attribute-dsl

attribute-dsl provides syn parsers for Rust proc-macro attributes built from a path root, ordered dot calls, optional labels, comma-separated entries, and named groups. It also supports rust-analyzer completion probes and _ placeholders for application-owned subject types.

Use it in derive-macro and attribute-macro implementation crates. The consumer keeps ownership of domain validation, constructors, and generated Rust.

Quick start

Add the crate alongside the syn dependency used by the macro:

cargo add attribute-dsl

Parse an attribute chain through syn:

use attribute_dsl::{AttributeChain, ChainCompletion};

let chain: AttributeChain =
    syn::parse_str("RootType::<_>.first(1).second::<String>(\"value\")")
        .expect("valid attribute chain");

assert_eq!(
    chain
        .root_path()
        .segments
        .last()
        .expect("a parsed path has a segment")
        .ident
        .to_string(),
    "RootType"
);
assert_eq!(chain.calls().len(), 2);
assert!(matches!(chain.completion(), ChainCompletion::None));

The result retains syn::Path, syn::Ident, and syn::Expr nodes so the consumer can preserve syntax and spans while quoting its expansion.

Capabilities

• Parse one chain, a labeled entry, a list, or a named group.
• Recover a trailing dot as a typed rust-analyzer completion probe.
• Inspect or replace _ type placeholders in paths, types, and expressions.
• Return syn::Error values for spanned proc-macro diagnostics.

Documentation

• Follow the attribute-dsl guide for parser selection, completion probes, infer substitution, and expansion patterns.
• Use the API documentation for public items and signatures.