Create ordered_multimap.py

ordered_multimap.py

@@ -0,0 +1,30 @@
+from collections import defaultdict
+
+class OrderedMultimap:
+    def __init__(self):
+        self.data = []
+        self.index_map = defaultdict(list)
+        self.keyless_values = []
+
+    def insert(self, key, value):
+        if key:
+            self.index_map[key].append(len(self.data))
+        else:
+            self.keyless_values.append(len(self.data))
+        self.data.append((key, value))
+
+    def get(self, key):
+        if key:
+            return [self.data[i][1] for i in self.index_map[key]]
+        else:
+            return [self.data[i][1] for i in self.keyless_values]
+
+    def items(self):
+        from collections import defaultdict
+        result = defaultdict(list)
+        for key, value in self.data:
+            result[key].append(value)
+        return result.items()
+
+    def all_items(self):
+        return self.data