111 lines
3.1 KiB
Rust
111 lines
3.1 KiB
Rust
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use proc_macro::TokenStream;
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use quote::{quote, format_ident};
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use syn::{parse_macro_input, DeriveInput, Data, Fields};
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#[proc_macro_derive(MakeEvent, attributes(MakeEvent, setter))]
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pub fn make_event_derive(input: TokenStream) -> TokenStream {
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let input = parse_macro_input!(input as DeriveInput);
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let struct_name = &input.ident;
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let event_name = input.attrs.iter()
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.find_map(|attr| {
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if attr.path().is_ident("MakeEvent") {
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attr.parse_args::<syn::LitStr>().ok()
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} else {
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None
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}
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})
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.expect("Expected MakeEvent attribute with a name argument")
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.value();
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let mut getters = Vec::new();
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let mut setters = Vec::new();
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let mut new_args = Vec::new();
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let mut new_inits = Vec::new();
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let mut has_cancelled_field = false;
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if let Data::Struct(data) = input.data {
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if let Fields::Named(fields) = data.fields {
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for field in fields.named.iter() {
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let field_name = &field.ident;
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let field_ty = &field.ty;
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if field_name.as_ref().map(|name| name == "cancelled").unwrap_or(false) {
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has_cancelled_field = true;
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} else {
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new_args.push(quote! { #field_name: #field_ty });
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new_inits.push(quote! { #field_name });
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}
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getters.push(quote! {
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pub fn #field_name(&self) -> &#field_ty {
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&self.#field_name
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}
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});
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if field.attrs.iter().any(|attr| attr.path().is_ident("setter")) {
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let setter_name = format_ident!("set_{}", field_name.as_ref().unwrap());
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setters.push(quote! {
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pub fn #setter_name(&mut self, value: #field_ty) {
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self.#field_name = value;
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}
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});
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}
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}
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}
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} else {
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panic!("MakeEvent can only be derived for structs with named fields");
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}
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let cancel_methods = if has_cancelled_field {
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quote! {
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fn cancel(&mut self) {
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self.cancelled = true;
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}
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fn is_cancelled(&self) -> bool {
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self.cancelled
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}
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}
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} else {
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quote! {}
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};
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let new_method = if has_cancelled_field {
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quote! {
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pub fn new(#(#new_args),*) -> Self {
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Self {
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#(#new_inits),*,
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cancelled: false,
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}
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}
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}
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} else {
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quote! {
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pub fn new(#(#new_args),*) -> Self {
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Self {
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#(#new_inits),*
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}
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}
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}
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};
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let expanded = quote! {
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impl #struct_name {
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#(#getters)*
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#(#setters)*
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#new_method
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}
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impl Event for #struct_name {
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#cancel_methods
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fn name(&self) -> String {
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#event_name.to_string()
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}
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}
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};
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TokenStream::from(expanded)
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}
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