Support for line continuation

README.md

@@ -34,7 +34,7 @@ fn main() -> Result<()> {
         println!("No previous history.");
     }
     loop {
-        let readline = rl.readline(">> ");
+        let readline = rl.readline(">> ", "");
         match readline {
             Ok(line) => {
                 rl.add_history_entry(line.as_str());

examples/custom_key_bindings.rs

@@ -101,7 +101,7 @@ fn main() -> Result<()> {
     );
 
     loop {
-        let line = rl.readline("> ")?;
+        let line = rl.readline("> ", "")?;
         rl.add_history_entry(line.as_str())?;
         println!("Line: {line}");
     }

examples/diy_hints.rs

@@ -90,7 +90,7 @@ fn main() -> Result<()> {
     rl.set_helper(Some(h));
 
     loop {
-        let input = rl.readline("> ")?;
+        let input = rl.readline("> ", "")?;
         println!("input: {input}");
     }
 }

examples/example.rs

@@ -73,7 +73,7 @@ fn main() -> rustyline::Result<()> {
     loop {
         let p = format!("{count}> ");
         rl.helper_mut().expect("No helper").colored_prompt = format!("\x1b[1;32m{p}\x1b[0m");
-        let readline = rl.readline(&p);
+        let readline = rl.readline(&p, "");
         match readline {
             Ok(line) => {
                 rl.add_history_entry(line.as_str())?;

examples/external_print.rs

@@ -22,7 +22,7 @@ fn main() -> Result<()> {
     });
 
     loop {
-        let line = rl.readline("> ")?;
+        let line = rl.readline("> ", "")?;
         rl.add_history_entry(line.as_str())?;
         println!("Line: {line}");
     }

examples/input_multiline.rs

@@ -23,7 +23,7 @@ fn main() -> Result<()> {
         EventHandler::Simple(Cmd::Newline),
     );
 
-    let input = rl.readline("> ")?;
+    let input = rl.readline("ml> ", "... ")?;
     println!("Input: {input}");
 
     Ok(())

examples/input_validation.rs

@@ -25,7 +25,7 @@ fn main() -> Result<()> {
     let mut rl = Editor::new()?;
     rl.set_helper(Some(h));
 
-    let input = rl.readline("> ")?;
+    let input = rl.readline("> ", "")?;
     println!("Input: {input}");
     Ok(())
 }

examples/minimal.rs

@@ -5,7 +5,7 @@ fn main() -> Result<()> {
     env_logger::init();
     let mut rl = DefaultEditor::new()?;
     loop {
-        let line = rl.readline("> ")?; // read
+        let line = rl.readline("> ", "")?; // read
         println!("Line: {line}"); // eval / print
     } // loop
 }

examples/numeric_input.rs

@@ -27,7 +27,7 @@ fn main() -> Result<()> {
     );
 
     loop {
-        let line = rl.readline("> ")?;
+        let line = rl.readline("> ", "")?;
         println!("Num: {line}");
     }
 }

examples/read_password.rs

@@ -35,14 +35,14 @@ fn main() -> Result<()> {
     let mut rl = Editor::new()?;
     rl.set_helper(Some(h));
 
-    let username = rl.readline("Username:")?;
+    let username = rl.readline("Username:", "")?;
     println!("Username: {username}");
 
     rl.helper_mut().expect("No helper").masking = true;
     rl.set_color_mode(ColorMode::Forced); // force masking
     rl.set_auto_add_history(false); // make sure password is not added to history
     let mut guard = rl.set_cursor_visibility(false)?;
-    let passwd = rl.readline("Password:")?;
+    let passwd = rl.readline("Password:", "")?;
     guard.take();
     println!("Secret: {passwd}");
     Ok(())

examples/sqlite_history.rs

@@ -11,7 +11,7 @@ fn main() -> Result<()> {
     };
     let mut rl: Editor<(), _> = Editor::with_history(config, history)?;
     loop {
-        let line = rl.readline("> ")?;
+        let line = rl.readline("> ", "")?;
         println!("{line}");
     }
 }

