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      1 # Copyright 2013 The Chromium Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 
      5 from file_system import FileSystem, FileNotFoundError, StatInfo
      6 from future import Future
      7 from path_util import AssertIsValid, AssertIsDirectory, IsDirectory
      8 
      9 
     10 def MoveTo(base, obj):
     11   '''Returns an object as |obj| moved to |base|. That is,
     12   MoveTo('foo/bar', {'a': 'b'}) -> {'foo': {'bar': {'a': 'b'}}}
     13   '''
     14   AssertIsDirectory(base)
     15   result = {}
     16   leaf = result
     17   for k in base.rstrip('/').split('/'):
     18     leaf[k] = {}
     19     leaf = leaf[k]
     20   leaf.update(obj)
     21   return result
     22 
     23 
     24 def MoveAllTo(base, obj):
     25   '''Moves every value in |obj| to |base|. See MoveTo.
     26   '''
     27   result = {}
     28   for key, value in obj.iteritems():
     29     result[key] = MoveTo(base, value)
     30   return result
     31 
     32 
     33 def _List(file_system):
     34   '''Returns a list of '/' separated paths derived from |file_system|.
     35   For example, {'index.html': '', 'www': {'file.txt': ''}} would return
     36   ['index.html', 'www/file.txt'].
     37   '''
     38   assert isinstance(file_system, dict)
     39   result = {}
     40   def update_result(item, path):
     41     AssertIsValid(path)
     42     if isinstance(item, dict):
     43       if path != '':
     44         path += '/'
     45       result[path] = [p if isinstance(content, basestring) else (p + '/')
     46                       for p, content in item.iteritems()]
     47       for subpath, subitem in item.iteritems():
     48         update_result(subitem, path + subpath)
     49     elif isinstance(item, basestring):
     50       result[path] = item
     51     else:
     52       raise ValueError('Unsupported item type: %s' % type(item))
     53   update_result(file_system, '')
     54   return result
     55 
     56 
     57 class _StatTracker(object):
     58   '''Maintains the versions of paths in a file system. The versions of files
     59   are changed either by |Increment| or |SetVersion|. The versions of
     60   directories are derived from the versions of files within it.
     61   '''
     62 
     63   def __init__(self):
     64     self._path_stats = {}
     65     self._global_stat = 0
     66 
     67   def Increment(self, path=None, by=1):
     68     if path is None:
     69       self._global_stat += by
     70     else:
     71       self.SetVersion(path, self._path_stats.get(path, 0) + by)
     72 
     73   def SetVersion(self, path, new_version):
     74     if IsDirectory(path):
     75       raise ValueError('Only files have an incrementable stat, '
     76                        'but "%s" is a directory' % path)
     77 
     78     # Update version of that file.
     79     self._path_stats[path] = new_version
     80 
     81     # Update all parent directory versions as well.
     82     slash_index = 0  # (deliberately including '' in the dir paths)
     83     while slash_index != -1:
     84       dir_path = path[:slash_index] + '/'
     85       self._path_stats[dir_path] = max(self._path_stats.get(dir_path, 0),
     86                                        new_version)
     87       if dir_path == '/':
     88         # Legacy support for '/' being the root of the file system rather
     89         # than ''. Eventually when the path normalisation logic is complete
     90         # this will be impossible and this logic will change slightly.
     91         self._path_stats[''] = self._path_stats['/']
     92       slash_index = path.find('/', slash_index + 1)
     93 
     94   def GetVersion(self, path):
     95     return self._global_stat + self._path_stats.get(path, 0)
     96 
     97 
     98 class TestFileSystem(FileSystem):
     99   '''A FileSystem backed by an object. Create with an object representing file
    100   paths such that {'a': {'b': 'hello'}} will resolve Read('a/b') as 'hello',
    101   Read('a/') as ['b'], and Stat determined by a value incremented via
    102   IncrementStat.
    103   '''
    104 
    105   def __init__(self, obj, relative_to=None, identity=None):
    106     assert obj is not None
    107     if relative_to is not None:
    108       obj = MoveTo(relative_to, obj)
    109     self._identity = identity or type(self).__name__
    110     self._path_values = _List(obj)
    111     self._stat_tracker = _StatTracker()
    112 
    113   #
    114   # FileSystem implementation.
    115   #
    116 
    117   def Read(self, paths, skip_not_found=False):
    118     for path in paths:
    119       if path not in self._path_values:
    120         if skip_not_found: continue
    121         return FileNotFoundError.RaiseInFuture(
    122             '%s not in %s' % (path, '\n'.join(self._path_values)))
    123     return Future(value=dict((k, v) for k, v in self._path_values.iteritems()
    124                              if k in paths))
    125 
    126   def Refresh(self):
    127     return Future(value=())
    128 
    129   def Stat(self, path):
    130     read_result = self.ReadSingle(path).Get()
    131     stat_result = StatInfo(str(self._stat_tracker.GetVersion(path)))
    132     if isinstance(read_result, list):
    133       stat_result.child_versions = dict(
    134           (file_result,
    135            str(self._stat_tracker.GetVersion('%s%s' % (path, file_result))))
    136           for file_result in read_result)
    137     return stat_result
    138 
    139   #
    140   # Testing methods.
    141   #
    142 
    143   def IncrementStat(self, path=None, by=1):
    144     self._stat_tracker.Increment(path, by=by)
    145 
    146   def GetIdentity(self):
    147     return self._identity
    148