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

#![allow(clippy::clippy::large_enum_variant)] // nope

use proc_macro::TokenStream;

mod drv_config_table;
use drv_config_table::derive_config_table_expand;

/// Generates necessary trait implementations to use a struct as a configuration table.
///
/// By itself, `#[derive(ConfigTable)]` won't do anything, as it requires additional markers to describe how exactly the struct will serve as a configuration table. Those markers are expressed using `#[snec(...)]` attributes. The following "Snec-commands" are supported:
/// - `#[snec(entry(`*`EntryMarker`*`))]` (one per struct field) — generates an uninhabited type which implements `Entry` and a `Get` implementation for it. `EntryMarker` is the optional name for the marker type which defaults to the field's name converted to camel case.
/// - `#[snec]` (one per struct field) — alias of `#[snec(entry)]`.
/// - `#[snec(use_entry(`*`entry_marker`*`))]` (one per struct field) — only adds a `Get` implementation for the specified entry identifier, without generating the type itself. `entry_marker` is given as an absolute or relative path to the entry type, i.e. it's not necessary for it to be in scope.
/// - `#[snec(receiver({`*`receiver_expression`*`}: `*`ReceiverType`*`))]` (can be one per struct field and also one on whole struct) — sets the receiver used in `get_handle` implementations for one struct field or the default for the whole struct to be used with `#[snec(entry)]`. *`receiver_expression`* is any valid Rust expression used to create the receiver, executed in the context of the `Get` implementation on the config struct. The type, *`ReceiverType`* must be annotated explicitly. If this attribute is not present, the receiver defaults to `EmptyReceiver`, which does nothing when notified.
/// - `#[snec(entry_module(`*`module_name`*`))]` (one on whole struct) — sets the module name in which the entry types generated by `#[snec(entry(...))]` will be placed to *`module_name`*. The default value is `entries`.
/// - `#[snec(entry_module_visibility(`*`visibility`*`))]` (one on whole struct) — visibility specifier the generated module for entry marker types. Uses private visibility by default.
/// - `#[snec(entry_module_attributes(...))]` (one on whole struct) — any Rust attributes applied to the generated module for entry marker types. Those attributes can be any valid Rust attributes, which include `///`-style and `/** */`-style documentation, but are *restricted to outer attributes*, i.e. `#[...]` and not `#![...]`.
///
/// # Example
/// ```no_run
/// # /*
/// #[derive(ConfigTable)]
/// #[snec(
///     receiver(
///         // We just use the name of the struct as an expression, since it is a unit struct
///         {MyReceiver}: MyReceiver
///     ),
///     entry_module_attributes(
///         /// The module containing attributes for `MyConfigTable`.
///     ),
///     entry_module_visibility(pub),
/// )]
/// struct MyConfigTable {
///     #[snec]
///     field_with_a_receiver: String,
///     #[snec(
///         entry,
///         receiver(
///             {EmptyReceiver::new()}: EmptyReceiver
///         ),
///     )]
///     field_without_a_receiver: i32,
/// }
/// struct MyReceiver;
/// impl Receiver<entries::FieldWithAReceiver> for MyReceiver {
///     fn receive(&mut self, new_value: &String) {
///         println!("Received a new value: {}", new_value);
///     }
/// }
/// # */
/// ```
#[proc_macro_derive(ConfigTable, attributes(snec))]
#[inline]
pub fn derive_config_table(input: TokenStream) -> TokenStream {
    derive_config_table_expand(input.into())
        .unwrap_or_else(|err| err.to_compile_error())
        .into()
}