feat: add SQL syntax highlighting in query editor

src/app.rs

@@ -11,7 +11,7 @@ use crate::{
     Result,
     connection::Input,
     db::{Column, Database, PAGE_SIZE, Page, QueryResult, Relation},
-    error_text,
+    error_text, sql,
 };
 
 #[derive(Clone, Copy, PartialEq, Eq)]
@@ -33,6 +33,7 @@ pub struct App {
     column_offset: usize,
     show_schema: bool,
     query: Input,
+    query_highlights: sql::Highlights,
     query_result: Option<QueryResult>,
     error: Option<String>,
 }
@@ -56,6 +57,7 @@ impl App {
             column_offset: 0,
             show_schema: false,
             query: Input::default(),
+            query_highlights: Vec::new(),
             query_result: None,
             error: None,
         };
@@ -104,16 +106,27 @@ impl App {
     }
 
     pub(crate) fn handle_query_key(&mut self, key: KeyEvent) {
+        let previous_len = self.query.value.len();
         match key.code {
             KeyCode::F(5) => self.execute_query(),
             KeyCode::Enter if key.modifiers.contains(KeyModifiers::CONTROL) => self.execute_query(),
             KeyCode::Enter => self.query.paste_multiline("\n"),
             _ => self.query.edit(key),
         }
+        self.highlight_query(previous_len);
     }
 
     pub(crate) fn paste_query(&mut self, text: &str) {
+        let previous_len = self.query.value.len();
         self.query.paste_multiline(text);
+        self.highlight_query(previous_len);
+    }
+
+    fn highlight_query(&mut self, previous_len: usize) {
+        // Editing inserts or removes bytes; cursor movement does not invalidate syntax.
+        if self.query.value.len() != previous_len {
+            self.query_highlights = sql::highlight(&self.query.value, self.db.name() == "SQLite");
+        }
     }
 
     fn execute_query(&mut self) {
@@ -232,6 +245,7 @@ impl App {
             " Query · F5 execute ",
             false,
             focus == Focus::Query,
+            Some(sql::text(&self.query.value, &self.query_highlights)),
         );
         let title = if self.query_result.is_some() {
             " Results "
@@ -432,6 +446,36 @@ mod tests {
         assert_eq!(moved_index(Some(1), 3, isize::MAX), Some(2));
     }
 
+    #[test]
+    fn query_colors_survive_editing_and_scrolling() -> crate::Result<()> {
+        use super::{App, Focus};
+        use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+        use ratatui::{Terminal, backend::TestBackend, style::Color};
+        let file = tempfile::NamedTempFile::new()?;
+        let mut app = App::new(crate::db::Database::open_sqlite(file.path())?)?;
+        let mut terminal = Terminal::new(TestBackend::new(60, 14))?;
+        app.paste_query("SELECT '界', 42;\n-- comment");
+        terminal.draw(|frame| app.draw(frame, frame.area(), Focus::Query))?;
+        let buffer = terminal.backend().buffer();
+        assert_eq!(buffer[(1, 2)].fg, Color::Cyan);
+        assert_eq!(buffer[(8, 2)].fg, Color::Green);
+        assert_eq!(buffer[(1, 3)].fg, Color::DarkGray);
+        app.handle_query_key(KeyEvent::new(KeyCode::Char('u'), KeyModifiers::CONTROL));
+        app.handle_query_key(KeyEvent::new(KeyCode::Char('\''), KeyModifiers::NONE));
+        app.paste_query("unfinished\nstring");
+        terminal.draw(|frame| app.draw(frame, frame.area(), Focus::Query))?;
+        assert_eq!(terminal.backend().buffer()[(1, 3)].fg, Color::Green);
+        app.handle_query_key(KeyEvent::new(KeyCode::Char('u'), KeyModifiers::CONTROL));
+        app.paste_query(&format!("{}--{}", "-- line\n".repeat(12), "x".repeat(90)));
+        terminal.draw(|frame| app.draw(frame, frame.area(), Focus::Query))?;
+        let cursor = terminal.get_cursor_position()?;
+        let buffer = terminal.backend().buffer();
+        assert_eq!(cursor.x, 58);
+        assert_eq!(buffer[(cursor.x - 1, cursor.y)].symbol(), "x");
+        assert_eq!(buffer[(1, cursor.y)].fg, Color::DarkGray);
+        Ok(())
+    }
+
     #[test]
     fn queries_replace_rows_and_preserve_results_on_error() -> crate::Result<()> {
         use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};