subtensor-macros 0.1.0

support macros for Subtensor
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84

use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::ToTokens;
use syn::{Error, ItemStruct, LitStr, Result, parse2, visit_mut::visit_item_struct_mut};

mod call_filter_group;
mod visitor;
use visitor::*;

/// Freezes the layout of a struct to the current hash of its fields, ensuring that future
/// changes require updating the hash.
///
/// ```
/// use subtensor_macros::freeze_struct;
///
/// #[freeze_struct("13f75e4ea46b4e80")]
/// #[derive(Copy, Clone, PartialEq, Eq)]
/// pub struct MyStruct {
///     pub a: u32,
///     pub b: u64,
/// }
/// ```
#[proc_macro_attribute]
pub fn freeze_struct(attr: TokenStream, tokens: TokenStream) -> TokenStream {
    match freeze_struct_impl(attr, tokens) {
        Ok(item_struct) => item_struct.to_token_stream().into(),
        Err(err) => err.to_compile_error().into(),
    }
}

/// Defines a reusable runtime call filter group and derives its metadata from the same allowlist.
///
/// Example: `call_filter_group!(GroupName, [RuntimeCall::Foobar(pallet_foobar::Call::some_call)]);`
#[proc_macro]
pub fn call_filter_group(input: TokenStream) -> TokenStream {
    let parsed = syn::parse_macro_input!(input as call_filter_group::CallFilterGroupInput);
    match call_filter_group::generate(parsed) {
        Ok(tokens) => tokens.into(),
        Err(err) => err.to_compile_error().into(),
    }
}

fn freeze_struct_impl(
    attr: impl Into<TokenStream2>,
    tokens: impl Into<TokenStream2>,
) -> Result<ItemStruct> {
    let attr = attr.into();
    let tokens = tokens.into();

    let item = parse2::<ItemStruct>(tokens)?;
    let mut item_clone = item.clone();

    let mut visitor = CleanDocComments::new();
    visit_item_struct_mut(&mut visitor, &mut item_clone);

    let calculated_hash = generate_hash(&item_clone);
    let calculated_hash_hex = format!("{calculated_hash:x}");

    if attr.is_empty() {
        return Err(Error::new_spanned(
            item,
            format!(
                "You must provide a hashcode in the `freeze_struct` attribute to freeze this struct.\n\n\
            expected hashcode: `#[freeze_struct(\"{calculated_hash_hex}\")]`"
            ),
        ));
    }

    let parsed_attr = parse2::<LitStr>(attr)?;
    let provided_hash_hex = parsed_attr.value().to_lowercase();

    if provided_hash_hex != calculated_hash_hex {
        return Err(Error::new_spanned(
            item,
            format!(
                "You have made a non-trivial change to this struct and the provided hashcode no longer matches:\n{provided_hash_hex} != {calculated_hash_hex}\n\n\
                If this was intentional, please update the hashcode in the `freeze_struct` attribute to:\n\
                {calculated_hash_hex}\n\nNote that if you are changing a storage struct in any way, including simply re-ordering fields, \
                you will need a migration to prevent data corruption."
            ),
        ));
    }
    Ok(item)
}