From fc78fbeb3e5e47505d1d1d77f29eb57186cacab2 Mon Sep 17 00:00:00 2001
From: Nathan Vegdahl <cessen@cessen.com>
Date: Fri, 2 Jan 2015 15:05:21 -0800
Subject: [PATCH] Non-uniform-width characters are now properly handled (modulo
 bugs).

---
 src/buffer/line.rs |  78 ++++++++++++++++++
 src/buffer/mod.rs  |  19 +++++
 src/editor.rs      | 196 ++++++++++++++++++++++++++++++++-------------
 src/term_ui.rs     |  14 ++--
 todo.md            |   3 -
 5 files changed, 243 insertions(+), 67 deletions(-)

diff --git a/src/buffer/line.rs b/src/buffer/line.rs
index 13fe5ff..69ec5e0 100644
--- a/src/buffer/line.rs
+++ b/src/buffer/line.rs
@@ -245,6 +245,56 @@ impl Line {
     }
     
     
+    /// Translates a grapheme index into a visual horizontal position
+    pub fn grapheme_index_to_closest_vis_pos(&self, index: uint) -> uint {
+        let mut pos = 0;
+        let mut iter = self.as_str().graphemes(true);
+        
+        for _ in range(0, index) {
+            if let Some(g) = iter.next() {
+                let w = grapheme_vis_width_at_vis_pos(g, pos);
+                pos += w;
+            }
+            else {
+                panic!("Line::grapheme_index_to_vis_pos(): index past end of line.");
+            }
+        }
+        
+        return pos;
+    }
+    
+    
+    /// Translates a visual horizontal position to the closest grapheme index
+    pub fn vis_pos_to_closest_grapheme_index(&self, vis_pos: uint) -> uint {
+        let mut pos = 0;
+        let mut i = 0;
+        let mut iter = self.as_str().graphemes(true);
+        
+        while pos < vis_pos {
+            if let Some(g) = iter.next() {
+                let w = grapheme_vis_width_at_vis_pos(g, pos);
+                if (w + pos) > vis_pos {
+                    let d1 = vis_pos - pos;
+                    let d2 = (pos + w) - vis_pos;
+                    if d2 < d1 {
+                        i += 1;
+                    }
+                    break;
+                }
+                else {
+                    pos += w;
+                    i += 1;
+                }
+            }
+            else {
+                break;
+            }
+        }
+        
+        return i;
+    }
+    
+    
     /// Returns an immutable string slice into the text block's memory
     pub fn as_str<'a>(&'a self) -> &'a str {
         unsafe {
@@ -828,6 +878,34 @@ fn text_line_split_beginning() {
     assert!(tl2.ending == LineEnding::CRLF);
 }
 
+#[test]
+fn grapheme_index_to_closest_vis_pos_1() {
+    let tl = Line::new_from_str("Hello!");
+    
+    assert!(tl.grapheme_index_to_closest_vis_pos(0) == 0);
+}
+
+#[test]
+fn grapheme_index_to_closest_vis_pos_2() {
+    let tl = Line::new_from_str("\tHello!");
+    
+    assert!(tl.grapheme_index_to_closest_vis_pos(1) == TAB_WIDTH);
+}
+
+#[test]
+fn vis_pos_to_closest_grapheme_index_1() {
+    let tl = Line::new_from_str("Hello!");
+    
+    assert!(tl.vis_pos_to_closest_grapheme_index(0) == 0);
+}
+
+#[test]
+fn vis_pos_to_closest_grapheme_index_2() {
+    let tl = Line::new_from_str("\tHello!");
+    
+    assert!(tl.vis_pos_to_closest_grapheme_index(TAB_WIDTH) == 1);
+}
+
 
