improved repl with a quit instruction

Cargo.lock

@@ -2,6 +2,34 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "bitflags"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf4b9d6a944f767f8e5e0db018570623c85f3d925ac718db4e06d0187adb21c1"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "cfg_aliases"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd16c4719339c4530435d38e511904438d07cce7950afa3718a84ac36c10e89e"
+
+[[package]]
+name = "ctrlc"
+version = "3.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "672465ae37dc1bc6380a6547a8883d5dd397b0f1faaad4f265726cc7042a5345"
+dependencies = [
+ "nix",
+ "windows-sys",
+]
+
 [[package]]
 name = "either"
 version = "1.12.0"
@@ -23,10 +51,102 @@ version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
+[[package]]
+name = "libc"
+version = "0.2.155"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+
 [[package]]
 name = "monkey-interpreter"
 version = "0.1.0"
 dependencies = [
+ "ctrlc",
  "itertools",
  "lazy_static",
 ]
+
+[[package]]
+name = "nix"
+version = "0.28.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ab2156c4fce2f8df6c499cc1c763e4394b7482525bf2a9701c9d79d215f519e4"
+dependencies = [
+ "bitflags",
+ "cfg-if",
+ "cfg_aliases",
+ "libc",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f0713a46559409d202e70e28227288446bf7841d3211583a4b53e3f6d96e7eb"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7088eed71e8b8dda258ecc8bac5fb1153c5cffaf2578fc8ff5d61e23578d3263"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9985fd1504e250c615ca5f281c3f7a6da76213ebd5ccc9561496568a2752afb6"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "88ba073cf16d5372720ec942a8ccbf61626074c6d4dd2e745299726ce8b89670"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87f4261229030a858f36b459e748ae97545d6f1ec60e5e0d6a3d32e0dc232ee9"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db3c2bf3d13d5b658be73463284eaf12830ac9a26a90c717b7f771dfe97487bf"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e4246f76bdeff09eb48875a0fd3e2af6aada79d409d33011886d3e1581517d9"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "852298e482cd67c356ddd9570386e2862b5673c85bd5f88df9ab6802b334c596"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bec47e5bfd1bff0eeaf6d8b485cc1074891a197ab4225d504cb7a1ab88b02bf0"

Cargo.toml

@@ -5,5 +5,6 @@ authors = ["ishanjain28 <ishanjain28@gmail.com>"]
 edition = "2018"
 
 [dependencies]
+ctrlc = "3.4.4"
 itertools = "0.10.5"
 lazy_static = "1.4.0"

src/main.rs

@@ -1,5 +1,3 @@
-#![feature(assert_matches)]
-
 #[macro_use]
 extern crate lazy_static;
 

src/repl.rs

@@ -8,6 +8,8 @@ use {
         cell::RefCell,
         io::{self, BufRead, Result as IoResult, Write},
         rc::Rc,
+        sync::mpsc,
+        time::Duration,
     },
 };
 
@@ -23,10 +25,33 @@ pub fn init() {
 }
 
 fn start<R: BufRead, W: Write>(mut ip: R, mut out: W) {
+    out.write_all(b"Welcome to Monkey! Press Ctrl+C twice and enter to quit\n")
+        .unwrap();
+
+    let (send, recv) = mpsc::channel();
+
+    let mut should_quit = false;
+    ctrlc::set_handler(move || {
+        send.send(()).expect("error in sending signal to channel");
+    })
+    .expect("error in setting Ctrl+C handler");
+
     let environment = Rc::new(RefCell::new(Environment::new()));
     loop {
         out.write_all(PROMPT).unwrap();
         out.flush().unwrap();
+        if recv.recv_timeout(Duration::from_millis(5)).is_ok() {
+            if should_quit {
+                std::process::exit(0);
+            }
+            should_quit = true;
+            out.write_all(b"\r                                                          \r")
+                .unwrap();
+            continue;
+        } else {
+            should_quit = false;
+        }
+
         let mut s = String::new();
         ip.read_line(&mut s).unwrap();