Basic undo functionality.

src/buffer/line.rs

@@ -5,8 +5,6 @@ use std::mem;
 use std::str::Graphemes;
 use string_utils::{grapheme_count, grapheme_pos_to_byte_pos, is_line_ending};
 
-const TAB_WIDTH: usize = 4;
-
 
 /// Returns the visual width of a grapheme given a starting
 /// position on a line.
@@ -690,16 +688,21 @@ impl<'a> Iterator for LineGraphemeVisIter<'a> {
 // Line tests
 //=========================================================================
 
-#[test]
+mod tests {
-fn new_text_line() {
+    use super::{Line, LineEnding, LineGraphemeIter, LineGraphemeVisIter};
+    const TAB_WIDTH: usize = 4;
+
+
+    #[test]
+    fn new_text_line() {
         let tl = Line::new();
         
         assert!(tl.text.len() == 0);
         assert!(tl.ending == LineEnding::None);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_str() {
+    fn new_text_line_from_str() {
         let tl = Line::new_from_str("Hello!");
         
         assert!(tl.text.len() == 6);
@@ -710,18 +713,18 @@ fn new_text_line_from_str() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::None);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_empty_str() {
+    fn new_text_line_from_empty_str() {
         let tl = Line::new_from_str("");
         
         assert!(tl.text.len() == 0);
         assert!(tl.ending == LineEnding::None);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_str_with_lf() {
+    fn new_text_line_from_str_with_lf() {
         let tl = Line::new_from_str("Hello!\n");
         
         assert!(tl.text.len() == 6);
@@ -732,10 +735,10 @@ fn new_text_line_from_str_with_lf() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::LF);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_str_with_crlf() {
+    fn new_text_line_from_str_with_crlf() {
         let tl = Line::new_from_str("Hello!\r\n");
         
         assert!(tl.text.len() == 6);
@@ -746,10 +749,10 @@ fn new_text_line_from_str_with_crlf() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_str_with_crlf_and_too_long() {
+    fn new_text_line_from_str_with_crlf_and_too_long() {
         let tl = Line::new_from_str("Hello!\r\nLa la la la");
         
         assert!(tl.text.len() == 6);
@@ -760,10 +763,10 @@ fn new_text_line_from_str_with_crlf_and_too_long() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_string_unchecked() {
+    fn new_text_line_from_string_unchecked() {
         let s = String::from_str("Hello!");
         
         let tl = Line::new_from_string_unchecked(s);
@@ -776,10 +779,10 @@ fn new_text_line_from_string_unchecked() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::None);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_string_unchecked_with_lf() {
+    fn new_text_line_from_string_unchecked_with_lf() {
         let s = String::from_str("Hello!\u{000A}");
         
         let tl = Line::new_from_string_unchecked(s);
@@ -792,10 +795,10 @@ fn new_text_line_from_string_unchecked_with_lf() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::LF);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_string_unchecked_with_crlf() {
+    fn new_text_line_from_string_unchecked_with_crlf() {
         let s = String::from_str("Hello!\u{000D}\u{000A}");
         
         let tl = Line::new_from_string_unchecked(s);
@@ -808,10 +811,10 @@ fn new_text_line_from_string_unchecked_with_crlf() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn new_text_line_from_string_unchecked_with_ls() {
+    fn new_text_line_from_string_unchecked_with_ls() {
         let s = String::from_str("Hello!\u{2028}");
         
         let tl = Line::new_from_string_unchecked(s);
@@ -824,10 +827,10 @@ fn new_text_line_from_string_unchecked_with_ls() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::LS);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_insert_text() {
+    fn text_line_insert_text() {
         let mut tl = Line::new_from_str("Hello!\r\n");
         
         tl.insert_text(" world", 5);
@@ -846,10 +849,10 @@ fn text_line_insert_text() {
         assert!(tl.text[10] == ('d' as u8));
         assert!(tl.text[11] == ('!' as u8));
         assert!(tl.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_append_text() {
+    fn text_line_append_text() {
         let mut tl = Line::new_from_str("Hello\r\n");
         
         tl.append_text(" world!");
@@ -868,10 +871,10 @@ fn text_line_append_text() {
         assert!(tl.text[10] == ('d' as u8));
         assert!(tl.text[11] == ('!' as u8));
         assert!(tl.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_remove_text() {
+    fn text_line_remove_text() {
         let mut tl = Line::new_from_str("Hello world!\r\n");
         
