Introduce Prompt trait for styling

examples/custom_key_bindings.rs

@@ -1,4 +1,4 @@
-use std::borrow::Cow::{self, Borrowed, Owned};
+use std::borrow::Cow::{self, Owned};
 
 use rustyline::highlight::Highlighter;
 use rustyline::hint::HistoryHinter;
@@ -13,18 +13,6 @@ use rustyline::{Completer, Helper, Hinter, Validator};
 struct MyHelper(#[rustyline(Hinter)] HistoryHinter);
 
 impl Highlighter for MyHelper {
-    fn highlight_prompt<'b, 's: 'b, 'p: 'b>(
-        &'s self,
-        prompt: &'p str,
-        default: bool,
-    ) -> Cow<'b, str> {
-        if default {
-            Owned(format!("\x1b[1;32m{prompt}\x1b[m"))
-        } else {
-            Borrowed(prompt)
-        }
-    }
-
     fn highlight_hint<'h>(&self, hint: &'h str) -> Cow<'h, str> {
         Owned(format!("\x1b[1m{hint}\x1b[m"))
     }
@@ -101,7 +89,7 @@ fn main() -> Result<()> {
     );
 
     loop {
-        let line = rl.readline("> ")?;
+        let line = rl.readline(&("> ", "\x1b[1;32m> \x1b[m"))?;
         rl.add_history_entry(line.as_str())?;
         println!("Line: {line}");
     }

examples/example.rs

@@ -1,4 +1,4 @@
-use std::borrow::Cow::{self, Borrowed, Owned};
+use std::borrow::Cow::{self, Owned};
 
 use rustyline::completion::FilenameCompleter;
 use rustyline::error::ReadlineError;
@@ -17,22 +17,9 @@ struct MyHelper {
     validator: MatchingBracketValidator,
     #[rustyline(Hinter)]
     hinter: HistoryHinter,
-    colored_prompt: String,
 }
 
 impl Highlighter for MyHelper {
-    fn highlight_prompt<'b, 's: 'b, 'p: 'b>(
-        &'s self,
-        prompt: &'p str,
-        default: bool,
-    ) -> Cow<'b, str> {
-        if default {
-            Borrowed(&self.colored_prompt)
-        } else {
-            Borrowed(prompt)
-        }
-    }
-
     fn highlight_hint<'h>(&self, hint: &'h str) -> Cow<'h, str> {
         Owned("\x1b[1m".to_owned() + hint + "\x1b[m")
     }
@@ -59,7 +46,6 @@ fn main() -> rustyline::Result<()> {
         completer: FilenameCompleter::new(),
         highlighter: MatchingBracketHighlighter::new(),
         hinter: HistoryHinter::new(),
-        colored_prompt: "".to_owned(),
         validator: MatchingBracketValidator::new(),
     };
     let mut rl = Editor::with_config(config)?;
@@ -72,8 +58,8 @@ fn main() -> rustyline::Result<()> {
     let mut count = 1;
     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 colored_prompt = format!("\x1b[1;32m{p}\x1b[0m");
+        let readline = rl.readline(&(p, colored_prompt));
         match readline {
             Ok(line) => {
                 rl.add_history_entry(line.as_str())?;

src/command.rs

@@ -8,16 +8,16 @@ use crate::keymap::{Anchor, At, Cmd, Movement, Word};
 use crate::keymap::{InputState, Refresher};
 use crate::kill_ring::{KillRing, Mode};
 use crate::line_buffer::WordAction;
-use crate::{Helper, Result};
+use crate::{Helper, Prompt, Result};
 
 pub enum Status {
     Proceed,
     Submit,
 }
 
-pub fn execute<H: Helper>(
+pub fn execute<H: Helper, P: Prompt + ?Sized>(
     cmd: Cmd,
-    s: &mut State<'_, '_, H>,
+    s: &mut State<'_, '_, H, P>,
     input_state: &InputState,
     kill_ring: &mut KillRing,
     config: &Config,

src/edit.rs

@@ -4,7 +4,7 @@ use log::debug;
 use std::fmt;
 use unicode_segmentation::UnicodeSegmentation;
 
-use super::{Context, Helper, Result};
+use super::{Context, Helper, Prompt, Result};
 use crate::error::{ReadlineError, Signal};
 use crate::highlight::{CmdKind, Highlighter};
 use crate::hint::Hint;
@@ -21,9 +21,9 @@ use RefreshKind::All;
 
 /// Represent the state during line editing.
 /// Implement rendering.
-pub struct State<'out, 'prompt, H: Helper> {
+pub struct State<'out, 'prompt, H: Helper, P: Prompt + ?Sized> {
     pub out: &'out mut <Terminal as Term>::Writer,
-    prompt: &'prompt str,  // Prompt to display (rl_prompt)
+    prompt: &'prompt P,    // Prompt to display (rl_prompt)
     prompt_size: Position, // Prompt Unicode/visible width and height
     pub line: LineBuffer,  // Edited line buffer
     pub layout: Layout,
@@ -51,14 +51,14 @@ pub enum RefreshKind {
     All,
 }
 
-impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
+impl<'out, 'prompt, H: Helper, P: Prompt + ?Sized> State<'out, 'prompt, H, P> {
     pub fn new(
         out: &'out mut <Terminal as Term>::Writer,
-        prompt: &'prompt str,
+        prompt: &'prompt P,
         helper: Option<&'out H>,
         ctx: Context<'out>,
     ) -> Self {
-        let prompt_size = out.calculate_position(prompt, Position::default());
+        let prompt_size = out.calculate_position(prompt.raw(), Position::default());
         let gcm = out.grapheme_cluster_mode();
         Self {
             out,
@@ -110,7 +110,7 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
                         {
                             self.prompt_size = self
                                 .out
-                                .calculate_position(self.prompt, Position::default());
+                                .calculate_position(self.prompt.raw(), Position::default());
                             self.refresh_line()?;
                         }
                         continue;
@@ -174,9 +174,9 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
         self.refresh(self.prompt, self.prompt_size, true, kind, Info::Hint)
     }
 
-    fn refresh(
+    fn refresh<Q: Prompt + ?Sized>(
         &mut self,
-        prompt: &str,
+        prompt: &Q,
         prompt_size: Position,
         default_prompt: bool,
         kind: RefreshKind,
@@ -279,13 +279,13 @@ impl<'out, 'prompt, H: Helper> State<'out, 'prompt, H> {
     }
 }
 
-impl<H: Helper> Invoke for State<'_, '_, H> {
+impl<H: Helper, P: Prompt + ?Sized> Invoke for State<'_, '_, H, P> {
     fn input(&self) -> &str {
         self.line.as_str()
     }
 }
 
-impl<H: Helper> Refresher for State<'_, '_, H> {
+impl<H: Helper, P: Prompt + ?Sized> Refresher for State<'_, '_, H, P> {
     fn refresh_line(&mut self) -> Result<()> {
         self.hint();
         self.highlight_char(CmdKind::Other);
@@ -349,10 +349,10 @@ impl<H: Helper> Refresher for State<'_, '_, H> {
     }
 }
 
-impl<H: Helper> fmt::Debug for State<'_, '_, H> {
+impl<H: Helper, P: Prompt + ?Sized> fmt::Debug for State<'_, '_, H, P> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("State")
-            .field("prompt", &self.prompt)
+            .field("prompt", &self.prompt.raw())
             .field("prompt_size", &self.prompt_size)
             .field("buf", &self.line)
             .field("cols", &self.out.get_columns())
@@ -362,7 +362,7 @@ impl<H: Helper> fmt::Debug for State<'_, '_, H> {
     }
 }
 
-impl<H: Helper> State<'_, '_, H> {
+impl<H: Helper, P: Prompt + ?Sized> State<'_, '_, H, P> {
     pub fn clear_screen(&mut self) -> Result<()> {
         self.out.clear_screen()?;
         self.layout.cursor = Position::default();
@@ -819,7 +819,7 @@ pub fn init_state<'out, H: Helper>(
     pos: usize,
     helper: Option<&'out H>,
     history: &'out crate::history::DefaultHistory,
-) -> State<'out, 'static, H> {
+) -> State<'out, 'static, H, str> {
     State {
         out,
         prompt: "",

src/lib.rs

@@ -34,6 +34,7 @@ mod keys;
 mod kill_ring;
 mod layout;
 pub mod line_buffer;
+mod prompt;
 #[cfg(feature = "with-sqlite-history")]
 pub mod sqlite_history;
 mod tty;
@@ -66,6 +67,7 @@ pub use crate::keys::{KeyCode, KeyEvent, Modifiers};
 use crate::kill_ring::KillRing;
 pub use crate::layout::GraphemeClusterMode;
 use crate::layout::Unit;
+pub use crate::prompt::Prompt;
 pub use crate::tty::ExternalPrinter;
 pub use crate::undo::Changeset;
 use crate::validate::Validator;
@@ -74,9 +76,9 @@ use crate::validate::Validator;
 pub type Result<T> = result::Result<T, ReadlineError>;
 
 /// Completes the line/word
-fn complete_line<H: Helper>(
+fn complete_line<H: Helper, P: Prompt + ?Sized>(
     rdr: &mut <Terminal as Term>::Reader,
-    s: &mut State<'_, '_, H>,
+    s: &mut State<'_, '_, H, P>,
     input_state: &mut InputState,
     config: &Config,
 ) -> Result<Option<Cmd>> {
@@ -266,7 +268,7 @@ fn complete_line<H: Helper>(
 }
 
 /// Completes the current hint
-fn complete_hint_line<H: Helper>(s: &mut State<'_, '_, H>) -> Result<()> {
+fn complete_hint_line<H: Helper, P: Prompt + ?Sized>(s: &mut State<'_, '_, H, P>) -> Result<()> {
     let Some(hint) = s.hint.as_ref() else {
         return Ok(());
     };
@@ -281,9 +283,9 @@ fn complete_hint_line<H: Helper>(s: &mut State<'_, '_, H>) -> Result<()> {
     s.refresh_line()
 }
 
