Struct VariantsHelper

pub struct VariantsHelper<'v, V: VariantInfo<F>, F: FieldInfo> { /* private fields */ }

Utility struct to work with enum’s variants

Implementations

impl<'v, V: VariantInfo<F>, F: FieldInfo> VariantsHelper<'v, V, F>

pub fn new(variants: &'v [V]) -> Self

Builds a new VariantsHelper

pub fn filtering_variants<P>(self, predicate: P) -> Self

where P: Fn(&V) -> bool + 'v,

Remove all variants v for which predicate(&v) returns false. This method operates in place, visiting each element exactly once in the original order, and preserves the order of the retained elements.

pub fn with_variant_attributes<P>(self, predicate: P) -> Self

where P: Fn(&V) -> Option<TokenStream> + 'v,

Adds an arbitrary number of attributes to each variant.

pub fn include_extra_variants( self, include_extra_variants: impl IntoIterator<Item = (impl ToTokens, Option<impl ToTokens>)>, ) -> Self

Include extra variants by including the given left and right sides (#left if right is None or #left => #right) at the end.

pub fn ignore_all_extra_variants(self, right_side: Option<TokenStream>) -> Self

Wether to ignore all extra variants with the given right side _ => #right, if Some.

It should be used only when collecting a match.

pub fn include_wrapper(self, include_wrapper: bool) -> Self

Wether to include the wrapper (curly braces), defaults to true.

pub fn left_collector<C>(self, left_collector: C) -> Self

where C: Fn(&V, FieldsHelper<'_, F>) -> TokenStream + 'v,

Specifies the left collector.

Defaults to VariantsCollector::variant_definition

pub fn right_collector<C>(self, right_collector: C) -> Self

where C: Fn(&V, FieldsHelper<'_, F>) -> TokenStream + 'v,

Specifies the right collector.

Defaults to VariantsCollector::empty

pub fn collect(self) -> TokenStream

Collects the fields.

Examples

If using the default collectors:

{
    Variant1,
    Variant2 = 5,
    Variant3 {
        field_1: String,
        field_2: i32,
    },
}

If using VariantsCollector::variant_fields_collector(quote!(SelfTy)) left collector and VariantsCollector::variant_fields_collector(quote!(OtherTy) right collector:

{
    SelfTy::Variant1 => OtherTy::Variant1,
    SelfTy::Variant2 {
        field_1: field_1,
        field_2: field_2,
    } => OtherTy::Variant2 {
        field_1: field_1,
        field_2: field_2,
    },
}