nodejs/lib/path.js

// 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.


var isWindows = process.platform === 'win32';


// 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;
}


if (isWindows) {

  // Regex to split a filename into [*, dir, basename, ext]
  // windows version
  var splitPathRe = /^(.+(?:[\\\/](?!$)|:)|[\\\/])?((?:.+?)?(\.[^.]*)?)$/;

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

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

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

      // Skip empty and invalid entries
      if (typeof path !== 'string' || !path) {
        continue;
      }

      var result = splitDeviceRe.exec(path),
          device = result[1] || '',
          isUnc = device && device.charAt(1) !== ':',
          isAbsolute = !!result[2] || isUnc, // UNC paths are always absolute
          tail = result[3];

      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;
      }
    }

    if (!resolvedAbsolute && resolvedDevice) {
      // If we still don't have an absolute path,
      // prepend the current path for the device found.

      // TODO
      // Windows stores the current directories for 'other' drives
      // as hidden environment variables like =C:=c:\windows (literally)
      // var deviceCwd = os.getCwdForDrive(resolvedDevice);
      var deviceCwd = '';

      // If there is no cwd set for the drive, it is at root
      resolvedTail = deviceCwd + '\\' + resolvedTail;
      resolvedAbsolute = true;
    }

    // Replace slashes (in UNC share name) by backslashes
    resolvedDevice = resolvedDevice.replace(/\//g, '\\');

    // 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

    function f(p) {
      return !!p;
    }

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

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

  // windows version
  exports.normalize = function(path) {
    var result = splitDeviceRe.exec(path),
        device = result[1] || '',
        isUnc = device && device.charAt(1) !== ':',
        isAbsolute = !!result[2] || isUnc, // UNC paths are always absolute
        tail = result[3],
        trailingSlash = /[\\\/]$/.test(tail);

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

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

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

  // windows version
  exports.join = function() {
    function f(p) {
      return p && typeof p === 'string';
    }

    var paths = Array.prototype.slice.call(arguments, 0).filter(f);
    var joined = paths.join('\\');

    // Make sure that the joined path doesn't start with two slashes
    // - it will be mistaken for an unc path by normalize() -
    // unless the paths[0] also starts with two slashes
    if (/^[\\\/]{2}/.test(joined) && !/^[\\\/]{2}/.test(paths[0])) {
      joined = joined.slice(1);
    }

    return exports.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'
  // windows version
  exports.relative = function(from, to) {
    from = exports.resolve(from);
    to = exports.resolve(to);

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

    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 lowerFromParts = trim(lowerFrom.split('\\'));
    var lowerToParts = trim(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 i = samePartsLength; i < lowerFromParts.length; i++) {
      outputParts.push('..');
    }

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

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


} else /* posix */ {

  // Regex to split a filename into [*, dir, basename, ext]
  // posix version
  var splitPathRe = /^([\s\S]+\/(?!$)|\/)?((?:[\s\S]+?)?(\.[^.]*)?)$/;

  // 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' || !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(resolvedPath.split('/').filter(function(p) {
      return !!p;
    }), !resolvedAbsolute).join('/');

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

  // path.normalize(path)
  // posix version
  exports.normalize = function(path) {
    var isAbsolute = path.charAt(0) === '/',
        trailingSlash = path.slice(-1) === '/';

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

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

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


  // posix version
  exports.join = function() {
    var paths = Array.prototype.slice.call(arguments, 0);
    return exports.normalize(paths.filter(function(p, index) {
      return p && typeof p === 'string';
    }).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.dirname = function(path) {
  var dir = splitPathRe.exec(path)[1] || '';
  if (!dir) {
    // No dirname
    return '.';
  } else if (dir.length === 1 ||
      (isWindows && dir.length <= 3 && dir.charAt(1) === ':')) {
    // It is just a slash or a drive letter with a slash
    return dir;
  } else {
    // It is a full dirname, strip trailing slash
    return dir.substring(0, dir.length - 1);
  }
};


exports.basename = function(path, ext) {
  var f = splitPathRe.exec(path)[2] || '';
  // TODO: make this comparison case-insensitive on windows?
  if (ext && f.substr(-1 * ext.length) === ext) {
    f = f.substr(0, f.length - ext.length);
  }
  return f;
};


exports.extname = function(path) {
  return splitPathRe.exec(path)[3] || '';
};


exports.exists = function(path, callback) {
  process.binding('fs').stat(path, function(err, stats) {
    if (callback) callback(err ? false : true);
  });
};


exports.existsSync = function(path) {
  try {
    process.binding('fs').stat(path);
    return true;
  } catch (e) {
    return false;
  }
};