 //=========================================================================
 // LineGraphemeIter tests
diff --git a/src/buffer/mod.rs b/src/buffer/mod.rs
index 238a242..fd631e4 100644
--- a/src/buffer/mod.rs
+++ b/src/buffer/mod.rs
@@ -89,10 +89,29 @@ impl Buffer {
         return self.root.pos_2d_to_closest_1d_recursive(pos);
     }
 
+
+    pub fn pos_vis_2d_to_closest_1d(&self, pos: (uint, uint)) -> uint {
+        if pos.0 >= self.line_count() {
+            return self.len();
+        }
+        else {
+            let gs = self.pos_2d_to_closest_1d((pos.0, 0));
+            let h = self.get_line(pos.0).vis_pos_to_closest_grapheme_index(pos.1);
+            return gs + h;
+        }
+    }
+
     
     pub fn pos_1d_to_closest_2d(&self, pos: uint) -> (uint, uint) {
         return self.root.pos_1d_to_closest_2d_recursive(pos);
     }
+    
+    
+    pub fn pos_1d_to_closest_vis_2d(&self, pos: uint) -> (uint, uint) {
+        let (v, h) = self.root.pos_1d_to_closest_2d_recursive(pos);
+        let vis_h = self.get_line(v).grapheme_index_to_closest_vis_pos(h);
+        return (v, vis_h);
+    }
 
     
     /// Insert 'text' at grapheme position 'pos'.
diff --git a/src/editor.rs b/src/editor.rs
index 59cc415..2fc1d1c 100644
--- a/src/editor.rs
+++ b/src/editor.rs
@@ -6,6 +6,32 @@ use files::{load_file_to_buffer, save_buffer_to_file};
 use string_utils::grapheme_count;
 
 
+/// A text cursor.  Also represents selections when range.0 != range.1.
+///
+/// `range` is a pair of 1d grapheme indexes into the text.
+///
+/// `vis_start` is the visual 2d horizontal position of the cursor.  This
+/// doesn't affect editing operations at all, but is used for cursor movement.
+pub struct Cursor {
+    pub range: (uint, uint),  // start, end
+    pub vis_start: uint,  // start
+}
+
+impl Cursor {
+    pub fn new() -> Cursor {
+        Cursor {
+            range: (0, 0),
+            vis_start: 0,
+        }
+    }
+    
+    pub fn update_vis_start(&mut self, buf: &Buffer) {
+        let (v, h) = buf.pos_1d_to_closest_2d(self.range.0);
+        self.vis_start = buf.get_line(v).grapheme_index_to_closest_vis_pos(h);
+    }
+}
+
+
 pub struct Editor {
     pub buffer: Buffer,
     pub file_path: Path,
@@ -16,7 +42,7 @@ pub struct Editor {
     pub view_pos: (uint, uint),  // (line, col)
     
     // The editing cursor position
-    pub cursor: (uint, uint),  // (line, col)
+    pub cursor: Cursor,  
 }
 
 
@@ -29,7 +55,7 @@ impl Editor {
             dirty: false,
             view_dim: (0, 0),
             view_pos: (0, 0),
-            cursor: (0, 0),
+            cursor: Cursor::new(),
         }
     }
     
@@ -42,7 +68,7 @@ impl Editor {
             dirty: false,
             view_dim: (0, 0),
             view_pos: (0, 0),
-            cursor: (0, 0),
+            cursor: Cursor::new(),
         }
     }
     
@@ -60,35 +86,38 @@ impl Editor {
     
     /// Moves the editor's view the minimum amount to show the cursor
     pub fn move_view_to_cursor(&mut self) {
+        let (v, h) = self.buffer.pos_1d_to_closest_vis_2d(self.cursor.range.0);
+        
         // Horizontal
-        if self.cursor.1 < self.view_pos.1 {
-            self.view_pos.1 = self.cursor.1;
+        if h < self.view_pos.1 {
+            self.view_pos.1 = h;
         }
-        else if self.cursor.1 >= (self.view_pos.1 + self.view_dim.1) {
-            self.view_pos.1 = 1 + self.cursor.1 - self.view_dim.1;
+        else if h >= (self.view_pos.1 + self.view_dim.1) {
+            self.view_pos.1 = 1 + h - self.view_dim.1;
         }
         
