// Copyright (C) 2012 Jeffrey Arnold
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //      http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  /**
   * @fileoverview
   * Support for R documentation (Rd) files
   *
   * Minimal highlighting or Rd files, basically just highlighting
   * macros. It does not try to identify verbatim or R-like regions of
   * macros as that is too complicated for a lexer.  Descriptions of the
   * Rd format can be found
   * http://cran.r-project.org/doc/manuals/R-exts.html and
   * http://developer.r-project.org/parseRd.pdf.
   *
   * @author Jeffrey Arnold
   */
  PR['registerLangHandler'](
      PR['createSimpleLexer'](
          [
              // whitespace
              [PR['PR_PLAIN'],   /^[\t
  \r \xA0]+/, null, '\t
  \r \xA0'],
              // all comments begin with '%'
              [PR['PR_COMMENT'], /^%[^\r
  ]*/, null, '%']
          ],
          [// special macros with no args
              [PR['PR_LITERAL'], /^\\(?:cr|l?dots|R|tab)\b/],
  	    // macros
              [PR['PR_KEYWORD'], /^\\[a-zA-Z@]+/],
  	    // highlighted as macros, since technically they are
              [PR['PR_KEYWORD'],  /^#(?:ifn?def|endif)/ ],
  	    // catch escaped brackets
  	    [PR['PR_PLAIN'], /^\\[{}]/],
              // punctuation
              [PR['PR_PUNCTUATION'], /^[{}()\[\]]+/]
          ]),
      ['Rd', 'rd']);