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extern crate proc_macro;
extern crate quote;
use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
use quote::quote;
use std::collections::BTreeMap;
use std::usize;
fn try_parse_c_const(value: &str) -> Option<usize> {
if value.starts_with("0x") {
usize::from_str_radix(value.trim_start_matches("0x"), 16).ok()
} else if value.starts_with("0b") {
usize::from_str_radix(value.trim_start_matches("0b"), 2).ok()
} else if value.starts_with("0") {
usize::from_str_radix(value.trim_start_matches("0"), 8).ok()
} else {
usize::from_str_radix(value, 10).ok()
}
}
#[proc_macro_attribute]
pub fn preprocessor(_attr: TokenStream, item: TokenStream) -> TokenStream {
let iters: Vec<TokenTree> = item.into_iter().collect();
let mut enum_name: Option<String> = None;
let mut gen_tokens: Vec<TokenTree> = Vec::new();
let mut enum_tokens: Vec<TokenTree> = Vec::new();
let mut mapping: BTreeMap<String, String> = BTreeMap::new();
for it in iters {
match it {
TokenTree::Ident(ref ident) => {
if ident.to_string() == "const" || ident.to_string() == "str" {
continue;
}
if enum_name.is_some() {
panic!("more than only name found");
}
enum_name = Some(ident.to_string());
}
TokenTree::Literal(ref literal) => {
let mut data = literal.to_string();
data.remove(data.len() - 1);
data.remove(0);
for line in data.split("\n") {
let tokens: Vec<&str> = line
.split(|ch| ch == ' ' || ch == '\t')
.filter(|s| s.len() > 0)
.collect();
if tokens.len() == 0 {
continue;
}
if tokens.len() != 3 {
panic!("unsupported line: {}", line);
}
if tokens[0] == "#define" {
let name = tokens[1];
let value = tokens[2];
mapping.insert(String::from(name), String::from(value));
if let Some(value_usize) = try_parse_c_const(value) {
gen_tokens
.push(TokenTree::Ident(Ident::new("const", Span::call_site())));
gen_tokens.push(TokenTree::Ident(Ident::new(
&format!("{}_{}", enum_name.as_ref().expect("no name found"), name),
Span::call_site(),
)));
gen_tokens.push(TokenTree::Punct(Punct::new(':', Spacing::Alone)));
gen_tokens
.push(TokenTree::Ident(Ident::new("usize", Span::call_site())));
gen_tokens.push(TokenTree::Punct(Punct::new('=', Spacing::Alone)));
gen_tokens
.push(TokenTree::Literal(Literal::usize_unsuffixed(value_usize)));
gen_tokens.push(TokenTree::Punct(Punct::new(';', Spacing::Alone)));
enum_tokens.push(TokenTree::Ident(Ident::new(name, Span::call_site())));
enum_tokens.push(TokenTree::Punct(Punct::new('=', Spacing::Alone)));
enum_tokens
.push(TokenTree::Literal(Literal::usize_unsuffixed(value_usize)));
enum_tokens.push(TokenTree::Punct(Punct::new(',', Spacing::Alone)));
} else if let Some(_) = mapping.get(value) {
gen_tokens
.push(TokenTree::Ident(Ident::new("const", Span::call_site())));
gen_tokens.push(TokenTree::Ident(Ident::new(
&format!("{}_{}", enum_name.as_ref().expect("no name found"), name),
Span::call_site(),
)));
gen_tokens.push(TokenTree::Punct(Punct::new(':', Spacing::Alone)));
gen_tokens
.push(TokenTree::Ident(Ident::new("usize", Span::call_site())));
gen_tokens.push(TokenTree::Punct(Punct::new('=', Spacing::Alone)));
gen_tokens.push(TokenTree::Ident(Ident::new(
&format!(
"{}_{}",
enum_name.as_ref().expect("no name found"),
value
),
Span::call_site(),
)));
gen_tokens.push(TokenTree::Punct(Punct::new(';', Spacing::Alone)));
}
}
}
}
_ => {}
}
}
let mut enum_stream = TokenStream::new();
enum_stream.extend(enum_tokens);
let group = Group::new(Delimiter::Brace, enum_stream);
let debug: TokenStream =
quote!(#[repr(usize)]#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]).into();
gen_tokens.extend(debug);
gen_tokens.push(TokenTree::Ident(Ident::new("enum", Span::call_site())));
gen_tokens.push(TokenTree::Ident(Ident::new(
enum_name.as_ref().expect("no name found"),
Span::call_site(),
)));
gen_tokens.push(TokenTree::Group(group));
let mut result = TokenStream::new();
result.extend(gen_tokens);
result.into()
}