Crate rtc_interceptor_derive 

Derive macros for RTC Interceptor trait.

This crate provides two macros that work together:

• #[derive(Interceptor)] - Marks a struct as an interceptor and identifies the next field
• #[interceptor] - Attribute macro for impl blocks to generate trait implementations

Design Pattern

The examples below are illustrative rather than compiled: the macros only expand to something meaningful in the presence of the Interceptor trait from rtc-interceptor, which depends on this crate — so a doctest here cannot import it. They are exercised for real by rtc-interceptor’s own documentation and tests.

The design follows Rust’s derive pattern (similar to #[derive(Default)] with #[default]):

use rtc_interceptor::{Interceptor, StreamInfo, TaggedPacket, interceptor};
use rtc_shared::error::Error;
use sansio::Protocol;
use std::collections::VecDeque;

#[derive(Interceptor)]
pub struct MyInterceptor<P: Interceptor> {
    #[next]
    next: P,  // The next interceptor in the chain (can use any field name)
    buffer: VecDeque<TaggedPacket>,
}

#[interceptor]
impl<P: Interceptor> MyInterceptor<P> {
    #[overrides]
    fn handle_read(&mut self, msg: TaggedPacket) -> Result<(), Self::Error> {
        // Custom logic here
        self.next.handle_read(msg)
    }
}

Pure Delegation (No Custom Logic)

For interceptors that just pass through without modification:

#[derive(Interceptor)]
pub struct PassthroughInterceptor<P: Interceptor> {
    #[next]
    next: P,
}

#[interceptor]
impl<P: Interceptor> PassthroughInterceptor<P> {}
// Empty impl block - all methods are auto-generated

Required Imports

The macros require certain types to be in scope:

The generated code names sansio::Protocol, Error, StreamInfo and TaggedPacket, so all four must be in scope at the use site — not only the macros themselves:

use rtc_interceptor::{Interceptor, StreamInfo, TaggedPacket, interceptor};
use rtc_shared::error::Error;
use sansio::Protocol;

Through the rtc umbrella crate the same imports are:

use rtc::interceptor::{Interceptor, StreamInfo, TaggedPacket, interceptor};
use rtc::sansio::Protocol;
use rtc::shared::error::Error;

Attribute Macros

interceptor

Attribute macro for impl blocks to generate Protocol and Interceptor implementations.

Derive Macros

Interceptor

Derive macro that marks a struct as an interceptor.