Module debug 

Debug formatting and printing for template expansions. Debug formatting utilities for macro expansions.

Provides a pipeline API for formatting generated TokenStreams into human-readable strings. Used internally by the debug attribute argument on #[zyn::element], #[zyn::pipe], #[zyn::derive], and #[zyn::attribute].

Formats

• Raw (always available) — calls TokenStream::to_string(), producing a flat single-line string with fully-qualified paths. No extra dependencies.

• Pretty (requires the pretty feature) — parses the token stream into a syn::File and formats it with prettyplease, producing properly indented Rust code. Enable with:

  zyn = { version = "0.4", features = ["pretty"] }

Usage

The [DebugExt] trait adds a .debug() method to proc_macro2::TokenStream, returning a [DebugTokens] builder with .raw() and .pretty() methods:

use zyn::debug::DebugExt;

let raw: String = tokens.debug().raw();

#[cfg(feature = "pretty")]
let pretty: String = tokens.debug().pretty();

Macro integration

In attribute macros, add debug (or with options) to emit the generated code as a compiler note diagnostic. Requires ZYN_DEBUG to be set:

#[zyn::element(debug)]                        // body only, raw
#[zyn::element(debug(pretty))]                // body only, pretty-printed
#[zyn::element(debug(full))]                  // full struct + impl, raw
#[zyn::element(debug(pretty, full))]          // full struct + impl, pretty-printed
#[zyn::element(debug(name = "Foo"))]          // inject prop value, raw
#[zyn::element(debug(pretty, name = "Foo"))]  // inject prop value, pretty-printed
fn greeting(name: syn::Ident) -> zyn::TokenStream { ... }

// ZYN_DEBUG="*" cargo build
// → note: zyn::element ─── Greeting
//
//         fn {{ name }}() {}

Structs

DebugTokens

Wraps a reference to a proc_macro2::TokenStream and provides formatting methods for debug output.

Traits

DebugExt

Extension trait that adds .debug() to proc_macro2::TokenStream.