fix: only read from stdin if it's not a terminal #17

src/main.rs

@@ -3,7 +3,7 @@
 //! This binary should just take any amount of numbers and print them out formatted to some other
 //! system.
 
-use std::io::Read;
+use std::io::{IsTerminal, Read};
 use std::process::exit;
 
 use clap::{CommandFactory, Parser};
@@ -16,32 +16,35 @@ fn main() {
     // try to read from stdin first, appending the numbers we read to the FormatOptions
     let mut options = FormatOptions::parse();
     let mut stdin_nums = Vec::new();
-    match std::io::stdin().lock().read_to_end(&mut stdin_nums) {
-        Ok(_) => {
-            let whole: String = match String::from_utf8(stdin_nums) {
-                Ok(r) => r,
-                Err(e) => {
-                    eprintln!("stdin for this program only accepts text: {e:#?}");
-                    exit(1);
-                }
-            };
-            let split = whole.split_whitespace();
-            for s in split {
-                let number = match numf_parser(s) {
-                    Ok(n) => n,
+    let stdin = std::io::stdin();
+    if !stdin.is_terminal() {
+        match stdin.lock().read_to_end(&mut stdin_nums) {
+            Ok(_) => {
+                let whole: String = match String::from_utf8(stdin_nums) {
+                    Ok(r) => r,
                     Err(e) => {
-                        eprintln!("could not parse number from stdin: {e:#?}");
-                        exit(2);
+                        eprintln!("stdin for this program only accepts text: {e:#?}");
+                        exit(1);
                     }
                 };
-                options.push_number(number)
+                let split = whole.split_whitespace();
+                for s in split {
+                    let number = match numf_parser(s) {
+                        Ok(n) => n,
+                        Err(e) => {
+                            eprintln!("could not parse number from stdin: {e:#?}");
+                            exit(2);
+                        }
+                    };
+                    options.push_number(number)
+                }
             }
-        }
-        Err(e) => {
-            eprintln!("could not read from stdin: {e:#?}");
-            exit(2);
-        }
-    };
+            Err(e) => {
+                eprintln!("could not read from stdin: {e:#?}");
+                exit(2);
+            }
+        };
+    }
 
     if options.numbers().is_empty() {
         format!("{}", FormatOptions::command().render_usage());