typ 0.1.1

Type-level programming in Rust
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
89
90
91
92

use crate::common::*;

struct SignedInteger {
    has_negative_op: bool,
    value: u128,
}

impl Parse for SignedInteger {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let has_negative_op = if input.peek(Token![-]) {
            input.parse::<Token![-]>()?;
            true
        } else {
            false
        };

        let literal = input.parse::<LitInt>()?;
        let value = literal.base10_parse::<u128>()?;

        let output = SignedInteger {
            has_negative_op,
            value,
        };

        Ok(output)
    }
}

struct UnsignedInteger {
    value: u128,
}

impl Parse for UnsignedInteger {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let literal = input.parse::<LitInt>()?;
        let value = literal.base10_parse::<u128>()?;

        let output = UnsignedInteger { value };

        Ok(output)
    }
}

pub fn tyint(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let SignedInteger {
        has_negative_op,
        value,
    } = parse_macro_input!(input as SignedInteger);

    let tokens = if value == 0 {
        quote! {
            typenum::consts::Z0
        }
    } else if has_negative_op {
        let uint_tokens = recursive_value_to_typeuint(value);
        quote! {
            typenum::int::NInt<#uint_tokens>
        }
    } else {
        let uint_tokens = recursive_value_to_typeuint(value);
        quote! {
            typenum::int::PInt<#uint_tokens>
        }
    };

    proc_macro::TokenStream::from(tokens)
}

pub fn tyuint(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    let UnsignedInteger { value } = parse_macro_input!(input as UnsignedInteger);

    let tokens = recursive_value_to_typeuint(value);
    proc_macro::TokenStream::from(tokens)
}

fn recursive_value_to_typeuint(value: u128) -> TokenStream {
    if value == 0 {
        quote! {
            typenum::uint::UTerm
        }
    } else if value & 1 == 1 {
        let sub_tokens = recursive_value_to_typeuint(value >> 1);
        quote! {
            typenum::uint::UInt<#sub_tokens, typenum::bit::B1>
        }
    } else {
        let sub_tokens = recursive_value_to_typeuint(value >> 1);
        quote! {
            typenum::uint::UInt<#sub_tokens, typenum::bit::B0>
        }
    }
}