Factor out a discriminant processing library
diff --git a/syntax/parse.rs b/syntax/parse.rs
index f84ff32..eff14c0 100644
--- a/syntax/parse.rs
+++ b/syntax/parse.rs
@@ -1,3 +1,4 @@
+use crate::syntax::discriminant::DiscriminantSet;
use crate::syntax::report::Errors;
use crate::syntax::Atom::*;
use crate::syntax::{
@@ -6,15 +7,12 @@
};
use proc_macro2::TokenStream;
use quote::{format_ident, quote};
-use std::collections::HashSet;
-use std::u32;
use syn::parse::{ParseStream, Parser};
use syn::punctuated::Punctuated;
use syn::{
- Abi, Attribute, Error, Expr, ExprLit, Fields, FnArg, ForeignItem, ForeignItemFn,
- ForeignItemType, GenericArgument, Ident, Item, ItemEnum, ItemForeignMod, ItemStruct, Lit, Pat,
- PathArguments, Result, ReturnType, Token, Type as RustType, TypeBareFn, TypePath,
- TypeReference, TypeSlice, Variant as RustVariant,
+ Abi, Attribute, Error, Fields, FnArg, ForeignItem, ForeignItemFn, ForeignItemType,
+ GenericArgument, Ident, Item, ItemEnum, ItemForeignMod, ItemStruct, Pat, PathArguments, Result,
+ ReturnType, Token, Type as RustType, TypeBareFn, TypePath, TypeReference, TypeSlice,
};
pub mod kw {
@@ -108,8 +106,7 @@
let doc = attrs::parse_doc(cx, &item.attrs);
let mut variants = Vec::new();
- let mut discriminants = HashSet::new();
- let mut prev_discriminant = None;
+ let mut discriminants = DiscriminantSet::new();
for variant in item.variants {
match variant.fields {
Fields::Unit => {}
@@ -120,21 +117,19 @@
));
}
}
- if variant.discriminant.is_none() && prev_discriminant == Some(u32::MAX) {
- let msg = format!("discriminant overflow on value after {}", u32::MAX);
- return Err(Error::new_spanned(variant, msg));
- }
- let discriminant =
- parse_discriminant(&variant)?.unwrap_or_else(|| prev_discriminant.map_or(0, |n| n + 1));
- if !discriminants.insert(discriminant) {
- let msg = format!("discriminant value `{}` already exists", discriminant);
- return Err(Error::new_spanned(variant, msg));
- }
+ let expr = variant.discriminant.as_ref().map(|(_, expr)| expr);
+ let try_discriminant = match &expr {
+ Some(lit) => discriminants.insert(lit),
+ None => discriminants.insert_next(),
+ };
+ let discriminant = match try_discriminant {
+ Ok(discriminant) => discriminant,
+ Err(err) => return Err(Error::new_spanned(variant, err)),
+ };
variants.push(Variant {
ident: variant.ident,
discriminant,
});
- prev_discriminant = Some(discriminant);
}
Ok(Api::Enum(Enum {
@@ -146,28 +141,6 @@
}))
}
-fn parse_discriminant(variant: &RustVariant) -> Result<Option<u32>> {
- match &variant.discriminant {
- None => Ok(None),
- Some((
- _,
- Expr::Lit(ExprLit {
- lit: Lit::Int(n), ..
- }),
- )) => match n.base10_parse() {
- Ok(val) => Ok(Some(val)),
- Err(_) => Err(Error::new_spanned(
- variant,
- "cannot parse enum discriminant as an integer",
- )),
- },
- _ => Err(Error::new_spanned(
- variant,
- "enums with non-integer literal discriminants are not supported yet",
- )),
- }
-}
-
fn parse_foreign_mod(cx: &mut Errors, foreign_mod: ItemForeignMod, out: &mut Vec<Api>) {
let lang = match parse_lang(foreign_mod.abi) {
Ok(lang) => lang,