         // Vertical
-        if self.cursor.0 < self.view_pos.0 {
-            self.view_pos.0 = self.cursor.0;
+        if v < self.view_pos.0 {
+            self.view_pos.0 = v;
         }
-        else if self.cursor.0 >= (self.view_pos.0 + self.view_dim.0) {
-            self.view_pos.0 = 1 + self.cursor.0 - self.view_dim.0;
+        else if v >= (self.view_pos.0 + self.view_dim.0) {
+            self.view_pos.0 = 1 + v - self.view_dim.0;
         }
     }
     
     pub fn insert_text_at_cursor(&mut self, text: &str) {
-        let pos = self.buffer.pos_2d_to_closest_1d(self.cursor);
         let str_len = grapheme_count(text);
-        let p = self.buffer.pos_2d_to_closest_1d(self.cursor);
         
         // Insert text
-        self.buffer.insert_text(text, pos);
+        self.buffer.insert_text(text, self.cursor.range.0);
         self.dirty = true;
         
         // Move cursor
-        self.cursor = self.buffer.pos_1d_to_closest_2d(p + str_len);
+        self.cursor.range.0 += str_len;
+        self.cursor.range.1 += str_len;
+        self.cursor.update_vis_start(&(self.buffer));
         
+        // Adjust view
         self.move_view_to_cursor();
     }
     
@@ -99,67 +128,127 @@ impl Editor {
     }
     
     pub fn remove_text_behind_cursor(&mut self, grapheme_count: uint) {
-        let pos_b = self.buffer.pos_2d_to_closest_1d(self.cursor);
+        let pos_b = self.cursor.range.0;
         let pos_a = if pos_b >= grapheme_count {pos_b - grapheme_count} else {0};
-        
-        // Move cursor
-        self.cursor = self.buffer.pos_1d_to_closest_2d(pos_a);
+        let tot_g = pos_b - pos_a;
         
         // Remove text
         self.buffer.remove_text(pos_a, pos_b);
-        
         self.dirty = true;
         
+        // Move cursor
+        self.cursor.range.0 -= tot_g;
+        self.cursor.range.1 -= tot_g;
+        self.cursor.update_vis_start(&(self.buffer));
+        
+        // Adjust view
+        self.move_view_to_cursor();
+    }
+    
+    pub fn remove_text_in_front_of_cursor(&mut self, grapheme_count: uint) {
+        let pos_a = self.cursor.range.1;
+        let pos_b = if (pos_a + grapheme_count) <= self.buffer.len() {pos_a + grapheme_count} else {self.buffer.len()};
+        
+        // Remove text
+        self.buffer.remove_text(pos_a, pos_b);
+        self.dirty = true;
+        
+        // Move cursor
+        self.cursor.update_vis_start(&(self.buffer));
+        
+        // Adjust view
+        self.move_view_to_cursor();
+    }
+    
+    pub fn remove_text_inside_cursor(&mut self) {
+        // If selection, remove text
+        if self.cursor.range.0 < self.cursor.range.1 {
+            self.buffer.remove_text(self.cursor.range.0, self.cursor.range.1);
+            self.dirty = true;
+        }
+        
+        // Move cursor
+        self.cursor.range.1 = self.cursor.range.0;
+        self.cursor.update_vis_start(&(self.buffer));
+        
+        // Adjust view
         self.move_view_to_cursor();
     }
     
     pub fn cursor_to_beginning_of_buffer(&mut self) {
-        self.cursor = (0, 0);
+        self.cursor.range = (0, 0);
+        self.cursor.update_vis_start(&(self.buffer));
+        
+        // Adjust view
+        self.move_view_to_cursor();
     }
     
     pub fn cursor_to_end_of_buffer(&mut self) {
-        self.cursor = self.buffer.pos_1d_to_closest_2d(self.buffer.len()+1);
+        let end = self.buffer.len();
+        self.cursor.range = (end, end);
+        self.cursor.update_vis_start(&(self.buffer));
+        
+        // Adjust view
+        self.move_view_to_cursor();
     }
     