         tl.remove_text(5, 11);
@@ -884,10 +887,10 @@ fn text_line_remove_text() {
         assert!(tl.text[4] == ('o' as u8));
         assert!(tl.text[5] == ('!' as u8));
         assert!(tl.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_split() {
+    fn text_line_split() {
         let mut tl1 = Line::new_from_str("Hello world!\r\n");
         
         let tl2 = tl1.split(LineEnding::LF, 5);
@@ -909,10 +912,10 @@ fn text_line_split() {
         assert!(tl2.text[5] == ('d' as u8));
         assert!(tl2.text[6] == ('!' as u8));
         assert!(tl2.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_split_beginning() {
+    fn text_line_split_beginning() {
         let mut tl1 = Line::new_from_str("Hello!\r\n");
         
         let tl2 = tl1.split(LineEnding::LF, 0);
@@ -928,43 +931,43 @@ fn text_line_split_beginning() {
         assert!(tl2.text[4] == ('o' as u8));
         assert!(tl2.text[5] == ('!' as u8));
         assert!(tl2.ending == LineEnding::CRLF);
-}
+    }
     
-#[test]
+    #[test]
-fn grapheme_index_to_closest_vis_pos_1() {
+    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);
+        assert!(tl.grapheme_index_to_closest_vis_pos(0, TAB_WIDTH) == 0);
-}
+    }
     
-#[test]
+    #[test]
-fn grapheme_index_to_closest_vis_pos_2() {
+    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);
+        assert!(tl.grapheme_index_to_closest_vis_pos(1, TAB_WIDTH) == TAB_WIDTH);
-}
+    }
     
-#[test]
+    #[test]
-fn vis_pos_to_closest_grapheme_index_1() {
+    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);
+        assert!(tl.vis_pos_to_closest_grapheme_index(0, TAB_WIDTH) == 0);
-}
+    }
     
-#[test]
+    #[test]
-fn vis_pos_to_closest_grapheme_index_2() {
+    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);
+        assert!(tl.vis_pos_to_closest_grapheme_index(TAB_WIDTH, TAB_WIDTH) == 1);
-}
+    }
     
     
-//=========================================================================
+    //=========================================================================
-// LineGraphemeIter tests
+    // LineGraphemeIter tests
-//=========================================================================
+    //=========================================================================
     
-#[test]
+    #[test]
-fn text_line_grapheme_iter() {
+    fn text_line_grapheme_iter() {
         let tl = Line::new_from_str("Hello!");
         let mut iter = tl.grapheme_iter();
         
@@ -975,10 +978,10 @@ fn text_line_grapheme_iter() {
         assert!(iter.next() == Some("o"));
         assert!(iter.next() == Some("!"));
         assert!(iter.next() == None);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_grapheme_iter_with_lf() {
+    fn text_line_grapheme_iter_with_lf() {
         let tl = Line::new_from_str("Hello!\n");
         let mut iter = tl.grapheme_iter();
         
@@ -990,10 +993,10 @@ fn text_line_grapheme_iter_with_lf() {
         assert!(iter.next() == Some("!"));
         assert!(iter.next() == Some("\n"));
         assert!(iter.next() == None);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_grapheme_iter_with_crlf() {
+    fn text_line_grapheme_iter_with_crlf() {
         let tl = Line::new_from_str("Hello!\r\n");
         let mut iter = tl.grapheme_iter();
         
@@ -1005,10 +1008,10 @@ fn text_line_grapheme_iter_with_crlf() {
         assert!(iter.next() == Some("!"));
         assert!(iter.next() == Some("\r\n"));
         assert!(iter.next() == None);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_grapheme_iter_at_index() {
+    fn text_line_grapheme_iter_at_index() {
         let tl = Line::new_from_str("Hello!");
         let mut iter = tl.grapheme_iter_at_index(2);
         
