diman_unit_system 0.5.0

Internal procedural macros for diman.
Documentation 
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use crate::dimension_math::BaseDimensions;
use proc_macro2::TokenStream;
use quote::{quote, quote_spanned};

use super::Codegen;

impl Codegen {
    pub fn get_dimension_expr(&self, dim: &BaseDimensions) -> TokenStream {
        let dimension_type = &self.defs.dimension_type;
        let field_updates: TokenStream = dim
            .fields()
            .map(|(field, value)| self.get_base_dimension_entry(field, value))
            .collect();
        let span = self.defs.quantity_type.span();
        let none_update = if dim.num_fields() < self.defs.base_dimensions.len() {
            quote! { ..#dimension_type::none() }
        } else {
            quote! {}
        };
        quote_spanned! {span =>
            #dimension_type {
                #field_updates
                #none_update
            }
        }
    }

    pub fn gen_dimensions(&self) -> TokenStream {
        let dimension_type = &self.defs.dimension_type;
        let quantity_type = &self.defs.quantity_type;
        let defs = self.gen_dimension_definitions();
        quote! {
            #[allow(unused)]
            pub mod dimensions {
                use super::#dimension_type;
                use super::#quantity_type;
                use super::Exponent;
                #defs
            }
        }
    }

    fn gen_dimension_definitions(&self) -> TokenStream {
        let dimensions: TokenStream = self
            .defs
            .dimensions
            .iter()
            .map(|quantity| {
                let dimension = self.get_dimension_expr(&quantity.dimensions);
                let quantity_type = &self.defs.quantity_type;
                let quantity_name = &quantity.name;
                let span = self.defs.dimension_type.span();
                quote_spanned! {span =>
                    pub type #quantity_name<S> = #quantity_type::<S, { #dimension }>;
                }
            })
            .collect();
        quote! {
            #dimensions
        }
    }
}