Struct PlanBuilder 

pub struct PlanBuilder<'w> {
    archetype: &'w Archetype,
    asked: Vec<(TypeId, &'static str, Mode)>,
    marker: PhantomData<&'w ()>,
}

What one archetype offers, and what a query asks of it while resolving its plan.

This is the only way a query reaches a column, so asking for one is the claim: there is no separate list of reached components that could disagree with what Query::read actually reads. A duplicate ask that would need two modes for one type is refused here, before anything is handed out.

Fields

archetype: &'w Archetype

asked: Vec<(TypeId, &'static str, Mode)>

marker: PhantomData<&'w ()>

Implementations

impl<'w> PlanBuilder<'w>

pub(crate) fn new( archetype: &'w Archetype, asked: Vec<(TypeId, &'static str, Mode)>, ) -> Self

pub(crate) fn asks(&self) -> &[(TypeId, &'static str, Mode)]

The asks recorded so far, which is what the holder claims.

pub(crate) fn into_asks(self) -> Vec<(TypeId, &'static str, Mode)>

Recover the buffer, so the next archetype reuses it instead of allocating.

pub fn read<T: 'static>(&mut self) -> Option<Col<'w, T>>

The archetype’s column of T, shared. None when it carries no T, which is what makes the query skip it.

pub fn write<T: 'static>(&mut self) -> Option<ColMut<'w, T>>

The archetype’s column of T, exclusive. None when it carries no T.

pub fn has<T: 'static>(&self) -> bool

Whether the archetype carries T.

Claims nothing: a yes/no answer cannot alias anything, which is what keeps (&mut T, Has<T>) legal.

pub fn entities(&self) -> &'w [Entity]

The entities of the archetype, one per row.

fn ask<T: 'static>(&mut self, mode: Mode) -> Option<&'w [UnsafeCell<T>]>

Record that the query reaches T in mode, and resolve its column.

Panics when the same query asks for T twice with at least one of the asks exclusive: the two would hand out references that cannot coexist.