brisk_it/
generator.rs

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//! Traits and structure used for generating the imperative representation from the declartive representation.

use std::collections::HashMap;

/// Result type, which return a token stream with the error
pub type Result<T> = std::result::Result<T, proc_macro2::TokenStream>;

/// Implement this trait to convert a ComponentInput into its imperative form.
pub trait Generator: Sync {
    /// Generate the imperative form.
    fn generate(
        &self,
        input: crate::component::ComponentInput,
        manager: &Manager,
    ) -> Result<proc_macro2::TokenStream>;
    /// Clone this generator
    fn boxed_clone(&self) -> Box<dyn Generator>;
}

/// A `Manager` contains a list of generator that can be used by `brisk_it` to generate the code.
pub struct Manager {
    generators: HashMap<String, Box<dyn Generator>>,
}

impl Manager {
    /// Generate the given component
    pub fn generate(
        &self,
        input: crate::component::ComponentInput,
    ) -> Result<proc_macro2::TokenStream> {
        if let Some(generator) = self.generators.get(&input.name.to_string()) {
            generator.generate(input, self)
        } else {
            Err(syn::Error::new(
                input.name.span(),
                format!("No generator for component: {}", input.name.to_string()),
            )
            .to_compile_error()
            .into())
        }
    }
}

/// Used to initialise a manager
pub struct ManagerBuilder {
    manager: Manager,
}

impl ManagerBuilder {
    /// Create an empty builder
    pub fn new() -> Self {
        Self {
            manager: Manager {
                generators: Default::default(),
            },
        }
    }
    /// Create a generator and add it to the builder
    pub fn create<T>(mut self, name: impl Into<String>) -> Self
    where
        T: Generator + 'static + Default,
    {
        self.manager
            .generators
            .insert(name.into(), Box::new(T::default()));
        self
    }
    /// Add a generator to the builder
    pub fn add<T>(mut self, name: impl Into<String>, generator: T) -> Self
    where
        T: Generator + 'static,
    {
        self.manager
            .generators
            .insert(name.into(), Box::new(generator));
        self
    }
    ///
    pub fn insert(mut self, manager: &Manager) -> Self {
        for (k, v) in manager.generators.iter() {
            self.manager
                .generators
                .insert(k.to_owned(), v.boxed_clone());
        }
        self
    }
}

impl Into<Manager> for ManagerBuilder {
    fn into(self) -> Manager {
        self.manager
    }
}