CodeMirror.defineMode("r", function(config) {
  function wordObj(str) {
    var words = str.split(" "), res = {};
    for (var i = 0; i < words.length; ++i) res[words[i]] = true;
    return res;
  }
  var atoms = wordObj("NULL NA Inf NaN NA_integer_ NA_real_ NA_complex_ NA_character_");
  var builtins = wordObj("list quote bquote eval return call parse deparse");
  var keywords = wordObj("if else repeat while function for in next break");
  var blockkeywords = wordObj("if else repeat while function for");
  var opChars = /[+\-*\/^<>=!&|~$:]/;
  var curPunc;

  function tokenBase(stream, state) {
    curPunc = null;
    var ch = stream.next();
    if (ch == "#") {
      stream.skipToEnd();
      return "comment";
    } else if (ch == "0" && stream.eat("x")) {
      stream.eatWhile(/[\da-f]/i);
      return "number";
    } else if (ch == "." && stream.eat(/\d/)) {
      stream.match(/\d*(?:e[+\-]?\d+)?/);
      return "number";
    } else if (/\d/.test(ch)) {
      stream.match(/\d*(?:\.\d+)?(?:e[+\-]\d+)?L?/);
      return "number";
    } else if (ch == "'" || ch == '"') {
      state.tokenize = tokenString(ch);
      return "string";
    } else if (ch == "." && stream.match(/.[.\d]+/)) {
      return "keyword";
    } else if (/[\w\.]/.test(ch) && ch != "_") {
      stream.eatWhile(/[\w\.]/);
      var word = stream.current();
      if (atoms.propertyIsEnumerable(word)) return "atom";
      if (keywords.propertyIsEnumerable(word)) {
        if (blockkeywords.propertyIsEnumerable(word)) curPunc = "block";
        return "keyword";
      }
      if (builtins.propertyIsEnumerable(word)) return "builtin";
      return "variable";
    } else if (ch == "%") {
      if (stream.skipTo("%")) stream.next();
      return "variable-2";
    } else if (ch == "<" && stream.eat("-")) {
      return "arrow";
    } else if (ch == "=" && state.ctx.argList) {
      return "arg-is";
    } else if (opChars.test(ch)) {
      if (ch == "$") return "dollar";
      stream.eatWhile(opChars);
      return "operator";
    } else if (/[\(\){}\[\];]/.test(ch)) {
      curPunc = ch;
      if (ch == ";") return "semi";
      return null;
    } else {
      return null;
    }
  }

  function tokenString(quote) {
    return function(stream, state) {
      if (stream.eat("\\")) {
        var ch = stream.next();
        if (ch == "x") stream.match(/^[a-f0-9]{2}/i);
        else if ((ch == "u" || ch == "U") && stream.eat("{") && stream.skipTo("}")) stream.next();
        else if (ch == "u") stream.match(/^[a-f0-9]{4}/i);
        else if (ch == "U") stream.match(/^[a-f0-9]{8}/i);
        else if (/[0-7]/.test(ch)) stream.match(/^[0-7]{1,2}/);
        return "string-2";
      } else {
        var next;
        while ((next = stream.next()) != null) {
          if (next == quote) { state.tokenize = tokenBase; break; }
          if (next == "\\") { stream.backUp(1); break; }
        }
        return "string";
      }
    };
  }

  function push(state, type, stream) {
    state.ctx = {type: type,
                 indent: state.indent,
                 align: null,
                 column: stream.column(),
                 prev: state.ctx};
  }
  function pop(state) {
    state.indent = state.ctx.indent;
    state.ctx = state.ctx.prev;
  }

  return {
    startState: function(base) {
      return {tokenize: tokenBase,
              ctx: {type: "top",
                    indent: -config.indentUnit,
                    align: false},
              indent: 0,
              afterIdent: false};
    },

    token: function(stream, state) {
      if (stream.sol()) {
        if (state.ctx.align == null) state.ctx.align = false;
        state.indent = stream.indentation();
      }
      if (stream.eatSpace()) return null;
      var style = state.tokenize(stream, state);
      if (style != "comment" && state.ctx.align == null) state.ctx.align = true;

      var ctype = state.ctx.type;
      if ((curPunc == ";" || curPunc == "{" || curPunc == "}") && ctype == "block") pop(state);
      if (curPunc == "{") push(state, "}", stream);
      else if (curPunc == "(") {
        push(state, ")", stream);
        if (state.afterIdent) state.ctx.argList = true;
      }
      else if (curPunc == "[") push(state, "]", stream);
      else if (curPunc == "block") push(state, "block", stream);
      else if (curPunc == ctype) pop(state);
      state.afterIdent = style == "variable" || style == "keyword";
      return style;
    },

    indent: function(state, textAfter) {
      if (state.tokenize != tokenBase) return 0;
      var firstChar = textAfter && textAfter.charAt(0), ctx = state.ctx,
          closing = firstChar == ctx.type;
      if (ctx.type == "block") return ctx.indent + (firstChar == "{" ? 0 : config.indentUnit);
      else if (ctx.align) return ctx.column + (closing ? 0 : 1);
      else return ctx.indent + (closing ? 0 : config.indentUnit);
    }
  };
});

CodeMirror.defineMIME("text/x-rsrc", "r");
