40 lines
1.2 KiB
Rust
40 lines
1.2 KiB
Rust
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use proc_macro::TokenStream;
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use quote::quote;
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use syn::{parse_macro_input, LitStr};
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/// Usage: brainfuck!("++>-[].,")
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#[proc_macro]
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pub fn brainfuck(input: TokenStream) -> TokenStream {
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let lit = parse_macro_input!(input as LitStr);
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let s = lit.value();
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// Map characters -> OpCode tokens
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let mut ops = Vec::new();
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for ch in s.chars() {
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let token = match ch {
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'>' => Some(quote! { OpCode::IncrementPointer }),
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'<' => Some(quote! { OpCode::DecrementPointer }),
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'+' => Some(quote! { OpCode::Increment }),
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'-' => Some(quote! { OpCode::Decrement }),
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'.' => Some(quote! { OpCode::Write }),
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',' => Some(quote! { OpCode::Read }),
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'[' => Some(quote! { OpCode::LoopBegin }),
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']' => Some(quote! { OpCode::LoopEnd }),
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_ => None, // ignore comments/whitespace
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};
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if let Some(t) = token {
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ops.push(t);
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}
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}
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let n = ops.len();
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// Expand to a const array; the caller gets a [OpCode; N]
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let expanded = quote! {
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{
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const __BF_OPS: [OpCode; #n] = [ #(#ops),* ];
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__BF_OPS
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}
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};
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expanded.into()
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}
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