Final performance improvements, finish tutorial

src/document.rs

@@ -17,14 +17,11 @@ impl Document {
     pub fn open(filename: &str) -> Result<Self, std::io::Error> {
         let contents = fs::read_to_string(filename)?;
         let file_type = FileType::from(filename);
-        let mut start_with_comment = false;
 
         let mut rows = Vec::new();
 
         for value in contents.lines() {
-            let mut row = Row::from(value);
-            start_with_comment = row.highlight(&file_type.highlighting_options(), None, start_with_comment);
-            rows.push(row);
+            rows.push(Row::from(value));
         }
 
         Ok(Self {
@@ -71,7 +68,7 @@ impl Document {
             row.insert(at.x, c);
         }
 
-        self.highlight(None);
+        self.unhighlight_rows(at.y);
     }
 
     #[allow(clippy::integer_arithmetic, clippy::indexing_slicing)]
@@ -93,23 +90,17 @@ impl Document {
             row.delete(at.x);
         }
 
-        self.highlight(None);
+        self.unhighlight_rows(at.y);
     }
 
     pub fn save(&mut self) -> Result<(), Error> {
         if let Some(file_name) = &self.file_name {
             let mut file = fs::File::create(file_name)?;
             self.file_type = FileType::from(file_name);
-            let mut start_with_comment = false;
 
             for row in &mut self.rows {
                 file.write_all(row.as_bytes())?;
                 file.write_all(b"\n")?;
-                start_with_comment = row.highlight(
-                    &self.file_type.highlighting_options(),
-                    None,
-                    start_with_comment,
-                );
             }
 
             // File has been cleaned! (Saved)
@@ -119,10 +110,20 @@ impl Document {
         Ok(())
     }
 
-    pub fn highlight(&mut self, word: Option<&str>) {
+    pub fn highlight(&mut self, word: &Option<String>, until: Option<usize>) {
         let mut start_with_comment = false;
+        let until = if let Some(until) = until {
+            if until.saturating_add(1) < self.rows.len() {
+                until.saturating_add(1)
+            } else {
+                self.rows.len()
+            }
+        } else {
+            self.rows.len()
+        };
 
-        for row in &mut self.rows {
+        #[allow(clippy::indexing_slicing)]
+        for row in &mut self.rows[..until] {
             start_with_comment = row.highlight(
                 &self.file_type.highlighting_options(),
                 word,
@@ -187,4 +188,11 @@ impl Document {
         #[allow(clippy::integer_arithmetic)]
         self.rows.insert(at.y + 1, new_row);
     }
+
+    fn unhighlight_rows(&mut self, start: usize) {
+        let start = start.saturating_sub(1);
+        for row in self.rows.iter_mut().skip(start) {
+            row.is_highlighted = false;
+        }
+    }
 }

src/editor.rs

@@ -55,6 +55,7 @@ pub struct Editor {
     document: Document,
     status_message: StatusMessage,
     quit_times: u8,
+    highlighted_word: Option<String>,
 }
 
 impl Editor {
@@ -96,16 +97,23 @@ impl Editor {
             offset: Position::default(),
             status_message: StatusMessage::from(initial_status),
             quit_times: QUIT_TIMES,
+            highlighted_word: None,
         }
     }
 
-    fn refresh_screen(&self) -> Result<(), std::io::Error> {
+    fn refresh_screen(&mut self) -> Result<(), std::io::Error> {
         Terminal::cursor_hide();
         Terminal::cursor_position(&Position::default());
         if self.should_quit {
             Terminal::clear_screen();
             println!("Goodbye.\r");
         } else {
+            self.document.highlight(
+                &self.highlighted_word,
+                Some(
+                    self.offset.y.saturating_add(self.terminal.size().height as usize),
+                )
+            );
             self.draw_rows();
             self.draw_status_bar();
             self.draw_message_bar();
@@ -222,7 +230,7 @@ impl Editor {
                         editor.move_cursor(Key::Left);
                     }
 
-                    editor.document.highlight(Some(query));
+                    editor.highlighted_word = Some(query.to_string());
                 },
             )
             .unwrap_or(None);
@@ -232,7 +240,7 @@ impl Editor {
             self.scroll();
         }
 
-        self.document.highlight(None);
+        self.highlighted_word = None;
     }
 
     fn process_keypress(&mut self) -> Result<(), std::io::Error> {

src/row.rs

@@ -9,6 +9,7 @@ use unicode_segmentation::UnicodeSegmentation;
 pub struct Row {
     string: String,
     highlighting: Vec<highlighting::Type>,
+    pub is_highlighted: bool,
     len: usize,
 }
 
@@ -17,6 +18,7 @@ impl From<&str> for Row {
         Self {
             string: String::from(slice),
             highlighting: Vec::new(),
+            is_highlighted: false,
             len: slice.graphemes(true).count(),
         }
     }
@@ -143,10 +145,12 @@ impl Row {
 
         self.string = row;
         self.len = length;
+        self.is_highlighted = false;
 
         Self {
             string: splitted_row,
             len: splittend_length,
+            is_highlighted: false,
             highlighting: Vec::new(),
         }
     }
@@ -190,7 +194,7 @@ impl Row {
         None
     }
 
-    fn highlight_match(&mut self, word: Option<&str>) {
+    fn highlight_match(&mut self, word: &Option<String>) {
         if let Some(word) = word {
             if word.is_empty() {
                 return;
@@ -454,11 +458,22 @@ impl Row {
     pub fn highlight(
         &mut self,
         opts: &HighlightingOptions,
-        word: Option<&str>,
+        word: &Option<String>,
         start_with_comment: bool,
     ) -> bool {
-        self.highlighting = Vec::new();
         let chars: Vec<char> = self.string.chars().collect();
+
+        if self.is_highlighted && word.is_none() {
+            if let Some(hl_type) = self.highlighting.last() {
+                if *hl_type == highlighting::Type::MultilineComment && self.string.len() > 1 && self.string[self.string.len() - 2..] == *"*/" {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        self.highlighting = Vec::new();
         let mut index = 0;
         let mut in_ml_comment = start_with_comment;
 
@@ -507,6 +522,8 @@ impl Row {
             return true;
         }
 
+        self.is_highlighted = true;
+
         false
     }
 }