DEV: repl ergonomic improvements.

* Ctrl-C, Ctrl-D now do the appropriate thing
* #exit will now exit the repl

src/help/repl.txt

@@ -15,4 +15,7 @@ Currently supported commands are:
 
 * #del <name>
   - deletes a previously created named binding
+
+* #exit
+  - Exits the repl.
   

src/io/mod.rs

@@ -24,6 +24,10 @@ impl StatementAccumulator {
         Self { acc: Vec::new() }
     }
 
+    pub fn reset(&mut self) {
+        self.acc = Vec::new();
+    }
+
     pub fn next_line(&self) -> usize {
         self.acc.len() + 1
     }

src/main.rs

@@ -27,6 +27,8 @@ use std::path::{Path, PathBuf};
 use std::process;
 use std::rc::Rc;
 
+use rustyline::error::ReadlineError;
+
 use ucglib::build;
 use ucglib::build::assets::{Cache, MemoryCache};
 use ucglib::build::Val;
@@ -585,12 +587,28 @@ fn do_repl<C: Cache>(
         build::FileBuilder::new(std::env::current_dir()?, import_paths, cache, registry);
     // loop
     let mut lines = ucglib::io::StatementAccumulator::new();
-    println!("Welcome to the UCG repl. Ctrl-D to exit");
+    println!("Welcome to the UCG repl. Ctrl-D to exit, Ctrl-C to abort expression.");
     println!("Type '#help' for help.");
     println!("");
     loop {
         // print prompt
-        let line = editor.readline(&format!("{}> ", lines.next_line()))?;
+        let line = match editor.readline(&format!("{}> ", lines.next_line())) {
+            Ok(l) => l,
+            Err(e) => {
+                if let ReadlineError::Eof = e {
+                    eprintln!("Recieved EOF Exiting...");
+                    process::exit(0);
+                }
+                if let ReadlineError::Interrupted = e {
+                    // Reset our lines and start over again
+                    eprintln!("Interrupted!");
+                    lines.reset();
+                    continue;
+                }
+                eprintln!("Error: {}", e);
+                process::exit(1);
+            }
+        };
         // repl commands are only valid while not accumulating a statement;
         let trimmed = line.trim();
         if trimmed.starts_with("#") {
@@ -612,6 +630,8 @@ fn do_repl<C: Cache>(
                         eprintln!("No such binding {}", key.val);
                     }
                 }
+            } else if trimmed.starts_with("#exit") {
+                process::exit(0);
             } else {
                 eprintln!("Invalid repl command...");
                 eprintln!("");