-    pub fn cursor_left(&mut self) {
-        let p = self.buffer.pos_2d_to_closest_1d(self.cursor);
-
-        if p > 0 {
-            self.cursor = self.buffer.pos_1d_to_closest_2d(p - 1);
+    pub fn cursor_left(&mut self, n: uint) {
+        if self.cursor.range.0 >= n {
+            self.cursor.range.0 -= n;
         }
         else {
-            self.cursor = self.buffer.pos_1d_to_closest_2d(0);
+            self.cursor.range.0 = 0;
         }
         
-        self.move_view_to_cursor();
-    }
-    
-    pub fn cursor_right(&mut self) {
-        let p = self.buffer.pos_2d_to_closest_1d(self.cursor);
-        self.cursor = self.buffer.pos_1d_to_closest_2d(p + 1);
+        self.cursor.range.1 = self.cursor.range.0;
+        self.cursor.update_vis_start(&(self.buffer));
         
+        // Adjust view
         self.move_view_to_cursor();
     }
     
-    pub fn cursor_up(&mut self) {
-        if self.cursor.0 > 0 {
-            self.cursor.0 -= 1;
+    pub fn cursor_right(&mut self, n: uint) {
+        if self.cursor.range.1 <= (self.buffer.len() - n) {
+            self.cursor.range.1 += n;
+        }
+        else {
+            self.cursor.range.1 = self.buffer.len();
+        }
+        
+        self.cursor.range.0 = self.cursor.range.1;
+        self.cursor.update_vis_start(&(self.buffer));
+        
+        // Adjust view
+        self.move_view_to_cursor();
+    }
+    
+    pub fn cursor_up(&mut self, n: uint) {
+        let (v, _) = self.buffer.pos_1d_to_closest_vis_2d(self.cursor.range.0);
+        
+        if v >= n {
+            self.cursor.range.0 = self.buffer.pos_vis_2d_to_closest_1d((v - n, self.cursor.vis_start));
+            self.cursor.range.1 = self.cursor.range.0;
         }
         else {
             self.cursor_to_beginning_of_buffer();
         }
         
+        // Adjust view
         self.move_view_to_cursor();
     }
     
-    pub fn cursor_down(&mut self) {
-        if self.cursor.0 < (self.buffer.line_count() - 1) {
-            self.cursor.0 += 1;
+    pub fn cursor_down(&mut self, n: uint) {
+        let (v, _) = self.buffer.pos_1d_to_closest_vis_2d(self.cursor.range.0);
+        
+        if v < (self.buffer.line_count() - n) {
+            self.cursor.range.0 = self.buffer.pos_vis_2d_to_closest_1d((v + n, self.cursor.vis_start));
+            self.cursor.range.1 = self.cursor.range.0;
         }
         else {
             self.cursor_to_end_of_buffer();
         }
         
+        // Adjust view
         self.move_view_to_cursor();
     }
     
@@ -167,35 +256,29 @@ impl Editor {
         if self.view_pos.0 > 0 {
             let move_amount = self.view_dim.0 - (self.view_dim.0 / 8);
             if self.view_pos.0 >= move_amount {
-                if self.cursor.0 >= move_amount {
-                    self.cursor.0 -= move_amount;
-                }
                 self.view_pos.0 -= move_amount;
             }
             else {
-                if self.cursor.0 >= self.view_pos.0 {
-                    self.cursor.0 -= self.view_pos.0;
-                }
-                else {
-                    self.cursor_to_beginning_of_buffer();
-                }
                 self.view_pos.0 = 0;
-            }   
+            }
+            
+            self.cursor_up(move_amount);
         }
         else {
             self.cursor_to_beginning_of_buffer();
         }
         
