Module typemap 

TypeRef → syn::Type mapping with unified position-based system.

Follows the wasm-bindgen WebIDL approach: a single to_syn_type function that uses TypePosition to determine how types are lowered to Rust.

TypePosition is a struct with two fields:

• direction: Argument or Return — controls borrowing (e.g., &str vs String)
• inner: whether we’re nested inside a generic container (e.g., Promise<T>)

When inner is true:

• Primitives map to JS wrapper types (Number, JsString, Boolean, Undefined)
• Nullable becomes JsOption<T> instead of Option<T>
• Argument-position types are NOT borrowed (owned T, not &T)

Structs

CodegenContext

Context for codegen that tracks locally-defined types and resolved type aliases.

TypePosition

Position context for type mapping, following the wasm-bindgen WebIDL pattern.

Enums

Direction

Direction of data flow at the FFI boundary.

Constants

JS_SYS_RESERVED

js_sys type names reserved by the use js_sys::* glob import. User-defined types that collide with these will be renamed.

Functions

to_return_type

Map an IR TypeRef to the type used in a wasm_bindgen return position, wrapping in Result<T, JsValue> when catch is true.

to_syn_type

Map an IR TypeRef to a proc_macro2::TokenStream representing the Rust type.