Rewrites a good amount of legality APIs pertaining to:
* Legal moves that can be learned
* Evolution chains & cross-generation paths
* Memory validation with forgotten moves
In generation 8, there are 3 separate contexts an entity can exist in: SW/SH, BD/SP, and LA. Not every entity can cross between them, and not every entity from generation 7 can exist in generation 8 (Gogoat, etc). By creating class models representing the restrictions to cross each boundary, we are able to better track and validate data.
The old implementation of validating moves was greedy: it would iterate for all generations and evolutions, and build a full list of every move that can be learned, storing it on the heap. Now, we check one game group at a time to see if the entity can learn a move that hasn't yet been validated. End result is an algorithm that requires 0 allocation, and a smaller/quicker search space.
The old implementation of storing move parses was inefficient; for each move that was parsed, a new object is created and adjusted depending on the parse. Now, move parse results are `struct` and store the move parse contiguously in memory. End result is faster parsing and 0 memory allocation.
* `PersonalTable` objects have been improved with new API methods to check if a species+form can exist in the game.
* `IEncounterTemplate` objects have been improved to indicate the `EntityContext` they originate in (similar to `Generation`).
* Some APIs have been extended to accept `Span<T>` instead of Array/IEnumerable
* Reuses move parse result objects for each encounter parsed in a LegalityCheck attempt, instead of creating a new object.
* Ensures the objects are never-null, and makes cleanup easier.
Slightly adjusts some other parts of the moveset validation to reduce allocations.
V### names weren't enjoyable to work with; use similar verbose style as
the program message strings.
updating the translation files with the remapped variable names shortly
remap list: https://pastebin.com/jybkVDAK
exercise in deferred execution/state machine, only calculate possible
matches until a sufficiently valid match is obtained. Previous setup
would try to calculate the 'best match' and had band-aid workarounds in
cases where a subsequent check may determine it to be a false match.
There's still more ways to improve speed:
- precalculate relationships for Encounter Slots rather than iterating
over every area
- yielding individual slots instead of an entire area
- group non-egg wondercards by ID in a dict/hashtable for faster
retrieval
reworked some internals:
- EncounterMatch is always an IEncounterable instead of an object, for
easy pattern matching.
- Splitbreed checking is done per encounter and is stored in the
EncounterEgg result
- Encounter validation uses Encounter/Move/RelearnMove/Evolution to
whittle to the final encounter.
As a part of the encounter matching, a lazy peek is used to check if an
invalid encounter should be retained instead of discarded; if another
encounter has not been checked, it'll stop the invalid checks and move
on. If it is the last encounter, no other valid encounters exist so it
will keep the parse for the invalid encounter.
If no encounters are yielded, then there is no encountermatch. An
EncounterInvalid is created to store basic details, and the parse is
carried out.
Breaks some legality checking features for flagging invalid moves in
more detail, but those can be re-added in a separate check (if
splitbreed & any move invalid -> check for other split moves).
Should now be easier to follow the flow & maintain 😄