@@ -1017,21 +1020,23 @@ fn text_line_grapheme_iter_at_index() {
         assert!(iter.next() == Some("o"));
         assert!(iter.next() == Some("!"));
         assert!(iter.next() == None);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_grapheme_iter_at_index_past_end() {
+    fn text_line_grapheme_iter_at_index_past_end() {
         let tl = Line::new_from_str("Hello!");
         let mut iter = tl.grapheme_iter_at_index(10);
         
         assert!(iter.next() == None);
-}
+    }
     
-#[test]
+    #[test]
-fn text_line_grapheme_iter_at_index_at_lf() {
+    fn text_line_grapheme_iter_at_index_at_lf() {
         let tl = Line::new_from_str("Hello!\n");
         let mut iter = tl.grapheme_iter_at_index(6);
         
         assert!(iter.next() == Some("\n"));
         assert!(iter.next() == None);
+    }
+    
 }

src/buffer/mod.rs

@@ -4,7 +4,7 @@ use std::mem;
 
 use self::node::{BufferNode, BufferNodeGraphemeIter, BufferNodeLineIter};
 use self::line::{Line, LineEnding};
-use string_utils::{is_line_ending};
+use string_utils::{is_line_ending, grapheme_count};
 
 pub mod line;
 mod node;
@@ -18,6 +18,7 @@ mod node;
 pub struct Buffer {
     text: BufferNode,
     pub line_ending_type: LineEnding,
+    undo_stack: Vec<Operation>,
 }
 
 
@@ -26,6 +27,7 @@ impl Buffer {
         Buffer {
             text: BufferNode::new(),
             line_ending_type: LineEnding::LF,
+            undo_stack: Vec::new(),
         }
     }
 
@@ -138,12 +140,27 @@ impl Buffer {
     
     /// Insert 'text' at grapheme position 'pos'.
     pub fn insert_text(&mut self, text: &str, pos: usize) {
+        self._insert_text(text, pos);
+        
+        self.undo_stack.push(Operation::InsertText(String::from_str(text), pos));
+    }
+    
+    fn _insert_text(&mut self, text: &str, pos: usize) {
         self.text.insert_text(text, pos);
     }
 
     
     /// Remove the text between grapheme positions 'pos_a' and 'pos_b'.
     pub fn remove_text(&mut self, pos_a: usize, pos_b: usize) {
+        let removed_text = self.string_from_range(pos_a, pos_b);
+    
+        self._remove_text(pos_a, pos_b);
+        
+        // Push operation to the undo stack
+        self.undo_stack.push(Operation::RemoveText(removed_text, pos_a));
+    }
+    
+    fn _remove_text(&mut self, pos_a: usize, pos_b: usize) {
         // Nothing to do
         if pos_a == pos_b {
             return;
@@ -171,6 +188,58 @@ impl Buffer {
     }
     
     
+    /// Undoes operations that were pushed to the undo stack, and returns a
+    /// cursor position that the cursor should jump to, if any.
+    pub fn undo(&mut self) -> Option<usize> {
+        if let Some(op) = self.undo_stack.pop() {
+            match op {
+                Operation::InsertText(ref s, p) => {
+                    let size = grapheme_count(s.as_slice());
+                    self._remove_text(p, p+size);
+                    return Some(p);
+                },
+                
+                Operation::RemoveText(ref s, p) => {
+                    let size = grapheme_count(s.as_slice());
+                    self._insert_text(s.as_slice(), p);
+                    return Some(p+size);
+                },
+            }
+        }
+        
+        return None;
+    }
+    
+    
+    /// Creates a String from the buffer text in grapheme range [pos_a, posb).
+    fn string_from_range(&self, pos_a: usize, pos_b: usize) -> String {
+        // Bounds checks
+        if pos_b < pos_a {
+            panic!("Buffer::string_from_range(): pos_a must be less than or equal to pos_b.");
+        }
+        else if pos_b > self.len() {
+            panic!("Buffer::string_from_range(): specified range is past end of buffer text.");
+        }
+        
+        let mut s = String::with_capacity(pos_b - pos_a);
+        
+        let mut iter = self.grapheme_iter_at_index(pos_a);
+        let mut i = 0;
+        let i_end = pos_b - pos_a;
+        
+        for g in iter {
+            if i == i_end {
+                break;
+            }
+            
+            s.push_str(g);
+            
+            i += 1;
+        }
+        
+        return s;
+    }
+    
     /// Creates an iterator at the first character
     pub fn grapheme_iter<'a>(&'a self) -> BufferGraphemeIter<'a> {
         BufferGraphemeIter {
@@ -278,13 +347,27 @@ impl<'a> Iterator for BufferLineIter<'a> {
 
 
 
+//================================================================
+// Buffer undo structures
+//================================================================
+
+enum Operation {
+    InsertText(String, usize),
+    RemoveText(String, usize),
+}
+
+
+
 
 //================================================================
 // TESTS
 //================================================================
 
