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
extern crate proc_macro;
use proc_macro::TokenStream;
use proc_macro2::Span;
use quote::quote;
use syn::{parse_macro_input, DeriveInput};
#[proc_macro_derive(Bundle)]
pub fn derive_bundle(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
if !input.generics.params.is_empty() {
return TokenStream::from(
quote! { compile_error!("derive(Bundle) does not support generics"); },
);
}
let data = match input.data {
syn::Data::Struct(s) => s,
_ => {
return TokenStream::from(
quote! { compile_error!("derive(Bundle) only supports structs"); },
)
}
};
let ident = input.ident;
let (tys, fields) = struct_fields(&data.fields);
let n = tys.len();
let code = quote! {
impl ::hecs::DynamicBundle for #ident {
fn with_ids<T>(&self, f: impl FnOnce(&[std::any::TypeId]) -> T) -> T {
Self::with_static_ids(f)
}
fn type_info(&self) -> Vec<::hecs::TypeInfo> {
let mut info = vec![#(::hecs::TypeInfo::of::<#tys>()),*];
info.sort_unstable();
info
}
unsafe fn put(mut self, mut f: impl FnMut(*mut u8, std::any::TypeId, usize) -> bool) {
#(
if f((&mut self.#fields as *mut #tys).cast::<u8>(), std::any::TypeId::of::<#tys>(), std::mem::size_of::<#tys>()) {
std::mem::forget(self.#fields);
}
)*
}
}
impl ::hecs::Bundle for #ident {
fn with_static_ids<T>(f: impl FnOnce(&[std::any::TypeId]) -> T) -> T {
use std::any::TypeId;
use std::mem;
::hecs::lazy_static::lazy_static! {
static ref ELEMENTS: [TypeId; #n] = {
let mut dedup = std::collections::HashSet::new();
for &(ty, name) in [#((std::any::TypeId::of::<#tys>(), std::any::type_name::<#tys>())),*].iter() {
if !dedup.insert(ty) {
panic!("{} has multiple {} fields; each type must occur at most once!", stringify!(#ident), name);
}
}
let mut tys = [#((mem::align_of::<#tys>(), TypeId::of::<#tys>())),*];
tys.sort_unstable_by(|x, y| x.0.cmp(&y.0).reverse().then(x.1.cmp(&y.1)));
let mut ids = [TypeId::of::<()>(); #n];
for (id, info) in ids.iter_mut().zip(tys.iter()) {
*id = info.1;
}
ids
};
}
f(&*ELEMENTS)
}
unsafe fn get(
mut f: impl FnMut(std::any::TypeId, usize) -> Option<std::ptr::NonNull<u8>>,
) -> Result<Self, MissingComponent> {
Ok(Self {
#(
#fields: f(std::any::TypeId::of::<#tys>(), std::mem::size_of::<#tys>())
.ok_or_else(MissingComponent::new::<#tys>)?
.cast::<#tys>()
.as_ptr()
.read(),
)*
})
}
}
};
TokenStream::from(code)
}
fn struct_fields(fields: &syn::Fields) -> (Vec<&syn::Type>, Vec<syn::Ident>) {
match fields {
syn::Fields::Named(ref fields) => fields
.named
.iter()
.map(|f| (&f.ty, f.ident.clone().unwrap()))
.unzip(),
syn::Fields::Unnamed(ref fields) => fields
.unnamed
.iter()
.enumerate()
.map(|(i, f)| (&f.ty, syn::Ident::new(&i.to_string(), Span::call_site())))
.unzip(),
syn::Fields::Unit => (Vec::new(), Vec::new()),
}
}