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derivative 0.3.1

A set of alternative `derive` attributes for Rust
Documentation 
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use ast;
use attr;
use bound;
use syn;

/// Make generic with all the generics in the input, plus a bound `T: <trait_path>` for each
/// generic field type that will be shown.
pub fn build_impl_generics<F, G, H>(
    item: &ast::Input,
    trait_path: &syn::Path,
    needs_debug_bound: F,
    field_bound: G,
    input_bound: H,
) -> syn::Generics
    where F: Fn(&attr::Field) -> bool,
          G: Fn(&attr::Field) -> Option<&[syn::WherePredicate]>,
          H: Fn(&attr::Input) -> Option<&[syn::WherePredicate]>,
{
    let generics = bound::without_defaults(item.generics);
    let generics = bound::with_where_predicates_from_fields(
        item, &generics, field_bound
    );

    match input_bound(&item.attrs) {
        Some(predicates) => {
            bound::with_where_predicates(&generics, predicates)
        }
        None => {
            bound::with_bound(item, &generics, needs_debug_bound, trait_path)
        }
    }
}

/// Construct a name for the inner type parameter that can't collide with any
/// type parameters of the item. This is achieved by starting with a base and
/// then concatenating the names of all other type parameters.
pub fn hygienic_type_parameter(item: &ast::Input, base: &str) -> syn::Ident {
    let mut typaram = String::from(base);

    for ty in &item.generics.ty_params {
        typaram.push_str(&ty.ident.as_ref());
    }

    syn::Ident::new(typaram)
}