-#[test]
+mod tests {
-fn insert_text() {
+    use super::{Buffer, Operation, BufferGraphemeIter, BufferLineIter};
+
+    #[test]
+    fn insert_text() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello 世界!", 0);
@@ -303,11 +386,11 @@ fn insert_text() {
         assert!(Some("界") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_with_newlines() {
+    fn insert_text_with_newlines() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -328,11 +411,11 @@ fn insert_text_with_newlines() {
         assert!(Some("\r\n") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_in_non_empty_buffer_1() {
+    fn insert_text_in_non_empty_buffer_1() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -360,11 +443,11 @@ fn insert_text_in_non_empty_buffer_1() {
         assert!(Some("\r\n") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_in_non_empty_buffer_2() {
+    fn insert_text_in_non_empty_buffer_2() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -392,11 +475,11 @@ fn insert_text_in_non_empty_buffer_2() {
         assert!(Some("\r\n") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_in_non_empty_buffer_3() {
+    fn insert_text_in_non_empty_buffer_3() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -423,11 +506,11 @@ fn insert_text_in_non_empty_buffer_3() {
         assert!(Some("\r\n") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_in_non_empty_buffer_4() {
+    fn insert_text_in_non_empty_buffer_4() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -454,11 +537,11 @@ fn insert_text_in_non_empty_buffer_4() {
         assert!(Some("i") == iter.next());
         assert!(Some("n") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_in_non_empty_buffer_5() {
+    fn insert_text_in_non_empty_buffer_5() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -486,11 +569,11 @@ fn insert_text_in_non_empty_buffer_5() {
         assert!(Some("!") == iter.next());
         
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_in_non_empty_buffer_6() {
+    fn insert_text_in_non_empty_buffer_6() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -518,11 +601,11 @@ fn insert_text_in_non_empty_buffer_6() {
         assert!(Some("!") == iter.next());
         
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn insert_text_in_non_empty_buffer_7() {
+    fn insert_text_in_non_empty_buffer_7() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\n 世界\r\n!", 0);
@@ -554,11 +637,11 @@ fn insert_text_in_non_empty_buffer_7() {
         assert!(Some("!") == iter.next());
         
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_1() {
+    fn remove_text_1() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -598,11 +681,11 @@ fn remove_text_1() {
         assert!(Some("d") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_2() {
+    fn remove_text_2() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -633,11 +716,11 @@ fn remove_text_2() {
         assert!(Some("d") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_3() {
+    fn remove_text_3() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -668,11 +751,11 @@ fn remove_text_3() {
         assert!(Some("d") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_4() {
+    fn remove_text_4() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -709,11 +792,11 @@ fn remove_text_4() {
         assert!(Some("e") == iter.next());
         assert!(Some("\n") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_5() {
+    fn remove_text_5() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -744,11 +827,11 @@ fn remove_text_5() {
         assert!(Some("\n") == iter.next());
         assert!(Some("o") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_6() {
+    fn remove_text_6() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\nworld!", 0);
@@ -765,11 +848,11 @@ fn remove_text_6() {
         assert!(Some("e") == iter.next());
         assert!(Some("l") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_7() {
+    fn remove_text_7() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\nworld!", 0);
@@ -788,11 +871,11 @@ fn remove_text_7() {
         assert!(Some("t") == iter.next());
         assert!(Some("h") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_8() {
+    fn remove_text_8() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\nworld!", 0);
@@ -810,11 +893,11 @@ fn remove_text_8() {
         assert!(Some("l") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_9() {
+    fn remove_text_9() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hello\nworld!", 0);
@@ -836,11 +919,11 @@ fn remove_text_9() {
         assert!(Some("w") == iter.next());
         assert!(Some("o") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_10() {
+    fn remove_text_10() {
         let mut buf = Buffer::new();
         
         buf.insert_text("12\n34\n56\n78", 0);
@@ -858,11 +941,11 @@ fn remove_text_10() {
         assert!(Some("\n") == iter.next());
         assert!(Some("3") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_text_11() {
+    fn remove_text_11() {
         let mut buf = Buffer::new();
         
         buf.insert_text("1234567890", 0);
@@ -885,11 +968,11 @@ fn remove_text_11() {
         assert!(Some("8") == iter.next());
         assert!(Some("9") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_lines_1() {
+    fn remove_lines_1() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -916,11 +999,11 @@ fn remove_lines_1() {
         assert!(Some("d") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_lines_2() {
+    fn remove_lines_2() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -947,11 +1030,11 @@ fn remove_lines_2() {
         assert!(Some("d") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn remove_lines_3() {
+    fn remove_lines_3() {
         let mut buf = Buffer::new();
         