src/edit.rs

@@ -27,7 +27,8 @@ pub struct State<'out, 'prompt, H: Helper> {
     pub out: &'out mut <Terminal as Term>::Writer,
     prompt: &'prompt str,  // Prompt to display (rl_prompt)
     prompt_size: Position, // Prompt Unicode/visible width and height
-    pub line: LineBuffer,  // Edited line buffer
+    continuation: &'prompt str,
+    pub line: LineBuffer, // Edited line buffer
     pub layout: Layout,
     saved_line_for_history: LineBuffer, // Current edited line before history browsing
     byte_buffer: [u8; 4],
@@ -48,14 +49,16 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
     pub fn new(
         out: &'out mut <Terminal as Term>::Writer,
         prompt: &'prompt str,
+        continuation: &'prompt str,
         helper: Option<&'out H>,
         ctx: Context<'out>,
     ) -> Self {
-        let prompt_size = out.calculate_position(prompt, Position::default());
+        let prompt_size = out.calculate_position(prompt, Position::default(), continuation);
         Self {
             out,
             prompt,
             prompt_size,
+            continuation,
             line: LineBuffer::with_capacity(MAX_LINE).can_growth(true),
             layout: Layout::default(),
             saved_line_for_history: LineBuffer::with_capacity(MAX_LINE).can_growth(true),
@@ -93,9 +96,11 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
                 if new_cols != old_cols
                     && (self.layout.end.row > 0 || self.layout.end.col >= new_cols)
                 {
-                    self.prompt_size = self
-                        .out
-                        .calculate_position(self.prompt, Position::default());
+                    self.prompt_size = self.out.calculate_position(
+                        self.prompt,
+                        Position::default(),
+                        self.continuation,
+                    );
                     self.refresh_line()?;
                 }
                 continue;
@@ -122,9 +127,11 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
 
     pub fn move_cursor(&mut self, kind: CmdKind) -> Result<()> {
         // calculate the desired position of the cursor
-        let cursor = self
-            .out
-            .calculate_position(&self.line[..self.line.pos()], self.prompt_size);
+        let cursor = self.out.calculate_position(
+            &self.line[..self.line.pos()],
+            self.prompt_size,
+            self.continuation,
+        );
         if self.layout.cursor == cursor {
             return Ok(());
         }
@@ -172,9 +179,13 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
             None
         };
 
-        let new_layout = self
-            .out
-            .compute_layout(prompt_size, default_prompt, &self.line, info);
+        let new_layout = self.out.compute_layout(
+            prompt_size,
+            default_prompt,
+            &self.line,
+            info,
+            self.continuation,
+        );
 
         debug!(target: "rustyline", "old layout: {:?}", self.layout);
         debug!(target: "rustyline", "new layout: {:?}", new_layout);
@@ -185,6 +196,7 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
             &self.layout,
             &new_layout,
             highlighter,
+            self.continuation,
         )?;
         self.layout = new_layout;
 
@@ -275,7 +287,9 @@ impl<H: Helper> Refresher for State<'_, '_, H> {
     }
 
     fn refresh_prompt_and_line(&mut self, prompt: &str) -> Result<()> {
-        let prompt_size = self.out.calculate_position(prompt, Position::default());
+        let prompt_size =
+            self.out
+                .calculate_position(prompt, Position::default(), self.continuation);
         self.hint();
         self.highlight_char(CmdKind::Other);
         self.refresh(prompt, prompt_size, false, Info::Hint)
@@ -753,6 +767,7 @@ pub fn init_state<'out, H: Helper>(
         out,
         prompt: "",
         prompt_size: Position::default(),
+        continuation: "",
         line: LineBuffer::init(line, pos),
         layout: Layout::default(),
         saved_line_for_history: LineBuffer::with_capacity(100),

src/lib.rs

@@ -9,7 +9,7 @@
 //!
 //! ```
 //! let mut rl = rustyline::DefaultEditor::new()?;
-//! let readline = rl.readline(">> ");
+//! let readline = rl.readline(">> ", "");
 //! match readline {
 //!     Ok(line) => println!("Line: {:?}", line),
 //!     Err(_) => println!("No input"),
@@ -634,8 +634,8 @@ impl<H: Helper, I: History> Editor<H, I> {
     /// terminal.
     /// Otherwise (e.g., if `stdin` is a pipe or the terminal is not supported),
     /// it uses file-style interaction.
-    pub fn readline(&mut self, prompt: &str) -> Result<String> {
-        self.readline_with(prompt, None)
+    pub fn readline(&mut self, prompt: &str, continuation: &str) -> Result<String> {
+        self.readline_with(prompt, continuation, None)
     }
 