+        // Adjust view
         self.move_view_to_cursor();
     }
     
     pub fn page_down(&mut self) {
+        // TODO
         let nlc = self.buffer.line_count() - 1;
         
         if self.view_pos.0 < nlc {
             let move_amount = self.view_dim.0 - (self.view_dim.0 / 8);
             let max_move = nlc - self.view_pos.0;
-            let cursor_max_move = nlc - self.cursor.0;
             
             if max_move >= move_amount {
                 self.view_pos.0 += move_amount;
@@ -204,14 +287,13 @@ impl Editor {
                 self.view_pos.0 += max_move;
             }
             
-            if cursor_max_move >= move_amount {
-                self.cursor.0 += move_amount;
-            }
-            else {
-                self.cursor_to_end_of_buffer();
-            }
+            self.cursor_down(move_amount);
+        }
+        else {
+            self.cursor_to_end_of_buffer();
         }
         
+        // Adjust view
         self.move_view_to_cursor();
     }
 }
diff --git a/src/term_ui.rs b/src/term_ui.rs
index af8f4c1..e828ee7 100644
--- a/src/term_ui.rs
+++ b/src/term_ui.rs
@@ -87,19 +87,19 @@ impl TermUI {
                             },
                             
                             K_UP => {
-                                self.editor.cursor_up();
+                                self.editor.cursor_up(1);
                             },
                             
                             K_DOWN => {
-                                self.editor.cursor_down();
+                                self.editor.cursor_down(1);
                             },
                             
                             K_LEFT => {
-                                self.editor.cursor_left();
+                                self.editor.cursor_left(1);
                             },
                             
                             K_RIGHT => {
-                                self.editor.cursor_right();
+                                self.editor.cursor_right(1);
                             },
                             
                             K_ENTER => {
@@ -151,6 +151,7 @@ impl TermUI {
         }
     }
 
+
     pub fn draw_editor(&self, editor: &Editor, c1: (uint, uint), c2: (uint, uint)) {
         let mut line_iter = editor.buffer.line_iter_at_index(editor.view_pos.0);
         
@@ -163,8 +164,7 @@ impl TermUI {
         let max_print_line = c2.0 - c1.0;
         let max_print_col = c2.1 - c1.1;
         
-        let cursor_pos_1d = editor.buffer.pos_2d_to_closest_1d(editor.cursor);
-        let cursor_pos = editor.buffer.pos_1d_to_closest_2d(cursor_pos_1d);
+        let cursor_pos = editor.buffer.pos_1d_to_closest_2d(editor.cursor.range.0);
         let print_cursor_pos = (cursor_pos.0 + editor.view_pos.0, cursor_pos.1 + editor.view_pos.1);
         
         loop {
@@ -207,7 +207,7 @@ impl TermUI {
                 }
             }
             else if print_cursor_pos.0 >= c1.0 && print_cursor_pos.0 < c2.0 && print_cursor_pos.1 >= c1.1 && print_cursor_pos.1 < c2.1 {
-                if cursor_pos_1d >= editor.buffer.len() {
+                if editor.cursor.range.0 >= editor.buffer.len() {
                     self.rb.print(print_cursor_pos.1, print_cursor_pos.0, rustbox::RB_NORMAL, Color::Black, Color::White, " ");
                 }
                 break;
diff --git a/todo.md b/todo.md
index 4a080b8..ad65714 100644
--- a/todo.md
+++ b/todo.md
@@ -1,6 +1,3 @@
-- Proper handling of non-uniform-width characters.  Specifically, this needs
-  to address tabs.  But it should be done to handle the general case anyway,
-  since that's unlikely to be more complex and will future-proof things.
 - Line number display
 - Editor info display (filename, current line/column, indentation style, etc.)
 - File opening by entering path