Parametrize Editor by the Completer type

This allows the `Editor` to implement `Sync` as long as it contains a completer which implement `Sync`. It lets the `Editor` take ownership of the completer.

README.md

@@ -27,7 +27,7 @@ use rustyline::error::ReadlineError;
 use rustyline::Editor;
 
 fn main() {
-    let mut rl = Editor::new();
+    let mut rl = Editor::<()>::new();
     if let Err(_) = rl.load_history("history.txt") {
         println!("No previous history.");
     }

examples/example.rs

@@ -16,7 +16,7 @@ static PROMPT: &'static str = ">> ";
 fn main() {
     let c = FilenameCompleter::new();
     let mut rl = Editor::new().history_ignore_space(true);
-    rl.set_completer(Some(&c));
+    rl.set_completer(Some(c));
     if let Err(_) = rl.load_history("history.txt") {
         println!("No previous history.");
     }

src/completion.rs

@@ -23,6 +23,42 @@ pub trait Completer {
     }
 }
 
+impl Completer for () {
+    fn complete(&self, _line: &str, _pos: usize) -> Result<(usize, Vec<String>)> {
+        Ok((0, Vec::new()))
+    }
+    fn update(&self, _line: &mut LineBuffer, _start: usize, _elected: &str) {
+        unreachable!()
+    }
+}
+
+impl<'c, C: ?Sized + Completer> Completer for &'c C {
+    fn complete(&self, line: &str, pos: usize) -> Result<(usize, Vec<String>)> {
+        (**self).complete(line, pos)
+    }
+    fn update(&self, line: &mut LineBuffer, start: usize, elected: &str) {
+        (**self).update(line, start, elected)
+    }
+}
+macro_rules! box_completer {
+    ($($id: ident)*) => {
+        $(
+            impl<C: ?Sized + Completer> Completer for $id<C> {
+                fn complete(&self, line: &str, pos: usize) -> Result<(usize, Vec<String>)> {
+                    (**self).complete(line, pos)
+                }
+                fn update(&self, line: &mut LineBuffer, start: usize, elected: &str) {
+                    (**self).update(line, start, elected)
+                }
+            }
+        )*
+    }
+}
+
+use std::sync::Arc;
+use std::rc::Rc;
+box_completer! { Box Rc Arc }
+
 pub struct FilenameCompleter {
     break_chars: BTreeSet<char>,
 }

src/lib.rs

@@ -7,7 +7,7 @@
 //! Usage
 //!
 //! ```
-//! let mut rl = rustyline::Editor::new();
+//! let mut rl = rustyline::Editor::<()>::new();
 //! let readline = rl.readline(">> ");
 //! match readline {
 //!     Ok(line) => println!("Line: {:?}",line),
@@ -888,18 +888,18 @@ fn readline_direct() -> Result<String> {
 }
 
 /// Line editor
-pub struct Editor<'completer> {
+pub struct Editor<C> {
     unsupported_term: bool,
     stdin_isatty: bool,
     stdout_isatty: bool,
     // cols: usize, // Number of columns in terminal
     history: History,
-    completer: Option<&'completer Completer>,
+    completer: Option<C>,
     kill_ring: KillRing,
 }
 
-impl<'completer> Editor<'completer> {
-    pub fn new() -> Editor<'completer> {
+impl<C> Editor<C> {
+    pub fn new() -> Editor<C> {
         // TODO check what is done in rl_initialize()
         // if the number of columns is stored here, we need a SIGWINCH handler...
         let editor = Editor {
@@ -916,32 +916,12 @@ impl<'completer> Editor<'completer> {
         editor
     }
 
-    /// This method will read a line from STDIN and will display a `prompt`
-    #[cfg_attr(feature="clippy", allow(if_not_else))]
-    pub fn readline(&mut self, prompt: &str) -> Result<String> {
-        if self.unsupported_term {
-            // Write prompt and flush it to stdout
-            let mut stdout = io::stdout();
-            try!(write_and_flush(&mut stdout, prompt.as_bytes()));
-
-            readline_direct()
-        } else if !self.stdin_isatty {
-            // Not a tty: read from file / pipe.
-            readline_direct()
-        } else {
-            readline_raw(prompt,
-                         &mut self.history,
-                         self.completer,
-                         &mut self.kill_ring)
-        }
-    }
-
-    pub fn history_ignore_space(mut self, yes: bool) -> Editor<'completer> {
+    pub fn history_ignore_space(mut self, yes: bool) -> Editor<C> {
         self.history.ignore_space(yes);
         self
     }
 
-    pub fn history_ignore_dups(mut self, yes: bool) -> Editor<'completer> {
+    pub fn history_ignore_dups(mut self, yes: bool) -> Editor<C> {
         self.history.ignore_dups(yes);
         self
     }
@@ -970,20 +950,42 @@ impl<'completer> Editor<'completer> {
     pub fn get_history(&mut self) -> &mut History {
         &mut self.history
     }
+}
+
+impl<C: Completer> Editor<C> {
+    /// This method will read a line from STDIN and will display a `prompt`
+    #[cfg_attr(feature="clippy", allow(if_not_else))]
+    pub fn readline(&mut self, prompt: &str) -> Result<String> {
+        if self.unsupported_term {
+            // Write prompt and flush it to stdout
+            let mut stdout = io::stdout();
+            try!(write_and_flush(&mut stdout, prompt.as_bytes()));
+
+            readline_direct()
+        } else if !self.stdin_isatty {
+            // Not a tty: read from file / pipe.
+            readline_direct()
+        } else {
+            readline_raw(prompt,
+                         &mut self.history,
+                         self.completer.as_ref().map(|c| c as &Completer),
+                         &mut self.kill_ring)
+        }
+    }
 
     /// Register a callback function to be called for tab-completion.
-    pub fn set_completer(&mut self, completer: Option<&'completer Completer>) {
+    pub fn set_completer(&mut self, completer: Option<C>) {
         self.completer = completer;
     }
 }
 
-impl<'completer> Default for Editor<'completer> {
-    fn default() -> Editor<'completer> {
+impl<C> Default for Editor<C> {
+    fn default() -> Editor<C> {
         Editor::new()
     }
 }
 
-impl<'completer> fmt::Debug for Editor<'completer> {
+impl<C> fmt::Debug for Editor<C> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("State")
             .field("unsupported_term", &self.unsupported_term)