From 52a61854559dedba844d1669849eed29d67b43b1 Mon Sep 17 00:00:00 2001
From: Zachary Yedidia <zyedidia@gmail.com>
Date: Mon, 14 Mar 2016 21:34:44 -0400
Subject: [PATCH] Handle tabs correctly

---
 Makefile     |  1 +
 src/buffer.d |  3 ++-
 src/cursor.d |  2 ++
 src/main.d   |  2 +-
 src/util.d   |  7 +++++++
 src/view.d   | 28 ++++++++++++++++++++++++----
 6 files changed, 37 insertions(+), 6 deletions(-)
 create mode 100644 Makefile
 create mode 100644 src/util.d

diff --git a/Makefile b/Makefile
new file mode 100644
index 00000000..9cd1487b
--- /dev/null
+++ b/Makefile
@@ -0,0 +1 @@
+	test
diff --git a/src/buffer.d b/src/buffer.d
index b1acae52..e191992b 100644
--- a/src/buffer.d
+++ b/src/buffer.d
@@ -1,6 +1,7 @@
 import rope;
 
-import std.string, std.stdio;
+import std.string: split;
+import std.stdio;
 
 class Buffer {
     private Rope text;
diff --git a/src/cursor.d b/src/cursor.d
index 7ee7172e..fe2148c9 100644
--- a/src/cursor.d
+++ b/src/cursor.d
@@ -4,6 +4,8 @@ class Cursor {
     int x, y;
     int lastX;
 
+    int offset;
+
     this() {}
 
     this(int x, int y) {
diff --git a/src/main.d b/src/main.d
index 95c7a201..5aa68c1a 100644
--- a/src/main.d
+++ b/src/main.d
@@ -5,7 +5,7 @@ import view;
 import clipboard;
 
 import std.stdio;
-import std.file;
+import std.file: readText, exists, isDir;
 
 void main(string[] args) {
     string filename = "";
diff --git a/src/util.d b/src/util.d
new file mode 100644
index 00000000..0f82fbbc
--- /dev/null
+++ b/src/util.d
@@ -0,0 +1,7 @@
+string emptyString(int size) {
+    string str;
+    foreach (i; 0 .. size) {
+        str ~= " ";
+    }
+    return str;
+}
diff --git a/src/view.d b/src/view.d
index 072e89ff..f4493717 100644
--- a/src/view.d
+++ b/src/view.d
@@ -3,10 +3,14 @@ import buffer;
 import clipboard;
 import cursor;
 import statusline;
+import util;
 
+import std.regex: regex, replaceAll;
 import std.conv: to;
 import std.utf: count;
 
+enum tabSize = 4;
+
 class View {
     uint topline;
     uint xOffset;
@@ -84,14 +88,24 @@ class View {
 
     void cursorRight() {
         if (cursor.x < buf.lines[cursor.y].length) {
-            cursor.x++;
+            if (buf.lines[cursor.y][cursor.x] == '\t') {
+                cursor.x++;
+                cursor.offset += tabSize-1;
+            } else {
+                cursor.x++;
+            }
             cursor.lastX = cursor.x;
         }
     }
 
     void cursorLeft() {
         if (cursor.x > 0) {
-            cursor.x--;
+            if (buf.lines[cursor.y][cursor.x-1] == '\t') {
+                cursor.x--;
+                cursor.offset -= tabSize-1;
+            } else {
+                cursor.x--;
+            }
             cursor.lastX = cursor.x;
         }
     }
@@ -146,8 +160,14 @@ class View {
                     cursorDown();
                     cursor.x = 0;
                     cursor.lastX = cursor.x;
+                } else if (e.key == Key.tab) {
+                    buf.insert(cloc, "\t");
+                    cursorRight();
                 } else if (e.key == Key.backspace2) {
                     if (cloc > 0) {
+                        if (buf.lines[cursor.y][cursor.x-1] == '\t') {
+                            cursor.offset -= tabSize-1;
+                        }
                         buf.remove(cloc-1, cloc);
                         setCursorLoc(cloc - 1);
                         cursor.lastX = cursor.x;
@@ -190,7 +210,7 @@ class View {
             setCell(cast(int) x++, cast(int) y, ' ', Color.basic, Color.basic);
 
             // Write the line
-            foreach (dchar ch; line) {
+            foreach (dchar ch; line.replaceAll(regex("\t"), emptyString(tabSize))) {
                 setCell(x++, y, ch, Color.basic, Color.basic);
             }
             y++;
@@ -200,7 +220,7 @@ class View {
         if (cursor.y - topline < 0 || cursor.y - topline > height-1) {
             hideCursor();
         } else {
-            setCursor(cursor.x + xOffset, cursor.y - topline);
+            setCursor(cursor.x + xOffset + cursor.offset, cursor.y - topline);
         }
 
         sl.display();