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
170
171
172
173
174
175
176
177
178
179
//! Derive macro for `bevy_simple_prefs`.
extern crate proc_macro;
use proc_macro::TokenStream;
use quote::quote;
use syn::{Data, DeriveInput, Fields, parse_macro_input};
/// Derive macro for `bevy_simple_prefs`.
#[proc_macro_derive(Prefs)]
pub fn prefs_derive(input: TokenStream) -> TokenStream {
// Parse the input tokens into a syntax tree
let input = parse_macro_input!(input as DeriveInput);
// Get the struct name
let name = &input.ident;
// Generate the code
let expanded = match input.data {
Data::Struct(ref data_struct) => {
let mut field_bindings = Vec::new();
let mut field_checks = Vec::new();
let mut fields = Vec::new();
let mut field_assignments = Vec::new();
let mut field_inits = Vec::new();
let mut field_inserts = Vec::new();
// This ensures field_checks will not generate an empty if expression.
field_checks.push(quote! { true });
// Iterate over the fields of the struct
match &data_struct.fields {
Fields::Named(fields_named) => {
for field in &fields_named.named {
let field_name = &field.ident;
let field_type = &field.ty;
field_bindings.push(quote! {
let #field_name = world.get_resource_ref::<#field_type>().unwrap();
});
field_checks.push(quote! {
!#field_name.is_changed()
});
fields.push(quote! {
#field_name: #field_type
});
field_assignments.push(quote! {
#field_name: #field_name.clone()
});
field_inits.push(quote! {
app.init_resource::<#field_type>();
});
field_inserts.push(quote! {
world.insert_resource(val.#field_name);
});
}
}
_ => {
unimplemented!("Prefs can only be derived for structs with named fields")
}
}
quote! {
impl Prefs for #name {
fn save(world: &mut World) {
#(#field_bindings)*
if #(#field_checks)&&* {
return;
}
// Prevent saving from happening on the initial change detection after
// inserting the resources on load.
let status = world.get_resource_ref::<::bevy_simple_prefs::PrefsStatus<#name>>().unwrap();
if status.is_changed() {
return;
}
::bevy::log::debug!("bevy_simple_prefs initiating save");
let to_save = #name {
#(#field_assignments,)*
};
let settings = world.resource::<::bevy_simple_prefs::PrefsSettings<#name>>();
let path = settings.path.clone();
let filename = settings.filename.clone();
::bevy::tasks::IoTaskPool::get()
.spawn(async move {
::bevy::log::debug!("bevy_simple_prefs saving");
let Ok(serialized_value) = ::bevy_simple_prefs::serialize(&to_save) else {
bevy::log::error!("Failed to serialize prefs.");
return;
};
::bevy_simple_prefs::save_str(&path, &filename, &serialized_value);
}).detach();
}
#[cfg(not(target_arch = "wasm32"))]
fn load(world: &mut World) {
::bevy::log::debug!("bevy_simple_prefs initiating load task");
let settings = world.resource::<::bevy_simple_prefs::PrefsSettings<#name>>();
let path = settings.path.clone();
let filename = settings.filename.clone();
let entity = world.spawn_empty().id();
let task = ::bevy::tasks::IoTaskPool::get().spawn(async move {
::bevy::log::debug!("bevy_simple_prefs loading");
let val = (|| {
let Some(serialized_value) = ::bevy_simple_prefs::load_str(&path, &filename) else {
return #name::default();
};
match ::bevy_simple_prefs::deserialize(&serialized_value) {
Ok(v) => v,
Err(e) => {
::bevy::log::error!("Failed to deserialize prefs: {}", e);
return #name::default();
}
}
})();
let mut command_queue = ::bevy::ecs::world::CommandQueue::default();
command_queue.push(move |world: &mut World| {
#(#field_inserts;)*;
world.resource_mut::<::bevy_simple_prefs::PrefsStatus<#name>>().loaded = true;
world.despawn(entity);
});
command_queue
});
world.entity_mut(entity).insert(::bevy_simple_prefs::LoadPrefsTask(task));
}
// There's no task pool and no multi-threading on wasm, so just load everything,
// toss it into the world, and update `PrefsStatus`.
#[cfg(target_arch = "wasm32")]
fn load(world: &mut World) {
::bevy::log::debug!("bevy_simple_prefs loading");
let settings = world.resource::<::bevy_simple_prefs::PrefsSettings<#name>>();
let val = (|| {
let Some(serialized_value) = ::bevy_simple_prefs::load_str(&settings.path, &settings.filename) else {
return #name::default();
};
match ::bevy_simple_prefs::deserialize(&serialized_value) {
Ok(v) => v,
Err(e) => {
::bevy::log::error!("bevy_simple_prefs failed to deserialize prefs: {}", e);
return #name::default();
}
}
})();
#(#field_inserts;)*;
world.resource_mut::<::bevy_simple_prefs::PrefsStatus<#name>>().loaded = true;
}
fn init(app: &mut App) {
#(#field_inits;)*
}
}
}
}
_ => unimplemented!("Prefs can only be derived for structs"),
};
// Hand the output tokens back to the compiler
TokenStream::from(expanded)
}