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- extern crate proc_macro;
- use quote::quote;
- use syn::parse_macro_input;
- /// The `#[state]` attribute defines the program's state struct, i.e., the
- /// program's global account singleton giving the program the illusion of state.
- ///
- /// To allocate space into the account on initialization, pass in the account
- /// size into the macro, e.g., `#[state(SIZE)]`. Otherwise, the size of the
- /// account returned by the struct's `new` constructor will determine the
- /// account size. When determining a size, make sure to reserve enough space
- /// for the 8 byte account discriminator prepended to the account. That is,
- /// always use 8 extra bytes.
- #[proc_macro_attribute]
- pub fn state(
- args: proc_macro::TokenStream,
- input: proc_macro::TokenStream,
- ) -> proc_macro::TokenStream {
- let item_struct = parse_macro_input!(input as syn::ItemStruct);
- let struct_ident = &item_struct.ident;
- let size_override = {
- if args.is_empty() {
- // No size override given. The account size is whatever is given
- // as the initialized value. Use the default implementation.
- quote! {
- impl anchor_lang::AccountSize for #struct_ident {
- fn size(&self) -> std::result::Result<u64, anchor_lang::solana_program::program_error::ProgramError> {
- Ok(8 + self
- .try_to_vec()
- .map_err(|_| ProgramError::Custom(1))?
- .len() as u64)
- }
- }
- }
- } else {
- let size = proc_macro2::TokenStream::from(args);
- // Size override given to the macro. Use it.
- quote! {
- impl anchor_lang::AccountSize for #struct_ident {
- fn size(&self) -> std::result::Result<u64, anchor_lang::solana_program::program_error::ProgramError> {
- Ok(#size)
- }
- }
- }
- }
- };
- proc_macro::TokenStream::from(quote! {
- #[account]
- #item_struct
- #size_override
- })
- }
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