add support for unlabeled and unindexed enum variants

sval-rs · Mar 26, 2024 · 072cff7 · 072cff7
1 parent 0b775c8
commit 072cff7
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Showing 2 changed files with 69 additions and 3 deletions.
diff --git a/derive_macros/src/attr.rs b/derive_macros/src/attr.rs
@@ -234,6 +234,56 @@ impl RawAttribute for UnindexedFieldsAttr {
     }
 }
 
+/**
+The `unlabeled_variants` attribute.
+
+This attribute signals that all variants should be unlabeled.
+*/
+pub(crate) struct UnlabeledVariantsAttr;
+
+impl SvalAttribute for UnlabeledVariantsAttr {
+    type Result = bool;
+
+    fn from_lit(&self, lit: &Lit) -> Self::Result {
+        if let Lit::Bool(ref b) = lit {
+            b.value
+        } else {
+            panic!("unexpected value")
+        }
+    }
+}
+
+impl RawAttribute for UnlabeledVariantsAttr {
+    fn key(&self) -> &str {
+        "unlabeled_variants"
+    }
+}
+
+/**
+The `unindexed_variants` attribute.
+
+This attribute signals that all variants should be unindexed.
+*/
+pub(crate) struct UnindexedVariantsAttr;
+
+impl SvalAttribute for UnindexedVariantsAttr {
+    type Result = bool;
+
+    fn from_lit(&self, lit: &Lit) -> Self::Result {
+        if let Lit::Bool(ref b) = lit {
+            b.value
+        } else {
+            panic!("unexpected value")
+        }
+    }
+}
+
+impl RawAttribute for UnindexedVariantsAttr {
+    fn key(&self) -> &str {
+        "unindexed_variants"
+    }
+}
+
 /**
 The `dynamic` attribute.
 

diff --git a/derive_macros/src/derive/derive_enum.rs b/derive_macros/src/derive/derive_enum.rs
@@ -17,6 +17,8 @@ pub(crate) struct EnumAttrs {
     tag: Option<Path>,
     label: Option<LabelValue>,
     index: Option<IndexValue>,
+    unlabeled_variants: bool,
+    unindexed_variants: bool,
     dynamic: bool,
 }
 
@@ -29,13 +31,17 @@ impl EnumAttrs {
                 &attr::LabelAttr,
                 &attr::IndexAttr,
                 &attr::DynamicAttr,
+                &attr::UnlabeledVariantsAttr,
+                &attr::UnindexedVariantsAttr,
             ],
             attrs,
         );
 
         let tag = attr::get_unchecked("enum", attr::TagAttr, attrs);
         let label = attr::get_unchecked("enum", attr::LabelAttr, attrs);
         let index = attr::get_unchecked("enum", attr::IndexAttr, attrs);
+        let unlabeled_variants = attr::get_unchecked("enum", attr::UnlabeledVariantsAttr, attrs).unwrap_or(false);
+        let unindexed_variants = attr::get_unchecked("enum", attr::UnindexedVariantsAttr, attrs).unwrap_or(false);
         let dynamic = attr::get_unchecked("enum", attr::DynamicAttr, attrs).unwrap_or(false);
 
         if dynamic {
@@ -48,6 +54,8 @@ impl EnumAttrs {
             tag,
             label,
             index,
+            unlabeled_variants,
+            unindexed_variants,
             dynamic,
         }
     }
@@ -81,7 +89,7 @@ pub(crate) fn derive_enum<'a>(
 
     let mut variant_index = |index: Option<Index>, discriminant: Option<IndexValue>| {
         index.or_else(|| {
-            if attrs.dynamic {
+            if attrs.dynamic || attrs.unindexed_variants {
                 None
             } else {
                 Some(index_allocator.next_const_index(discriminant))
@@ -90,7 +98,15 @@ pub(crate) fn derive_enum<'a>(
     };
 
     let variant_label = |label: Option<LabelValue>, ident: &Ident| {
-        if attrs.dynamic {
+        if attrs.dynamic || attrs.unlabeled_variants {
+            None
+        } else {
+            Some(label_or_ident(label, ident))
+        }
+    };
+
+    let unit_variant_label = |label: Option<LabelValue>, ident: &Ident| {
+        if attrs.unlabeled_variants {
             None
         } else {
             Some(label_or_ident(label, ident))
@@ -142,7 +158,7 @@ pub(crate) fn derive_enum<'a>(
                 stream_tag(
                     quote!(#ident :: #variant_ident),
                     attrs.tag(),
-                    Some(label_or_ident(attrs.label(), variant_ident)),
+                    unit_variant_label(attrs.label(), variant_ident),
                     variant_index(attrs.index(), discriminant),
                 )
             }