Implement initial unicode movement and repaint

TODO.txt

@@ -16,9 +16,14 @@ X Fixed the scroll-off-the-bottom issue
   X Initial commands for the engine
   * Output commands from engine to the line editor
 * UTF-8 support
-* History
-* Up/down history
-* Home/end
+  X Line buffer
+  X Backspace/delete
+  * Navigation
+X History
+X Up/down history
+X Home/end
+* Refactor keypresses to flush at the end
+* Ctrl-A, Ctrl-K, etc
 * Under status
 * Async/parallel prompt
 * Validation

src/line_buffer.rs

@@ -40,14 +40,6 @@ impl LineBuffer {
     }
 
     pub fn inc_insertion_point(&mut self) {
-        // let char_indices: Vec<_> = self.buffer.char_indices().collect();
-
-        // for i in 0..char_indices.len() {
-
-        // }
-        // for (idx, c) in char_indices {
-        //     if idx == self.insertion_point
-        // }
         let grapheme_indices = self.get_grapheme_indices();
         for i in 0..grapheme_indices.len() {
             if grapheme_indices[i].0 == self.insertion_point && i < (grapheme_indices.len() - 1) {
@@ -109,6 +101,34 @@ impl LineBuffer {
         self.buffer.clear()
     }
 
+    // pub fn get_grapheme_index_left(&self) -> usize {
+    //     let grapheme_indices = self.get_grapheme_indices();
+
+    //     let mut prev = 0;
+    //     for (idx, _) in grapheme_indices {
+    //         if idx >= self.insertion_point {
+    //             return prev;
+    //         }
+    //         prev = idx;
+    //     }
+
+    //     prev
+    // }
+
+    // pub fn get_grapheme_index_right(&self) -> usize {
+    //     let grapheme_indices = self.get_grapheme_indices();
+
+    //     let mut next = self.buffer.len();
+    //     for (idx, _) in grapheme_indices.iter().rev() {
+    //         if *idx <= self.insertion_point {
+    //             return next;
+    //         }
+    //         next = *idx;
+    //     }
+
+    //     next
+    // }
+
     pub fn move_word_left(&mut self) -> usize {
         let mut words = self.buffer[..self.insertion_point]
             .split_word_bound_indices()

src/main.rs

@@ -1,7 +1,9 @@
 use std::io::{stdout, Write};
 
 use crossterm::{
-    cursor::{position, MoveLeft, MoveRight, MoveToColumn, MoveToNextLine},
+    cursor::{
+        position, MoveLeft, MoveRight, MoveToColumn, MoveToNextLine, RestorePosition, SavePosition,
+    },
     event::read,
     event::{Event, KeyCode, KeyEvent, KeyModifiers},
     style::{Color, Print, ResetColor, SetForegroundColor},
@@ -28,6 +30,23 @@ fn print_message(stdout: &mut Stdout, msg: &str) -> Result<()> {
     Ok(())
 }
 
+fn buffer_repaint(
+    stdout: &mut Stdout,
+    buffer: &LineBuffer,
+    prompt_offset: u16,
+    new_index: usize,
+) -> Result<()> {
+    let raw_buffer = buffer.get_buffer();
+
+    stdout.queue(MoveToColumn(prompt_offset))?;
+    stdout.queue(Print(&raw_buffer[0..new_index]))?;
+    stdout.queue(SavePosition)?;
+    stdout.queue(Print(&raw_buffer[new_index..]))?;
+    stdout.queue(RestorePosition)?;
+
+    Ok(())
+}
+
 fn main() -> Result<()> {
     let mut stdout = stdout();
 
@@ -109,6 +128,17 @@ fn main() -> Result<()> {
                                 stdout.flush()?;
                             }
                         }
+                        KeyCode::Home => {
+                            buffer_repaint(&mut stdout, &buffer, prompt_offset, 0)?;
+                            stdout.flush()?;
+                            buffer.set_insertion_point(0);
+                        }
+                        KeyCode::End => {
+                            let buffer_len = buffer.get_buffer_len();
+                            buffer.set_insertion_point(buffer_len);
+                            buffer_repaint(&mut stdout, &buffer, prompt_offset, buffer_len)?;
+                            stdout.flush()?;
+                        }
                         KeyCode::Enter => {
                             if buffer.get_buffer() == "exit" {
                                 break 'repl;
@@ -215,8 +245,15 @@ fn main() -> Result<()> {
                                         new_insertion_point as u16 + prompt_offset,
                                     ))?;
                                 } else {
-                                    stdout.queue(MoveLeft(1))?;
+                                    // Start after the prompt
+                                    // Draw the string slice from 0 to the grapheme start left of insertion point
+                                    // Then, get the position on the screen
+                                    // Then draw the remainer of the buffer from above
+                                    // Finally, reset the cursor to the saved position
                                     buffer.dec_insertion_point();
+                                    // let idx = buffer.get_grapheme_index_left();
+                                    let idx = buffer.get_insertion_point();
+                                    buffer_repaint(&mut stdout, &buffer, prompt_offset, idx)?;
                                 }
                                 stdout.flush()?;
                             }
@@ -229,8 +266,9 @@ fn main() -> Result<()> {
                                         new_insertion_point as u16 + prompt_offset,
                                     ))?;
                                 } else {
-                                    stdout.queue(MoveRight(1))?;
                                     buffer.inc_insertion_point();
+                                    let idx = buffer.get_insertion_point();
+                                    buffer_repaint(&mut stdout, &buffer, prompt_offset, idx)?;
                                 }
                                 stdout.flush()?;
                             }