node/lib/path.js

'use strict';

const util = require('util');
const isWindows = process.platform === 'win32';

function assertPath(path) {
  if (typeof path !== 'string') {
    throw new TypeError('Path must be a string. Received ' +
                        util.inspect(path));
  }
}

// resolves . and .. elements in a path array with directory names there
// must be no slashes 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) {
  var res = [];
  for (var i = 0; i < parts.length; i++) {
    var p = parts[i];

    // ignore empty parts
    if (!p || p === '.')
      continue;

    if (p === '..') {
      if (res.length && res[res.length - 1] !== '..') {
        res.pop();
      } else if (allowAboveRoot) {
        res.push('..');
      }
    } else {
      res.push(p);
    }
  }

  return res;
}

// Returns an array with empty elements removed from either end of the input
// array or the original array if no elements need to be removed
function trimArray(arr) {
  var lastIndex = arr.length - 1;
  var start = 0;
  for (; start <= lastIndex; start++) {
    if (arr[start])
      break;
  }

  var end = lastIndex;
  for (; end >= 0; end--) {
    if (arr[end])
      break;
  }

  if (start === 0 && end === lastIndex)
    return arr;
  if (start > end)
    return [];
  return arr.slice(start, end + 1);
}

// Regex to split a windows path into three parts: [*, device, slash,
// tail] windows-only
const splitDeviceRe =
    /^([a-zA-Z]:|[\\\/]{2}[^\\\/]+[\\\/]+[^\\\/]+)?([\\\/])?([\s\S]*?)$/;

var win32 = {};

function win32StatPath(path) {
  const result = splitDeviceRe.exec(path);
  const device = result[1] || '';
  const isUnc = !!device && device[1] !== ':';
  return {
    device,
    isUnc,
    isAbsolute: isUnc || !!result[2], // UNC paths are always absolute
    tail: result[3]
  };
}

function normalizeUNCRoot(device) {
  return '\\\\' + device.replace(/^[\\\/]+/, '').replace(/[\\\/]+/g, '\\');
}

// path.resolve([from ...], to)
win32.resolve = function() {
  var resolvedDevice = '';
  var resolvedTail = '';
  var resolvedAbsolute = false;

  for (var i = arguments.length - 1; i >= -1; i--) {
    var path;
    if (i >= 0) {
      path = arguments[i];
    } else if (!resolvedDevice) {
      path = process.cwd();
    } else {
      // Windows has the concept of drive-specific current working
      // directories. If we've resolved a drive letter but not yet an
      // absolute path, get cwd for that drive. We're sure the device is not
      // an unc path at this points, because unc paths are always absolute.
      path = process.env['=' + resolvedDevice];
      // Verify that a drive-local cwd was found and that it actually points
      // to our drive. If not, default to the drive's root.
      if (!path || path.substr(0, 3).toLowerCase() !==
          resolvedDevice.toLowerCase() + '\\') {
        path = resolvedDevice + '\\';
      }
    }

    assertPath(path);

    // Skip empty entries
    if (path === '') {
      continue;
    }

    const result = win32StatPath(path);
    const device = result.device;
    var isUnc = result.isUnc;
    const isAbsolute = result.isAbsolute;
    const tail = result.tail;

    if (device &&
        resolvedDevice &&
        device.toLowerCase() !== resolvedDevice.toLowerCase()) {
      // This path points to another device so it is not applicable
      continue;
    }

    if (!resolvedDevice) {
      resolvedDevice = device;
    }
    if (!resolvedAbsolute) {
      resolvedTail = tail + '\\' + resolvedTail;
      resolvedAbsolute = isAbsolute;
    }

    if (resolvedDevice && resolvedAbsolute) {
      break;
    }
  }

  // Convert slashes to backslashes when `resolvedDevice` points to an UNC
  // root. Also squash multiple slashes into a single one where appropriate.
  if (isUnc) {
    resolvedDevice = normalizeUNCRoot(resolvedDevice);
  }

  // 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 tail path
  resolvedTail = normalizeArray(resolvedTail.split(/[\\\/]+/),
                                !resolvedAbsolute).join('\\');

  return (resolvedDevice + (resolvedAbsolute ? '\\' : '') + resolvedTail) ||
         '.';
};


win32.normalize = function(path) {
  assertPath(path);

  const result = win32StatPath(path);
  var device = result.device;
  const isUnc = result.isUnc;
  const isAbsolute = result.isAbsolute;
  var tail = result.tail;
  const trailingSlash = /[\\\/]$/.test(tail);

