From 263cb0a5e3cd7dffc8fd72b8492452a05d928734 Mon Sep 17 00:00:00 2001
From: Thomas Voss <mail@thomasvoss.com>
Date: Wed, 2 Aug 2023 04:18:16 +0200
Subject: Genesis commit

---
 src/lib.rs | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 src/lib.rs

(limited to 'src')

diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..685c023
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,124 @@
+#![doc = include_str!("../README.md")]
+
+#[doc(hidden)]
+pub use std::{env, process};
+
+/// Print a diagnostic message to stderr and exit with a given code.
+///
+/// This macro is analagous to the BSD [`errx(3)`] C function.  It takes at a
+/// minimum two arguments.  The first argument is the code with passed to
+/// [`std::process::exit()`] with which we exit the program.  The second and
+/// optional additional arguments are passed to the [`eprintln!`] macro.
+///
+/// When invoked, the given format and arguments are printed to the standard
+/// error, prepended by the string `"progname: "`, where `progname` is the
+/// program name as defined by the first element in [`std::env::args`].  If for
+/// whatever reason no such element exists (which is possible), we default to
+/// simply using `"Error"` as the program name.
+///
+/// If you do not care about specifying a specific exit code and are fine with
+/// simply defaulting to `1`, you may prefer to use [`err!`].
+///
+/// # Panics
+///
+/// Calls [`eprint!`], [`eprintln!`], and [`std::env::args`] which may all panic
+/// if they fail.
+///
+/// # Examples
+///
+/// Print a diagnostic in the form `progname: path: error`, and then exit the
+/// program with an exit status of 2.
+///
+/// ```
+/// use std::fs;
+/// use cerm::err_code;
+///
+/// let res = match fs::create_dir(&path) {
+/// 	Ok(v) => v,
+/// 	Err(e) => { err_code!(2, "{}: {}", path, e); }
+/// };
+/// ```
+///
+/// [`errx(3)`]: https://man.openbsd.org/err.3
+#[macro_export]
+macro_rules! err_code {
+	($code:tt, $($fmt:tt)+) => {
+		eprint!("{}: ", $crate::env::args().next().unwrap_or("Error".into()));
+		eprintln!($($fmt)*);
+		$crate::process::exit($code);
+	};
+}
+
+/// The same thing as [`err_code!`], but the exit code is always 1.
+///
+/// This macro is simply a wrapper around [`err_code!`], but with `1` passed as
+/// the first argument; everything else is the same.  For documentation on this
+/// macro, read the documentation for [`err_code!`] instead.
+///
+/// # Panics
+///
+/// Calls [`err!`] which may panic if it fails.
+///
+/// # Examples
+///
+/// Print a diagnostic in the form `progname: path: error`, and then exit the
+/// program with an exit status of 1.
+///
+/// ```
+/// use std::fs;
+/// use cerm::err_code;
+///
+/// let res = match fs::create_dir(&path) {
+/// 	Ok(v) => v,
+/// 	Err(e) => { err!("{}: {}", path, e); }
+/// };
+/// ```
+#[macro_export]
+macro_rules! err {
+	($($fmt:tt)+) => {
+		$crate::err_code!(1, $($fmt)*);
+	}
+}
+
+/// Print a diagnostic message to stderr
+///
+/// This macro is analagous to the BSD [`warnx(3)`] C function.  It takes the
+/// same arguments one would pass to a macro like [`println!`].  In fact, the
+/// arguments are passed directly to [`eprintln]`.
+///
+/// When invoked, the given format and arguments are printed to the standard
+/// error, prepended by the string `"progname: "`, where `progname` is the
+/// program name as defined by the first element in [`std::env::args`].  If for
+/// whatever reason no such element exists (which is possible), we default to
+/// simply using `"Error"` as the program name.
+///
+/// # Panics
+///
+/// Calls [`eprint!`], [`eprintln!`], and [`std::env::args`] which may all panic
+/// if they fail.
+///
+/// # Examples
+///
+/// Print a diagnostic in the form `progname: path: error`
+///
+/// ```
+/// use std::fs;
+/// use cerm::warn;
+///
+/// let res = match fs::create_dir(&path) {
+/// 	Ok(v) => v,
+/// 	Err(e) => {
+/// 		warn!("{}: {}", path, e);
+/// 		/* … */
+/// 	}
+/// };
+/// ```
+///
+/// [`errx(3)`]: https://man.openbsd.org/err.3
+#[macro_export]
+macro_rules! warn {
+	($($fmt:tt)+) => {
+		eprint!("{}: ", $crate::env::args().next().unwrap_or("Error".into()));
+		eprintln!($($fmt)*);
+	};
+}
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