     /// This function behaves in the exact same manner as `readline`, except
@@ -645,11 +645,21 @@ impl<H: Helper, I: History> Editor<H, I> {
     /// The string on the left of the tuple is what will appear to the left of
     /// the cursor and the string on the right is what will appear to the
     /// right of the cursor.
-    pub fn readline_with_initial(&mut self, prompt: &str, initial: (&str, &str)) -> Result<String> {
-        self.readline_with(prompt, Some(initial))
+    pub fn readline_with_initial(
+        &mut self,
+        prompt: &str,
+        continuation: &str,
+        initial: (&str, &str),
+    ) -> Result<String> {
+        self.readline_with(prompt, continuation, Some(initial))
     }
 
-    fn readline_with(&mut self, prompt: &str, initial: Option<(&str, &str)>) -> Result<String> {
+    fn readline_with(
+        &mut self,
+        prompt: &str,
+        continuation: &str,
+        initial: Option<(&str, &str)>,
+    ) -> Result<String> {
         if self.term.is_unsupported() {
             debug!(target: "rustyline", "unsupported terminal");
             // Write prompt and flush it to stdout
@@ -661,7 +671,8 @@ impl<H: Helper, I: History> Editor<H, I> {
         } else if self.term.is_input_tty() {
             let (original_mode, term_key_map) = self.term.enable_raw_mode()?;
             let guard = Guard(&original_mode);
-            let user_input = self.readline_edit(prompt, initial, &original_mode, term_key_map);
+            let user_input =
+                self.readline_edit(prompt, continuation, initial, &original_mode, term_key_map);
             if self.config.auto_add_history() {
                 if let Ok(ref line) = user_input {
                     self.add_history_entry(line.as_str())?;
@@ -683,6 +694,7 @@ impl<H: Helper, I: History> Editor<H, I> {
     fn readline_edit(
         &mut self,
         prompt: &str,
+        continuation: &str,
         initial: Option<(&str, &str)>,
         original_mode: &tty::Mode,
         term_key_map: tty::KeyMap,
@@ -691,7 +703,7 @@ impl<H: Helper, I: History> Editor<H, I> {
 
         self.kill_ring.reset(); // TODO recreate a new kill ring vs reset
         let ctx = Context::new(&self.history);
-        let mut s = State::new(&mut stdout, prompt, self.helper.as_ref(), ctx);
+        let mut s = State::new(&mut stdout, prompt, continuation, self.helper.as_ref(), ctx);
 
         let mut input_state = InputState::new(&self.config, &self.custom_bindings);
 
@@ -872,7 +884,7 @@ impl<H: Helper, I: History> Editor<H, I> {
     /// Iterator ends at [EOF](ReadlineError::Eof).
     /// ```
     /// let mut rl = rustyline::DefaultEditor::new()?;
-    /// for readline in rl.iter("> ") {
+    /// for readline in rl.iter("> ", "") {
     ///     match readline {
     ///         Ok(line) => {
     ///             println!("Line: {}", line);
@@ -885,10 +897,15 @@ impl<H: Helper, I: History> Editor<H, I> {
     /// }
     /// # Ok::<(), rustyline::error::ReadlineError>(())
     /// ```
-    pub fn iter<'a>(&'a mut self, prompt: &'a str) -> impl Iterator<Item = Result<String>> + 'a {
+    pub fn iter<'a>(
+        &'a mut self,
+        prompt: &'a str,
+        continuation: &'a str,
+    ) -> impl Iterator<Item = Result<String>> + 'a {
         Iter {
             editor: self,
             prompt,
+            continuation,
         }
     }
 
