From df78a1ad2eefffd5d37f3075d35ed9e6cf1ed282 Mon Sep 17 00:00:00 2001
From: Cacahuete Lenovo Ubuntu <cacahuete@dapeach.fr>
Date: Mon, 17 Sep 2018 22:11:46 +0200
Subject: [PATCH] Reimplemented __hash__ and __eq__ in StrType, 'cause we want
 the comparison to be based on class name instead of instance's ID. Added a
 'folding' feature in order to hide elements based on keys

---
 nested_mapping.py | 63 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 49 insertions(+), 14 deletions(-)

diff --git a/nested_mapping.py b/nested_mapping.py
index c3ac3de..e08d222 100644
--- a/nested_mapping.py
+++ b/nested_mapping.py
@@ -1,19 +1,32 @@
 from collections import Iterable
-
+from boltons.iterutils import remap
 
 def unique(seq):
-    """Return a new sequence made of unique elements from seq."""
+    """Return a new sequence made of unique elements from seq.
+       Code borrowed from the Internet.
+    """
     uniques = []
     [uniques.append(x) for x in seq if not uniques.count(x)]
     return type(seq)(uniques)
 
 
 class StrType(str):
-    """Helper class to print and compare object types.
-       Provide the object whose type you want to print.
+    """Helper class to print and compare object types (used in function 'get_structure').
+       When instanciating this class, provide the object whose type you want to print.
+       __hash__ and __eq__ implemented in order to filter duplicates and yet stay compatible with
+       uniqueness detection (to fit in sets for instance).
     """
     def __init__(self, obj):
         self.value = type(obj).__name__
+        
+    def __hash__(self):
+        return hash(self.value)
+    
+    def __eq__(self, other):
+        if not isinstance(other, StrType):
+            return False
+        else:
+            return self.value == other.value
     
     def __str__(self):
         return f"<{self.value}>"
@@ -21,18 +34,38 @@ class StrType(str):
     __repr__ = __str__
 
 
-def get_structure(data):
+def get_structure(data, folding_keys=[], folding_tag=" (folded)"):
     """Return a kind of map of the could-be nested data.
        Duplicates are removed from sequences.
+       If 'folding_keys' are provided then the corresponding values in the data set will be folded,
+       that is to say replaced by their data type (thus transformed into leaves). The key will be
+       appended with 'folding_tag'.
     """
-    if isinstance(data, dict):
-        return {key:get_structure(value) for key, value in data.items()}
-    elif (isinstance(data, Iterable)
-             and not isinstance(data, str)
-             and not isinstance(data, bytes)):
-        if data:
+    if folding_keys:
+        def visit_fold(path, key, value):
+            if key in folding_keys:
+                # We only fold iterable types (except for strings and bytes).
+                if (isinstance(data, Iterable)
+                        and not isinstance(data, str)
+                        and not isinstance(data, bytes)):
+                    return "".join([key, folding_tag]), type(value)()
+            return True
+        
+        data = remap(data, visit=visit_fold)
+    
+    def extract_structure(data):
+        if data and isinstance(data, dict):
+            return {key:get_structure(value) for key, value in data.items()}
+        elif data and (isinstance(data, Iterable)
+                 and not isinstance(data, str)
+                 and not isinstance(data, bytes)):
+            # The iterable is not empty, we map each of its elements
             return unique(type(data)([get_structure(item) for item in data]))
-    return StrType(data)
+        # It's a leaf (or empty iterable),
+        # we return the name of its type
+        return StrType(data)
+    
+    return extract_structure(data)
 
 
 if __name__ == "__main__":        
@@ -64,9 +97,11 @@ if __name__ == "__main__":
               '2 same dict 1 other': [{'same':3, 'as':b'the other'},
                                       {'same':3, 'as':b'the other'},
                                       {'different':'from','the':'other'}],
-              'play me': MaClasse}
+              'play me': MaClasse,
+              'Two folded keys':{'Fold me :)':[1,2,3,4,5],
+                                 'Fold me too':"folded, can't see me!"}}
     
-    structure = get_structure(nested)
+    structure = get_structure(nested, ['Fold me :)','Fold me too'], ' [+]')
 
     print("The nested data:")
     pprint(nested)