tools/tryselect/util/dicttools.py

   1 # This Source Code Form is subject to the terms of the Mozilla Public
   2 # License, v. 2.0. If a copy of the MPL was not distributed with this
   3 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
   4
   5
   6 import copy
   7
   8
   9 def merge_to(source, dest):
  10     """
  11     Merge dict and arrays (override scalar values)
  12
  13     Keys from source override keys from dest, and elements from lists in source
  14     are appended to lists in dest.
  15
  16     :param dict source: to copy from
  17     :param dict dest: to copy to (modified in place)
  18     """
  19
  20     for key, value in source.items():
  21         # Override mismatching or empty types
  22         if type(value) != type(dest.get(key)):  # noqa
  23             dest[key] = source[key]
  24             continue
  25
  26         # Merge dict
  27         if isinstance(value, dict):
  28             merge_to(value, dest[key])
  29             continue
  30
  31         if isinstance(value, list):
  32             dest[key] = dest[key] + source[key]
  33             continue
  34
  35         dest[key] = source[key]
  36
  37     return dest
  38
  39
  40 def merge(*objects):
  41     """
  42     Merge the given objects, using the semantics described for merge_to, with
  43     objects later in the list taking precedence.  From an inheritance
  44     perspective, "parents" should be listed before "children".
  45
  46     Returns the result without modifying any arguments.
  47     """
  48     if len(objects) == 1:
  49         return copy.deepcopy(objects[0])
  50     return merge_to(objects[-1], merge(*objects[:-1]))