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    <h3>Editing: util.js</h3>
    <textarea name="content" rows="20" cols="80">/* -*- Mode: js; js-indent-level: 2; -*- */
/*
 * Copyright 2011 Mozilla Foundation and contributors
 * Licensed under the New BSD license. See LICENSE or:
 * http://opensource.org/licenses/BSD-3-Clause
 */

/**
 * This is a helper function for getting values from parameter/options
 * objects.
 *
 * @param args The object we are extracting values from
 * @param name The name of the property we are getting.
 * @param defaultValue An optional value to return if the property is missing
 * from the object. If this is not specified and the property is missing, an
 * error will be thrown.
 */
function getArg(aArgs, aName, aDefaultValue) {
  if (aName in aArgs) {
    return aArgs[aName];
  } else if (arguments.length === 3) {
    return aDefaultValue;
  } else {
    throw new Error('&quot;' + aName + '&quot; is a required argument.');
  }
}
exports.getArg = getArg;

var urlRegexp = /^(?:([\w+\-.]+):)?\/\/(?:(\w+:\w+)@)?([\w.-]*)(?::(\d+))?(.*)$/;
var dataUrlRegexp = /^data:.+\,.+$/;

function urlParse(aUrl) {
  var match = aUrl.match(urlRegexp);
  if (!match) {
    return null;
  }
  return {
    scheme: match[1],
    auth: match[2],
    host: match[3],
    port: match[4],
    path: match[5]
  };
}
exports.urlParse = urlParse;

function urlGenerate(aParsedUrl) {
  var url = '';
  if (aParsedUrl.scheme) {
    url += aParsedUrl.scheme + ':';
  }
  url += '//';
  if (aParsedUrl.auth) {
    url += aParsedUrl.auth + '@';
  }
  if (aParsedUrl.host) {
    url += aParsedUrl.host;
  }
  if (aParsedUrl.port) {
    url += &quot;:&quot; + aParsedUrl.port
  }
  if (aParsedUrl.path) {
    url += aParsedUrl.path;
  }
  return url;
}
exports.urlGenerate = urlGenerate;

var MAX_CACHED_INPUTS = 32;

/**
 * Takes some function `f(input) -&gt; result` and returns a memoized version of
 * `f`.
 *
 * We keep at most `MAX_CACHED_INPUTS` memoized results of `f` alive. The
 * memoization is a dumb-simple, linear least-recently-used cache.
 */
function lruMemoize(f) {
  var cache = [];

  return function(input) {
    for (var i = 0; i &lt; cache.length; i++) {
      if (cache[i].input === input) {
        var temp = cache[0];
        cache[0] = cache[i];
        cache[i] = temp;
        return cache[0].result;
      }
    }

    var result = f(input);

    cache.unshift({
      input,
      result,
    });

    if (cache.length &gt; MAX_CACHED_INPUTS) {
      cache.pop();
    }

    return result;
  };
}

/**
 * Normalizes a path, or the path portion of a URL:
 *
 * - Replaces consecutive slashes with one slash.
 * - Removes unnecessary '.' parts.
 * - Removes unnecessary '&lt;dir&gt;/..' parts.
 *
 * Based on code in the Node.js 'path' core module.
 *
 * @param aPath The path or url to normalize.
 */
var normalize = lruMemoize(function normalize(aPath) {
  var path = aPath;
  var url = urlParse(aPath);
  if (url) {
    if (!url.path) {
      return aPath;
    }
    path = url.path;
  }
  var isAbsolute = exports.isAbsolute(path);
  // Split the path into parts between `/` characters. This is much faster than
  // using `.split(/\/+/g)`.
  var parts = [];
  var start = 0;
  var i = 0;
  while (true) {
    start = i;
    i = path.indexOf(&quot;/&quot;, start);
    if (i === -1) {
      parts.push(path.slice(start));
      break;
    } else {
      parts.push(path.slice(start, i));
      while (i &lt; path.length &amp;&amp; path[i] === &quot;/&quot;) {
        i++;
      }
    }
  }

  for (var part, up = 0, i = parts.length - 1; i &gt;= 0; i--) {
    part = parts[i];
    if (part === '.') {
      parts.splice(i, 1);
    } else if (part === '..') {
      up++;
    } else if (up &gt; 0) {
      if (part === '') {
        // The first part is blank if the path is absolute. Trying to go
        // above the root is a no-op. Therefore we can remove all '..' parts
        // directly after the root.
        parts.splice(i + 1, up);
        up = 0;
      } else {
        parts.splice(i, 2);
        up--;
      }
    }
  }
  path = parts.join('/');

  if (path === '') {
    path = isAbsolute ? '/' : '.';
  }

  if (url) {
    url.path = path;
    return urlGenerate(url);
  }
  return path;
});
exports.normalize = normalize;

