Source: util/ndn-regex-matcher.js

  1. /**
  2.  * Copyright (C) 2014-2016 Regents of the University of California.
  3.  * @author: Jeff Thompson <jefft0@remap.ucla.edu>
  4.  * From PyNDN ndn_regex.py by Adeola Bannis.
  5.  * Originally from Yingdi Yu <http://irl.cs.ucla.edu/~yingdi/>.
  6.  *
  7.  * This program is free software: you can redistribute it and/or modify
  8.  * it under the terms of the GNU Lesser General Public License as published by
  9.  * the Free Software Foundation, either version 3 of the License, or
  10.  * (at your option) any later version.
  11.  *
  12.  * This program is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.  * GNU Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public License
  18.  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19.  * A copy of the GNU Lesser General Public License is in the file COPYING.
  20.  */
  22. /** @ignore */
  23. var Name = require('../name.js').Name;
  25. /**
  26.  * An NdnRegexMatcher has static methods to convert an NDN regex
  27.  * (http://redmine.named-data.net/projects/ndn-cxx/wiki/Regex) to a JavaScript
  28.  * RegExp that can match against URIs.
  29.  * @constructor
  30.  */
  31. var NdnRegexMatcher = function NdnRegexMatcher()
  32. {
  33. };
  35. exports.NdnRegexMatcher = NdnRegexMatcher;
  37. /**
  38.  * Determine if the provided NDN regex matches the given Name.
  39.  * @param {string} pattern The NDN regex.
  40.  * @param {Name} name The Name to match against the regex.
  41.  * @returns {Object} The match object from String.match, or null if the pattern
  42.  * does not match.
  43.  */
  44. NdnRegexMatcher.match = function(pattern, name)
  45. {
  46.   var nameUri = name.toUri();
  48.   pattern = NdnRegexMatcher.sanitizeSets(pattern);
  50.   pattern = pattern.replace(/<>/g, "(?:<.+?>)");
  51.   pattern = pattern.replace(/>/g, "");
  52.   pattern = pattern.replace(/<(?!!)/g, "/");
  54.   return nameUri.match(new RegExp(pattern));
  55. };
  57. NdnRegexMatcher.sanitizeSets = function(pattern)
  58. {
  59.   var newPattern = pattern;
  61.   // Positive sets can be changed to (comp1|comp2).
  62.   // Negative sets must be changed to negative lookahead assertions.
  64.   var regex1 = /\[(\^?)(.*?)\]/g;
  65.   var match;
  66.   while ((match = regex1.exec(pattern)) !== null) {
  67.     // Insert | between components.
  68.     // Match 2 is the last match, so we use the hack of working backwards from
  69.     //   lastIndex.  If possible, this should be changed to a more direct solution.
  70.     var start = regex1.lastIndex - "]".length - match[2].length;
  71.     var end = start + match[2].length;
  72.     if (start - end === 0)
  73.       continue;
  74.     var oldStr = match[2];
  75.     var newStr = oldStr.replace(/></g, ">|<");
  76.     newPattern = newPattern.substr(0, start) + newStr + newPattern.substr(end);
  77.   }
  79.   // Replace [] with (),  or (?! ) for negative lookahead.
  80.   // If we use negative lookahead, we also have to consume one component.
  81.   var isNegative = newPattern.indexOf("[^") >= 0;
  82.   if (isNegative) {
  83.     newPattern = newPattern.replace(/\[\^/g, "(?:(?!");
  84.     newPattern = newPattern.replace(/\]/g, ")(?:/.*)*)");
  85.   }
  86.   else {
  87.     newPattern = newPattern.replace(/\[/g, "(");
  88.     newPattern = newPattern.replace(/\]/g, ")");
  89.   }
  91.   return newPattern;
  92. };