From 8d63388d7bcd39926feaa02a84ea684ac3b0f3f3 Mon Sep 17 00:00:00 2001
From: John Sekar <johnarul.sekar@gmail.com>
Date: Wed, 9 Mar 2022 02:16:51 -0500
Subject: [PATCH] DatabaseAlias

Have to code and test filtering
---
 tests_rete/test_db.py         | 65 +++++++++++++++++++++++++++++++++++
 wc_rules/matcher/dbase.py     | 20 ++++++++++-
 wc_rules/utils/collections.py | 32 ++++++++++++++++-
 3 files changed, 115 insertions(+), 2 deletions(-)
 create mode 100644 tests_rete/test_db.py

diff --git a/tests_rete/test_db.py b/tests_rete/test_db.py
new file mode 100644
index 0000000..c8847b9
--- /dev/null
+++ b/tests_rete/test_db.py
@@ -0,0 +1,65 @@
+from wc_rules.matcher.dbase import Database, DatabaseAlias
+from wc_rules.utils.collections import SimpleMapping
+
+import unittest
+
+class TestDatabase(unittest.TestCase):
+
+	def test_db(self):
+
+		db = Database(list('abc'))
+		self.assertEqual(db.fields,list('abc'))
+		self.assertEqual(len(db.filter(dict(a=1))),0)
+
+		record = dict(a=1,b=2,c=3)
+		db.insert(record)
+		self.assertEqual(len(db),1)
+		self.assertEqual(len(db.filter(dict(a=1))),1)
+		self.assertEqual(db.filter_one(dict(a=1)),dict(a=1,b=2,c=3))
+
+		record = dict(a=1,b=3,c=4)
+		db.insert(record)
+		self.assertEqual(len(db),2)
+		self.assertEqual(len(db.filter(dict(a=1))),2)
+		self.assertEqual(len(db.filter(dict(b=2))),1)
+
+		records = db.delete(dict(c=3))
+		self.assertEqual(len(records),1)
+		self.assertEqual(len(db),1)
+
+		records = db.delete(dict(c=4))
+		self.assertEqual(len(records),1)
+		self.assertEqual(len(db),0)
+
+class TestAlias(unittest.TestCase):
+
+	def test_mapping(self):
+
+		m1 = SimpleMapping(zip('xyz','abc'))
+		self.assertEqual(m1,dict(zip('xyz','abc')))
+		self.assertEqual(m1.reverse,dict(zip('abc','xyz')))
+
+		m2 = SimpleMapping(zip('pqr','xyz'))
+		# testing multiply
+		self.assertEqual(m1*m2,dict(zip('pqr','abc')))
+		v = dict(zip('abc',range(3)))
+
+		self.assertEqual(m1.premultiply(v),dict(zip('xyz',range(3))))
+		self.assertEqual(SimpleMapping(m1*m2).premultiply(v),dict(zip('pqr',range(3))))
+
+
+	def test_database_alias(self):
+		db = Database(list('abc'))
+		db.insert(dict(a=1,b=2,c=3))
+
+		alias1 = DatabaseAlias(db, dict(zip('xyz','abc')))
+		alias2 = DatabaseAlias(alias1,dict(zip('pqr','xyz')))
+		alias3 = DatabaseAlias(alias2,dict(zip('ijk','pqr')))
+		
+		self.assertEqual(alias1.target, db)
+		self.assertEqual(alias2.target, db)
+		self.assertEqual(alias3.target, db)
+		
+		self.assertEqual(alias1.mapping, dict(zip('xyz','abc')))
+		self.assertEqual(alias2.mapping, dict(zip('pqr','abc')))
+		self.assertEqual(alias3.mapping, dict(zip('ijk','abc')))
diff --git a/wc_rules/matcher/dbase.py b/wc_rules/matcher/dbase.py
index d3e0f98..e79d8c5 100644
--- a/wc_rules/matcher/dbase.py
+++ b/wc_rules/matcher/dbase.py
@@ -1,4 +1,5 @@
 from pydblite import Base
+from ..utils.collections import SimpleMapping
 
 def dict_overlap(d1,d2):
 	return len(set(d1.items()) & set(d2.items())) > 0
@@ -40,4 +41,21 @@ def filter_one(self,include_kwargs):
 		return None
 
 	def __len__(self):
-		return len(self._db)
\ No newline at end of file
+		return len(self._db)
+
+class DatabaseAlias:
+
+
+	def __init__(self,target,mapping):
+		
+		# NOTE: mapping has keys=CURRENT variables, values=variables of cache it is aliasing
+		if isinstance(target,DatabaseAlias):
+			target, mapping = target.target, target.mapping*mapping
+
+		#assert isinstance(target,Database) and set(mapping.values())==target.fields
+
+		self.target = target
+		self.mapping = SimpleMapping(mapping)
+		
+
+	
\ No newline at end of file
diff --git a/wc_rules/utils/collections.py b/wc_rules/utils/collections.py
index f58bce5..91557dc 100644
--- a/wc_rules/utils/collections.py
+++ b/wc_rules/utils/collections.py
@@ -8,7 +8,27 @@
 from dataclasses import dataclass, field
 from typing import Tuple, Dict
 from backports.cached_property import cached_property
-from collections import defaultdict
+from collections import defaultdict, UserDict
+
+class SimpleMapping(UserDict):
+
+    def __init__(self,*args,**kwargs):
+        super().__init__(*args,**kwargs)
+
+    def __mul__(self,other):
+        # convention self * other == f o g
+        # takes g's keys and f's values
+        return {k:self[v] for k,v in other.items() if v in self}
+
+    @cached_property
+    def reverse(self):
+        return SimpleMapping({v:k for k,v in self.items()})
+
+    def premultiply(self,other):
+        return {k:other[v] for k,v in self.items() if v in other}
+
+
+
 
 @dataclass(order=True,frozen=True)
 class Mapping:
@@ -233,6 +253,16 @@ def remap_values(d,oldvalues,newvalue):
     return d
 
 ###### Methods ######
+def compose_mapping(m1,m2):
+    # mappings are simple dict
+    # downgrade Mapping above????
+    # m1: ad,be,cf
+    # m2: dg,eh,fi
+    # produces: ag,bh,ci
+    # equivalent to m2 o m1
+    return {k:m2[v] for k in m1 if v in m2}
+
+
 def get_values(d,keys):
     return [d[k] for k in keys]