1 use proc_macro::TokenStream;
4 braced, parse_macro_input,
6 use syn::parse::{Result, Parse, ParseStream};
8 use std::collections::HashSet;
11 #[allow(non_camel_case_types)]
13 syn::custom_keyword!(Keywords);
14 syn::custom_keyword!(Symbols);
22 impl Parse for Keyword {
23 fn parse(input: ParseStream<'_>) -> Result<Self> {
24 let name = input.parse()?;
25 input.parse::<Token![:]>()?;
26 let value = input.parse()?;
27 input.parse::<Token![,]>()?;
38 value: Option<LitStr>,
41 impl Parse for Symbol {
42 fn parse(input: ParseStream<'_>) -> Result<Self> {
43 let name = input.parse()?;
44 let value = match input.parse::<Token![:]>() {
45 Ok(_) => Some(input.parse()?),
48 input.parse::<Token![,]>()?;
57 /// A type used to greedily parse another type until the input is empty.
58 struct List<T>(Vec<T>);
60 impl<T: Parse> Parse for List<T> {
61 fn parse(input: ParseStream<'_>) -> Result<Self> {
62 let mut list = Vec::new();
63 while !input.is_empty() {
64 list.push(input.parse()?);
71 keywords: List<Keyword>,
72 symbols: List<Symbol>,
75 impl Parse for Input {
76 fn parse(input: ParseStream<'_>) -> Result<Self> {
77 input.parse::<kw::Keywords>()?;
79 braced!(content in input);
80 let keywords = content.parse()?;
82 input.parse::<kw::Symbols>()?;
84 braced!(content in input);
85 let symbols = content.parse()?;
94 pub fn symbols(input: TokenStream) -> TokenStream {
95 let input = parse_macro_input!(input as Input);
97 let mut keyword_stream = quote! {};
98 let mut symbols_stream = quote! {};
99 let mut prefill_stream = quote! {};
100 let mut counter = 0u32;
101 let mut keys = HashSet::<String>::new();
103 let mut check_dup = |str: &str| {
104 if !keys.insert(str.to_string()) {
105 panic!("Symbol `{}` is duplicated", str);
109 for keyword in &input.keywords.0 {
110 let name = &keyword.name;
111 let value = &keyword.value;
112 check_dup(&value.value());
113 prefill_stream.extend(quote! {
116 keyword_stream.extend(quote! {
117 pub const #name: Symbol = Symbol::new(#counter);
122 for symbol in &input.symbols.0 {
123 let name = &symbol.name;
124 let value = match &symbol.value {
125 Some(value) => value.value(),
126 None => name.to_string(),
129 prefill_stream.extend(quote! {
132 symbols_stream.extend(quote! {
133 pub const #name: Symbol = Symbol::new(#counter);
138 let tt = TokenStream::from(quote! {
139 macro_rules! keywords {
145 macro_rules! symbols {
152 pub fn fresh() -> Self {
160 // To see the generated code generated, uncomment this line, recompile, and
161 // run the resulting output through `rustfmt`.
162 //eprintln!("{}", tt);