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quick modifier parser macro

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Breval Ferrari 2024-10-10 19:43:40 -04:00
parent f9841267ec
commit 2d5291c07b
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GPG key ID: 6FED68D87C479A59
4 changed files with 67 additions and 3 deletions
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46
bng_macros/src/lib.rs
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@ -15,6 +15,12 @@ pub fn slope_modifier_parser(input: TokenStream) -> TokenStream {
impl_slope_modifier_parser(ast)
}
#[proc_macro_derive(QuickModifierParser)]
pub fn quick_modifier_parser(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
impl_quick_modifier_parser(ast)
}
fn impl_modifier_parser(ast: DeriveInput) -> TokenStream {
let name = &ast.ident;
if let Data::Enum(DataEnum { variants, .. }) = ast.data {
@ -77,3 +83,43 @@ fn impl_slope_modifier_parser(ast: DeriveInput) -> TokenStream {
panic!("this macro only works on enums")
}
}
fn impl_quick_modifier_parser(ast: DeriveInput) -> TokenStream {
let name = &ast.ident;
if let Data::Enum(DataEnum { variants, .. }) = ast.data {
let match_arms = variants.iter().map(|variant| {
let variant_name = &variant.ident;
quote! {
nom::combinator::map(
nom::branch::alt(
(
nom::combinator::value(
true,
nom::character::complete::char(#name::#variant_name(Default::default()).token()[0])
),
nom::combinator::value(
false,
nom::character::complete::char(#name::#variant_name(Default::default()).token()[1])
)
)
),
#name::#variant_name
)
}
});
quote! {
impl lex::lexer::Parse for #name {
fn parse(input: &str) -> nom::IResult<&str, #name> {
nom::branch::alt((
#(#match_arms),*
))(input)
}
}
}
.into()
} else {
panic!("this macro only works on enums")
}
}