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Use a proc macro to declare preallocated symbols
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,173 @@ | ||
| use proc_macro::TokenStream; | ||
| use syn::{ | ||
| Token, Ident, LitStr, | ||
| braced, parse_macro_input, | ||
| }; | ||
| use syn::parse::{Result, Parse, ParseStream}; | ||
| use syn; | ||
| use std::collections::HashSet; | ||
| use quote::quote; | ||
|
|
||
| #[allow(non_camel_case_types)] | ||
| mod kw { | ||
| syn::custom_keyword!(Keywords); | ||
| syn::custom_keyword!(Other); | ||
| } | ||
|
|
||
| struct Keyword { | ||
| name: Ident, | ||
| value: LitStr, | ||
| } | ||
|
|
||
| impl Parse for Keyword { | ||
| fn parse(input: ParseStream<'_>) -> Result<Self> { | ||
| let name = input.parse()?; | ||
| input.parse::<Token![,]>()?; | ||
| let value = input.parse()?; | ||
| input.parse::<Token![,]>()?; | ||
|
|
||
| Ok(Keyword { | ||
| name, | ||
| value, | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| struct Symbol(Ident); | ||
|
|
||
| impl Parse for Symbol { | ||
| fn parse(input: ParseStream<'_>) -> Result<Self> { | ||
| let ident: Ident = input.parse()?; | ||
| input.parse::<Token![,]>()?; | ||
|
|
||
| Ok(Symbol(ident)) | ||
| } | ||
| } | ||
|
|
||
| /// A type used to greedily parse another type until the input is empty. | ||
| struct List<T>(Vec<T>); | ||
|
|
||
| impl<T: Parse> Parse for List<T> { | ||
| fn parse(input: ParseStream<'_>) -> Result<Self> { | ||
| let mut list = Vec::new(); | ||
| while !input.is_empty() { | ||
| list.push(input.parse()?); | ||
| } | ||
| Ok(List(list)) | ||
| } | ||
| } | ||
|
|
||
| struct Input { | ||
| keywords: List<Keyword>, | ||
| symbols: List<Symbol>, | ||
| } | ||
|
|
||
| impl Parse for Input { | ||
| fn parse(input: ParseStream<'_>) -> Result<Self> { | ||
| input.parse::<kw::Keywords>()?; | ||
| let content; | ||
| braced!(content in input); | ||
| let keywords = content.parse()?; | ||
|
|
||
| input.parse::<kw::Other>()?; | ||
| let content; | ||
| braced!(content in input); | ||
| let symbols = content.parse()?; | ||
|
|
||
| Ok(Input { | ||
| keywords, | ||
| symbols, | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| pub fn symbols(input: TokenStream) -> TokenStream { | ||
| let input = parse_macro_input!(input as Input); | ||
|
|
||
| let mut keyword_stream = quote! {}; | ||
| let mut symbols_stream = quote! {}; | ||
| let mut prefill_stream = quote! {}; | ||
| let mut from_str_stream = quote! {}; | ||
| let mut counter = 0u32; | ||
| let mut keys = HashSet::<String>::new(); | ||
|
|
||
| let mut check_dup = |str: &str| { | ||
| if !keys.insert(str.to_string()) { | ||
| panic!("Symbol `{}` is duplicated", str); | ||
| } | ||
| }; | ||
|
|
||
| for keyword in &input.keywords.0 { | ||
| let name = &keyword.name; | ||
| let value = &keyword.value; | ||
| check_dup(&value.value()); | ||
| prefill_stream.extend(quote! { | ||
| #value, | ||
| }); | ||
| keyword_stream.extend(quote! { | ||
| pub const #name: Keyword = Keyword { | ||
| ident: Ident::with_empty_ctxt(super::Symbol::new(#counter)) | ||
| }; | ||
| }); | ||
| from_str_stream.extend(quote! { | ||
| #value => Ok(#name), | ||
| }); | ||
| counter += 1; | ||
| } | ||
|
|
||
| for symbol in &input.symbols.0 { | ||
| let value = &symbol.0; | ||
| let value_str = value.to_string(); | ||
| check_dup(&value_str); | ||
| prefill_stream.extend(quote! { | ||
| #value_str, | ||
| }); | ||
| symbols_stream.extend(quote! { | ||
| pub const #value: Symbol = Symbol::new(#counter); | ||
| }); | ||
| counter += 1; | ||
| } | ||
|
|
||
| TokenStream::from(quote! { | ||
| #[allow(non_upper_case_globals)] | ||
| pub mod keywords { | ||
| use super::{Symbol, Ident}; | ||
| #[derive(Clone, Copy, PartialEq, Eq)] | ||
| pub struct Keyword { | ||
| ident: Ident, | ||
| } | ||
| impl Keyword { | ||
| #[inline] pub fn ident(self) -> Ident { self.ident } | ||
| #[inline] pub fn name(self) -> Symbol { self.ident.name } | ||
| } | ||
|
|
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| #keyword_stream | ||
|
|
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| impl std::str::FromStr for Keyword { | ||
| type Err = (); | ||
|
|
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| fn from_str(s: &str) -> Result<Self, ()> { | ||
| match s { | ||
| #from_str_stream | ||
| _ => Err(()), | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
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| #[allow(non_upper_case_globals)] | ||
| pub mod symbols { | ||
| use super::Symbol; | ||
|
|
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| #symbols_stream | ||
| } | ||
|
|
||
| impl Interner { | ||
| pub fn fresh() -> Self { | ||
| Interner::prefill(&[ | ||
| #prefill_stream | ||
| ]) | ||
| } | ||
| } | ||
| }) | ||
| } |
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207 161 macro_rules! symbols {
208 163 #symbols_stream
https://github.com/rust-lang/rust/tree/master/src/librustc_macros/src/symbols.rs#L163