::ExecFail, span, "expected an autocmd kind".to_string()));
+	};
+
+	let Ok(autocmd_kind) = autocmd_kind.0.parse::<AutoCmdKind>() else {
+		return Err(ShErr::at(ShErrKind::ExecFail, autocmd_kind.1.clone(), format!("invalid autocmd kind: {}", autocmd_kind.0)));
+	};
+
+	if autocmd_opts.clear {
+		write_logic(|l| l.clear_autocmds(autocmd_kind));
+		state::set_status(0);
+		return Ok(());
+	}
+
+	let Some(autocmd_cmd) = args.next() else {
+		return Err(ShErr::at(ShErrKind::ExecFail, span, "expected an autocmd command".to_string()));
+	};
+
+	let autocmd = AutoCmd {
+		pattern: autocmd_opts.pattern,
+		command: autocmd_cmd.0.clone(),
+	};
+
+	write_logic(|l| l.insert_autocmd(autocmd_kind, autocmd));
+
+  state::set_status(0);
+  Ok(())
+}