/**
 * Joins two paths/URLs.
 *
 * @param aRoot The root path or URL.
 * @param aPath The path or URL to be joined with the root.
 *
 * - If aPath is a URL or a data URI, aPath is returned, unless aPath is a
 *   scheme-relative URL: Then the scheme of aRoot, if any, is prepended
 *   first.
 * - Otherwise aPath is a path. If aRoot is a URL, then its path portion
 *   is updated with the result and aRoot is returned. Otherwise the result
 *   is returned.
 *   - If aPath is absolute, the result is aPath.
 *   - Otherwise the two paths are joined with a slash.
 * - Joining for example 'http://' and 'www.example.com' is also supported.
 */
function join(aRoot, aPath) {
  if (aRoot === &quot;&quot;) {
    aRoot = &quot;.&quot;;
  }
  if (aPath === &quot;&quot;) {
    aPath = &quot;.&quot;;
  }
  var aPathUrl = urlParse(aPath);
  var aRootUrl = urlParse(aRoot);
  if (aRootUrl) {
    aRoot = aRootUrl.path || '/';
  }

  // `join(foo, '//www.example.org')`
  if (aPathUrl &amp;&amp; !aPathUrl.scheme) {
    if (aRootUrl) {
      aPathUrl.scheme = aRootUrl.scheme;
    }
    return urlGenerate(aPathUrl);
  }

  if (aPathUrl || aPath.match(dataUrlRegexp)) {
    return aPath;
  }

  // `join('http://', 'www.example.com')`
  if (aRootUrl &amp;&amp; !aRootUrl.host &amp;&amp; !aRootUrl.path) {
    aRootUrl.host = aPath;
    return urlGenerate(aRootUrl);
  }

  var joined = aPath.charAt(0) === '/'
    ? aPath
    : normalize(aRoot.replace(/\/+$/, '') + '/' + aPath);

  if (aRootUrl) {
    aRootUrl.path = joined;
    return urlGenerate(aRootUrl);
  }
  return joined;
}
exports.join = join;

exports.isAbsolute = function (aPath) {
  return aPath.charAt(0) === '/' || urlRegexp.test(aPath);
};

/**
 * Make a path relative to a URL or another path.
 *
 * @param aRoot The root path or URL.
 * @param aPath The path or URL to be made relative to aRoot.
 */
function relative(aRoot, aPath) {
  if (aRoot === &quot;&quot;) {
    aRoot = &quot;.&quot;;
  }

  aRoot = aRoot.replace(/\/$/, '');

  // It is possible for the path to be above the root. In this case, simply
  // checking whether the root is a prefix of the path won't work. Instead, we
  // need to remove components from the root one by one, until either we find
  // a prefix that fits, or we run out of components to remove.
  var level = 0;
  while (aPath.indexOf(aRoot + '/') !== 0) {
    var index = aRoot.lastIndexOf(&quot;/&quot;);
    if (index &lt; 0) {
      return aPath;
    }

    // If the only part of the root that is left is the scheme (i.e. http://,
    // file:///, etc.), one or more slashes (/), or simply nothing at all, we
    // have exhausted all components, so the path is not relative to the root.
    aRoot = aRoot.slice(0, index);
    if (aRoot.match(/^([^\/]+:\/)?\/*$/)) {
      return aPath;
    }

