Enum JournalKind 

pub enum JournalKind {
    Overwrite,
    InPlace,
    Collection,
    CrdtSnapshot,
}

What a RevClass::Journaled op must record on the history tape to be reversible — the minimal destroyed information (Bennett/Landauer embedding), not a full state snapshot.

Variants

Overwrite

Writes a destination register/global that is NOT one of its operands: the operands survive, so reversal only needs the destination’s PRIOR value (one entry). Covers the bulk of the three-address ISA — arithmetic, comparisons, constructors, loads, field reads.

InPlace

Writes a destination that IS one of its operands (x := x ⊕ e): the prior value is lost. Reversible algebraically when ⊕ is an abelian group op (the R1 promotion to Bijection), or by journaling the prior value.

Collection

Mutates a heap collection in place (push / pop / remove / index-store / struct-field write): reversal records the structural delta (the pushed slot to pop, the popped element + index to re-insert, the overwritten slot’s old value).

CrdtSnapshot

A CRDT join-semilattice step (merge / resolve) that collapses lattice points and cannot be inverted algebraically: reversal snapshots the target replica’s pre-state (bounded to that one value, not the whole machine).

Trait Implementations

impl Clone for JournalKind

fn clone(&self) -> JournalKind

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for JournalKind

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for JournalKind

fn eq(&self, other: &JournalKind) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for JournalKind

impl Eq for JournalKind

impl StructuralPartialEq for JournalKind