Lazy Aiger (#118)

* Started working on lazy AIG variant.

* Implemented Lazy Sequential Composition.

* Implemented parallel composition

* Change shim to support latches easily

* flake8

* bump to python 3.7

* update lock file

* First draft as flattening LazyAIG

* draft of lazy aiger with similar initial performance.

* Implement parcompose + simplifications

* flake8

* implement getitems via lazyaig

* reimplement cutlatches w.r.t. lazy cutlatches.

* flake8

* Implemented loopback

* Implemented loopback in terms of lazy aig

* remove dead code.

* update versions.

* initial unrolled implementatino.

* flake8

* Implement unrolling.

* fix typo.

* Revert aig to use original implementations until stable.

* Use master's expr.py

* Allow lazy export of .aig

* flake8

* add lazy_aig attribute.

* fix bug in latch handling in flatten.

* Update tests

* Added tests to show bugs in current implementation.

* Replaced lazy implementations that are confirmed to work.

* commiting before changing approaches.

* Start alternative lazy implementation around classes.

* Start combining Lazy objects into EDSL

* Draft of fully functioning lazy aiger!

* FrozenSet -> PMap

* Bump major version.

* Move test location outside of module.

* drop cnf as circular dependency

* bump py-aiger dependency

* clean ups

* flake8

Author: mvcisback

.drone.yml

@@ -3,7 +3,7 @@ name: default
 
 steps:
 - name: test
-  image: python:3.6
+  image: python:3.7
   environment:
     CODECOV_TOKEN:
       from_secret: codecov_token

aiger/__init__.py

@@ -4,3 +4,4 @@
 from aiger.common import tee, empty, identity, delay, parity_gate
 from aiger.parser import parse, load
 from aiger.expr import atom, atoms, ite, BoolExpr
+from aiger.lazy import *