1 files changed, 99 insertions, 0 deletions
diff --git a/game/python-extra/utils/dicts/helpers.py b/game/python-extra/utils/dicts/helpers.py
new file mode 100644
index 0000000..8b1f594
--- /dev/null
+++ b/game/python-extra/utils/dicts/helpers.py
@@ -0,0 +1,99 @@
+from collections import namedtuple
+
+
+def from_keyed_iterable(iterable, key, filter_func=None):
+    """Construct a dictionary out of an iterable, using an attribute name as
+    the key. Optionally provide a filter function, to determine what should be
+    kept in the dictionary."""
+
+    generated = {}
+
+    for element in iterable:
+        try:
+            k = getattr(element, key)
+        except AttributeError:
+            raise RuntimeError("{} does not have the keyed attribute: {}".format(
+                element, key
+            ))
+
+        if filter_func is None or filter_func(element):
+            if k in generated:
+                generated[k] += [element]
+            else:
+                generated[k] = [element]
+
+    return generated
+
+
+def subtract_by_key(dict_a, dict_b):
+    """given two dicts, a and b, this function returns c = a - b, where
+    a - b is defined as the key difference between a and b.
+
+    e.g.,
+    {1:None, 2:3, 3:"yellow", 4:True} - {2:4, 1:"green"} =
+        {3:"yellow", 4:True}
+
+    """
+    difference_dict = {}
+    for key in dict_a:
+        if key not in dict_b:
+            difference_dict[key] = dict_a[key]
+
+    return difference_dict
+
+
+def subtract(dict_a, dict_b, strict=False):
+    """a stricter form of subtract_by_key(), this version will only remove an
+    entry from dict_a if the key is in dict_b *and* the value at that key
+    matches"""
+    if not strict:
+        return subtract_by_key(dict_a, dict_b)
+
+    difference_dict = {}
+    for key in dict_a:
+        if key not in dict_b or dict_b[key] != dict_a[key]:
+            difference_dict[key] = dict_a[key]
+
+    return difference_dict
+
+
+WinnowedResult = namedtuple("WinnowedResult", ['has', 'has_not'])
+def winnow_by_keys(dct, keys=None, filter_func=None):
+    """separates a dict into has-keys and not-has-keys pairs, using either
+    a list of keys or a filtering function."""
+    has = {}
+    has_not = {}
+
+    for key in dct:
+        key_passes_check = False
+        if keys is not None:
+            key_passes_check = key in keys
+        elif filter_func is not None:
+            key_passes_check = filter_func(key)
+
+        if key_passes_check:
+            has[key] = dct[key]
+        else:
+            has_not[key] = dct[key]
+
+    return WinnowedResult(has, has_not)
+
+
+def intersection(dict_a, dict_b, strict=True):
+    intersection_dict = {}
+
+    for key in dict_a:
+        if key in dict_b:
+            if not strict or dict_a[key] == dict_b[key]:
+                intersection_dict[key] = dict_a[key]
+
+    return intersection_dict
+
+
+def setdefaults(dct, defaults):
+    """Given a target dct and a dict of {key:default value} pairs,
+    calls setdefault for all of those pairs."""
+    for key in defaults:
+        dct.setdefault(key, defaults[key])
+
+    return dct