function autoCloseGT(cm) {
    if (cm.getOption("disableInput")) return CodeMirror.Pass;
    var ranges = cm.listSelections(), replacements = [];
    var opt = cm.getOption("autoCloseTags");
    for (var i = 0; i < ranges.length; i++) {
      if (!ranges[i].empty()) return CodeMirror.Pass;
      var pos = ranges[i].head, tok = cm.getTokenAt(pos);
      var inner = CodeMirror.innerMode(cm.getMode(), tok.state), state = inner.state;
      var tagInfo = inner.mode.xmlCurrentTag && inner.mode.xmlCurrentTag(state)
      var tagName = tagInfo && tagInfo.name
      if (!tagName) return CodeMirror.Pass

      var html = inner.mode.configuration == "html";
      var dontCloseTags = (typeof opt == "object" && opt.dontCloseTags) || (html && htmlDontClose);
      var indentTags = (typeof opt == "object" && opt.indentTags) || (html && htmlIndent);

      if (tok.end > pos.ch) tagName = tagName.slice(0, tagName.length - tok.end + pos.ch);
      var lowerTagName = tagName.toLowerCase();
      // Don't process the '>' at the end of an end-tag or self-closing tag
      if (!tagName ||
          tok.type == "string" && (tok.end != pos.ch || !/[\"\']/.test(tok.string.charAt(tok.string.length - 1)) || tok.string.length == 1) ||
          tok.type == "tag" && tagInfo.close ||
          tok.string.indexOf("/") == (pos.ch - tok.start - 1) || // match something like <someTagName />
          dontCloseTags && indexOf(dontCloseTags, lowerTagName) > -1 ||
          closingTagExists(cm, inner.mode.xmlCurrentContext && inner.mode.xmlCurrentContext(state) || [], tagName, pos, true))
        return CodeMirror.Pass;

      var emptyTags = typeof opt == "object" && opt.emptyTags;
      if (emptyTags && indexOf(emptyTags, tagName) > -1) {
        replacements[i] = { text: "/>", newPos: CodeMirror.Pos(pos.line, pos.ch + 2) };
        continue;
      }

      var indent = indentTags && indexOf(indentTags, lowerTagName) > -1;
      replacements[i] = {indent: indent,
                         text: ">" + (indent ? "\n\n" : "") + "</" + tagName + ">",
                         newPos: indent ? CodeMirror.Pos(pos.line + 1, 0) : CodeMirror.Pos(pos.line, pos.ch + 1)};
    }

    var dontIndentOnAutoClose = (typeof opt == "object" && opt.dontIndentOnAutoClose);
    for (var i = ranges.length - 1; i >= 0; i--) {
      var info = replacements[i];
      cm.replaceRange(info.text, ranges[i].head, ranges[i].anchor, "+insert");
      var sel = cm.listSelections().slice(0);
      sel[i] = {head: info.newPos, anchor: info.newPos};
      cm.setSelections(sel);
      if (!dontIndentOnAutoClose && info.indent) {
        cm.indentLine(info.newPos.line, null, true);
        cm.indentLine(info.newPos.line + 1, null, true);
      }
    }
  }
Tag-closer extension for CodeMirror.

This extension adds an "autoCloseTags" option that can be set to
either true to get the default behavior, or an object to further
configure its behavior.

These are supported options:

`whenClosing` (default true)
  Whether to autoclose when the '/' of a closing tag is typed.
`whenOpening` (default true)
  Whether to autoclose the tag when the final '>' of an opening
  tag is typed.
`dontCloseTags` (default is empty tags for HTML, none for XML)
  An array of tag names that should not be autoclosed.
`indentTags` (default is block tags for HTML, none for XML)
  An array of tag names that should, when opened, cause a
  blank line to be added inside the tag, and the blank line and
  closing line to be indented.
`emptyTags` (default is none)
  An array of XML tag names that should be autoclosed with '/>'.

See demos/closetag.html for a usage example.