feat: default to reedline and add syntax highlighting support (#187)

Enable reedline as default input backend, with rustyline an alternative option.

Also adds an off-by-default syntax highlighting option via the reedline input backend, enabled when passing --enable-highlighting on the brush command line. The highlighting is very much a first cut, with some known issues from a few heuristics and potential perf/latency questions.

Author: reubeno

brush-core/src/expansion.rs

@@ -420,7 +420,7 @@ impl<'a> WordExpander<'a> {
 
         let mut expansions = vec![];
         for piece in pieces {
-            let piece_expansion = self.expand_word_piece(piece).await?;
+            let piece_expansion = self.expand_word_piece(piece.piece).await?;
             expansions.push(piece_expansion);
         }
 
@@ -540,7 +540,7 @@ impl<'a> WordExpander<'a> {
                         fields: this_fields,
                         concatenate,
                         undefined: _undefined,
-                    } = self.expand_word_piece(piece).await?;
+                    } = self.expand_word_piece(piece.piece).await?;
 
                     let fields_to_append = if concatenate {
                         #[allow(unstable_name_collisions)]
@@ -603,7 +603,8 @@ impl<'a> WordExpander<'a> {
             brush_parser::word::WordPiece::ParameterExpansion(p) => {
                 self.expand_parameter_expr(p).await?
             }
-            brush_parser::word::WordPiece::CommandSubstitution(s) => {
+            brush_parser::word::WordPiece::BackquotedCommandSubstitution(s)
+            | brush_parser::word::WordPiece::CommandSubstitution(s) => {
                 // Insantiate a subshell to run the command in.
                 let mut subshell = self.shell.clone();
 

brush-core/src/shell.rs

@@ -745,7 +745,7 @@ impl Shell {
 
     /// Returns the options that should be used for parsing shell programs; reflects
     /// the current configuration state of the shell and may change over time.
-    pub(crate) fn parser_options(&self) -> brush_parser::ParserOptions {
+    pub fn parser_options(&self) -> brush_parser::ParserOptions {
         brush_parser::ParserOptions {
             enable_extended_globbing: self.options.extended_globbing,
             posix_mode: self.options.posix_mode,
@@ -880,7 +880,7 @@ impl Shell {
     ///
     /// * `required_glob_pattern` - The glob pattern to match against.
     #[allow(clippy::manual_flatten)]
-    pub(crate) fn find_executables_in_path(&self, required_glob_pattern: &str) -> Vec<PathBuf> {
+    pub fn find_executables_in_path(&self, required_glob_pattern: &str) -> Vec<PathBuf> {
         let is_executable = |path: &Path| path.executable();
 
         let mut executables = vec![];
@@ -1055,6 +1055,19 @@ impl Shell {
         }
     }
 
+    /// Checks if the given string is a keyword reserved in this shell.
+    ///
+    /// # Arguments
+    ///
+    /// * `s` - The string to check.
+    pub fn is_keyword(&self, s: &str) -> bool {
+        if self.options.sh_mode {
+            keywords::SH_MODE_KEYWORDS.contains(s)
+        } else {
+            keywords::KEYWORDS.contains(s)
+        }
+    }
+
     /// Checks for completed jobs in the shell, reporting any changes found.
     pub fn check_for_completed_jobs(&mut self) -> Result<(), error::Error> {
         let results = self.jobs.poll()?;
@@ -1078,7 +1091,7 @@ impl Shell {
     }
 }
 
-#[cached::proc_macro::cached(size = 32, result = true)]
+#[cached::proc_macro::cached(size = 64, result = true)]
 fn parse_string_impl(
     s: String,
     parser_options: brush_parser::ParserOptions,

brush-interactive/src/reedline/completer.rs

@@ -28,19 +28,30 @@ impl ReedlineCompleter {
         completions
             .candidates
             .into_iter()
-            .map(|candidate| {
-                reedline::Suggestion {
-                    value: candidate,
-                    description: None, // TODO: fill in description
-                    style: None,       // TODO: fill in style
-                    extra: None,       // TODO: fill in extras
-                    span: reedline::Span {
-                        start: insertion_index,
-                        end: insertion_index + delete_count,
-                    },
-                    append_whitespace: false, // TODO: compute this
-                }
-            })
+            .map(|candidate| Self::to_suggestion(candidate, insertion_index, delete_count))
             .collect()
     }
+
+    fn to_suggestion(
+        candidate: String,
+        insertion_index: usize,
+        delete_count: usize,
+    ) -> reedline::Suggestion {
+        let mut style = nu_ansi_term::Style::new().dimmed();
+        if candidate.ends_with(std::path::MAIN_SEPARATOR) {
+            style = style.fg(nu_ansi_term::Color::Green);
+        }
+
+        reedline::Suggestion {
+            value: candidate,
+            description: None, // TODO: fill in description
+            style: Some(style),
+            extra: None,
+            span: reedline::Span {
+                start: insertion_index,
+                end: insertion_index + delete_count,
+            },
+            append_whitespace: false, // TODO: compute this
+        }
+    }
 }