io: add insertion mechanism to RecursiveDict

mpcontribs/io/mpfile.py

@@ -96,7 +96,9 @@ def make_general_section(self):
             for idx, mp_cat_id in enumerate(self.document.keys()):
                 general_section = self.document[mp_cat_id].pop(mp_level01_titles[0])
                 if not idx:
-                    self.document[mp_level01_titles[0]] = general_section
+                    self.document.insert_before(
+                        mp_cat_id, (mp_level01_titles[0], general_section)
+                    )
 
     def get_string(self, with_comments=False):
         """Returns a string to be written as a file"""

mpcontribs/io/utils.py

@@ -1,9 +1,10 @@
-from collections import OrderedDict, Mapping
+from collections import OrderedDict as _OrderedDict
+from collections import Mapping as _Mapping
 from ..config import indent_symbol, min_separator_length, mp_level01_titles
 import pandas as pd
 import numpy as np
 
-class RecursiveDict(OrderedDict):
+class RecursiveDict(_OrderedDict):
     """extension of dict for internal representation of MPFile"""
 
     def rec_update(self, other):
@@ -23,7 +24,7 @@ def iterate(self, nested_dict=None):
         if nested_dict is None: self.level = 0
         self.items = []
         for key,value in d.iteritems():
-            if isinstance(value, Mapping):
+            if isinstance(value, _Mapping):
                 # FIXME: currently skipping all plots sections in output
                 if self.level == 1 and key == mp_level01_titles[2]: continue
                 yield get_indentor(n=self.level), key
@@ -43,6 +44,23 @@ def iterate(self, nested_dict=None):
             else:
                 yield key, value
 
+    # insertion mechanism from https://gist.github.com/jaredks/6276032
+    def __insertion(self, link_prev, key_value):
+        key, value = key_value
+        if link_prev[2] != key:
+            if key in self:
+                del self[key]
+            link_next = link_prev[1]
+            self._OrderedDict__map[key] = link_prev[1] = link_next[0] = [link_prev, link_next, key]
+        dict.__setitem__(self, key, value)
+
+    def insert_after(self, existing_key, key_value):
+        self.__insertion(self._OrderedDict__map[existing_key], key_value)
+
+    def insert_before(self, existing_key, key_value):
+        self.__insertion(self._OrderedDict__map[existing_key][0], key_value)
+
+
 def nest_dict(dct, keys):
     """nest dict under list of keys"""
     nested_dict = dct