extensor-macros 0.1.0

proc macro backend for the extensor crate.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88

use proc_macro::TokenStream;
use proc_macro2::Span;
use quote::quote;
use syn::{parse_macro_input, DeriveInput, GenericParam, Ident};

#[proc_macro_derive(MultilinearMap)]
pub fn multilinear_map_derive(input: TokenStream) -> TokenStream {
    let ast = parse_macro_input!(input as DeriveInput);
    let struct_name = &ast.ident;

    let generics = &ast.generics;
    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();

    // Type?
    let const_generics: Vec<_> = generics
        .params
        .iter()
        .filter_map(|param| match param {
            GenericParam::Const(const_param) => Some(&const_param.ident),
            _ => None,
        })
        .collect();

    // use proc_macro2::{Ident, Span};
    //
    // Span::call_site()
    //
    // pub fn multilinear_map(
    //     &self,
    //     v_0: V<M, F>,
    //     v_1: V<N, F>,
    //     v_2: V<P, F>,
    // )
    let input_params = const_generics.iter().enumerate().map(|(i, ident)| {
        // Is this identifier actually scoped correctly to the function? Or, by using
        // ::new raw, have we just made a global or something? span => scope?
        //
        // let param_name = Ident::new(&format!("v_{}", i), ident.span());
        let param_name = Ident::new(&format!("v_{}", i), Span::call_site());
        quote! { #param_name: V<#ident, F> }
    });

    let loop_indices: Vec<_> = (0..const_generics.len())
        .map(|i| Ident::new(&format!("i_{}", i), proc_macro2::Span::call_site()))
        .collect();

    let component_product = loop_indices.iter().zip(0..).map(|(index, i)| {
        let param_name = Ident::new(&format!("v_{}", i), index.span());
        quote! { * #param_name.0[#index] }
    });

    // Add the calculation to the innermost loop
    let coefficient_access =
        loop_indices
            .iter()
            .fold(quote! { self.coefficients }, |acc, index| {
                quote! { #acc.0[#index] }
            });

    let mut loop_nest = quote! {
        sum += #coefficient_access #(#component_product)*;
    };

    for (index, ident) in loop_indices.iter().rev().zip(const_generics.iter().rev()) {
        loop_nest = quote! {
            for #index in 0..#ident {
                #loop_nest
            }
        };
    }

    loop_nest = quote! {
        #loop_nest

    };

    let expanded = quote! {
        impl #impl_generics #struct_name #ty_generics #where_clause {
            pub fn multilinear_map(&self, #(#input_params),*) -> F {
                let mut sum = F::default();
                #loop_nest
                sum
            }
        }
    };

    TokenStream::from(expanded)
}