Struct BattleCtx 

pub struct BattleCtx<'a, P: EffectProvider + ?Sized> {
    pub state: &'a mut BattleState<P>,
    pub effects: &'a mut Vec<EffectState<P>>,
    pub mv: &'a mut MoveContext,
    pub rng: &'a mut dyn BattleRng,
}

Split-borrow context handed to every handler (design §3.2). A handler’s only mutable path into the battle is through this struct’s accessors.

Fields

state: &'a mut BattleState<P>

The shared battle state (the two party Vecs live here).

effects: &'a mut Vec<EffectState<P>>

The per-effect-instance arena, kept sorted by id.

mv: &'a mut MoveContext

Per-move scratch.

rng: &'a mut dyn BattleRng

The ONLY randomness source (design §4).

Implementations

impl<'a, P: EffectProvider + ?Sized> BattleCtx<'a, P>

pub fn battler_mut(&mut self, r: BattlerRef) -> &mut BattlerState<P>

One battler as &mut. Cross-side is trivial (two different Vecs).

pub fn battler(&self, r: BattlerRef) -> &BattlerState<P>

One battler as & (read-only).

pub fn pair_mut( &mut self, a: BattlerRef, b: BattlerRef, ) -> (&mut BattlerState<P>, &mut BattlerState<P>)

Two disjoint battler refs as two &mut (design §3.2). This is the borrow-checker crux that lets a Counter-shaped handler mutate target while reading source’s host.

• Cross-side (a.side != b.side): the two sides are separate Vecs, so the refs are provably non-aliasing. This is the one localized, documented unsafe in the engine hot path (design §3.2).
• Same-side: a real disjoint split via split_at_mut — fully safe, no raw pointer. (Once MSRV permits, <[T]>::get_disjoint_mut.)

Panics

Debug-asserts a != b (the two refs must address distinct battlers).

pub fn effect_mut(&mut self, id: EffectId) -> Option<&mut EffectState<P>>

Mutable access to a live effect’s state by id (binary search; the arena is kept sorted). Returns None if no such effect is live.

pub fn effect(&self, id: EffectId) -> Option<&EffectState<P>>

Read access to a live effect’s state by id.

pub fn install_effect( &mut self, host: BattlerRef, kind: P::EffectStateKind, ) -> EffectId

Install a new game-defined effect (volatile) on host, allocating a fresh arena id + creation order and keeping the arena sorted by id. Returns the new id. The engine treats kind OPAQUELY — this is the generic seam a data InflictVolatile op uses; the game constructs the P::EffectStateKind (via its binding) and the engine only stores it.