Enum ContributionReason 

pub enum ContributionReason {
    AlreadyAromaticContext,
    CarbonEndocyclicDouble,
    CarbonExocyclicHeteroatomDouble,
    CarbonCarbanionLonePair,
    CarbonCationVacant,
    CarbonSp3Ineligible,
    NitrogenPyrroleTypeH,
    NitrogenPyridineTypeExplicitDouble,
    NitrogenBridgeheadOrSubstitutedLonePair,
    NitrogenAromaticInRing,
    NitrogenIneligible,
    ChalcogenLonePair,
    ChalcogenCationPyridineType,
    ChalcogenIneligible,
    UnsupportedElement,
}

Reason a ring atom contributes (or fails to contribute) pi electrons, mirroring ring_pi_electrons’s branches one-to-one. Purely diagnostic.

Variants

AlreadyAromaticContext

Already aromatic from a previous Pass 1/Pass 2 ring: contributes 1π unconditionally.

CarbonEndocyclicDouble

Carbon with an endocyclic double/aromatic bond: 1π.

CarbonExocyclicHeteroatomDouble

Carbon whose only double bond is exocyclic to O/N/S: 0π (e.g. a carbonyl carbon).

CarbonCarbanionLonePair

Carbanion with no double bond: 2π (lone pair).

CarbonCationVacant

Cationic ring carbon (e.g. tropylium’s [cH+]): empty p-orbital electron acceptor, 0π, regardless of representation (Kekule or aromatic-bond) – mirrors CarbonCarbanionLonePair’s anion rule at the opposite electron-count extreme.

CarbonSp3Ineligible

sp3 carbon (no double bond, not a carbanion): ineligible.

NitrogenPyrroleTypeH

Pyrrole-type N with an H, neutral or anionic: 2π.

NitrogenPyridineTypeExplicitDouble

Pyridine-type N with an explicit double bond (bare, or protonated N-H+ once it has a Kekule double bond): 1π.

NitrogenBridgeheadOrSubstitutedLonePair

Bridgehead N (or N-substituted azole N), neutral or anionic: all-sigma valence, lone pair in p orbital: 2π.

NitrogenAromaticInRing

N with an in-ring aromatic bond, not a bridgehead (pyridine-type notation, or a charged N-H+ in aromatic-bond representation): 1π.

NitrogenIneligible

N matching none of the above rules: ineligible.

ChalcogenLonePair

O/S/Se/Te lone-pair donor, neutral or anionic, ring-degree 2: 2π.

ChalcogenCationPyridineType

Charged O/S (e.g. pyrylium’s [o+]): the positive charge consumes the lone pair, so this atom needs pyridine-type treatment (1π via its own ring double/aromatic bond) instead of donating 2π.

ChalcogenIneligible

O/S/Se/Te with the wrong ring degree, an exocyclic X=O, (Se/Te) non-RdkitLike mode, or a charged O/S with no ring double/aromatic bond to fall back on: ineligible.

UnsupportedElement

Element not supported by the model: ineligible.

Implementations

impl ContributionReason

pub fn is_eligible(self) -> bool

Whether this reason is an eligible contribution (matches ring_pi_electrons returning Some) rather than one that disqualifies the whole ring (matches it returning None).

pub fn eligibility(self) -> PiEligibility

Coarse PiEligibility bucket for this fine-grained reason (Aromaticity-A1-1a). AlreadyAromaticContext has no single fixed bucket – it always carries exactly 1π, so it maps to OneElectron.

Trait Implementations

impl Clone for ContributionReason

fn clone(&self) -> ContributionReason

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ContributionReason

impl Debug for ContributionReason

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

Formats the value using the given formatter.

impl Eq for ContributionReason

impl PartialEq for ContributionReason

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ContributionReason