  // Normalize the tail path
  tail = normalizeArray(tail.split(/[\\\/]+/), !isAbsolute).join('\\');

  if (!tail && !isAbsolute) {
    tail = '.';
  }
  if (tail && trailingSlash) {
    tail += '\\';
  }

  // Convert slashes to backslashes when `device` points to an UNC root.
  // Also squash multiple slashes into a single one where appropriate.
  if (isUnc) {
    device = normalizeUNCRoot(device);
  }

  return device + (isAbsolute ? '\\' : '') + tail;
};


win32.isAbsolute = function(path) {
  assertPath(path);
  return win32StatPath(path).isAbsolute;
};

win32.join = function() {
  var paths = [];
  for (var i = 0; i < arguments.length; i++) {
    var arg = arguments[i];
    assertPath(arg);
    if (arg) {
      paths.push(arg);
    }
  }

  var joined = paths.join('\\');

  // Make sure that the joined path doesn't start with two slashes, because
  // normalize() will mistake it for an UNC path then.
  //
  // This step is skipped when it is very clear that the user actually
  // intended to point at an UNC path. This is assumed when the first
  // non-empty string arguments starts with exactly two slashes followed by
  // at least one more non-slash character.
  //
  // Note that for normalize() to treat a path as an UNC path it needs to
  // have at least 2 components, so we don't filter for that here.
  // This means that the user can use join to construct UNC paths from
  // a server name and a share name; for example:
  //   path.join('//server', 'share') -> '\\\\server\\share\')
  if (!/^[\\\/]{2}[^\\\/]/.test(paths[0])) {
    joined = joined.replace(/^[\\\/]{2,}/, '\\');
  }

  return win32.normalize(joined);
};


// path.relative(from, to)
// it will solve the relative path from 'from' to 'to', for instance:
// from = 'C:\\orandea\\test\\aaa'
// to = 'C:\\orandea\\impl\\bbb'
// The output of the function should be: '..\\..\\impl\\bbb'
win32.relative = function(from, to) {
  assertPath(from);
  assertPath(to);

  from = win32.resolve(from);
  to = win32.resolve(to);

  // windows is not case sensitive
  var lowerFrom = from.toLowerCase();
  var lowerTo = to.toLowerCase();

  var toParts = trimArray(to.split('\\'));

  var lowerFromParts = trimArray(lowerFrom.split('\\'));
  var lowerToParts = trimArray(lowerTo.split('\\'));

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

  if (samePartsLength === 0) {
    return to;
  }

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

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

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


win32._makeLong = function(path) {
  // Note: this will *probably* throw somewhere.
  if (typeof path !== 'string')
    return path;

  if (!path) {
    return '';
  }

  var resolvedPath = win32.resolve(path);

  if (/^[a-zA-Z]\:\\/.test(resolvedPath)) {
    // path is local filesystem path, which needs to be converted
    // to long UNC path.
    return '\\\\?\\' + resolvedPath;
  } else if (/^\\\\[^?.]/.test(resolvedPath)) {
    // path is network UNC path, which needs to be converted
    // to long UNC path.
    return '\\\\?\\UNC\\' + resolvedPath.substring(2);
  }

  return path;
};


win32.dirname = function(path) {
  const len = path.length;
  if (len === 0)
    return '.';
  var rootEnd = -1;
  var end = -1;
  var matchedSlash = true;
  var offset = 0;
  var code = path.charCodeAt(0);

  // Try to match a root
  if (len > 1) {
    if (code === 47/*/*/ || code === 92/*\*/) {
      // Possible UNC root

      rootEnd = offset = 1;

      code = path.charCodeAt(1);
      if (code === 47/*/*/ || code === 92/*\*/) {
        // Matched double path separator at beginning
        var j = 2;
        var last = j;
        // Match 1 or more non-path separators
        for (; j < len; ++j) {
          code = path.charCodeAt(j);
          if (code === 47/*/*/ || code === 92/*\*/)
            break;
        }
        if (j < len && j !== last) {
          // Matched!
          last = j;
          // Match 1 or more path separators
          for (; j < len; ++j) {
            code = path.charCodeAt(j);
            if (code !== 47/*/*/ && code !== 92/*\*/)
              break;
          }
          if (j < len && j !== last) {
            // Matched!
            last = j;
            // Match 1 or more non-path separators
            for (; j < len; ++j) {
              code = path.charCodeAt(j);
              if (code === 47/*/*/ || code === 92/*\*/)
                break;
            }
            if (j === len) {
              // We matched a UNC root only
              return path;
            }
            if (j !== last) {
              // We matched a UNC root with leftovers

