index.js

/**
 * Require the module at `name`.
 *
 * @param {String} name
 * @return {Object} exports
 * @api public
 */

function require(name) {
  var module = require.modules[name];
  if (!module) throw new Error('failed to require "' + name + '"');

  if (!('exports' in module) && typeof module.definition === 'function') {
    module.client = module.component = true;
    module.definition.call(this, module.exports = {}, module);
    delete module.definition;
  }

  return module.exports;
}

/**
 * Meta info, accessible in the global scope unless you use AMD option.
 */

require.loader = 'component';

/**
 * Internal helper object, contains a sorting function for semantiv versioning
 */
require.helper = {};
require.helper.semVerSort = function(a, b) {
  var aArray = a.version.split('.');
  var bArray = b.version.split('.');
  for (var i=0; i<aArray.length; ++i) {
    var aInt = parseInt(aArray[i], 10);
    var bInt = parseInt(bArray[i], 10);
    if (aInt === bInt) {
      var aLex = aArray[i].substr((""+aInt).length);
      var bLex = bArray[i].substr((""+bInt).length);
      if (aLex === '' && bLex !== '') return 1;
      if (aLex !== '' && bLex === '') return -1;
      if (aLex !== '' && bLex !== '') return aLex > bLex ? 1 : -1;
      continue;
    } else if (aInt > bInt) {
      return 1;
    } else {
      return -1;
    }
  }
  return 0;
}

/**
 * Find and require a module which name starts with the provided name.
 * If multiple modules exists, the highest semver is used. 
 * This function can only be used for remote dependencies.

 * @param {String} name - module name: `user~repo`
 * @param {Boolean} returnPath - returns the canonical require path if true, 
 *                               otherwise it returns the epxorted module
 */
require.latest = function (name, returnPath) {
  function showError(name) {
    throw new Error('failed to find latest module of "' + name + '"');
  }
  // only remotes with semvers, ignore local files conataining a '/'
  var versionRegexp = /(.*)~(.*)@v?(\d+\.\d+\.\d+[^\/]*)$/;
  var remoteRegexp = /(.*)~(.*)/;
  if (!remoteRegexp.test(name)) showError(name);
  var moduleNames = Object.keys(require.modules);
  var semVerCandidates = [];
  var otherCandidates = []; // for instance: name of the git branch
  for (var i=0; i<moduleNames.length; i++) {
    var moduleName = moduleNames[i];
    if (new RegExp(name + '@').test(moduleName)) {
        var version = moduleName.substr(name.length+1);
        var semVerMatch = versionRegexp.exec(moduleName);
        if (semVerMatch != null) {
          semVerCandidates.push({version: version, name: moduleName});
        } else {
          otherCandidates.push({version: version, name: moduleName});
        } 
    }
  }
  if (semVerCandidates.concat(otherCandidates).length === 0) {
    showError(name);
  }
  if (semVerCandidates.length > 0) {
    var module = semVerCandidates.sort(require.helper.semVerSort).pop().name;
    if (returnPath === true) {
      return module;
    }
    return require(module);
  }
  // if the build contains more than one branch of the same module
  // you should not use this funciton
  var module = otherCandidates.pop().name;
  if (returnPath === true) {
    return module;
  }
  return require(module);
}

/**
 * Registered modules.
 */

require.modules = {};

/**
 * Register module at `name` with callback `definition`.
 *
 * @param {String} name
 * @param {Function} definition
 * @api private
 */

require.register = function (name, definition) {
  require.modules[name] = {
    definition: definition
  };
};

/**
 * Define a module's exports immediately with `exports`.
 *
 * @param {String} name
 * @param {Generic} exports
 * @api private
 */

require.define = function (name, exports) {
  require.modules[name] = {
    exports: exports
  };
};