Add the derive proc macro
This commit is contained in:
Mihai Dinculescu
@@ -1,7 +1,341 @@
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extern crate proc_macro;
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use proc_macro::TokenStream;
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use std::collections::HashMap;
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#[proc_macro_derive(SimConnectObject, attributes(field))]
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pub fn derive(_: TokenStream) -> TokenStream {
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TokenStream::new()
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use once_cell::sync::Lazy;
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use proc_macro::TokenStream;
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use quote::quote;
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use syn::{parse_macro_input, DeriveInput};
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struct FieldInfo {
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required: bool,
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accepted_values: Vec<String>,
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}
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static ALLOWED_CLASS_ATTRIBUTES: Lazy<HashMap<String, FieldInfo>> = Lazy::new(|| {
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let mut map = HashMap::new();
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map.insert(
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"period".to_string(),
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FieldInfo {
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required: true,
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accepted_values: vec![
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"once".to_string(),
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"visual-frame".to_string(),
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"sim-frame".to_string(),
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"second".to_string(),
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],
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},
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);
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map.insert(
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"condition".to_string(),
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FieldInfo {
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required: false,
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accepted_values: vec!["none".to_string(), "changed".to_string()],
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},
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);
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map
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});
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static ALLOWED_FIELD_ATTRIBUTES: Lazy<HashMap<String, FieldInfo>> = Lazy::new(|| {
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let mut map = HashMap::new();
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map.insert(
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"name".to_string(),
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FieldInfo {
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required: true,
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accepted_values: vec![],
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},
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);
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map.insert(
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"unit".to_string(),
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FieldInfo {
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required: true,
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accepted_values: vec![],
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},
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);
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map
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});
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const SUPPORTED_FIELD_TYPES: [&str; 2] = ["f64", "bool"];
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/// SimConnectObject derive macro.
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///
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/// # Struct Arguments
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/// * `period` - Required. One of `once`, `visual-frame`, `sim-frame`, `second`.
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/// * `condition` - Optional. The condition of the data. Must be either `none` or `changed`. Defaults to `none`.
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///
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/// # Field Arguments
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/// * `name` - Required. The name of the field. One from <http://www.prepar3d.com/SDKv3/LearningCenter/utilities/variables/simulation_variables.html#Simulation%20Variables>.
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/// * `unit` - Required. The unit of the field.
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///
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/// # Example
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/// ```rust
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/// use simconnect_sdk::SimConnectObject;
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///
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/// #[derive(Debug, Clone, SimConnectObject)]
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/// #[simconnect(period = "second")]
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/// struct GpsData {
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/// #[simconnect(name = "PLANE LATITUDE", unit = "degrees")]
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/// lat: f64,
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/// #[simconnect(name = "PLANE LONGITUDE", unit = "degrees")]
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/// lon: f64,
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/// #[simconnect(name = "PLANE LONGITUDE", unit = "degrees")]
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/// alt: f64,
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/// }
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/// ```
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#[proc_macro_derive(SimConnectObject, attributes(simconnect))]
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pub fn derive(input: TokenStream) -> TokenStream {
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let ast = parse_macro_input!(input as DeriveInput);
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let name = &ast.ident;
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let fields = if let syn::Data::Struct(syn::DataStruct {
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fields: syn::Fields::Named(syn::FieldsNamed { ref named, .. }),
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..
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}) = ast.data
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{
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named
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} else {
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return mk_err(
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ast,
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"Unsupported field type. Only named fields are supported.",
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)
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.into();
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};
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let build_fields = fields.iter().map(parse_field);
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let request_data = request_data(&ast);
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let expanded = quote! {
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impl simconnect_sdk::SimConnectObjectExt for #name {
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fn register(client: &mut simconnect_sdk::SimConnect, id: u32) -> Result<(), simconnect_sdk::SimConnectError> {
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#(#build_fields)*
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#request_data
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Ok(())
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}
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}
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impl TryFrom<&simconnect_sdk::NotificationData> for #name {
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type Error = simconnect_sdk::SimConnectError;
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fn try_from(value: &simconnect_sdk::NotificationData) -> Result<Self, Self::Error> {
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value.try_transmute::<#name>()
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}
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}
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};
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expanded.into()
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}
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fn parse_field(f: &syn::Field) -> proc_macro2::TokenStream {
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let error_message = "expected attribute `#[simconnect(name = \"...\", unit = \"...\")]`";
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let attr = get_attribute(&f.attrs);
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match attr {
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Some(attr) => {
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let ty = &f.ty;
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let properties =
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extract_attribute_string_properties(attr, &ALLOWED_FIELD_ATTRIBUTES, error_message);
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match properties {
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Ok(properties) => {
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let error_message_supported_types = &format!(
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"Field type must be one of ['{}']",
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SUPPORTED_FIELD_TYPES.join("', '")
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);
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match ty {
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syn::Type::Path(syn::TypePath { path, .. }) => {
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let path = &path.segments;
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let path = path.iter().map(|s| &s.ident);
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let name = properties.get("name").expect("this should never happen");
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let unit = properties.get("unit").expect("this should never happen");
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match path.last() {
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Some(value) if value == "f64" => {
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quote! {
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client.add_to_data_definition(id, #name, #unit, simconnect_sdk::DataType::Float64)?;
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}
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}
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Some(value) if value == "bool" => {
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quote! {
