82 lines
2.4 KiB
Rust
82 lines
2.4 KiB
Rust
extern crate proc_macro;
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use quote::quote;
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use syn::parse_macro_input;
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/// Executes the given access control method before running the decorated
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/// instruction handler. Any method in scope of the attribute can be invoked
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/// with any arguments from the associated instruction handler.
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///
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/// # Example
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///
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/// ```ignore
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/// use anchor_lang::prelude::*;
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///
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/// #[program]
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/// mod errors {
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/// use super::*;
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///
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/// #[access_control(Create::accounts(&ctx, bump_seed))]
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/// pub fn create(ctx: Context<Create>, bump_seed: u8) -> Result<()> {
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/// let my_account = &mut ctx.accounts.my_account;
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/// my_account.bump_seed = bump_seed;
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/// }
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/// }
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///
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/// #[derive(Accounts)]
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/// pub struct Create {
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/// #[account(init)]
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/// my_account: Account<'info, MyAccount>,
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/// }
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///
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/// impl Create {
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/// pub fn accounts(ctx: &Context<Create>, bump_seed: u8) -> Result<()> {
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/// let seeds = &[ctx.accounts.my_account.to_account_info().key.as_ref(), &[bump_seed]];
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/// Pubkey::create_program_address(seeds, ctx.program_id)
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/// .map_err(|_| ErrorCode::InvalidNonce)?;
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/// Ok(())
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/// }
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/// }
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/// ```
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///
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/// This example demonstrates a useful pattern. Not only can you use
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/// `#[access_control]` to ensure any invariants or preconditions hold prior to
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/// executing an instruction, but also it can be used to finish any validation
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/// on the `Accounts` struct, particularly when instruction arguments are
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/// needed. Here, we use the given `bump_seed` to verify it creates a valid
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/// program-derived address.
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#[proc_macro_attribute]
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pub fn access_control(
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args: proc_macro::TokenStream,
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input: proc_macro::TokenStream,
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) -> proc_macro::TokenStream {
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let mut args = args.to_string();
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args.retain(|c| !c.is_whitespace());
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let access_control: Vec<proc_macro2::TokenStream> = args
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.split(')')
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.filter(|ac| !ac.is_empty())
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.map(|ac| format!("{})", ac)) // Put back on the split char.
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.map(|ac| format!("{}?;", ac)) // Add `?;` syntax.
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.map(|ac| ac.parse().unwrap())
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.collect();
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let item_fn = parse_macro_input!(input as syn::ItemFn);
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let fn_attrs = item_fn.attrs;
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let fn_vis = item_fn.vis;
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let fn_sig = item_fn.sig;
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let fn_block = item_fn.block;
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let fn_stmts = fn_block.stmts;
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proc_macro::TokenStream::from(quote! {
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#(#fn_attrs)*
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#fn_vis #fn_sig {
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#(#access_control)*
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#(#fn_stmts)*
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}
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})
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}
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