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Derive with strings not quote #14

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103 changes: 50 additions & 53 deletions num_enum_derive/src/lib.rs
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Original file line number Diff line number Diff line change
@@ -1,13 +1,16 @@
extern crate alloc;
extern crate proc_macro;
use ::proc_macro::TokenStream;
use ::proc_macro2::Span;
use ::quote::quote;
use ::quote::{quote, ToTokens};
use ::std::iter::FromIterator;
use ::syn::{
parse::{Parse, ParseStream},
parse_macro_input, parse_quote, Data, DeriveInput, Error, Expr, Ident, LitInt, LitStr, Meta,
Result,
};
use alloc::format;
use alloc::str::FromStr;

macro_rules! die {
($span:expr=>
Expand Down Expand Up @@ -93,7 +96,7 @@ impl Parse for EnumInfo {
} else {
next_discriminant.clone()
};
let ref variant_ident = variant.ident;
let variant_ident = &variant.ident;
next_discriminant = parse_quote! {
#repr::wrapping_add(#variant_ident, 1)
};
Expand Down Expand Up @@ -180,9 +183,6 @@ pub fn derive_try_from_primitive(input: TokenStream) -> TokenStream {
value_expressions_to_enum_keys,
} = parse_macro_input!(input);

let (match_const_exprs, enum_keys): (Vec<Expr>, Vec<Ident>) =
value_expressions_to_enum_keys.into_iter().unzip();

let krate = Ident::new(
&::proc_macro_crate::crate_name("num_enum")
.map(::std::borrow::Cow::from)
Expand All @@ -193,55 +193,52 @@ pub fn derive_try_from_primitive(input: TokenStream) -> TokenStream {
Span::call_site(),
);

TokenStream::from(quote! {
impl ::#krate::TryFromPrimitive for #name {
type Primitive = #repr;

const NAME: &'static str = stringify!(#name);

fn try_from_primitive (
number: Self::Primitive,
) -> ::core::result::Result<
Self,
::#krate::TryFromPrimitiveError<Self>,
>
{
// Use intermediate const(s) so that enums defined like
// `Two = ONE + 1u8` work properly.
#![allow(non_upper_case_globals)]
#(
const #enum_keys: #repr =
#match_const_exprs
;
)*
match number {
#(
| #enum_keys => ::core::result::Result::Ok(
#name::#enum_keys
),
)*
| _ => ::core::result::Result::Err(
::#krate::TryFromPrimitiveError { number }
),
}
}
}

impl ::core::convert::TryFrom<#repr> for #name {
type Error = ::#krate::TryFromPrimitiveError<Self>;
let mut s = String::new();
s.push_str(&format!(
r#"impl ::{krate}::TryFromPrimitive for {name} {{
type Primitive = {repr};
const NAME: &'static str = "{name}";
fn try_from_primitive(
number: Self::Primitive,
) -> ::core::result::Result<Self, ::{krate}::TryFromPrimitiveError<Self>> {{
#![allow(non_upper_case_globals)]
"#,
krate = krate,
repr = repr,
name = name
));
for (match_const_expr, enum_key) in &value_expressions_to_enum_keys {
s.push_str(&format!(
" const {enum_key}: {repr} = {match_const_expr};\n",
enum_key = enum_key,
repr = repr,
match_const_expr = match_const_expr.into_token_stream(),
));
}
s.push_str(" match number {\n");
for (_match_const_expr, enum_key) in &value_expressions_to_enum_keys {
s.push_str(&format!(
" {enum_key} => ::core::result::Result::Ok({name}::{enum_key}),\n",
enum_key = enum_key,
name = name
));
}
s.push_str(&format!(r#" _ => ::core::result::Result::Err(::{krate}::TryFromPrimitiveError {{ number }}),
}}
}}
}}
impl ::core::convert::TryFrom<{repr}> for {name} {{
type Error = ::{krate}::TryFromPrimitiveError<Self>;
#[inline]
fn try_from(
number: {repr},
) -> ::core::result::Result<Self, ::{krate}::TryFromPrimitiveError<Self>> {{
::{krate}::TryFromPrimitive::try_from_primitive(number)
}}
}}
"#, krate=krate, repr=repr, name=name));

#[inline]
fn try_from (
number: #repr,
) -> ::core::result::Result<
Self,
::#krate::TryFromPrimitiveError<Self>,
>
{
::#krate::TryFromPrimitive::try_from_primitive(number)
}
}
})
TokenStream::from_str(&s).unwrap()
}

/// Generates a `unsafe fn from_unchecked (number: Primitive) -> Self`
Expand Down