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
@@ -980,65 +1063,87 @@ fn remove_lines_3() {
         assert!(Some("l") == iter.next());
         assert!(Some("e") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn pos_2d_to_closest_1d_1() {
+    fn pos_2d_to_closest_1d_1() {
         let mut buf = Buffer::new();
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
         
         let pos = buf.pos_2d_to_closest_1d((2, 3));
         
         assert!(pos == 12);
-}
+    }
     
     
-#[test]
+    #[test]
-fn pos_2d_to_closest_1d_2() {
+    fn pos_2d_to_closest_1d_2() {
         let mut buf = Buffer::new();
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
         
         let pos = buf.pos_2d_to_closest_1d((2, 10));
         
         assert!(pos == 15);
-}
+    }
     
-#[test]
+    #[test]
-fn pos_2d_to_closest_1d_3() {
+    fn pos_2d_to_closest_1d_3() {
         let mut buf = Buffer::new();
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
         
         let pos = buf.pos_2d_to_closest_1d((10, 2));
         
         assert!(pos == 29);
-}
+    }
     
     
-#[test]
+    #[test]
-fn pos_1d_to_closest_2d_1() {
+    fn pos_1d_to_closest_2d_1() {
         let mut buf = Buffer::new();
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
         
         let pos = buf.pos_1d_to_closest_2d(5);
         
         assert!(pos == (1, 2));
-}
+    }
     
     
-#[test]
+    #[test]
-fn pos_1d_to_closest_2d_2() {
+    fn pos_1d_to_closest_2d_2() {
         let mut buf = Buffer::new();
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
         
         let pos = buf.pos_1d_to_closest_2d(50);
         
         assert!(pos == (5, 6));
-}
+    }
     
     
-#[test]
+    #[test]
-fn grapheme_iter_at_index_1() {
+    fn string_from_range_1() {
+        let mut buf = Buffer::new();
+        buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
+        
+        let s = buf.string_from_range(1, 12);
+        
+        assert!(s.as_slice() == "i\nthere\npeo");
+    }
+    
+    
+    #[test]
+    fn string_from_range_2() {
+        let mut buf = Buffer::new();
+        buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
+        
+        let s = buf.string_from_range(0, 29);
+        
+        assert!(s.as_slice() == "Hi\nthere\npeople\nof\nthe\nworld!");
+    }
+    
+    
+    #[test]
+    fn grapheme_iter_at_index_1() {
         let mut buf = Buffer::new();
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
         
@@ -1058,19 +1163,19 @@ fn grapheme_iter_at_index_1() {
         assert!(Some("d") == iter.next());
         assert!(Some("!") == iter.next());
         assert!(None == iter.next());
-}
+    }
     
     
-#[test]
+    #[test]
-fn grapheme_iter_at_index_2() {
+    fn grapheme_iter_at_index_2() {
         let mut buf = Buffer::new();
         buf.insert_text("Hi\nthere\npeople\nof\nthe\nworld!", 0);
         
         let mut iter = buf.grapheme_iter_at_index(29);
         
         assert!(None == iter.next());
+    }
+    
+    
 }
 
-
-
-

src/editor.rs

@@ -189,6 +189,17 @@ impl Editor {
     }
     
     
+    pub fn undo(&mut self) {
+        if let Some(pos) = self.buffer.undo() {
+            self.cursor.range.0 = pos;
+            self.cursor.range.1 = pos;
+            self.cursor.update_vis_start(&(self.buffer), self.tab_width);
+            
+            self.move_view_to_cursor();
+        }
+    }
+    
+    
     /// 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, self.tab_width);

src/term_ui.rs

@@ -25,6 +25,7 @@ const K_CTRL_L: u16 = 12;
 const K_CTRL_O: u16 = 15;
 const K_CTRL_Q: u16 = 17;
 const K_CTRL_S: u16 = 19;
+const K_CTRL_Z: u16 = 26;
 
 
 pub struct TermUI {
@@ -98,6 +99,10 @@ impl TermUI {
                                 self.editor.save_if_dirty();
                             },
                             
+                            K_CTRL_Z => {
+                                self.editor.undo();
+                            },
+                            
                             K_CTRL_L => {
                                 self.go_to_line_ui_loop();
                             },