The default tell protocol assumes an exception is to be thrown
in case predicate is not satisfied. This may lead to unnecessary
exceptions being thrown in a situation where a simple failure
status would have been sufficient.
Introduce feedback basis to track dependencies on rules.
Index journal chunks by evidence for quick lookup.
The feedback basis is the collection of principal rules tags
from the justifications of the current match.
For this several notions are introduced.
Logical variable is called "principal" if it is used in principal
occurrences and at some point during evaluation is unified or bound.
Principal occurrence is called "volatile" if it uses principal logicals.
PrincipalObserverDispatcher's task is to track volatile occurrences
by enabling uni observers on all free logicals in principal occ-s.
RewindVolatileOccurrencesStage then on events of incremental usage
of volatile occurrences (e.g. match on it, or continued activation)
resets journal cursor to the position of initial occurrence activation,
where it can be re-evaluated with fresh, unaffected, logicals.
It's the only stage that goes backwards in journal.
So in this way unification is incrementally cancelled.
link to MPSCR-62 (docs)
Rename NonIncrementalProcessing -> DefaultProcessing
Add GroundProcessing as common superclass to handle OccurrenceContractObserver
Add another test for this occurrence contract logic.
Allows to carry logically connected information in one object.
Needed for subsequent changes to ConstraintOccurrence, which
must have better information on source rule: rule template name.
Used by occurrence cache.
Introduced to discern incremental strategies: Full,Preamble,Default.
because how SessionToken is used and stored depends on it.
EvaluationSessionImpl now simply dispatches to it.
Also rename 'IncrementalProcessing' to 'ProcessingStrategy'.
The test substructuralTS_indirectResourceDependency is not doing what it's intended
to be doing b/c of apparenly wrongly understood contract of the `also()` method.
It is not supposed to pass the result of the computation to the "chained" method.
Compare `T.also(block: (T) -> Unit): T` and `T.let(block: (T) -> R): R`.
After having fixed the code, the test no longer passes.
Previously only logicals directly used ar occurrence args
were observed. Now terms in occurrence args are traversed
recursively and all contained logicals are observed.
Also clear occurrence contract observers on discarding occ-s.
Introduce a generic way to clear observers in LogicalState.
Instead of simple allowed/not option sometimes Unsafe
is useful. 'Unsafe' status may be present when there're
few "bad" rules.
With this level end code may resolve to go with
incrementality without strict guarantees.
It seems to reflect the exact information needed: there's
one-to-one correspondence between feedback and its match.
While using rule unique tag as feedback key in TypesIndex
relied on several assumptions.
Also there's less use of MatchJournal information with this.
Previously parent principal match was passed to FeedbackConsumer.
Fixes IncrClassHierarchy.modifyClsHierarchyTypeParams test.
Key point is that changes to rules causing their
regeneration must be reflected in program.
There appeared to be cases when it's not true.
It's a case of non-principal rules with origins.
Such rules are called "weak principal" rules.
Matches of weak principal rules are not recorded
in Journal (as is for principal rules), but instead
they become part of their parent MatchChunk.
(In essense, tags of weak principal rules are
recorded in parent chunk).
With this, when a weak principal rule changes,
matches of all principal rules whose computation
depends on them are correctly invalidated.
(Example rules: findHierarchy_Classifier)
Relevant for MPSCR-62.
Now Evidence isn't unique for each Chunk: Occurrence Chunks fully
share evidence and justifications with their activating match.
So, less collections of justifications are created, approx. 2 times less.
Relates to machinery introduced in MPSCR-47.
Previously parent match was maintained in Controller on Java call stack.
Now this stack of parent matches is maintained manually in MatchJournal.
So MatchJournal gains new invariant: parentChunk()
returns correct parent after each logMatch() call.
Several tests fail, also need to maintain this
invariant after logActivation() calls.
Fedor Isakov