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|
use proc_macro::TokenStream;
use quote::quote;
use std::collections::HashSet;
use syn::parse::{Parse, ParseStream, Result};
use syn::{braced, parse_macro_input, Ident, LitStr, Token};
mod kw {
syn::custom_keyword!(Keywords);
syn::custom_keyword!(Symbols);
}
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 {
name: Ident,
value: Option<LitStr>,
}
impl Parse for Symbol {
fn parse(input: ParseStream<'_>) -> Result<Self> {
let name = input.parse()?;
let value = match input.parse::<Token![:]>() {
Ok(_) => Some(input.parse()?),
Err(_) => None,
};
input.parse::<Token![,]>()?;
Ok(Symbol { name, value })
}
}
/// 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::Symbols>()?;
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 digits_stream = quote! {};
let mut prefill_stream = quote! {};
let mut counter = 0u32;
let mut keys = HashSet::<String>::new();
let mut prev_key: Option<String> = None;
let mut errors = Vec::<String>::new();
let mut check_dup = |str: &str, errors: &mut Vec<String>| {
if !keys.insert(str.to_string()) {
errors.push(format!("Symbol `{}` is duplicated", str));
}
};
let mut check_order = |str: &str, errors: &mut Vec<String>| {
if let Some(ref prev_str) = prev_key {
if str < prev_str {
errors.push(format!("Symbol `{}` must precede `{}`", str, prev_str));
}
}
prev_key = Some(str.to_string());
};
// Generate the listed keywords.
for keyword in &input.keywords.0 {
let name = &keyword.name;
let value = &keyword.value;
check_dup(&value.value(), &mut errors);
prefill_stream.extend(quote! {
#value,
});
keyword_stream.extend(quote! {
#[allow(non_upper_case_globals)]
pub const #name: Symbol = Symbol::new(#counter);
});
counter += 1;
}
// Generate the listed symbols.
for symbol in &input.symbols.0 {
let name = &symbol.name;
let value = match &symbol.value {
Some(value) => value.value(),
None => name.to_string(),
};
check_dup(&value, &mut errors);
check_order(&name.to_string(), &mut errors);
prefill_stream.extend(quote! {
#value,
});
symbols_stream.extend(quote! {
#[allow(rustc::default_hash_types)]
#[allow(non_upper_case_globals)]
pub const #name: Symbol = Symbol::new(#counter);
});
counter += 1;
}
// Generate symbols for the strings "0", "1", ..., "9".
for n in 0..10 {
let n = n.to_string();
check_dup(&n, &mut errors);
prefill_stream.extend(quote! {
#n,
});
digits_stream.extend(quote! {
Symbol::new(#counter),
});
counter += 1;
}
if !errors.is_empty() {
for error in errors.into_iter() {
eprintln!("error: {}", error)
}
panic!("errors in `Keywords` and/or `Symbols`");
}
let tt = TokenStream::from(quote! {
macro_rules! keywords {
() => {
#keyword_stream
}
}
macro_rules! define_symbols {
() => {
#symbols_stream
#[allow(non_upper_case_globals)]
pub const digits_array: &[Symbol; 10] = &[
#digits_stream
];
}
}
impl Interner {
pub fn fresh() -> Self {
Interner::prefill(&[
#prefill_stream
])
}
}
});
// To see the generated code generated, uncomment this line, recompile, and
// run the resulting output through `rustfmt`.
//eprintln!("{}", tt);
tt
}
|
