PKHeX/PKHeX.Core/Legality/Evolutions/EvolutionSets/EvolutionSet4.cs
Kurt 9166d0eb64
Refactoring: Move Source (Legality) (#3560)
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
2022-08-03 16:15:27 -07:00

63 lines
2.1 KiB
C#

using System;
using System.Collections.Generic;
using static System.Buffers.Binary.BinaryPrimitives;
namespace PKHeX.Core;
/// <summary>
/// Generation 4 Evolution Branch Entries
/// </summary>
public static class EvolutionSet4
{
private static EvolutionMethod GetMethod(ReadOnlySpan<byte> data)
{
var method = data[0]; // other byte unnecessary
var arg = ReadUInt16LittleEndian(data[2..]);
var species = ReadUInt16LittleEndian(data[4..]);
if (method == 0)
throw new ArgumentOutOfRangeException(nameof(method));
// To have the same structure as gen 6
// Gen 4 Method 6 is Gen 6 Method 7, G4 7 = G6 8, and so on
if (method > 6)
method++;
var lvl = EvolutionSet6.IsMethodWithArg(method) ? 0 : arg;
var type = (EvolutionType)method;
var lvlup = type.IsLevelUpRequired() ? (byte)1 : (byte)0;
return new EvolutionMethod(type, species, Argument: arg, Level: (byte)lvl, LevelUp: lvlup);
}
public static IReadOnlyList<EvolutionMethod[]> GetArray(ReadOnlySpan<byte> data)
{
const int bpe = 6; // bytes per evolution entry
const int entries = 7; // amount of entries per species
const int size = (entries * bpe) + 2; // bytes per species entry, + 2 alignment bytes
var evos = new EvolutionMethod[data.Length / size][];
for (int i = 0; i < evos.Length; i++)
{
int offset = i * size;
int count = 0;
for (; count < entries; count++)
{
var methodOffset = offset + (count * bpe);
var method = data[methodOffset];
if (method == 0)
break;
}
if (count == 0)
{
evos[i] = Array.Empty<EvolutionMethod>();
continue;
}
var set = new EvolutionMethod[count];
for (int j = 0; j < set.Length; j++)
set[j] = GetMethod(data.Slice(offset + (j * bpe), bpe));
evos[i] = set;
}
return evos;
}
}