42 lines
1.4 KiB
Rust
42 lines
1.4 KiB
Rust
//@ force-host
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//@ no-prefer-dynamic
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#![crate_type = "proc-macro"]
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extern crate proc_macro;
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use proc_macro::{Group, Spacing, Punct, TokenTree, TokenStream};
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// This macro exists as part of a reproduction of #61963 but without using quote/syn/proc_macro2.
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#[proc_macro_attribute]
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pub fn dom_struct(_: TokenStream, input: TokenStream) -> TokenStream {
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// Construct the expected output tokens - the input but with a `#[derive(DomObject)]` applied.
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let attributes: TokenStream =
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"#[derive(DomObject)]".to_string().parse().unwrap();
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let output: TokenStream = attributes.into_iter()
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.chain(input.into_iter()).collect();
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let mut tokens: Vec<_> = output.into_iter().collect();
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// Adjust the spacing of `>` tokens to match what `quote` would produce.
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for token in tokens.iter_mut() {
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if let TokenTree::Group(group) = token {
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let mut tokens: Vec<_> = group.stream().into_iter().collect();
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for token in tokens.iter_mut() {
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if let TokenTree::Punct(p) = token {
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if p.as_char() == '>' {
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*p = Punct::new('>', Spacing::Alone);
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}
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}
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}
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let mut stream = TokenStream::new();
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stream.extend(tokens);
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*group = Group::new(group.delimiter(), stream);
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}
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}
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let mut output = TokenStream::new();
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output.extend(tokens);
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output
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}
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