From ef64bd8f1c228bc029aafc4b677b1f5151595998 Mon Sep 17 00:00:00 2001
From: Nathan Vegdahl <cessen@cessen.com>
Date: Fri, 19 Dec 2014 00:23:08 -0800
Subject: [PATCH] Fixed bug in tree balancing.  Text rope is now fully
 self-balancing.

---
 src/buffer.rs | 49 +++++++++++++++++++++++++++++++++--------
 src/main.rs   | 60 ++++++++++++++++++++++++++++-----------------------
 2 files changed, 73 insertions(+), 36 deletions(-)

diff --git a/src/buffer.rs b/src/buffer.rs
index 307134b..78053a1 100644
--- a/src/buffer.rs
+++ b/src/buffer.rs
@@ -206,6 +206,23 @@ impl TextNode {
         }
     }
     
+    pub fn update_stats(&mut self) {
+        match self.data {
+            TextNodeData::Leaf(ref tb) => {
+                self.tree_height = 1;
+                let (cc, nlc) = char_and_newline_count(tb.as_str());
+                self.char_count = cc;
+                self.newline_count = nlc;
+            },
+            
+            TextNodeData::Branch(ref left, ref right) => {
+                self.tree_height = max(left.tree_height, right.tree_height) + 1;
+                self.char_count = left.char_count + right.char_count;
+                self.newline_count = left.newline_count + right.newline_count;
+            }
+        }
+    }
+    
     pub fn rotate_left(&mut self) {
         let mut temp = TextNode::new();
         
@@ -213,16 +230,23 @@ impl TextNode {
             mem::swap(&mut temp, &mut (**right));
             
             if let TextNodeData::Branch(ref mut left, _) = temp.data {   
-                mem::swap(left, right);
+                mem::swap(&mut (**left), &mut (**right));
             }
+            else {
+                panic!("rotate_left(): attempting to rotate node without branching right child.");
+            }
+        }
+        else {
+            panic!("rotate_left(): attempting to rotate leaf node.");
         }
         
         if let TextNodeData::Branch(ref mut left, _) = temp.data {
             mem::swap(&mut (**left), self);
-            left.update_height();
+            left.update_stats();
         }
         
-        self.update_height();
+        mem::swap(&mut temp, self);
+        self.update_stats();
     }
     
     pub fn rotate_right(&mut self) {
@@ -232,21 +256,28 @@ impl TextNode {
             mem::swap(&mut temp, &mut (**left));
             
             if let TextNodeData::Branch(_, ref mut right) = temp.data {   
-                mem::swap(right, left);
+                mem::swap(&mut (**right), &mut (**left));
             }
+            else {
+                panic!("rotate_right(): attempting to rotate node without branching left child.");
+            }
+        }
+        else {
+            panic!("rotate_right(): attempting to rotate leaf node.");
         }
         
         if let TextNodeData::Branch(_, ref mut right) = temp.data {
             mem::swap(&mut (**right), self);
-            right.update_height();
+            right.update_stats();
         }
         
-        self.update_height();
+        mem::swap(&mut temp, self);
+        self.update_stats();
     }
     
     pub fn rebalance(&mut self) {
         loop {
-            let mut rot: int = 0;
+            let mut rot: int;
             
             if let TextNodeData::Branch(ref mut left, ref mut right) = self.data {
                 let height_diff = (left.tree_height as int) - (right.tree_height as int);
@@ -262,7 +293,7 @@ impl TextNode {
                     
                     if child_rot {
                         if let TextNodeData::Branch(_, ref mut rc) = right.data {
-                            rc.rotate_right();
+                            rc.rotate_left();
                         }
                     }
                     
@@ -297,7 +328,7 @@ impl TextNode {
             if rot == 1 {
                 self.rotate_right();
             }
-            else if rot == 1 {
+            else if rot == -1 {
                 self.rotate_left();
             }
         }
diff --git a/src/main.rs b/src/main.rs
index 7004709..d3f8e66 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,6 +2,7 @@ extern crate rustbox;
 extern crate docopt;
 extern crate serialize;
 
+
 use std::char;
 use docopt::Docopt;
 use buffer::TextBuffer; 
@@ -39,40 +40,44 @@ fn main() {
     
     rustbox::init();
 
+    let enough_time_has_passed: bool = true;
+    
     loop {
         // Draw the text buffer to screen
-        rustbox::clear();
-        {
-            let mut tb_iter = tb.root_iter();
-            let mut line: uint = 0;
-            let mut column: uint = 0;
-            
-            loop {
-                if let Option::Some(c) = tb_iter.next() {
-                    if c == '\n' {
+        if enough_time_has_passed {
+            rustbox::clear();
+            {
+                let mut tb_iter = tb.root_iter();
+                let mut line: uint = 0;
+                let mut column: uint = 0;
+                
+                loop {
+                    if let Option::Some(c) = tb_iter.next() {
+                        if c == '\n' {
+                            line += 1;
+                            column = 0;
+                            continue;
+                        }
+                        rustbox::print(column, line, Style::Normal, Color::White, Color::Black, c.to_string());
+                        column += 1;
+                    }
+                    else {
+                        break;
+                    }
+                    
+                    if line > height {
+                        break;
+                    }
+                    
+                    if column > width {
+                        tb_iter.next_line();
                         line += 1;
                         column = 0;
-                        continue;
                     }
-                    rustbox::print(column, line, Style::Normal, Color::White, Color::Black, c.to_string());
-                    column += 1;
-                }
-                else {
-                    break;
-                }
-                
-                if line > height {
-                    break;
-                }
-                
-                if column > width {
-                    tb_iter.next_line();
-                    line += 1;
-                    column = 0;
                 }
             }
+            rustbox::present();
         }
-        rustbox::present();
         
         // Handle events
         match rustbox::poll_event() {
@@ -98,9 +103,10 @@ fn main() {
                 height = h as uint;
             }
             
-            _ => { }
+            _ => {break;}
         }
     }
+    
     rustbox::shutdown();
     
     println!("{}", tb.root.tree_height);