extruct-macros 0.2.1

use proc_macro::TokenStream;

#[cfg(any(feature = "extruct_from", doc))]
mod extruct_from;
#[cfg(any(feature = "fields", doc))]
mod fields;
mod utils;

/// A derive macro implements the [`Fields`](trait.Fields.html) trait for a struct.
///
/// [`Fields`] can annotate a named struct, a unit struct or an empty unnamed
/// (tuple-like) struct, including generic structs.
/// It collects names of the fields from the struct definition and represents
/// them as a list of string literals accessible through [`Fields::fields()`](trait.Fields.html#tymethod.fields).
///
/// ```rust
/// # use extruct_core as extruct;
/// # use extruct::Fields;
/// # use extruct_macros::Fields;
/// #[derive(Fields)]
/// struct NamedStruct {
///     one: String,
///     two: u32,
///     three: char,
/// }
/// assert_eq!(NamedStruct::fields(), ["one", "two", "three"]);
/// ```
#[cfg(any(feature = "fields", doc))]
#[proc_macro_derive(Fields)]
pub fn get_struct_fields(item: TokenStream) -> TokenStream {
    match fields::parse(item.into()) {
        Ok(ast) => {
            let model = fields::analyze(ast);
            let code = fields::codegen(model);

            code.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// An attribute macro implements the [`std::convert::From`](https://doc.rust-lang.org/std/convert/trait.From.html)
/// trait for an annotated non-generic named struct using a "superstruct" specified as
/// the attribute parameter as a source type and the [`ExtructedFrom`](trait.ExtructedFrom.html)
/// marker trait that indicates that struct fields populated during conversion from
/// superstruct all have same names in both structs.
///
/// [`extruct_from`](macro@extruct_from) accepts a single parameter which is a non-generic type name referring
/// to a named struct.
///
/// ```rust
/// # use extruct_core as extruct;
/// # use extruct::ExtructedFrom;
/// # use extruct_macros::extruct_from;
/// struct SuperStruct {
///     one_field: String,
///     another_field: u32,
///     and_one_more: char,
/// }
///
/// #[extruct_from(SuperStruct)]
/// struct SubStruct {
///     and_one_more: String,
/// }
///
/// fn convert_preserving_names<T, S>(sup: S) -> T
/// where
///     T: ExtructedFrom<S>
/// {
///     sup.into()
/// }
///
/// let sup = SuperStruct {
///     one_field: "str".to_owned(),
///     another_field: 1135,
///     and_one_more: 'x',
/// };
///
/// let sub: SubStruct = convert_preserving_names(sup);
/// ```
#[cfg(any(feature = "extruct_from", doc))]
#[proc_macro_attribute]
pub fn extruct_from(attr: TokenStream, item: TokenStream) -> TokenStream {
    match extruct_from::parse(attr.into(), item.into()) {
        Ok(ast) => {
            let model = extruct_from::analyze(ast);
            let code = extruct_from::codegen(model);

            code.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}