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

   1 """
   2 Optional fixer to transform set() calls to set literals.
   3 """
   4
   5 # Author: Benjamin Peterson
   6
   7 from lib2to3 import fixer_base, pytree
   8 from lib2to3.fixer_util import token, syms
   9
  10
  11
  12 class FixSetLiteral(fixer_base.BaseFix):
  13
  14     BM_compatible = True
  15     explicit = True
  16
  17     PATTERN = """power< 'set' trailer< '('
  18                      (atom=atom< '[' (items=listmaker< any ((',' any)* [',']) >
  19                                 |
  20                                 single=any) ']' >
  21                      |
  22                      atom< '(' items=testlist_gexp< any ((',' any)* [',']) > ')' >
  23                      )
  24                      ')' > >
  25               """
  26
  27     def transform(self, node, results):
  28         single = results.get("single")
  29         if single:
  30             # Make a fake listmaker
  31             fake = pytree.Node(syms.listmaker, [single.clone()])
  32             single.replace(fake)
  33             items = fake
  34         else:
  35             items = results["items"]
  36
  37         # Build the contents of the literal
  38         literal = [pytree.Leaf(token.LBRACE, u"{")]
  39         literal.extend(n.clone() for n in items.children)
  40         literal.append(pytree.Leaf(token.RBRACE, u"}"))
  41         # Set the prefix of the right brace to that of the ')' or ']'
  42         literal[-1].prefix = items.next_sibling.prefix
  43         maker = pytree.Node(syms.dictsetmaker, literal)
  44         maker.prefix = node.prefix
  45
  46         # If the original was a one tuple, we need to remove the extra comma.
  47         if len(maker.children) == 4:
  48             n = maker.children[2]
  49             n.remove()
  50             maker.children[-1].prefix = n.prefix
  51
  52         # Finally, replace the set call with our shiny new literal.
  53         return maker