@@ -965,13 +982,14 @@ impl<H: Helper, I: History> fmt::Debug for Editor<H, I> {
 struct Iter<'a, H: Helper, I: History> {
     editor: &'a mut Editor<H, I>,
     prompt: &'a str,
+    continuation: &'a str,
 }
 
 impl<H: Helper, I: History> Iterator for Iter<'_, H, I> {
     type Item = Result<String>;
 
     fn next(&mut self) -> Option<Result<String>> {
-        let readline = self.editor.readline(self.prompt);
+        let readline = self.editor.readline(self.prompt, self.continuation);
         match readline {
             Ok(l) => Some(Ok(l)),
             Err(ReadlineError::Eof) => None,

src/test/common.rs

@@ -157,7 +157,7 @@ fn newline_key() {
 fn eof_key() {
     for mode in &[EditMode::Emacs, EditMode::Vi] {
         let mut editor = init_editor(*mode, &[E::ctrl('D')]);
-        let err = editor.readline(">>");
+        let err = editor.readline(">>", "");
         assert_matches!(err, Err(ReadlineError::Eof));
     }
     assert_line(
@@ -176,16 +176,16 @@ fn eof_key() {
 fn interrupt_key() {
     for mode in &[EditMode::Emacs, EditMode::Vi] {
         let mut editor = init_editor(*mode, &[E::ctrl('C')]);
-        let err = editor.readline(">>");
+        let err = editor.readline(">>", "");
         assert_matches!(err, Err(ReadlineError::Interrupted));
 
         let mut editor = init_editor(*mode, &[E::ctrl('C')]);
-        let err = editor.readline_with_initial(">>", ("Hi", ""));
+        let err = editor.readline_with_initial(">>", "", ("Hi", ""));
         assert_matches!(err, Err(ReadlineError::Interrupted));
         if *mode == EditMode::Vi {
             // vi command mode
             let mut editor = init_editor(*mode, &[E::ESC, E::ctrl('C')]);
-            let err = editor.readline_with_initial(">>", ("Hi", ""));
+            let err = editor.readline_with_initial(">>", "", ("Hi", ""));
             assert_matches!(err, Err(ReadlineError::Interrupted));
         }
     }

src/test/mod.rs

@@ -104,7 +104,7 @@ fn complete_symbol() {
 // `expected_line`: line after enter key
 fn assert_line(mode: EditMode, keys: &[KeyEvent], expected_line: &str) {
     let mut editor = init_editor(mode, keys);
-    let actual_line = editor.readline(">>").unwrap();
+    let actual_line = editor.readline(">>", "").unwrap();
     assert_eq!(expected_line, actual_line);
 }
 
@@ -118,7 +118,7 @@ fn assert_line_with_initial(
     expected_line: &str,
 ) {
     let mut editor = init_editor(mode, keys);
-    let actual_line = editor.readline_with_initial(">>", initial).unwrap();
+    let actual_line = editor.readline_with_initial(">>", "", initial).unwrap();
     assert_eq!(expected_line, actual_line);
 }
 
@@ -127,7 +127,7 @@ fn assert_line_with_initial(
 // `expected`: line status before enter key: strings before and after cursor
 fn assert_cursor(mode: EditMode, initial: (&str, &str), keys: &[KeyEvent], expected: (&str, &str)) {
     let mut editor = init_editor(mode, keys);
-    let actual_line = editor.readline_with_initial("", initial).unwrap();
+    let actual_line = editor.readline_with_initial("", "", initial).unwrap();
     assert_eq!(expected.0.to_owned() + expected.1, actual_line);
     assert_eq!(expected.0.len(), editor.term.cursor);
 }
@@ -146,7 +146,7 @@ fn assert_history(
     for entry in entries {
         editor.history.add(entry).unwrap();
     }
-    let actual_line = editor.readline(prompt).unwrap();
+    let actual_line = editor.readline(prompt, "").unwrap();
     assert_eq!(expected.0.to_owned() + expected.1, actual_line);
     if prompt.is_empty() {
         assert_eq!(expected.0.len(), editor.term.cursor);