add echo

Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "boreutils"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name = "echo"
+path = "src/echo.rs"
+
+[dependencies]
+aho-corasick = "1.1.3"
+clap = { version = "4.5.20", features = ["derive"] }
+
+[dev-dependencies]
+assert_cmd = "2.0.16"
+predicates = "3.1.2"

src/echo.rs

@@ -0,0 +1,59 @@
+use std::io::Write;
+
+use clap::Parser;
+use aho_corasick::AhoCorasick;
+
+/// Utility command to output information
+#[derive(Parser, Debug)]
+#[command(version, about, long_about = None)]
+struct Args {
+	/// Removes the \n from the end of the output string
+	#[arg(short, long)]
+	noendl: bool,
+
+	/// Parse escapes in the given string
+	#[arg(short, long)]
+	escape: bool,
+
+	/// String to be output
+	#[arg()]
+	data: Option<String>,
+}
+
+fn main() {
+	let args = Args::parse();
+
+	let mut data = match args.data {
+		Some(s) => s,
+		None => String::new()
+	};
+
+	let mut noendl = args.noendl;
+
+	let patterns = &["\\\\", "\\a", "\\b", "\\e", "\\f", "\\n", "\\r", "\\t", "\\v"];
+	let replacements = &["\\", "\x07", "\x08", "\x1B", "\x0C", "\n", "\r", "\t", "\x0B"];
+
+	if args.escape {
+		let ac = AhoCorasick::new(patterns).unwrap();
+		data = ac.replace_all(data.as_str(), replacements);
+		let idx = data.find("\\c");
+		if let Some(n) = idx {
+			data = (&data[0..n]).to_string();
+			noendl = true;
+		}
+	}
+
+	if !noendl {
+		data.push('\n');
+	}
+
+	let mut out = std::io::stdout();
+
+	match out.write_all(data.as_bytes()) {
+		Err(e) => {
+			eprintln!("Failed to write to stdout: {e}");
+			std::process::exit(1);
+		},
+		Ok(()) => ()
+	};
+}

tests/echo.rs

@@ -0,0 +1,53 @@
+use assert_cmd::prelude::*;
+use predicates::prelude::*;
+use std::process::Command;
+
+#[test]
+fn literal_output() -> Result<(), Box<dyn std::error::Error>> {
+    let mut cmd = Command::cargo_bin("echo")?;
+
+    cmd.arg("abc\\ndef");
+    cmd.assert()
+        .success()
+        .stdout(predicate::str::contains("abc\\ndef\n"));
+
+    Ok(())
+}
+
+#[test]
+fn newline_escape() -> Result<(), Box<dyn std::error::Error>> {
+	let mut cmd = Command::cargo_bin("echo")?;
+
+	cmd.arg("-e").arg("abc\\ndef");
+	cmd.assert()
+		.success()
+		.stdout(predicate::str::contains("abc\ndef"));
+
+	Ok(())
+}
+
+#[test]
+fn cut_output_escape() -> Result<(), Box<dyn std::error::Error>> {
+	let mut cmd = Command::cargo_bin("echo")?;
+
+	cmd.arg("-e").arg("abc\\cdef");
+	cmd.assert()
+		.success()
+		.stdout(predicate::str::contains("abc"))
+		.stdout(predicate::str::contains("def\n").not());
+
+	Ok(())
+}
+
+#[test]
+fn omit_endline() -> Result<(), Box<dyn std::error::Error>> {
+	let mut cmd = Command::cargo_bin("echo")?;
+
+	cmd.arg("-n").arg("abcdef");
+	cmd.assert()
+		.success()
+		.stdout(predicate::str::contains("abcdef"))
+		.stdout(predicate::str::contains("\n").not());
+
+	Ok(())
+}