(core) move data engine code to core

Summary:
this moves sandbox/grist to core, and adds a requirements.txt
file for reconstructing the content of sandbox/thirdparty.

Test Plan:
existing tests pass.
Tested core functionality manually.  Tested docker build manually.

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2563

sandbox/grist/test_twowaymap.py

@@ -0,0 +1,154 @@
+import unittest
+import twowaymap
+
+class TestTwoWayMap(unittest.TestCase):
+  def assertTwoWayMap(self, twmap, forward, reverse):
+    map_repr = (
+      { k: twmap.lookup_left(k) for k in twmap.left_all() },
+      { k: twmap.lookup_right(k) for k in twmap.right_all() }
+    )
+    self.assertEqual(map_repr, (forward, reverse))
+
+  def test_set_list(self):
+    tmap = twowaymap.TwoWayMap(left=set, right=list)
+
+    self.assertFalse(tmap)
+    tmap.insert(1, "a")
+    self.assertTrue(tmap)
+    self.assertTwoWayMap(tmap, {1: ["a"]}, {"a": {1}})
+
+    tmap.insert(1, "a")   # should be a no-op, since this pair already exists
+    tmap.insert(1, "b")
+    tmap.insert(2, "a")
+    self.assertTwoWayMap(tmap, {1: ["a", "b"], 2: ["a"]}, {"a": {1,2}, "b": {1}})
+
+    tmap.insert(1, "b")
+    tmap.insert(2, "b")
+    self.assertTwoWayMap(tmap, {1: ["a", "b"], 2: ["a", "b"]}, {"a": {1,2}, "b": {1,2}})
+
+    tmap.remove(1, "b")
+    tmap.remove(2, "b")
+    self.assertTwoWayMap(tmap, {1: ["a"], 2: ["a"]}, {"a": {1,2}})
+
+    tmap.insert(1, "b")
+    tmap.insert(2, "b")
+    tmap.remove_left(1)
+    self.assertTwoWayMap(tmap, {2: ["a", "b"]}, {"a": {2}, "b": {2}})
+
+    tmap.insert(1, "a")
+    tmap.insert(2, "b")
+    tmap.remove_right("b")
+    self.assertTwoWayMap(tmap, {1: ["a"], 2: ["a"]}, {"a": {1,2}})
+
+    self.assertTrue(tmap)
+    tmap.clear()
+    self.assertTwoWayMap(tmap, {}, {})
+    self.assertFalse(tmap)
+
+  def test_set_single(self):
+    tmap = twowaymap.TwoWayMap(left=set, right="single")
+
+    self.assertFalse(tmap)
+    tmap.insert(1, "a")
+    self.assertTrue(tmap)
+    self.assertTwoWayMap(tmap, {1: "a"}, {"a": {1}})
+
+    tmap.insert(1, "a")   # should be a no-op, since this pair already exists
+    tmap.insert(1, "b")
+    tmap.insert(2, "a")
+    self.assertTwoWayMap(tmap, {1: "b", 2: "a"}, {"a": {2}, "b": {1}})
+
+    tmap.insert(1, "b")
+    tmap.insert(2, "b")
+    self.assertTwoWayMap(tmap, {1: "b", 2: "b"}, {"b": {1,2}})
+
+    tmap.remove(1, "b")
+    self.assertTwoWayMap(tmap, {2: "b"}, {"b": {2}})
+    tmap.remove(2, "b")
+    self.assertTwoWayMap(tmap, {}, {})
+
+    tmap.insert(1, "b")
+    tmap.insert(2, "b")
+    self.assertTwoWayMap(tmap, {1: "b", 2: "b"}, {"b": {1,2}})
+    tmap.remove_left(1)
+    self.assertTwoWayMap(tmap, {2: "b"}, {"b": {2}})
+
+    tmap.insert(1, "a")
+    tmap.insert(2, "b")
+    tmap.remove_right("b")
+    self.assertTwoWayMap(tmap, {1: "a"}, {"a": {1}})
+
+    self.assertTrue(tmap)
+    tmap.clear()
+    self.assertTwoWayMap(tmap, {}, {})
+    self.assertFalse(tmap)
+
+  def test_strict_list(self):
+    tmap = twowaymap.TwoWayMap(left="strict", right=list)
+
+    self.assertFalse(tmap)
+    tmap.insert(1, "a")
+    self.assertTrue(tmap)
+    self.assertTwoWayMap(tmap, {1: ["a"]}, {"a": 1})
+
+    tmap.insert(1, "a")   # should be a no-op, since this pair already exists
+    tmap.insert(1, "b")
+    with self.assertRaises(ValueError):
+      tmap.insert(2, "a")
+    self.assertTwoWayMap(tmap, {1: ["a", "b"]}, {"a": 1, "b": 1})
+
+    tmap.insert(1, "b")
+    with self.assertRaises(ValueError):
+      tmap.insert(2, "b")
+    tmap.insert(2, "c")
+    self.assertTwoWayMap(tmap, {1: ["a", "b"], 2: ["c"]}, {"a": 1, "b": 1, "c": 2})
+
+    tmap.remove(1, "b")
+    self.assertTwoWayMap(tmap, {1: ["a"], 2: ["c"]}, {"a": 1, "c": 2})
+    tmap.remove(2, "b")
+    self.assertTwoWayMap(tmap, {1: ["a"], 2: ["c"]}, {"a": 1, "c": 2})
+
+    tmap.insert(1, "b")
+    with self.assertRaises(ValueError):
+      tmap.insert(2, "b")
+    self.assertTwoWayMap(tmap, {1: ["a", "b"], 2: ["c"]}, {"a": 1, "b": 1, "c": 2})
+    tmap.remove_left(1)
+    self.assertTwoWayMap(tmap, {2: ["c"]}, {"c": 2})
+
+    tmap.insert(1, "a")
+    tmap.insert(2, "b")
+    tmap.remove_right("b")
+    self.assertTwoWayMap(tmap, {1: ["a"], 2: ["c"]}, {"a": 1, "c": 2})
+
+    self.assertTrue(tmap)
+    tmap.clear()
+    self.assertTwoWayMap(tmap, {}, {})
+    self.assertFalse(tmap)
+
+  def test_strict_single(self):
+    tmap = twowaymap.TwoWayMap(left="strict", right="single")
+    tmap.insert(1, "a")
+    tmap.insert(2, "b")
+    tmap.insert(2, "c")
+    self.assertTwoWayMap(tmap, {1: "a", 2: "c"}, {"a": 1, "c": 2})
+    with self.assertRaises(ValueError):
+      tmap.insert(2, "a")
+    tmap.insert(2, "c")   # This pair already exists, so not an error.
+    self.assertTwoWayMap(tmap, {1: "a", 2: "c"}, {"a": 1, "c": 2})
+
+  def test_nonhashable(self):
+    # Test that we don't get into an inconsistent state if we attempt to use a non-hashable value.
+    tmap = twowaymap.TwoWayMap(left=list, right=list)
+    tmap.insert(1, "a")
+    self.assertTwoWayMap(tmap, {1: ["a"]}, {"a": [1]})
+
+    with self.assertRaises(TypeError):
+      tmap.insert(1, {})
+    with self.assertRaises(TypeError):
+      tmap.insert({}, "a")
+
+    self.assertTwoWayMap(tmap, {1: ["a"]}, {"a": [1]})
+
+
+if __name__ == "__main__":
+  unittest.main()