Files
simconnect-sdk-rs/simconnect-sdk-derive/src/lib.rs
Mihai Dinculescu 88d9f78e59 Update crates
2023-02-09 10:34:40 +00:00

264 lines
9.0 KiB
Rust

//! This crate provides the [`crate::SimConnectObject`] derive macro of simconnect-sdk.
extern crate proc_macro;
use std::collections::HashMap;
use fields::{extract_attribute_properties, parse_field_attributes, ALLOWED_CLASS_ATTRIBUTES};
use helpers::{get_attribute, mk_err};
use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, DeriveInput};
mod fields;
mod helpers;
/// SimConnectObject derive macro.
///
/// # Struct Arguments
/// * `period` - Required. One of `once`, `visual-frame`, `sim-frame`, `second`.
/// * `condition` - Optional. Defaults to `none`. The condition of the data. Must be either `none` or `changed`. `changed` = Data will only be sent to the client when one or more values have changed. All the variables in a data definition will be returned if just one of the values changes.
/// * `interval` - Optional. Defaults to `0`. The number of period events that should elapse between transmissions of the data. `0` means the data is transmitted every Period, `1` means that the data is transmitted every other Period, etc.
///
/// # Field Arguments
/// * `name` - Required. The name of the field. One from <https://www.prepar3d.com/SDKv5/sdk/references/variables/simulation_variables.html>.
/// * `unit` - Optional. The unit of the field. For `string`s and `bool`s it should be left out or be empty string. For numeric fields it should be one from <https://www.prepar3d.com/SDKv5/sdk/references/variables/simulation_variables.html>.
///
/// # Example
///
/// ```rust
/// # use simconnect_sdk_derive::SimConnectObject;
///
/// #[derive(Debug, Clone, SimConnectObject)]
/// #[simconnect(period = "second")]
/// struct AirplaneData {
/// #[simconnect(name = "TITLE")]
/// title: String,
/// #[simconnect(name = "CATEGORY")]
/// category: String,
/// #[simconnect(name = "PLANE LATITUDE", unit = "degrees")]
/// lat: f64,
/// #[simconnect(name = "PLANE LONGITUDE", unit = "degrees")]
/// lon: f64,
/// #[simconnect(name = "PLANE ALTITUDE", unit = "feet")]
/// alt: f64,
/// #[simconnect(name = "SIM ON GROUND", unit = "bool")]
/// sim_on_ground: bool,
/// }
/// ```
#[proc_macro_derive(SimConnectObject, attributes(simconnect))]
pub fn derive(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
let name_ident = &ast.ident;
let packed_ident = syn::Ident::new(&format!("{name_ident}CPacked"), name_ident.span());
let fields = if let syn::Data::Struct(syn::DataStruct {
fields: syn::Fields::Named(syn::FieldsNamed { ref named, .. }),
..
