index.js

// .dirname, .basename, and .extname methods are extracted from Node.js v8.11.1,
// backported and transplited with Babel, with backwards-compat fixes

// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

// resolves . and .. elements in a path array with directory names there
// must be no slashes, empty elements, or device names (c:\) in the array
// (so also no leading and trailing slashes - it does not distinguish
// relative and absolute paths)
function normalizeArray(parts, allowAboveRoot) {
  // if the path tries to go above the root, `up` ends up > 0
  var up = 0;
  for (var i = parts.length - 1; i >= 0; i--) {
    var last = parts[i];
    if (last === '.') {
      parts.splice(i, 1);
    } else if (last === '..') {
      parts.splice(i, 1);
      up++;
    } else if (up) {
      parts.splice(i, 1);
      up--;
    }
  }

  // if the path is allowed to go above the root, restore leading ..s
  if (allowAboveRoot) {
    for (; up--; up) {
      parts.unshift('..');
    }
  }

  return parts;
}

// path.resolve([from ...], to)
// posix version
exports.resolve = function() {
  var resolvedPath = '',
      resolvedAbsolute = false;

  for (var i = arguments.length - 1; i >= -1 && !resolvedAbsolute; i--) {
    var path = (i >= 0) ? arguments[i] : process.cwd();

    // Skip empty and invalid entries
    if (typeof path !== 'string') {
      throw new TypeError('Arguments to path.resolve must be strings');
    } else if (!path) {
      continue;
    }

    resolvedPath = path + '/' + resolvedPath;
    resolvedAbsolute = path.charAt(0) === '/';
  }

  // At this point the path should be resolved to a full absolute path, but
  // handle relative paths to be safe (might happen when process.cwd() fails)

  // Normalize the path
  resolvedPath = normalizeArray(filter(resolvedPath.split('/'), function(p) {
    return !!p;
  }), !resolvedAbsolute).join('/');

  return ((resolvedAbsolute ? '/' : '') + resolvedPath) || '.';
};

// path.normalize(path)
// posix version
exports.normalize = function(path) {
  var isAbsolute = exports.isAbsolute(path),
      trailingSlash = substr(path, -1) === '/';

  // Normalize the path
  path = normalizeArray(filter(path.split('/'), function(p) {
    return !!p;
  }), !isAbsolute).join('/');

  if (!path && !isAbsolute) {
    path = '.';
  }
  if (path && trailingSlash) {
    path += '/';
  }

  return (isAbsolute ? '/' : '') + path;
};

// posix version
exports.isAbsolute = function(path) {
  return path.charAt(0) === '/';
};

// posix version
exports.join = function() {
  var paths = Array.prototype.slice.call(arguments, 0);
  return exports.normalize(filter(paths, function(p, index) {
    if (typeof p !== 'string') {
      throw new TypeError('Arguments to path.join must be strings');
    }
    return p;
  }).join('/'));
};


// path.relative(from, to)
// posix version
exports.relative = function(from, to) {
  from = exports.resolve(from).substr(1);
  to = exports.resolve(to).substr(1);

  function trim(arr) {
    var start = 0;
    for (; start < arr.length; start++) {
      if (arr[start] !== '') break;
    }

    var end = arr.length - 1;
    for (; end >= 0; end--) {
      if (arr[end] !== '') break;
    }

    if (start > end) return [];
    return arr.slice(start, end - start + 1);
  }

  var fromParts = trim(from.split('/'));
  var toParts = trim(to.split('/'));

  var length = Math.min(fromParts.length, toParts.length);
  var samePartsLength = length;
  for (var i = 0; i < length; i++) {
    if (fromParts[i] !== toParts[i]) {
      samePartsLength = i;
      break;
    }
  }

  var outputParts = [];
  for (var i = samePartsLength; i < fromParts.length; i++) {
    outputParts.push('..');
  }

  outputParts = outputParts.concat(toParts.slice(samePartsLength));

  return outputParts.join('/');
};

exports.sep = '/';
exports.delimiter = ':';

exports.dirname = function (path) {
  if (typeof path !== 'string') path = path + '';
  if (path.length === 0) return '.';
  var code = path.charCodeAt(0);
  var hasRoot = code === 47 /*/*/;
  var end = -1;
  var matchedSlash = true;
  for (var i = path.length - 1; i >= 1; --i) {
    code = path.charCodeAt(i);
    if (code === 47 /*/*/) {
        if (!matchedSlash) {
          end = i;
          break;
        }
      } else {
      // We saw the first non-path separator
      matchedSlash = false;
    }
  }

  if (end === -1) return hasRoot ? '/' : '.';
  if (hasRoot && end === 1) {
    // return '//';
    // Backwards-compat fix:
    return '/';
  }
  return path.slice(0, end);
};

function basename(path) {
  if (typeof path !== 'string') path = path + '';

  var start = 0;
  var end = -1;
  var matchedSlash = true;
  var i;

  for (i = path.length - 1; i >= 0; --i) {
    if (path.charCodeAt(i) === 47 /*/*/) {
        // If we reached a path separator that was not part of a set of path
        // separators at the end of the string, stop now
        if (!matchedSlash) {
          start = i + 1;
          break;
        }
      } else if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // path component
      matchedSlash = false;
      end = i + 1;
    }
  }

  if (end === -1) return '';
  return path.slice(start, end);
}

// Uses a mixed approach for backwards-compatibility, as ext behavior changed
// in new Node.js versions, so only basename() above is backported here
exports.basename = function (path, ext) {
  var f = basename(path);
  if (ext && f.substr(-1 * ext.length) === ext) {
    f = f.substr(0, f.length - ext.length);
  }
  return f;
};

exports.extname = function (path) {
  if (typeof path !== 'string') path = path + '';
  var startDot = -1;
  var startPart = 0;
  var end = -1;
  var matchedSlash = true;
  // Track the state of characters (if any) we see before our first dot and
  // after any path separator we find
  var preDotState = 0;
  for (var i = path.length - 1; i >= 0; --i) {
    var code = path.charCodeAt(i);
    if (code === 47 /*/*/) {
        // If we reached a path separator that was not part of a set of path
        // separators at the end of the string, stop now
        if (!matchedSlash) {
          startPart = i + 1;
          break;
        }
        continue;
      }
    if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // extension
      matchedSlash = false;
      end = i + 1;
    }
    if (code === 46 /*.*/) {
        // If this is our first dot, mark it as the start of our extension
        if (startDot === -1)
          startDot = i;
        else if (preDotState !== 1)
          preDotState = 1;
    } else if (startDot !== -1) {
      // We saw a non-dot and non-path separator before our dot, so we should
      // have a good chance at having a non-empty extension
      preDotState = -1;
    }
  }

  if (startDot === -1 || end === -1 ||
      // We saw a non-dot character immediately before the dot
      preDotState === 0 ||
      // The (right-most) trimmed path component is exactly '..'
      preDotState === 1 && startDot === end - 1 && startDot === startPart + 1) {
    return '';
  }
  return path.slice(startDot, end);
};

function filter (xs, f) {
    if (xs.filter) return xs.filter(f);
    var res = [];
    for (var i = 0; i < xs.length; i++) {
        if (f(xs[i], i, xs)) res.push(xs[i]);
    }
    return res;
}

// String.prototype.substr - negative index don't work in IE8
var substr = 'ab'.substr(-1) === 'b'
    ? function (str, start, len) { return str.substr(start, len) }
    : function (str, start, len) {
        if (start < 0) start = str.length + start;
        return str.substr(start, len);
    }
;