Initial commit. Basic models mostly done.

venv/lib/python3.8/site-packages/pip/_internal/utils/models.py

@@ -0,0 +1,42 @@
+"""Utilities for defining models
+"""
+# The following comment should be removed at some point in the future.
+# mypy: disallow-untyped-defs=False
+
+import operator
+
+
+class KeyBasedCompareMixin(object):
+    """Provides comparison capabilities that is based on a key
+    """
+
+    def __init__(self, key, defining_class):
+        self._compare_key = key
+        self._defining_class = defining_class
+
+    def __hash__(self):
+        return hash(self._compare_key)
+
+    def __lt__(self, other):
+        return self._compare(other, operator.__lt__)
+
+    def __le__(self, other):
+        return self._compare(other, operator.__le__)
+
+    def __gt__(self, other):
+        return self._compare(other, operator.__gt__)
+
+    def __ge__(self, other):
+        return self._compare(other, operator.__ge__)
+
+    def __eq__(self, other):
+        return self._compare(other, operator.__eq__)
+
+    def __ne__(self, other):
+        return self._compare(other, operator.__ne__)
+
+    def _compare(self, other, method):
+        if not isinstance(other, self._defining_class):
+            return NotImplemented
+
+        return method(self._compare_key, other._compare_key)