}) = ast.data
{
named
} else {
return mk_err(
ast,
"Unsupported field type. Only named fields are supported.",
)
.into();
};
// parse the fields and their attributes
let mut parsed_fields = Vec::with_capacity(fields.len());
for field in fields {
let result = parse_field_attributes(field);
match result {
Ok(field) => {
parsed_fields.push(field);
}
Err(e) => return e.into(),
}
}
// packed struct fields
let packed_fields = parsed_fields
.iter()
.map(|(ident, path, _)| build_packed_field(ident, path));
let packed_fields_assignments = parsed_fields
.iter()
.map(|(ident, path, _)| build_packed_field_assignment(ident, path));
// SC fields
let sc_definition = parsed_fields
.iter()
.map(|(_, path, properties)| build_sc_definition(path, properties));
let sc_request = build_sc_request(&ast);
// put everything together
let expanded = quote! {
#[repr(C, packed)]
struct #packed_ident {
#(#packed_fields,)*
}
impl simconnect_sdk::SimConnectObjectExt for #name_ident {
fn register(client: &mut simconnect_sdk::SimConnect, id: u32) -> Result<(), simconnect_sdk::SimConnectError> {
#(#sc_definition)*
#sc_request
Ok(())
}
}
impl TryFrom<&simconnect_sdk::Object> for #name_ident {
type Error = simconnect_sdk::SimConnectError;
fn try_from(value: &simconnect_sdk::Object) -> Result<Self, Self::Error> {
let raw = value.try_transmute::<#name_ident, #packed_ident>()?;
Ok(#name_ident {
#(#packed_fields_assignments,)*
})
}
}
};
expanded.into()
}
fn build_packed_field(ident: &proc_macro2::Ident, path: &syn::Path) -> proc_macro2::TokenStream {
let path_segments = &path.segments;
let path_idents = path_segments.iter().map(|s| &s.ident);
match path_idents.last() {
Some(value) if value == "String" => {
quote! {
#ident: [std::primitive::i8; 256]
}
}
_ => {
quote! {
#ident: #path
}
}
}
}
fn build_packed_field_assignment(
ident: &proc_macro2::Ident,
path: &syn::Path,
) -> proc_macro2::TokenStream {
let path_segments = &path.segments;
let path_idents = path_segments.iter().map(|s| &s.ident);
match path_idents.last() {
Some(value) if value == "String" => {
quote! {
#ident: simconnect_sdk::fixed_c_str_to_string(&raw.#ident)
}
}
_ => {
quote! {
#ident: raw.#ident
}
}
}
}
fn build_sc_definition(
path: &syn::Path,
properties: &HashMap<String, String>,
) -> proc_macro2::TokenStream {
let error_message =
"expected attribute `#[simconnect(name = \"...\", unit = \"...\")]`. `unit` is optional.";
let path_segments = &path.segments;
let path_idents = path_segments.iter().map(|s| &s.ident);
let name = properties.get("name").expect("this should never happen");
let unit = match properties.get("unit") {
Some(unit) => unit,
None => "",
};
match path_idents.last() {
Some(value) if value == "f64" => {
quote! {
client.add_to_data_definition(id, #name, #unit, simconnect_sdk::DataType::Float64)?;
}
}
Some(value) if value == "bool" => {
quote! {
client.add_to_data_definition(id, #name, #unit, simconnect_sdk::DataType::Bool)?;
}
}
Some(value) if value == "String" => {
quote! {
client.add_to_data_definition(id, #name, #unit, simconnect_sdk::DataType::String)?;
}
}
_ => {
// this error is already caught in `parse_field_attributes`
mk_err(path, error_message)
}
}
}
fn build_sc_request(ast: &DeriveInput) -> proc_macro2::TokenStream {
let attr = get_attribute(&ast.attrs);
let error_message = "expected attribute `#[simconnect(period = \"...\", condition = \"...\", interval = ...)]`. `condition` and `interval` are optional.";
match attr {
Some(attr) => {
let properties =
extract_attribute_properties(attr, &ALLOWED_CLASS_ATTRIBUTES, error_message);
match properties {
Ok(properties) => {
let period = match properties.get("period") {
Some(p) if p == "once" => {
quote! {
simconnect_sdk::Period::Once
}
}
Some(p) if p == "visual-frame" => {
quote! {
simconnect_sdk::Period::VisualFrame
}
}
Some(p) if p == "sim-frame" => {
quote! {
simconnect_sdk::Period::SimFrame
}
}
_ => {
quote! {
simconnect_sdk::Period::Second
}
}
};
let condition = match properties.get("condition") {
Some(c) if c == "changed" => {
quote! {
simconnect_sdk::Condition::Changed
}
}
_ => {
quote! {
simconnect_sdk::Condition::None
}
}
};
let interval = match properties.get("interval") {
Some(i) => i.parse::<u32>().unwrap_or_default(),
None => 0,
};
quote! {
client.request_data_on_sim_object(id, #period, #condition, #interval)?;
}
}
Err(e) => e,
}
}
None => mk_err(ast, error_message),
}
}