1 files changed, 117 insertions, 0 deletions
diff --git a/src/macros/strings/as_ref_str.rs b/src/macros/strings/as_ref_str.rs
new file mode 100644
index 0000000..617b887
--- /dev/null
+++ b/src/macros/strings/as_ref_str.rs
@@ -0,0 +1,117 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{parse_quote, Data, DeriveInput, Fields};
+
+use crate::helpers::{non_enum_error, HasStrumVariantProperties, HasTypeProperties};
+
+fn get_arms(ast: &DeriveInput) -> syn::Result<Vec<TokenStream>> {
+    let name = &ast.ident;
+    let mut arms = Vec::new();
+    let variants = match &ast.data {
+        Data::Enum(v) => &v.variants,
+        _ => return Err(non_enum_error()),
+    };
+
+    let type_properties = ast.get_type_properties()?;
+
+    for variant in variants {
+        let ident = &variant.ident;
+        let variant_properties = variant.get_variant_properties()?;
+
+        if variant_properties.disabled.is_some() {
+            continue;
+        }
+
+        // Look at all the serialize attributes.
+        // Use `to_string` attribute (not `as_ref_str` or something) to keep things consistent
+        // (i.e. always `enum.as_ref().to_string() == enum.to_string()`).
+        let output = variant_properties.get_preferred_name(type_properties.case_style);
+        let params = match variant.fields {
+            Fields::Unit => quote! {},
+            Fields::Unnamed(..) => quote! { (..) },
+            Fields::Named(..) => quote! { {..} },
+        };
+
+        arms.push(quote! { #name::#ident #params => #output });
+    }
+
+    if arms.len() < variants.len() {
+        arms.push(quote! {
+            _ => panic!(
+                "AsRef::<str>::as_ref() or AsStaticRef::<str>::as_static() \
+                 called on disabled variant.",
+            )
+        });
+    }
+
+    Ok(arms)
+}
+
+pub fn as_ref_str_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
+    let name = &ast.ident;
+    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
+    let arms = get_arms(ast)?;
+    Ok(quote! {
+        impl #impl_generics ::core::convert::AsRef<str> for #name #ty_generics #where_clause {
+            fn as_ref(&self) -> &str {
+                match *self {
+                    #(#arms),*
+                }
+            }
+        }
+    })
+}
+
+pub enum GenerateTraitVariant {
+    AsStaticStr,
+    From,
+}
+
+pub fn as_static_str_inner(
+    ast: &DeriveInput,
+    trait_variant: &GenerateTraitVariant,
+) -> syn::Result<TokenStream> {
+    let name = &ast.ident;
+    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
+    let arms = get_arms(ast)?;
+    let type_properties = ast.get_type_properties()?;
+    let strum_module_path = type_properties.crate_module_path();
+
+    let mut generics = ast.generics.clone();
+    generics
+        .params
+        .push(syn::GenericParam::Lifetime(syn::LifetimeParam::new(
+            parse_quote!('_derivative_strum),
+        )));
+    let (impl_generics2, _, _) = generics.split_for_impl();
+    let arms2 = arms.clone();
+    let arms3 = arms.clone();
+
+    Ok(match trait_variant {
+        GenerateTraitVariant::AsStaticStr => quote! {
+            impl #impl_generics #strum_module_path::AsStaticRef<str> for #name #ty_generics #where_clause {
+                fn as_static(&self) -> &'static str {
+                    match *self {
+                        #(#arms),*
+                    }
+                }
+            }
+        },
+        GenerateTraitVariant::From => quote! {
+            impl #impl_generics ::core::convert::From<#name #ty_generics> for &'static str #where_clause {
+                fn from(x: #name #ty_generics) -> &'static str {
+                    match x {
+                        #(#arms2),*
+                    }
+                }
+            }
+            impl #impl_generics2 ::core::convert::From<&'_derivative_strum #name #ty_generics> for &'static str #where_clause {
+                fn from(x: &'_derivative_strum #name #ty_generics) -> &'static str {
+                    match *x {
+                        #(#arms3),*
+                    }
+                }
+            }
+        },
+    })
+}