From 10c2f72720628c952138bc87dffd6505576fdcd0 Mon Sep 17 00:00:00 2001
From: webzwo0i <webzwo0i@c3d2.de>
Date: Thu, 4 Dec 2014 16:01:39 +0100
Subject: [PATCH] dont remove more lines than exist in the whole text

---
 src/static/js/Changeset.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index 355bef4a9..366ad15f9 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -903,6 +903,8 @@ exports.pack = function (oldLen, newLen, opsStr, bank) {
  * @params str {string} String to which a Changeset should be applied
  */
 exports.applyToText = function (cs, str) {
+  var totalNrOfLines = str.split("\n").length;
+  var removedLines = 0;
   var unpacked = exports.unpack(cs);
   exports.assert(str.length == unpacked.oldLen, "mismatched apply: ", str.length, " / ", unpacked.oldLen);
   var csIter = exports.opIterator(unpacked.ops);
@@ -916,6 +918,7 @@ exports.applyToText = function (cs, str) {
       assem.append(bankIter.take(op.chars));
       break;
     case '-':
+      removedLines += op.lines;
       strIter.skip(op.chars);
       break;
     case '=':
@@ -923,6 +926,7 @@ exports.applyToText = function (cs, str) {
       break;
     }
   }
+  exports.assert(totalNrOfLines >= removedLines,"cannot remove ", removedLines, " lines from text with ", totalNrOfLines, " lines");
   assem.append(strIter.take(strIter.remaining()));
   return assem.toString();
 };