editor.md/lib/codemirror/addon/edit/continuelist.js

// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: http://codemirror.net/LICENSE

(function(mod) {
  if (typeof exports == "object" && typeof module == "object") // CommonJS
    mod(require("../../lib/codemirror"));
  else if (typeof define == "function" && define.amd) // AMD
    define(["../../lib/codemirror"], mod);
  else // Plain browser env
    mod(CodeMirror);
})(function(CodeMirror) {
  "use strict";

  var listRE = /^(\s*)(>[> ]*|[*+-]\s|(\d+)\.)(\s*)/,
      emptyListRE = /^(\s*)(>[> ]*|[*+-]|(\d+)\.)(\s*)$/,
      unorderedListRE = /[*+-]\s/;

  CodeMirror.commands.newlineAndIndentContinueMarkdownList = function(cm) {
    if (cm.getOption("disableInput")) return CodeMirror.Pass;
    var ranges = cm.listSelections(), replacements = [];
    for (var i = 0; i < ranges.length; i++) {
      var pos = ranges[i].head, match;
      var eolState = cm.getStateAfter(pos.line);
      var inList = eolState.list !== false;
      var inQuote = eolState.quote !== false;

      if (!ranges[i].empty() || (!inList && !inQuote) || !(match = cm.getLine(pos.line).match(listRE))) {
        cm.execCommand("newlineAndIndent");
        return;
      }
      if (cm.getLine(pos.line).match(emptyListRE)) {
        cm.replaceRange("", {
          line: pos.line, ch: 0
        }, {
          line: pos.line, ch: pos.ch + 1
        });
        replacements[i] = "\n";

      } else {
        var indent = match[1], after = match[4];
        var bullet = unorderedListRE.test(match[2]) || match[2].indexOf(">") >= 0
          ? match[2]
          : (parseInt(match[3], 10) + 1) + ".";

        replacements[i] = "\n" + indent + bullet + after;
      }
    }

    cm.replaceSelections(replacements);
  };
});