Implemented an abstraction for extracting flags from builtins

src/builtin/echo.rs

@@ -1,25 +1,70 @@
-use crate::{builtin::setup_builtin, jobs::{ChildProc, JobBldr}, libsh::error::ShResult, parse::{execute::prepare_argv, NdRule, Node}, prelude::*, procio::{borrow_fd, IoStack}, state};
+use std::sync::Arc;
+
+use crate::{builtin::setup_builtin, getopt::{get_opts_from_tokens, Opt, ECHO_OPTS}, jobs::{ChildProc, JobBldr}, libsh::error::{ShErr, ShErrKind, ShResult, ShResultExt}, parse::{execute::prepare_argv, NdRule, Node}, prelude::*, procio::{borrow_fd, IoStack}, state};
+
+bitflags! {
+	pub struct EchoFlags: u32 {
+		const NO_NEWLINE = 0b000001;
+		const USE_STDERR = 0b000010;
+		const USE_ESCAPE = 0b000100;
+	}
+}
 
 pub fn echo(node: Node, io_stack: &mut IoStack, job: &mut JobBldr) -> ShResult<()> {
+	let blame = node.get_span().clone();
 	let NdRule::Command { assignments: _, argv } = node.class else {
 		unreachable!()
 	};
 	assert!(!argv.is_empty());
-
+	let (argv,opts) = get_opts_from_tokens(argv);
+	let flags = get_echo_flags(opts).blame(blame)?;
 	let (argv,io_frame) = setup_builtin(argv, job, Some((io_stack,node.redirs)))?;
 
-	let stdout = borrow_fd(STDOUT_FILENO);
+	let output_channel = if flags.contains(EchoFlags::USE_STDERR) {
+		borrow_fd(STDERR_FILENO)
+	} else {
+		borrow_fd(STDOUT_FILENO)
+	};
 
 	let mut echo_output = argv.into_iter()
 		.map(|a| a.0) // Extract the String from the tuple of (String,Span)
 		.collect::<Vec<_>>()
 		.join(" ");
 
-	echo_output.push('\n');
+	if !flags.contains(EchoFlags::NO_NEWLINE) {
+		echo_output.push('\n')
+	}
 
-	write(stdout, echo_output.as_bytes())?;
+	write(output_channel, echo_output.as_bytes())?;
 
 	io_frame.unwrap().restore()?;
 	state::set_status(0);
 	Ok(())
 }
+
+pub fn get_echo_flags(mut opts: Vec<Opt>) -> ShResult<EchoFlags> {
+	let mut flags = EchoFlags::empty();
+
+	while let Some(opt) = opts.pop() {
+		if !ECHO_OPTS.contains(&opt) {
+			return Err(
+				ShErr::simple(
+					ShErrKind::ExecFail,
+					format!("echo: Unexpected flag '{opt}'"),
+				)
+			)
+		}
+		let Opt::Short(opt) = opt else {
+			unreachable!()
+		};
+
+		match opt {
+			'n' => flags |= EchoFlags::NO_NEWLINE,
+			'r' => flags |= EchoFlags::USE_STDERR,
+			'e' => flags |= EchoFlags::USE_ESCAPE,
+			_ => unreachable!()
+		}
+	}
+
+	Ok(flags)
+}