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
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169

use crate::lifetimes::LifetimeExt;
use crate::names::Names;

use proc_macro2::{Literal, TokenStream};
use quote::quote;
use witx::Layout;

pub(super) fn define_variant(names: &Names, name: &witx::Id, v: &witx::Variant) -> TokenStream {
    let rt = names.runtime_mod();
    let ident = names.type_(name);
    let size = v.mem_size_align().size as u32;
    let align = v.mem_size_align().align as usize;
    let contents_offset = v.payload_offset() as u32;

    let lifetime = quote!('a);
    let tag_ty = super::int_repr_tokens(v.tag_repr);

    let variants = v.cases.iter().map(|c| {
        let var_name = names.enum_variant(&c.name);
        if let Some(tref) = &c.tref {
            let var_type = names.type_ref(&tref, lifetime.clone());
            quote!(#var_name(#var_type))
        } else {
            quote!(#var_name)
        }
    });

    let read_variant = v.cases.iter().enumerate().map(|(i, c)| {
        let i = Literal::usize_unsuffixed(i);
        let variantname = names.enum_variant(&c.name);
        if let Some(tref) = &c.tref {
            let varianttype = names.type_ref(tref, lifetime.clone());
            quote! {
                #i => {
                    let variant_ptr = location.cast::<u8>().add(#contents_offset)?;
                    let variant_val = <#varianttype as #rt::GuestType>::read(&variant_ptr.cast())?;
                    Ok(#ident::#variantname(variant_val))
                }
            }
        } else {
            quote! { #i => Ok(#ident::#variantname), }
        }
    });

    let write_variant = v.cases.iter().enumerate().map(|(i, c)| {
        let variantname = names.enum_variant(&c.name);
        let write_tag = quote! {
            location.cast().write(#i as #tag_ty)?;
        };
        if let Some(tref) = &c.tref {
            let varianttype = names.type_ref(tref, lifetime.clone());
            quote! {
                #ident::#variantname(contents) => {
                    #write_tag
                    let variant_ptr = location.cast::<u8>().add(#contents_offset)?;
                    <#varianttype as #rt::GuestType>::write(&variant_ptr.cast(), contents)?;
                }
            }
        } else {
            quote! {
                #ident::#variantname => {
                    #write_tag
                }
            }
        }
    });

    let mut extra_derive = quote!();
    let enum_try_from = if v.cases.iter().all(|c| c.tref.is_none()) {
        let tryfrom_repr_cases = v.cases.iter().enumerate().map(|(i, c)| {
            let variant_name = names.enum_variant(&c.name);
            let n = Literal::usize_unsuffixed(i);
            quote!(#n => Ok(#ident::#variant_name))
        });
        let abi_ty = names.wasm_type(v.tag_repr.into());
        extra_derive = quote!(, Copy);
        quote! {
            impl TryFrom<#tag_ty> for #ident {
                type Error = #rt::GuestError;
                fn try_from(value: #tag_ty) -> Result<#ident, #rt::GuestError> {
                    match value {
                        #(#tryfrom_repr_cases),*,
                        _ => Err( #rt::GuestError::InvalidEnumValue(stringify!(#ident))),
                    }
                }
            }

            impl TryFrom<#abi_ty> for #ident {
                type Error = #rt::GuestError;
                fn try_from(value: #abi_ty) -> Result<#ident, #rt::GuestError> {
                    #ident::try_from(#tag_ty::try_from(value)?)
                }
            }
        }
    } else {
        quote!()
    };

    let enum_from = if v.cases.iter().all(|c| c.tref.is_none()) {
        let from_repr_cases = v.cases.iter().enumerate().map(|(i, c)| {
            let variant_name = names.enum_variant(&c.name);
            let n = Literal::usize_unsuffixed(i);
            quote!(#ident::#variant_name => #n)
        });
        quote! {
            impl From<#ident> for #tag_ty {
                fn from(v: #ident) -> #tag_ty {
                    match v {
                        #(#from_repr_cases),*,
                    }
                }
            }
        }
    } else {
        quote!()
    };

    let (enum_lifetime, extra_derive) = if v.needs_lifetime() {
        (quote!(<'a>), quote!())
    } else {
        (quote!(), quote!(, PartialEq #extra_derive))
    };

    quote! {
        #[derive(Clone, Debug #extra_derive)]
        pub enum #ident #enum_lifetime {
            #(#variants),*
        }

        #enum_try_from
        #enum_from

        impl<'a> #rt::GuestType<'a> for #ident #enum_lifetime {
            fn guest_size() -> u32 {
                #size
            }

            fn guest_align() -> usize {
                #align
            }

            fn read(location: &#rt::GuestPtr<'a, Self>)
                -> Result<Self, #rt::GuestError>
            {
                let tag = location.cast::<#tag_ty>().read()?;
                match tag {
                    #(#read_variant)*
                    _ => Err(#rt::GuestError::InvalidEnumValue(stringify!(#ident))),
                }

            }

            fn write(location: &#rt::GuestPtr<'_, Self>, val: Self)
                -> Result<(), #rt::GuestError>
            {
                match val {
                    #(#write_variant)*
                }
                Ok(())
            }
        }
    }
}

impl super::WiggleType for witx::Variant {
    fn impls_display(&self) -> bool {
        false
    }
}