1 files changed, 30 insertions, 8 deletions

diff --git a/imports/codemirror/lib/util/runmode.js b/imports/codemirror/lib/util/runmode.js
index de4a7602..fc58d857 100755..100644
--- a/imports/codemirror/lib/util/runmode.js
+++ b/imports/codemirror/lib/util/runmode.js
@@ -1,15 +1,37 @@
-CodeMirror.runMode = function(string, modespec, callback) {
-  var mode = CodeMirror.getMode({indentUnit: 2}, modespec);
+CodeMirror.runMode = function(string, modespec, callback, options) {
+  var mode = CodeMirror.getMode(CodeMirror.defaults, modespec);
   var isNode = callback.nodeType == 1;
+  var tabSize = (options && options.tabSize) || CodeMirror.defaults.tabSize;
   if (isNode) {
-    var node = callback, accum = [];
-    callback = function(string, style) {
-      if (string == "\n")
+    var node = callback, accum = [], col = 0;
+    callback = function(text, style) {
+      if (text == "\n") {
         accum.push("<br>");
-      else if (style)
-        accum.push("<span class=\"cm-" + CodeMirror.htmlEscape(style) + "\">" + CodeMirror.htmlEscape(string) + "</span>");
+        col = 0;
+        return;
+      }
+      var escaped = "";
+      // HTML-escape and replace tabs
+      for (var pos = 0;;) {
+        var idx = text.indexOf("\t", pos);
+        if (idx == -1) {
+          escaped += CodeMirror.htmlEscape(text.slice(pos));
+          col += text.length - pos;
+          break;
+        } else {
+          col += idx - pos;
+          escaped += CodeMirror.htmlEscape(text.slice(pos, idx));
+          var size = tabSize - col % tabSize;
+          col += size;
+          for (var i = 0; i < size; ++i) escaped += " ";
+          pos = idx + 1;
+        }
+      }
+
+      if (style) 
+        accum.push("<span class=\"cm-" + CodeMirror.htmlEscape(style) + "\">" + escaped + "</span>");
       else
-        accum.push(CodeMirror.htmlEscape(string));
+        accum.push(escaped);
     }
   }
   var lines = CodeMirror.splitLines(string), state = CodeMirror.startState(mode);