Better error messages.

src/main.rs

@@ -23,7 +23,6 @@
  */
 
 use std::env;
-use std::io;
 use std::process;
 
 use crate::worker::work;
@@ -52,7 +51,7 @@ fn print_help() {
 		env!("CARGO_PKG_NAME"), env!("CARGO_PKG_NAME"));
 }
 
-fn main() -> io::Result<()> {
+fn main() {
 	let args:Vec<String> = env::args().collect();
 	let mut in_path:Option<&str> = None;
 	let mut out_path:Option<&str> = None;
@@ -66,10 +65,10 @@ fn main() -> io::Result<()> {
 	for i in &args[1..args.len()] {
 		if i == "-h" {
 			print_help();
-			return Ok(());
+			return;
 		} else if i == "-v" {
 			print_version();
-			return Ok(());
+			return;
 		} else if i.starts_with("-") && i != "-" {
 			eprintln!("Invalid argument '{}'. Use -h for help information.", i);
 			process::exit(1);
@@ -83,5 +82,9 @@ fn main() -> io::Result<()> {
 		out_path = Some(args[2].as_str());
 	}
 
-	work(in_path, out_path)
+	let res = work(in_path, out_path);
+	if let Err(err) = res {
+		eprintln!("{}", err);
+		process::exit(1);
+	}
 }

src/worker.rs

@@ -6,11 +6,14 @@ use std::boxed::Box;
 // Read 1KiB of the file at a time.
 static BLOCK_SIZE:usize = 1024;
 
-pub fn work(in_path:Option<&str>, out_path:Option<&str>) -> io::Result<()>  {
+pub fn work(in_path:Option<&str>, out_path:Option<&str>) -> Result<(), String>  {
 	let mut in_reader:Box<dyn io::Read> = match in_path {
-		Some(x) => {
-			let in_file = fs::File::open(x)?;
-			Box::new(io::BufReader::new(in_file))
+		Some(path) => {
+			let in_file = fs::File::open(path);
+			if let Err(e) = in_file {
+				return Err(format!("{path}: {e}"));
+			}
+			Box::new(io::BufReader::new(in_file.unwrap()))
 		},
 		None => {
 			Box::new(io::stdin())
@@ -18,9 +21,12 @@ pub fn work(in_path:Option<&str>, out_path:Option<&str>) -> io::Result<()>  {
 	};
 
 	let mut out_writer:Box<dyn io::Write> = match out_path {
-		Some(x) => {
-			let out_file = fs::File::create(x)?;
-			Box::new(io::BufWriter::new(out_file))
+		Some(path) => {
+			let out_file = fs::File::create(path);
+			if let Err(e) = out_file {
+				return Err(format!("{path}: {e}"));
+			}
+			Box::new(io::BufWriter::new(out_file.unwrap()))
 		},
 		None => {
 			Box::new(io::stdout())
@@ -31,37 +37,37 @@ pub fn work(in_path:Option<&str>, out_path:Option<&str>) -> io::Result<()>  {
 	let mut last_ch:char = '\0';
 	let mut tab_num = 0;
 
-	while in_reader.read(&mut read_buf)? > 0 {
+	while in_reader.read(&mut read_buf).unwrap() > 0 {
 		for i in read_buf {
 			let ch = i as char;
 			match ch {
 				'[' | '{' => {
 					tab_num += 1;
-					out_writer.write(format!("{}\n", ch).as_bytes())?;
+					out_writer.write(format!("{}\n", ch).as_bytes()).unwrap();
 					for _ in 0..tab_num {
-						out_writer.write(b"  ")?;
+						out_writer.write(b"  ").unwrap();
 					}
 					last_ch = ' ';
 				},
 				']' | '}' => {
 					tab_num -= 1;
-					out_writer.write(b"\n")?;
+					out_writer.write(b"\n").unwrap();
 					for _ in 0..tab_num {
-						out_writer.write(b"  ")?;
+						out_writer.write(b"  ").unwrap();
 					}
-					out_writer.write(format!("{}", ch).as_bytes())?;
+					out_writer.write(format!("{}", ch).as_bytes()).unwrap();
 					last_ch = ch;
 				},
 				',' => {
-					out_writer.write(format!("{}\n", ch).as_bytes())?;
+					out_writer.write(format!("{}\n", ch).as_bytes()).unwrap();
 					for _ in 0..tab_num {
-						out_writer.write(b"  ")?;
+						out_writer.write(b"  ").unwrap();
 					}
 					last_ch = ' ';
 				},
 				_ => {
 					if ch != ' ' || last_ch != ' ' {
-						out_writer.write(format!("{}", ch).as_bytes())?;
+						out_writer.write(format!("{}", ch).as_bytes()).unwrap();
 						last_ch = ch;
 					}
 				},
@@ -69,8 +75,7 @@ pub fn work(in_path:Option<&str>, out_path:Option<&str>) -> io::Result<()>  {
 		}
 	}
 
-	out_writer.flush()?;
+	out_writer.flush().unwrap();
 
 	Ok(())
-
 }