mser_macro 3.0.0

mser_macro
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
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132

use crate::{V7MAX, V21MAX, kw};
use quote::quote;

pub fn serialize_struct(
    input: syn::DeriveInput,
    cratename: syn::Path,
) -> syn::Result<proc_macro2::TokenStream> {
    let name = &input.ident;
    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
    let fields = match &input.data {
        syn::Data::Struct(data) => &data.fields,
        _ => unreachable!(),
    };
    let write = fields
        .iter()
        .enumerate()
        .map(|(idx, field)| match &field.ident {
            Some(ident) => quote!(::#cratename::Write::write(&self.#ident, __w);),
            None => {
                let l = proc_macro2::Literal::usize_unsuffixed(idx);
                quote!(::#cratename::Write::write(&self.#l, __w);)
            }
        });
    let len_s = fields
        .iter()
        .enumerate()
        .map(|(idx, field)| match &field.ident {
            Some(ident) => quote!(::#cratename::Write::len_s(&self.#ident)),
            None => {
                let l = proc_macro2::Literal::usize_unsuffixed(idx);
                quote!(::#cratename::Write::len_s(&self.#l))
            }
        });

    Ok(quote! {
        #[automatically_derived]
        impl #impl_generics ::#cratename::Write for #name #ty_generics #where_clause {
            #[inline]
            unsafe fn write(&self, __w: &mut ::#cratename::Writer) {
                unsafe {
                    #(#write)*
                }
            }

            #[inline]
            fn len_s(&self) -> usize {
                let mut __l = 0usize;
                #(__l += #len_s;)*
                __l
            }
        }
    })
}

pub fn serialize_enum(
    input: syn::DeriveInput,
    cratename: syn::Path,
) -> syn::Result<proc_macro2::TokenStream> {
    let name = &input.ident;
    let mut repr = None;
    let mut varint = false;
    let variants = match &input.data {
        syn::Data::Enum(data) => &data.variants,
        _ => unreachable!(),
    };
    let len = variants.len();
    for attr in &input.attrs {
        if attr.path().is_ident("mser") {
            attr.meta.require_list()?.parse_args::<kw::varint>()?;
            varint = true;
        }
    }
    for attr in &input.attrs {
        if attr.path().is_ident("repr") {
            attr.parse_nested_meta(|meta| {
                if meta.path.is_ident("u8") {
                    if varint && len > V7MAX {
                        repr = Some(quote!(::#cratename::V21(*self as u32)));
                    } else {
                        repr = Some(quote!(*self as u8));
                    }
                } else if meta.path.is_ident("u16") {
                    if varint && len > V7MAX {
                        repr = Some(quote!(::#cratename::V21(*self as u32)));
                    } else {
                        repr = Some(quote!(*self as u16));
                    }
                } else if meta.path.is_ident("u32") {
                    if varint && len > V21MAX {
                        repr = Some(quote!(::#cratename::V32(*self as u32)));
                    } else if varint && len > V7MAX {
                        repr = Some(quote!(::#cratename::V21(*self as u32)));
                    } else {
                        repr = Some(quote!(*self as u32));
                    }
                } else if meta.path.is_ident("u64") {
                    if varint && len > u32::MAX as usize {
                        repr = Some(quote!(::#cratename::V64(*self as u64)));
                    } else if varint && len > V21MAX {
                        repr = Some(quote!(::#cratename::V32(*self as u64 as u32)));
                    } else if varint && len > V7MAX {
                        repr = Some(quote!(::#cratename::V21(*self as u64 as u32)));
                    } else {
                        repr = Some(quote!(*self as u64));
                    }
                }
                Ok(())
            })?;
        }
    }

    let repr =
        repr.ok_or_else(|| syn::Error::new_spanned(&input, "expected `#[repr(...)]` attribute"))?;
    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();

    Ok(quote! {
        #[automatically_derived]
        impl #impl_generics ::#cratename::Write for #name #ty_generics #where_clause {
            #[inline]
            unsafe fn write(&self, w: &mut ::#cratename::Writer) {
                unsafe {
                    ::#cratename::Write::write(&(#repr), w);
                }
            }

            #[inline]
            fn len_s(&self) -> usize {
                ::#cratename::Write::len_s(&(#repr))
            }
        }
    })
}