              // Offset by 1 to include the separator after the UNC root to
              // treat it as a "normal root" on top of a (UNC) root
              rootEnd = offset = j + 1;
            }
          }
        }
      }
    } else if ((code >= 65/*A*/ && code <= 90/*Z*/) ||
               (code >= 97/*a*/ && code <= 122/*z*/)) {
      // Possible device root

      if (path.charCodeAt(1) === 58/*:*/) {
        rootEnd = offset = 2;
        if (len > 2) {
          code = path.charCodeAt(2);
          if (code === 47/*/*/ || code === 92/*\*/)
            rootEnd = offset = 3;
        }
      }
    }
  } else if (code === 47/*/*/ || code === 92/*\*/) {
    // `path` contains just a path separator, exit early to avoid
    // unnecessary work
    return path;
  }

  for (var i = len - 1; i >= offset; --i) {
    code = path.charCodeAt(i);
    if (code === 47/*/*/ || code === 92/*\*/) {
      if (!matchedSlash) {
        end = i;
        break;
      }
    } else {
      // We saw the first non-path separator
      matchedSlash = false;
    }
  }

  if (end === -1) {
    if (rootEnd === -1)
      return '.';
    else
      end = rootEnd;
  }
  return path.slice(0, end);
};


win32.basename = function(path, ext) {
  if (ext !== undefined && typeof ext !== 'string')
    throw new TypeError('ext must be a string');

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

  // Check for a drive letter prefix so as not to mistake the following
  // path separator as an extra separator at the end of the path that can be
  // disregarded
  if (path.length >= 2) {
    const drive = path.charCodeAt(0);
    if ((drive >= 65/*A*/ && drive <= 90/*Z*/) ||
        (drive >= 97/*a*/ && drive <= 122/*z*/)) {
      if (path.charCodeAt(1) === 58/*:*/)
        start = 2;
    }
  }

  if (ext !== undefined && ext.length > 0 && ext.length <= path.length) {
    if (ext.length === path.length && ext === path)
      return '';
    var extIdx = ext.length - 1;
    var firstNonSlashEnd = -1;
    for (i = path.length - 1; i >= start; --i) {
      const code = path.charCodeAt(i);
      if (code === 47/*/*/ || code === 92/*\*/) {
        // 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 (firstNonSlashEnd === -1) {
          // We saw the first non-path separator, remember this index in case
          // we need it if the extension ends up not matching
          matchedSlash = false;
          firstNonSlashEnd = i + 1;
        }
        if (extIdx >= 0) {
          // Try to match the explicit extension
          if (code === ext.charCodeAt(extIdx)) {
            if (--extIdx === -1) {
              // We matched the extension, so mark this as the end of our path
              // component
              end = i;
            }
          } else {
            // Extension does not match, so our result is the entire path
            // component
            extIdx = -1;
            end = firstNonSlashEnd;
          }
        }
      }
    }

    if (start === end)
      end = firstNonSlashEnd;
    else if (end === -1)
      end = path.length;
    return path.slice(start, end);
  } else {
    for (i = path.length - 1; i >= start; --i) {
      const code = path.charCodeAt(i);
      if (code === 47/*/*/ || code === 92/*\*/) {
        // 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);
  }
};


win32.extname = function(path) {
  var start = 0;
  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;

  // Check for a drive letter prefix so as not to mistake the following
  // path separator as an extra separator at the end of the path that can be
  // disregarded
  if (path.length >= 2) {
    const code = path.charCodeAt(0);
    if (path.charCodeAt(1) === 58/*:*/ &&
        ((code >= 65/*A*/ && code <= 90/*Z*/) ||
         (code >= 97/*a*/ && code <= 122/*z*/))) {
      start = startPart = 2;
    }
  }

  for (var i = path.length - 1; i >= start; --i) {
    const code = path.charCodeAt(i);
    if (code === 47/*/*/ || code === 92/*\*/) {
      // 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);
};


win32.format = function(pathObject) {
  if (pathObject === null || typeof pathObject !== 'object') {
    throw new TypeError(
        "Parameter 'pathObject' must be an object, not " + typeof pathObject
    );
  }

  var root = pathObject.root || '';

  if (typeof root !== 'string') {
    throw new TypeError(
        "'pathObject.root' must be a string or undefined, not " +
        typeof pathObject.root
    );
  }

  var dir = pathObject.dir;
  var base = pathObject.base || '';
  if (!dir) {
    return base;
  }
  if (dir[dir.length - 1] === win32.sep) {
    return dir + base;
  }
  return dir + win32.sep + base;
};


win32.parse = function(path) {
  assertPath(path);

  var ret = { root: '', dir: '', base: '', ext: '', name: '' };
  if (path.length === 0)
    return ret;

  var len = path.length;
  var rootEnd = 0;
  var code = path.charCodeAt(0);

