AppPkg/Applications/Python/Python-2.7.2/Lib/lib2to3/fixes/fix_import.py

   1 """Fixer for import statements.
   2 If spam is being imported from the local directory, this import:
   3     from spam import eggs
   4 Becomes:
   5     from .spam import eggs
   6
   7 And this import:
   8     import spam
   9 Becomes:
  10     from . import spam
  11 """
  12
  13 # Local imports
  14 from .. import fixer_base
  15 from os.path import dirname, join, exists, sep
  16 from ..fixer_util import FromImport, syms, token
  17
  18
  19 def traverse_imports(names):
  20     """
  21     Walks over all the names imported in a dotted_as_names node.
  22     """
  23     pending = [names]
  24     while pending:
  25         node = pending.pop()
  26         if node.type == token.NAME:
  27             yield node.value
  28         elif node.type == syms.dotted_name:
  29             yield "".join([ch.value for ch in node.children])
  30         elif node.type == syms.dotted_as_name:
  31             pending.append(node.children[0])
  32         elif node.type == syms.dotted_as_names:
  33             pending.extend(node.children[::-2])
  34         else:
  35             raise AssertionError("unkown node type")
  36
  37
  38 class FixImport(fixer_base.BaseFix):
  39     BM_compatible = True
  40
  41     PATTERN = """
  42     import_from< 'from' imp=any 'import' ['('] any [')'] >
  43     |
  44     import_name< 'import' imp=any >
  45     """
  46
  47     def start_tree(self, tree, name):
  48         super(FixImport, self).start_tree(tree, name)
  49         self.skip = "absolute_import" in tree.future_features
  50
  51     def transform(self, node, results):
  52         if self.skip:
  53             return
  54         imp = results['imp']
  55
  56         if node.type == syms.import_from:
  57             # Some imps are top-level (eg: 'import ham')
  58             # some are first level (eg: 'import ham.eggs')
  59             # some are third level (eg: 'import ham.eggs as spam')
  60             # Hence, the loop
  61             while not hasattr(imp, 'value'):
  62                 imp = imp.children[0]
  63             if self.probably_a_local_import(imp.value):
  64                 imp.value = u"." + imp.value
  65                 imp.changed()
  66         else:
  67             have_local = False
  68             have_absolute = False
  69             for mod_name in traverse_imports(imp):
  70                 if self.probably_a_local_import(mod_name):
  71                     have_local = True
  72                 else:
  73                     have_absolute = True
  74             if have_absolute:
  75                 if have_local:
  76                     # We won't handle both sibling and absolute imports in the
  77                     # same statement at the moment.
  78                     self.warning(node, "absolute and local imports together")
  79                 return
  80
  81             new = FromImport(u".", [imp])
  82             new.prefix = node.prefix
  83             return new
  84
  85     def probably_a_local_import(self, imp_name):
  86         if imp_name.startswith(u"."):
  87             # Relative imports are certainly not local imports.
  88             return False
  89         imp_name = imp_name.split(u".", 1)[0]
  90         base_path = dirname(self.filename)
  91         base_path = join(base_path, imp_name)
  92         # If there is no __init__.py next to the file its not in a package
  93         # so can't be a relative import.
  94         if not exists(join(dirname(base_path), "__init__.py")):
  95             return False
  96         for ext in [".py", sep, ".pyc", ".so", ".sl", ".pyd"]:
  97             if exists(base_path + ext):
  98                 return True
  99         return False