The former is very low level and generic. The later abstarct the former for dense expressions. This refactoring permits
to get rid of the very ugly SwapWrapper and SelfCwiseBinaryOp classes.
In the future, this will also permit to simplify all these evaluation loops and perhaps to reuse them for reduxions.
That will also permit to specialize for operations like expr1 += expr2 outside Eigen, and so for any kind
of expressions (dense, sparse, tensor, etc.)
* Wrap expression inside EvalToTemp in copy_using_evaluators() if we
assume aliasing for that expression (that is, for products)
* Remove temporary kludge of evaluating expression to temporary in
AllAtOnce traversal
* Implement EvalToTemp expression object
* Make product EvalAtOnce in cases OuterProduct, GemmProduct and
GemvProduct
* Ensure that product evaluators are nested inside EvalToTemp
evaluator
* As temporary kludge, evaluate expression to temporary in AllAtOnce
traversal and pass expression operator to evalTo()
- Add evaluator_traits with HasEvalTo flag, which is true if evaluator
has evalTo() function.
- Add AllAtOnce traversal, which calls evalTo() in evaluator.
- If source evaluator in copy_using_evaluator has HasEvalTo set, then
use AllAtOnce traversal.
* Rename the old copy_using_evaluators to noalias_copy_using_evaluators.
* Write a new copy_using_evaluators which strips NoAlias expression, if present,
and calls noalias_copy_using_evaluators; in future, it will also take care of
aliasing in products.
* Add expression() getter to NoAlias.
