diff options
Diffstat (limited to 'util-macros/src')
| -rw-r--r-- | util-macros/src/lib.rs | 47 |
1 files changed, 44 insertions, 3 deletions
diff --git a/util-macros/src/lib.rs b/util-macros/src/lib.rs index 036ffc8..26f1936 100644 --- a/util-macros/src/lib.rs +++ b/util-macros/src/lib.rs @@ -1,10 +1,12 @@ use proc_macro::{TokenStream, TokenTree}; use quote::quote; -/// Subtracts two numbers and calls a given callback macro with the result. +/// Subtracts two numbers and calls a given callback macro with the result. Optionally, a +/// additional argument (delimeted) can be given which will also be passed to the +/// callback. /// /// # Input -/// `number - number, callback` +/// `$num_a - $num_b, $callback $(, $user_data)?` /// /// # Examples /// ``` @@ -23,6 +25,23 @@ use quote::quote; /// ``` /// <br> /// +/// The callback macro can be called with extra arguments. +/// ``` +/// # use std::any::TypeId; +/// use util_macros::sub; +/// +/// macro_rules! sub_cb { +/// ($num: literal, $to_multiply: literal) => { +/// $num * $to_multiply +/// }; +/// } +/// +/// type Foo = [u8; sub!(5 - 2, sub_cb, (20))]; +/// +/// assert_eq!(TypeId::of::<Foo>(), TypeId::of::<[u8; 60]>()); +/// ``` +/// <br> +/// /// The callback is called with the identifier `overflow` if a overflow occurs. /// ``` /// # use std::any::TypeId; @@ -84,6 +103,28 @@ pub fn sub(input: TokenStream) -> TokenStream } }; + let opt_user_data = input_tt_iter + .next() + .map(|comma_tt| { + match comma_tt { + TokenTree::Punct(punct) if punct.as_char() == ',' => {} + _ => { + panic!("Expected a ',' token"); + } + }; + + let user_data_tt = input_tt_iter.next().unwrap(); + + let TokenTree::Group(group) = user_data_tt else { + panic!("User data must be a delimeted") + }; + + let inside: proc_macro2::TokenStream = group.stream().into(); + + quote! {, #inside } + }) + .unwrap_or_default(); + let Some(subtracted) = num_a.checked_sub(num_b) else { return quote! { #cb_ident!(overflow) @@ -94,7 +135,7 @@ pub fn sub(input: TokenStream) -> TokenStream let subtracted_lit = proc_macro2::Literal::u32_unsuffixed(subtracted); quote! { - #cb_ident!(#subtracted_lit) + #cb_ident!(#subtracted_lit #opt_user_data) } .into() } |