node/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';
var util = require('util');


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

  // Regex to split the tail part of the above into [*, dir, basename, ext]
  var splitTailRe =
      /^([\s\S]+[\\\/](?!$)|[\\\/])?((?:\.{1,2}$|[\s\S]+?)?(\.[^.\/\\]*)?)$/;

  // Function to split a filename into [root, dir, basename, ext]
  // windows version
  var splitPath = function(filename) {
    // Separate device+slash from tail
    var result = splitDeviceRe.exec(filename),
        device = (result[1] || '') + (result[2] || ''),
        tail = result[3] || '';
    // Split the tail into dir, basename and extension
    var result2 = splitTailRe.exec(tail),
        dir = result2[1] || '',
        basename = result2[2] || '',
        ext = result2[3] || '';
    return [device, dir, basename, ext];
  };

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

  // 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;
      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 + '\\';
        }
      }

      // 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;
      }
    }

    // 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

    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 += '\\';
    }

    // 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;
  };

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

    var paths = Array.prototype.filter.call(arguments, f);
    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 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 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('\\');
  };

  exports.sep = '\\';
  exports.delimiter = ';';

} else /* posix */ {

  // Split a filename into [root, dir, basename, ext], unix version
  // 'root' is just a slash, or nothing.
  var splitPathRe =
      /^(\/?)([\s\S]+\/(?!$)|\/)?((?:\.{1,2}$|[\s\S]+?)?(\.[^.\/]*)?)$/;
  var splitPath = function(filename) {
    var result = splitPathRe.exec(filename);
    return [result[1] || '', result[2] || '', result[3] || '', result[4] || ''];
  };

  // 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.substr(-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.sep = '/';
  exports.delimiter = ':';
}


exports.dirname = function(path) {
  var result = splitPath(path),
      root = result[0],
      dir = result[1];

  if (!root && !dir) {
    // No dirname whatsoever
    return '.';
  }

  if (dir) {
    // It has a dirname, strip trailing slash
    dir = dir.substr(0, dir.length - 1);
  }

  return root + dir;
};


exports.basename = function(path, ext) {
  var f = splitPath(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 splitPath(path)[3];
};


exports.exists = util.deprecate(function(path, callback) {
  require('fs').exists(path, callback);
}, 'path.exists is now called `fs.exists`.');


exports.existsSync = util.deprecate(function(path) {
  return require('fs').existsSync(path);
}, 'path.existsSync is now called `fs.existsSync`.');


if (isWindows) {
  exports._makeLong = function(path) {
    path = '' + path;
    if (!path) {
      return '';
    }

    var resolvedPath = exports.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;
  };
} else {
  exports._makeLong = function(path) {
    return path;
  };
}