es-module-loader/src/system.js at 0.17 · ModuleLoader/es-module-loader · GitHub

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/*
*********************************************************************************************

  System Loader Implementation

    - Implemented to https://github.com/jorendorff/js-loaders/blob/master/browser-loader.js

    - <script type="module"> supported

*********************************************************************************************
*/

var System;

function SystemLoader() {
  Loader.call(this);
  this.paths = {};
}

// NB no specification provided for System.paths, used ideas discussed in https://github.com/jorendorff/js-loaders/issues/25
function applyPaths(paths, name) {
  // most specific (most number of slashes in path) match wins
  var pathMatch = '', wildcard, maxWildcardPrefixLen = 0;

  // check to see if we have a paths entry
  for (var p in paths) {
    if (paths.hasOwnProperty && !paths.hasOwnProperty(p))
      continue;

    // exact path match
    if (p.indexOf('*') === -1) {
      if (name == p)
        return paths[p];

      // support trailing / in paths rules
      else if (name.substr(0, p.length - 1) == p.substr(0, p.length - 1) && (name.length < p.length || name[p.length - 1] == p[p.length - 1]) && (paths[p][paths[p].length - 1] == '/' || paths[p] == '')) {
        return paths[p].substr(0, paths[p].length - 1) + (name.length > p.length ? (paths[p] && '/' || '') + name.substr(p.length) : '');
      }
    }
    // wildcard path match
    else {
      var pathParts = p.split('*');
      if (pathParts.length > 2)
        throw new TypeError('Only one wildcard in a path is permitted');

      var wildcardPrefixLen = pathParts[0].length;
      if (wildcardPrefixLen >= maxWildcardPrefixLen &&
          name.substr(0, pathParts[0].length) == pathParts[0] &&
          name.substr(name.length - pathParts[1].length) == pathParts[1]) {
            maxWildcardPrefixLen = wildcardPrefixLen;
            pathMatch = p;
            wildcard = name.substr(pathParts[0].length, name.length - pathParts[1].length - pathParts[0].length);
          }
    }
  }

  var outPath = paths[pathMatch];
  if (typeof wildcard == 'string')
    outPath = outPath.replace('*', wildcard);

  return outPath;
}

// inline Object.create-style class extension
function LoaderProto() {}
LoaderProto.prototype = Loader.prototype;
SystemLoader.prototype = new LoaderProto();