Struct FoldPlan 

pub struct FoldPlan {
    pub target: TypeRef,
    pub by_ref: bool,
    pub shape: FoldShape,
    pub leaves: Vec<FoldLeaf>,
    pub selector: Option<usize>,
    pub present: Option<usize>,
    pub variants: Vec<FoldVariant>,
}

A resolved expansion for one (function, parameter).

Fields

target: TypeRef

Owned type the core construct produces — what the underlying call needs (before any Self::shape wrapping). A reading: target.spell() for generated Rust, target.key() for a lookup.

by_ref: bool

True when the original parameter was &T / Option<&T>: the call receives &folded (or folded.as_ref() when also optional). A call-site concern (the resolver’s &_ handler shares the inner converter the same way), not part of the fold.

shape: FoldShape

Outer shape over the core construct (Construct for a plain T/&T param; Optional(Construct) for Option<T>/Option<&T>).

leaves: Vec<FoldLeaf>

Flattened wire leaves, in foreign-signature order.

selector: Option<usize>

Index into Self::leaves of the selector leaf; None for a single constructor (the sole variant is applied unconditionally). Under an Optional shape the selector also encodes absence: -1 = None, 0..n-1 = the taken arm.

present: Option<usize>

Index into Self::leaves of the explicit presence-flag (bool) leaf for a multi-argument Optional shape (Option<T> built from a constructor taking ≥2 args): the flag decides Some/None, the arg leaves are plain (non-Option). None for a non-optional fold or the legacy single-arg Optional (where presence rides the sole leaf’s own Option-ness). A separate flag avoids boxing a nullable primitive arg (e.g. Option<i32> → Integer?) on the wire.

variants: Vec<FoldVariant>

Dispatch arms — one for a single constructor, selector order for a combined one.

Implementations

impl FoldPlan

pub fn produces_option(&self) -> bool

True when the fold produces an Option<_> (outermost shape layer is Optional) — drives the by-ref call-site form (folded.as_ref()).

Trait Implementations

impl Clone for FoldPlan

fn clone(&self) -> FoldPlan

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.