  // Try to match a root
  if (len > 1) {
    if (code === 47/*/*/ || code === 92/*\*/) {
      // Possible UNC root

      code = path.charCodeAt(1);
      rootEnd = 1;
      if (code === 47/*/*/ || code === 92/*\*/) {
        // Matched double path separator at beginning
        var j = 2;
        var last = j;
        // Match 1 or more non-path separators
        for (; j < len; ++j) {
          code = path.charCodeAt(j);
          if (code === 47/*/*/ || code === 92/*\*/)
            break;
        }
        if (j < len && j !== last) {
          // Matched!
          last = j;
          // Match 1 or more path separators
          for (; j < len; ++j) {
            code = path.charCodeAt(j);
            if (code !== 47/*/*/ && code !== 92/*\*/)
              break;
          }
          if (j < len && j !== last) {
            // Matched!
            last = j;
            // Match 1 or more non-path separators
            for (; j < len; ++j) {
              code = path.charCodeAt(j);
              if (code === 47/*/*/ || code === 92/*\*/)
                break;
            }
            if (j === len) {
              // We matched a UNC root only

              rootEnd = j;
            } else if (j !== last) {
              // We matched a UNC root with leftovers

              rootEnd = j + 1;
            }
          }
        }
      }
    } else if ((code >= 65/*A*/ && code <= 90/*Z*/) ||
               (code >= 97/*a*/ && code <= 122/*z*/)) {
      // Possible device root

      if (path.charCodeAt(1) === 58/*:*/) {
        rootEnd = 2;
        if (len > 2) {
          code = path.charCodeAt(2);
          if (code === 47/*/*/ || code === 92/*\*/) {
            if (len === 3) {
              // `path` contains just a drive root, exit early to avoid
              // unnecessary work
              ret.root = ret.dir = path;
              return ret;
            }
            rootEnd = 3;
          }
        } else {
          // `path` contains just a drive root, exit early to avoid
          // unnecessary work
          ret.root = ret.dir = path;
          return ret;
        }
      }
    }
  } else if (code === 47/*/*/ || code === 92/*\*/) {
    // `path` contains just a path separator, exit early to avoid
    // unnecessary work
    ret.root = ret.dir = path;
    return ret;
  }

  if (rootEnd > 0)
    ret.root = path.slice(0, rootEnd);

  var startDot = -1;
  var startPart = rootEnd;
  var end = -1;
  var matchedSlash = true;
  var i = path.length - 1;

  // Track the state of characters (if any) we see before our first dot and
  // after any path separator we find
  var preDotState = 0;

  // Get non-dir info
  for (; i >= rootEnd; --i) {
    code = path.charCodeAt(i);
    if (code === 47/*/*/ || code === 92/*\*/) {
      // 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)) {
    if (end !== -1) {
      ret.base = ret.name = path.slice(startPart, end);
    }
  } else {
    ret.name = path.slice(startPart, startDot);
    ret.base = path.slice(startPart, end);
    ret.ext = path.slice(startDot, end);
  }

  // If the directory is the root, use the entire root as the `dir` including
  // the trailing slash if any (`C:\abc` -> `C:\`). Otherwise, strip out the
  // trailing slash (`C:\abc\def` -> `C:\abc`).
  if (startPart > 0 && startPart !== rootEnd)
    ret.dir = path.slice(0, startPart - 1);
  else
    ret.dir = ret.root;

  return ret;
};


win32.sep = '\\';
win32.delimiter = ';';

var posix = {};

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

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

    assertPath(path);

    // Skip empty entries
    if (path === '') {
      continue;
    }

    resolvedPath = path + '/' + resolvedPath;
    resolvedAbsolute = path[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(resolvedPath.split('/'),
                                !resolvedAbsolute).join('/');

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

// path.normalize(path)
// posix version
posix.normalize = function(path) {
  assertPath(path);

  const isAbsolute = posix.isAbsolute(path);
  const trailingSlash = path && path[path.length - 1] === '/';

  // Normalize the path
  path = normalizeArray(path.split('/'), !isAbsolute).join('/');

