Initial commit

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "rot13"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "rot13"
+version = "0.1.0"
+edition = "2021"

readme.md

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+# ROT13 CLI
+
+A simple CLI tool that "encrypts" text using rot13
+
+## Usage
+
+```shell
+rot13 [input]
+echo [input] | rot13
+```

src/main.rs

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+use std::env;
+use std::io;
+use std::io::BufRead;
+use std::process;
+
+fn main() {
+    // check for direct params
+    let args: Vec<String> = env::args().collect();
+    let arg_input = args.get(1);
+
+    if let Some(x) = arg_input {
+        println!("{}", rot13(x));
+        process::exit(0);
+    }
+
+    // fallback to stdin if no params have been supplied directly
+    let mut std_input = String::new();
+    let stdin = io::stdin();
+    let mut handle = stdin.lock();
+    handle.read_line(&mut std_input).unwrap();
+
+    if !std_input.is_empty() {
+        println!("{}", rot13(&std_input));
+        process::exit(0);
+    }
+
+    // exit with error if neither direct params nor stdin have been supplied
+    process::exit(1);
+}
+
+pub fn rot13(text: &str) -> String {
+    text.chars().map(|c| {
+        match c {
+            'A' ..= 'M' | 'a' ..= 'm' => ((c as u8) + 13) as char,
+            'N' ..= 'Z' | 'n' ..= 'z' => ((c as u8) - 13) as char,
+            _ => c
+        }
+    }).collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn rot13_test() {
+        assert_eq!(rot13("abc123"), "nop123");
+        assert_eq!(rot13("KlmnoP"), "XyzabC");
+    }
+}