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client.add_to_data_definition(id, #name, #unit, simconnect_sdk::DataType::Bool)?;
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}
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}
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_ => mk_err(f, error_message_supported_types),
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}
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}
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_ => mk_err(f, error_message_supported_types),
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}
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}
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Err(e) => e,
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}
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}
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None => mk_err(f, error_message),
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}
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}
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fn request_data(ast: &DeriveInput) -> proc_macro2::TokenStream {
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let attr = get_attribute(&ast.attrs);
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let error_message = "expected attribute `#[simconnect(period = \"...\", condition = \"...\")]`";
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match attr {
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Some(attr) => {
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let properties =
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extract_attribute_string_properties(attr, &ALLOWED_CLASS_ATTRIBUTES, error_message);
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match properties {
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Ok(properties) => {
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let period = match properties.get("period") {
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Some(p) if p == "once" => {
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quote! {
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simconnect_sdk::Period::Once
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}
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}
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Some(p) if p == "visual-frame" => {
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quote! {
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simconnect_sdk::Period::VisualFrame
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}
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}
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Some(p) if p == "sim-frame" => {
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quote! {
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simconnect_sdk::Period::SimFrame
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}
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}
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_ => {
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quote! {
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simconnect_sdk::Period::Second
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}
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}
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};
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let condition = match properties.get("condition") {
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Some(c) if c == "changed" => {
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quote! {
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simconnect_sdk::Condition::Changed
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}
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}
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_ => {
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quote! {
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simconnect_sdk::Condition::None
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}
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}
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};
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quote! {
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client.request_data_on_sim_object(id, #period, #condition, 0)?;
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}
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}
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Err(e) => e,
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}
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}
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None => mk_err(ast, error_message),
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}
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}
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fn get_attribute(attrs: &[syn::Attribute]) -> Option<&syn::Attribute> {
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attrs
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.iter()
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.find(|&attr| attr.path.segments.len() == 1 && attr.path.segments[0].ident == "simconnect")
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}
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fn extract_attribute_string_properties(
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attr: &syn::Attribute,
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allowed_properties: &HashMap<String, FieldInfo>,
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error_message: &str,
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) -> Result<HashMap<String, String>, proc_macro2::TokenStream> {
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let mut results = HashMap::new();
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match attr.parse_meta() {
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Ok(syn::Meta::List(nvs)) => {
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for item in nvs.nested.iter() {
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match &item {
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syn::NestedMeta::Meta(syn::Meta::NameValue(nv)) => {
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match nv.path.get_ident() {
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Some(ident) => {
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let ident_string = ident.to_string();
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let allowed_property = allowed_properties.get(&ident_string);
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match allowed_property {
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Some(property) => {
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if results.contains_key(&ident_string) {
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// found a duplicate property name
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return Err(mk_err(nvs.clone(), error_message));
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}
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match &nv.lit {
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syn::Lit::Str(s) => {
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let value = s.value();
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if !property.accepted_values.is_empty()
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&& !property.accepted_values.contains(&value)
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{
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// found an invalid value
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return Err(mk_err(
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nv,
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&format!(
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"`{ident_string}` must be one of ['{}']",
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property.accepted_values.join("', '")
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),
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));
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}
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results.insert(ident_string, value);
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}
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lit => {
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return Err(syn::Error::new_spanned(
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nv,
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format!("expected string, found {lit:?}"),
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)
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.to_compile_error())
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}
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}
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}
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None => {
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// found an unexpected property name
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return Err(mk_err(nvs.clone(), error_message));
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}
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}
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}
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None => {
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// no ident found
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return Err(mk_err(nvs.clone(), error_message));
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}
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}
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}
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meta => {
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// nvc.nested[] was not k = v
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return Err(mk_err(meta, error_message));
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}
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}
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}
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// check that all required properties are specified
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for (field, _) in allowed_properties.iter().filter(|(_, fi)| fi.required) {
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if !results.contains_key(field) {
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return Err(mk_err(nvs, error_message));
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}
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}
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}
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Ok(meta) => {
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// inside of #[] there was just an identifier (`#[simconnect]`)
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// or a key-value mapping (`#[simconnect = "foo"]`), neither of which are okay.
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return Err(mk_err(meta, error_message));
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}
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Err(e) => {
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return Err(e.to_compile_error());
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}
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};
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Ok(results)
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}
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fn mk_err<T: quote::ToTokens>(t: T, message: &str) -> proc_macro2::TokenStream {
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syn::Error::new_spanned(t, message).to_compile_error()
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}
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