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

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

// posix version
posix.isAbsolute = function(path) {
  assertPath(path);
  return !!path && path[0] === '/';
};

// posix version
posix.join = function() {
  var path = '';
  for (var i = 0; i < arguments.length; i++) {
    var segment = arguments[i];
    assertPath(segment);
    if (segment) {
      if (!path) {
        path += segment;
      } else {
        path += '/' + segment;
      }
    }
  }
  return posix.normalize(path);
};


// path.relative(from, to)
// posix version
posix.relative = function(from, to) {
  assertPath(from);
  assertPath(to);

  from = posix.resolve(from).substr(1);
  to = posix.resolve(to).substr(1);

  var fromParts = trimArray(from.split('/'));
  var toParts = trimArray(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 j = samePartsLength; j < fromParts.length; j++) {
    outputParts.push('..');
  }

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

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


posix._makeLong = function(path) {
  return path;
};


posix.dirname = function(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 '//';
  return path.slice(0, end);
};


posix.basename = function(path, ext) {
  if (ext !== undefined && typeof ext !== 'string')
    throw new TypeError('ext must be a string');

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

  if (ext !== undefined && ext.length > 0 && ext.length <= path.length) {
    if (ext.length === path.length && ext === path)
      return '';
    var extIdx = ext.length - 1;
    var firstNonSlashEnd = -1;
    for (i = path.length - 1; i >= 0; --i) {
      const 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) {
          start = i + 1;
          break;
        }
      } else {
        if (firstNonSlashEnd === -1) {
          // We saw the first non-path separator, remember this index in case
          // we need it if the extension ends up not matching
          matchedSlash = false;
          firstNonSlashEnd = i + 1;
        }
        if (extIdx >= 0) {
          // Try to match the explicit extension
          if (code === ext.charCodeAt(extIdx)) {
            if (--extIdx === -1) {
              // We matched the extension, so mark this as the end of our path
              // component
              end = i;
            }
          } else {
            // Extension does not match, so our result is the entire path
            // component
            extIdx = -1;
            end = firstNonSlashEnd;
          }
        }
      }
    }

    if (start === end)
      end = firstNonSlashEnd;
    else if (end === -1)
      end = path.length;
    return path.slice(start, end);
  } else {
    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);
  }
};


posix.extname = function(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) {
    const 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);
};


posix.format = function(pathObject) {
  if (pathObject === null || typeof pathObject !== 'object') {
    throw new TypeError(
        "Parameter 'pathObject' must be an object, not " + typeof pathObject
    );
  }

  var root = pathObject.root || '';

  if (typeof root !== 'string') {
    throw new TypeError(
        "'pathObject.root' must be a string or undefined, not " +
        typeof pathObject.root
    );
  }

  var dir = pathObject.dir ? pathObject.dir + posix.sep : '';
  var base = pathObject.base || '';
  return dir + base;
};


posix.parse = function(pathString) {
  assertPath(pathString);
  var ret = { root: '', dir: '', base: '', ext: '', name: '' };
  if (pathString.length === 0)
    return ret;
  var code = pathString.charCodeAt(0);
  var isAbsolute = (code === 47);
  var start;
  if (isAbsolute) {
    ret.root = '/';
    start = 1;
  } else {
    start = 0;
  }
  var startDot = -1;
  var startPart = 0;
  var end = -1;
  var matchedSlash = true;
  var i = pathString.length - 1;

  // Track the state of characters (if any) we see before our first dot and
  // after any path separator we find
  var preDotState = 0;

  // Get non-dir info
  for (; i >= start; --i) {
    code = pathString.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)) {
    if (end !== -1) {
      if (startPart === 0 && isAbsolute)
        ret.base = ret.name = pathString.slice(1, end);
      else
        ret.base = ret.name = pathString.slice(startPart, end);
    }
  } else {
    if (startPart === 0 && isAbsolute) {
      ret.name = pathString.slice(1, startDot);
      ret.base = pathString.slice(1, end);
    } else {
      ret.name = pathString.slice(startPart, startDot);
      ret.base = pathString.slice(startPart, end);
    }
    ret.ext = pathString.slice(startDot, end);
  }

  if (startPart > 0)
    ret.dir = pathString.slice(0, startPart - 1);
  else if (isAbsolute)
    ret.dir = '/';

  return ret;
};


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


if (isWindows)
  module.exports = win32;
else /* posix */
  module.exports = posix;

module.exports.posix = posix;
module.exports.win32 = win32;