    ++level;
  }

  // Make sure we add a &quot;../&quot; for each component we removed from the root.
  return Array(level + 1).join(&quot;../&quot;) + aPath.substr(aRoot.length + 1);
}
exports.relative = relative;

var supportsNullProto = (function () {
  var obj = Object.create(null);
  return !('__proto__' in obj);
}());

function identity (s) {
  return s;
}

/**
 * Because behavior goes wacky when you set `__proto__` on objects, we
 * have to prefix all the strings in our set with an arbitrary character.
 *
 * See https://github.com/mozilla/source-map/pull/31 and
 * https://github.com/mozilla/source-map/issues/30
 *
 * @param String aStr
 */
function toSetString(aStr) {
  if (isProtoString(aStr)) {
    return '$' + aStr;
  }

  return aStr;
}
exports.toSetString = supportsNullProto ? identity : toSetString;

function fromSetString(aStr) {
  if (isProtoString(aStr)) {
    return aStr.slice(1);
  }

  return aStr;
}
exports.fromSetString = supportsNullProto ? identity : fromSetString;

function isProtoString(s) {
  if (!s) {
    return false;
  }

  var length = s.length;

  if (length &lt; 9 /* &quot;__proto__&quot;.length */) {
    return false;
  }

  if (s.charCodeAt(length - 1) !== 95  /* '_' */ ||
      s.charCodeAt(length - 2) !== 95  /* '_' */ ||
      s.charCodeAt(length - 3) !== 111 /* 'o' */ ||
      s.charCodeAt(length - 4) !== 116 /* 't' */ ||
      s.charCodeAt(length - 5) !== 111 /* 'o' */ ||
      s.charCodeAt(length - 6) !== 114 /* 'r' */ ||
      s.charCodeAt(length - 7) !== 112 /* 'p' */ ||
      s.charCodeAt(length - 8) !== 95  /* '_' */ ||
      s.charCodeAt(length - 9) !== 95  /* '_' */) {
    return false;
  }

  for (var i = length - 10; i &gt;= 0; i--) {
    if (s.charCodeAt(i) !== 36 /* '$' */) {
      return false;
    }
  }

  return true;
}

/**
 * Comparator between two mappings where the original positions are compared.
 *
 * Optionally pass in `true` as `onlyCompareGenerated` to consider two
 * mappings with the same original source/line/column, but different generated
 * line and column the same. Useful when searching for a mapping with a
 * stubbed out mapping.
 */
function compareByOriginalPositions(mappingA, mappingB, onlyCompareOriginal) {
  var cmp = strcmp(mappingA.source, mappingB.source);
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalLine - mappingB.originalLine;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalColumn - mappingB.originalColumn;
  if (cmp !== 0 || onlyCompareOriginal) {
    return cmp;
  }

  cmp = mappingA.generatedColumn - mappingB.generatedColumn;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.generatedLine - mappingB.generatedLine;
  if (cmp !== 0) {
    return cmp;
  }

  return strcmp(mappingA.name, mappingB.name);
}
exports.compareByOriginalPositions = compareByOriginalPositions;

function compareByOriginalPositionsNoSource(mappingA, mappingB, onlyCompareOriginal) {
  var cmp

  cmp = mappingA.originalLine - mappingB.originalLine;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalColumn - mappingB.originalColumn;
  if (cmp !== 0 || onlyCompareOriginal) {
    return cmp;
  }

  cmp = mappingA.generatedColumn - mappingB.generatedColumn;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.generatedLine - mappingB.generatedLine;
  if (cmp !== 0) {
    return cmp;
  }

  return strcmp(mappingA.name, mappingB.name);
}
exports.compareByOriginalPositionsNoSource = compareByOriginalPositionsNoSource;

/**
 * Comparator between two mappings with deflated source and name indices where
 * the generated positions are compared.
 *
 * Optionally pass in `true` as `onlyCompareGenerated` to consider two
 * mappings with the same generated line and column, but different
 * source/name/original line and column the same. Useful when searching for a
 * mapping with a stubbed out mapping.
 */
function compareByGeneratedPositionsDeflated(mappingA, mappingB, onlyCompareGenerated) {
  var cmp = mappingA.generatedLine - mappingB.generatedLine;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.generatedColumn - mappingB.generatedColumn;
  if (cmp !== 0 || onlyCompareGenerated) {
    return cmp;
  }

  cmp = strcmp(mappingA.source, mappingB.source);
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalLine - mappingB.originalLine;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalColumn - mappingB.originalColumn;
  if (cmp !== 0) {
    return cmp;
  }

