added help and splash message

shuffle3rs/Cargo.toml

@@ -15,14 +15,17 @@ opt-level = 1
 opt-level = 1
 
 [features]
-default = ["deferred-drop"]
+default = ["splash", "deferred-drop"]
+
+# Print name and info when printing help info
+splash = []
 
 # Move large objects to a seperate thread to be dropped.
-deferred-drop = ["lazy_static"]
+deferred-drop = []
 
 [dependencies]
 cfg-if = "1.0.0"
-lazy_static = {version = "1.4.0", optional = true}
+lazy_static = "1.4.0"
 rand = "0.8.3"
 
 [dev-dependencies]

shuffle3rs/src/arg.rs

@@ -0,0 +1,38 @@
+
+
+/// The executable program name
+pub fn program_name() -> &'static str
+{
+    lazy_static! {
+	static ref NAME: String = std::env::args().next().unwrap();
+    }
+    &NAME[..]
+}
+
+#[cfg(feature="splash")]
+#[inline] fn splash()
+{
+    println!("shuffle3rs (v{}) - improved 3 pass binary shuffler (Rust ver)", env!("CARGO_PKG_VERSION"));
+    println!(" written by {} with <3", env!("CARGO_PKG_AUTHORS"));
+    println!(" licensed with GPL v3.0 or later\n");
+}
+
+/// Print usage message
+pub fn usage()
+{
+    #[cfg(feature="splash")] splash();
+
+    println!("Usage: {} -s <file>", program_name());
+    println!("Usage: {} -u <file>", program_name());
+    println!("\nOPTIONS:");
+    println!("  -s\tShuffle file in place");
+    println!("  -u\tUnshuffle file in place");
+}
+
+/// Print usage message and then exit with error code `2`.
+#[inline] pub fn help() -> !
+{
+    usage();
+
+    std::process::exit(2)
+}

shuffle3rs/src/main.rs

@@ -8,11 +8,11 @@
 
 #[cfg(feature="deferred-drop")] mod defer_drop;
 mod shuffle;
-
+mod arg;
 
 
 fn main() {
-    println!("Hello, world!");
+    arg::help();
 }
 
 #[cfg(test)] mod test;