implement a circuit registry with a factory pattern

[0xjei]

The goal is just to replac manual match statements with dynamic registry, that's it.

We can do this via creating a CircuitRegistry struct with HashMap<String, CircuitFactory> and use the new() method to register the circuits. Then, with getters we can take them.

some explanatory code - DO NOT USE IN PROD IS AUTOGEN

use std::collections::HashMap;

pub struct CircuitRegistry {
    circuits: HashMap<String, CircuitFactory>,
}

type CircuitFactory = Box<dyn Fn(CircuitConfig) -> Box<dyn Circuit>>;

impl CircuitRegistry {
    pub fn new() -> Self {
        let mut registry = Self {
            circuits: HashMap::new(),
        };

        // Register all circuits
        registry.register("enc-bfv", |config| {
            Box::new(enc_bfv::codegen::EncBfvCircuit::new(
                config.parameter_type,
                config.lambda,
            ))
        });

        registry.register("enc-trbfv", |config| {
            Box::new(enc_trbfv::codegen::GrecoCircuit::new(
                config.parameter_type,
                config.sample_type,
                config.lambda,
            ))
        });

        // ... register other circuits

        registry
    }

    pub fn get(&self, name: &str, config: CircuitConfig) -> Result<Box<dyn Circuit>> {
        let factory = self.circuits
            .get(name)
            .ok_or_else(|| anyhow!("Unknown circuit: {}", name))?;
        Ok(factory(config))
    }
}