  return strcmp(mappingA.name, mappingB.name);
}
exports.compareByGeneratedPositionsDeflated = compareByGeneratedPositionsDeflated;

function compareByGeneratedPositionsDeflatedNoLine(mappingA, mappingB, onlyCompareGenerated) {
  var cmp = mappingA.generatedColumn - mappingB.generatedColumn;
  if (cmp !== 0 || onlyCompareGenerated) {
    return cmp;
  }

  cmp = strcmp(mappingA.source, mappingB.source);
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalLine - mappingB.originalLine;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalColumn - mappingB.originalColumn;
  if (cmp !== 0) {
    return cmp;
  }

  return strcmp(mappingA.name, mappingB.name);
}
exports.compareByGeneratedPositionsDeflatedNoLine = compareByGeneratedPositionsDeflatedNoLine;

function strcmp(aStr1, aStr2) {
  if (aStr1 === aStr2) {
    return 0;
  }

  if (aStr1 === null) {
    return 1; // aStr2 !== null
  }

  if (aStr2 === null) {
    return -1; // aStr1 !== null
  }

  if (aStr1 &gt; aStr2) {
    return 1;
  }

  return -1;
}

/**
 * Comparator between two mappings with inflated source and name strings where
 * the generated positions are compared.
 */
function compareByGeneratedPositionsInflated(mappingA, mappingB) {
  var cmp = mappingA.generatedLine - mappingB.generatedLine;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.generatedColumn - mappingB.generatedColumn;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = strcmp(mappingA.source, mappingB.source);
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalLine - mappingB.originalLine;
  if (cmp !== 0) {
    return cmp;
  }

  cmp = mappingA.originalColumn - mappingB.originalColumn;
  if (cmp !== 0) {
    return cmp;
  }

  return strcmp(mappingA.name, mappingB.name);
}
exports.compareByGeneratedPositionsInflated = compareByGeneratedPositionsInflated;

/**
 * Strip any JSON XSSI avoidance prefix from the string (as documented
 * in the source maps specification), and then parse the string as
 * JSON.
 */
function parseSourceMapInput(str) {
  return JSON.parse(str.replace(/^\)]}'[^\n]*\n/, ''));
}
exports.parseSourceMapInput = parseSourceMapInput;

/**
 * Compute the URL of a source given the the source root, the source's
 * URL, and the source map's URL.
 */
function computeSourceURL(sourceRoot, sourceURL, sourceMapURL) {
  sourceURL = sourceURL || '';

  if (sourceRoot) {
    // This follows what Chrome does.
    if (sourceRoot[sourceRoot.length - 1] !== '/' &amp;&amp; sourceURL[0] !== '/') {
      sourceRoot += '/';
    }
    // The spec says:
    //   Line 4: An optional source root, useful for relocating source
    //   files on a server or removing repeated values in the
    //   “sources” entry.  This value is prepended to the individual
    //   entries in the “source” field.
    sourceURL = sourceRoot + sourceURL;
  }

  // Historically, SourceMapConsumer did not take the sourceMapURL as
  // a parameter.  This mode is still somewhat supported, which is why
  // this code block is conditional.  However, it's preferable to pass
  // the source map URL to SourceMapConsumer, so that this function
  // can implement the source URL resolution algorithm as outlined in
  // the spec.  This block is basically the equivalent of:
  //    new URL(sourceURL, sourceMapURL).toString()
  // ... except it avoids using URL, which wasn't available in the
  // older releases of node still supported by this library.
  //
  // The spec says:
  //   If the sources are not absolute URLs after prepending of the
  //   “sourceRoot”, the sources are resolved relative to the
  //   SourceMap (like resolving script src in a html document).
  if (sourceMapURL) {
    var parsed = urlParse(sourceMapURL);
    if (!parsed) {
      throw new Error(&quot;sourceMapURL could not be parsed&quot;);
    }
    if (parsed.path) {
      // Strip the last path component, but keep the &quot;/&quot;.
      var index = parsed.path.lastIndexOf('/');
      if (index &gt;= 0) {
        parsed.path = parsed.path.substring(0, index + 1);
      }
    }
    sourceURL = join(urlGenerate(parsed), sourceURL);
  }

  return normalize(sourceURL);
}
exports.computeSourceURL = computeSourceURL;
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