Feature Request: Input Highlighting about irust HOT 13 CLOSED

diff --git a/Cargo.toml b/Cargo.toml
index 76ca31b..b24a878 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,4 +20,3 @@ nix = "0.14.1"
 [features]
 default = ["highlight"]
 highlight = ["syntect"]
-
diff --git a/src/irust/events.rs b/src/irust/events.rs
index 646c063..bd12c42 100644
--- a/src/irust/events.rs
+++ b/src/irust/events.rs
@@ -5,6 +5,8 @@ use crate::irust::{IRust, IRustError};
 use crate::utils::StringTools;
 use crossterm::ClearType;
 
+use crate::irust::highlight::*;
+
 impl IRust {
     pub fn handle_character(&mut self, c: char) -> Result<(), IRustError> {
         // clear suggestion
@@ -18,6 +20,7 @@ impl IRust {
         // Insert input char in buffer
         StringTools::insert_at_char_idx(&mut self.buffer, self.internal_cursor.buffer_pos, c);
 
+
         // update histroy current
         self.history.update_current(&self.buffer);
 
@@ -27,8 +30,9 @@ impl IRust {
         // unbound upper limit
         self.internal_cursor.current_bounds_mut().1 = self.size.0;
 
-        // Write input char
-        self.write_insert(Some(&c.to_string()))?;
+        self.printer = highlight(&self.buffer);
+
+        self.write_out()?;
 
         Ok(())
     }
diff --git a/src/irust/highlight.rs b/src/irust/highlight.rs
index b5afe0b..b4c2d9e 100644
--- a/src/irust/highlight.rs
+++ b/src/irust/highlight.rs
@@ -1,20 +1,22 @@
 use super::printer::{Printer, PrinterItem, PrinterItemType};
 use syntect::easy::HighlightLines;
-use syntect::highlighting::{Color, ThemeSet};
+use syntect::highlighting::{ Color, ThemeSet };
 use syntect::parsing::SyntaxSet;
-use syntect::util::LinesWithEndings;
+use syntect::util::{ LinesWithEndings };
 
-pub fn highlight(c: &str) -> Printer {
-    let ps = SyntaxSet::load_defaults_newlines();
-    let ts = ThemeSet::load_defaults();
+use once_cell::sync::Lazy;
 
-    let syntax = ps.find_syntax_by_extension("rs").unwrap();
-    let mut h = HighlightLines::new(syntax, &ts.themes["base16-ocean.dark"]);
+static PS: Lazy<SyntaxSet> = Lazy::new(|| SyntaxSet::load_defaults_newlines());
+static TS: Lazy<ThemeSet> = Lazy::new(|| ThemeSet::load_defaults());
+
+pub fn highlight(string: &str) -> Printer {
+    let syntax = PS.find_syntax_by_extension("rs").unwrap();
+    let mut h = HighlightLines::new(syntax, &TS.themes["base16-ocean.dark"]);
 
     let mut printer = Printer::default();
 
-    for line in LinesWithEndings::from(c) {
-        h.highlight(line, &ps)
+    for line in LinesWithEndings::from(string) {
+        h.highlight(line, &PS)
             .into_iter()
             .for_each(|(style, part)| {
                 let fg_color = match style.foreground {

diff --git a/src/irust/events.rs b/src/irust/events.rs
index 5a94297..cff656b 100644
--- a/src/irust/events.rs
+++ b/src/irust/events.rs
@@ -7,6 +7,9 @@ use crossterm::ClearType;
 
 impl IRust {
     pub fn handle_character(&mut self, c: char) -> Result<(), IRustError> {
+        // hide cursor
+        let _ = self.cursor.hide();
+
         // clear suggestion
         self.clear_suggestion()?;
 
@@ -30,6 +33,18 @@ impl IRust {
         // Write input char
         self.write_insert(Some(&c.to_string()))?;
+        // We are doing incremental changes to the codebase
+        // So instead of changing handle_char function we just repaint the buffer

+        // go to lock_pos before printing, lock_pos = starting position
+        // print from the start then restore the cursor to its original position
+        let _ = self.cursor.save_position();
+        self.move_cursor_to(
+            self.internal_cursor.lock_pos.0,
+            self.internal_cursor.lock_pos.1,
+        )?;
+        self.printer = super::highlight::highlight(&self.buffer);
+        let _ = self.write_out();
+        let _ = self.cursor.reset_position();
+
+        // show cursor
+        let _ = self.cursor.show();
+
         Ok(())
     }
 
diff --git a/src/irust/highlight.rs b/src/irust/highlight.rs
index b5afe0b..239212c 100644
--- a/src/irust/highlight.rs
+++ b/src/irust/highlight.rs
@@ -1,20 +1,21 @@
 use super::printer::{Printer, PrinterItem, PrinterItemType};
+use once_cell::sync::Lazy;
 use syntect::easy::HighlightLines;
 use syntect::highlighting::{Color, ThemeSet};
-use syntect::parsing::SyntaxSet;
+use syntect::parsing::{SyntaxReference, SyntaxSet};
 use syntect::util::LinesWithEndings;
 
-pub fn highlight(c: &str) -> Printer {
-    let ps = SyntaxSet::load_defaults_newlines();
-    let ts = ThemeSet::load_defaults();
+static PS: Lazy<SyntaxSet> = Lazy::new(SyntaxSet::load_defaults_newlines);
+static TS: Lazy<ThemeSet> = Lazy::new(ThemeSet::load_defaults);
+static SYNTAX: Lazy<&SyntaxReference> = Lazy::new(|| PS.find_syntax_by_extension("rs").unwrap());
 
-    let syntax = ps.find_syntax_by_extension("rs").unwrap();
-    let mut h = HighlightLines::new(syntax, &ts.themes["base16-ocean.dark"]);
+pub fn highlight(c: &str) -> Printer {
+    let mut h = HighlightLines::new(&SYNTAX, &TS.themes["base16-ocean.dark"]);
 
     let mut printer = Printer::default();
 
     for line in LinesWithEndings::from(c) {
-        h.highlight(line, &ps)
+        h.highlight(line, &PS)
             .into_iter()
             .for_each(|(style, part)| {
                 let fg_color = match style.foreground {
@@ -28,5 +29,7 @@ pub fn highlight(c: &str) -> Printer {
         printer.add_new_line(1);
     }
 
+   // highlight adds a new line for each printer element in the loop
+  // the last newline is undesirable and causes issues with printing the buffer
+    printer.pop();
+
     printer
 }
diff --git a/src/irust/printer.rs b/src/irust/printer.rs
index 81a7be4..b4de1cd 100644
--- a/src/irust/printer.rs
+++ b/src/irust/printer.rs
@@ -50,6 +50,10 @@ impl Printer {
     pub fn is_empty(&self) -> bool {
         self.inner.is_empty()
     }
+
+    pub fn pop(&mut self) -> Option<PrinterItem> {
+        self.inner.pop()
+    }
 }
 
 impl Iterator for Printer {