-fn page_completions<C: Candidate, H: Helper>(
+fn page_completions<C: Candidate, H: Helper, P: Prompt + ?Sized>(
     rdr: &mut <Terminal as Term>::Reader,
-    s: &mut State<'_, '_, H>,
+    s: &mut State<'_, '_, H, P>,
     input_state: &mut InputState,
     candidates: &[C],
 ) -> Result<Option<Cmd>> {
@@ -361,9 +363,9 @@ fn page_completions<C: Candidate, H: Helper>(
 }
 
 /// Incremental search
-fn reverse_incremental_search<H: Helper, I: History>(
+fn reverse_incremental_search<H: Helper, I: History, P: Prompt + ?Sized>(
     rdr: &mut <Terminal as Term>::Reader,
-    s: &mut State<'_, '_, H>,
+    s: &mut State<'_, '_, H, P>,
     input_state: &mut InputState,
     history: &I,
 ) -> Result<Option<Cmd>> {
@@ -633,7 +635,7 @@ 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> {
+    pub fn readline<P: Prompt + ?Sized>(&mut self, prompt: &P) -> Result<String> {
         self.readline_with(prompt, None)
     }
 
@@ -644,21 +646,24 @@ 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> {
+    pub fn readline_with_initial<P: Prompt + ?Sized>(
+        &mut self,
+        prompt: &P,
+        initial: (&str, &str),
+    ) -> Result<String> {
         self.readline_with(prompt, Some(initial))
     }
 
-    fn readline_with(&mut self, prompt: &str, initial: Option<(&str, &str)>) -> Result<String> {
-        #[cfg(windows)]
-        debug_assert!(
-            memchr::memmem::find(prompt.as_bytes(), b"\x1b[").is_none(),
-            "prompt should not be styled"
-        );
+    fn readline_with<P: Prompt + ?Sized>(
+        &mut self,
+        prompt: &P,
+        initial: Option<(&str, &str)>,
+    ) -> Result<String> {
         if self.term.is_unsupported() {
             debug!(target: "rustyline", "unsupported terminal");
             // Write prompt and flush it to stdout
             let mut stdout = io::stdout();
-            stdout.write_all(prompt.as_bytes())?;
+            stdout.write_all(prompt.raw().as_bytes())?;
             stdout.flush()?;
 
             readline_direct(io::stdin().lock(), io::stderr(), &self.helper)
@@ -684,9 +689,9 @@ impl<H: Helper, I: History> Editor<H, I> {
     /// Handles reading and editing the readline buffer.
     /// It will also handle special inputs in an appropriate fashion
     /// (e.g., C-c will exit readline)
-    fn readline_edit(
+    fn readline_edit<P: Prompt + ?Sized>(
         &mut self,
-        prompt: &str,
+        prompt: &P,
         initial: Option<(&str, &str)>,
         original_mode: &tty::Mode,
         term_key_map: tty::KeyMap,

src/prompt.rs

@@ -0,0 +1,37 @@
+/// Provide two versions of the prompt:
+/// - the `raw` version used when `stdout` is not a tty, or when the terminal is
+///   not supported or in `NO_COLOR` mode
+/// - the `styled` version
+pub trait Prompt {
+    /// No style, no ANSI escape sequence
+    fn raw(&self) -> &str;
+    /// With style(s), ANSI escape sequences
+    ///
+    /// Currently, the styled version *must* have the same display width as
+    /// the raw version.
+    ///
+    /// By default, returns the raw string.
+    fn styled(&self) -> &str {
+        self.raw()
+    }
+}
+
+impl Prompt for str {
+    fn raw(&self) -> &str {
+        self
+    }
+}
+impl Prompt for String {
+    fn raw(&self) -> &str {
+        self.as_str()
+    }
+}
+impl<Raw: AsRef<str>, Styled: AsRef<str>> Prompt for (Raw, Styled) {
+    fn raw(&self) -> &str {
+        self.0.as_ref()
+    }
+
+    fn styled(&self) -> &str {
+        self.1.as_ref()
+    }
+}

src/tty/mod.rs

@@ -8,7 +8,7 @@ use crate::highlight::Highlighter;
 use crate::keys::KeyEvent;
 use crate::layout::{GraphemeClusterMode, Layout, Position, Unit};
 use crate::line_buffer::LineBuffer;
-use crate::{Cmd, Result};
+use crate::{Cmd, Prompt, Result};
 
 /// Terminal state
 pub trait RawMode: Sized {
@@ -49,9 +49,9 @@ pub trait Renderer {
     fn move_cursor(&mut self, old: Position, new: Position) -> Result<()>;
 
     /// Display `prompt`, line and cursor in terminal output
-    fn refresh_line(
+    fn refresh_line<P: Prompt + ?Sized>(
         &mut self,
-        prompt: &str,
+        prompt: &P,
         line: &LineBuffer,
         hint: Option<&str>,
         old_layout: Option<&Layout>, // used to clear old rows