message: Add more helpers for LookupPattern
diff: @@ -340,6 +340,24 @@ impl LookupPattern {
  }
  }
  }
  +
  + pub fn table(&self) -> Option<GateLookupTable> {
  + match self {
  + LookupPattern::ChaCha | LookupPattern::ChaChaFinal => Some(GateLookupTable::Xor),
  + LookupPattern::LookupGate => None,
  + }
  + }
  +
  + pub fn from_gate(gate_type: GateType, curr_or_next: CurrOrNext) -> Option<Self> {
  + use CurrOrNext::*;
  + use GateType::*;
  + match (gate_type, curr_or_next) {
  + (ChaCha0 | ChaCha1 | ChaCha2, Curr | Next) => Some(LookupPattern::ChaCha),
  + (ChaChaFinal, Curr | Next) => Some(LookupPattern::ChaChaFinal),
  + (Lookup, Curr) => Some(LookupPattern::LookupGate),
  + _ => None,
  + }
  + }
  }
  impl GateType {
  