feat(napi-derive): add optional enum_string case conversion (#1995)

crates/macro/src/parser/attrs.rs

@@ -71,7 +71,7 @@ macro_rules! attrgen {
       (ts_return_type, TsReturnType(Span, String, Span)),
       (ts_type, TsType(Span, String, Span)),
       (ts_generic_types, TsGenericTypes(Span, String, Span)),
-      (string_enum, StringEnum(Span)),
+      (string_enum, StringEnum(Span, Option<(String, Span)>)),
       (use_nullable, UseNullable(Span, Option<bool>), false),
 
       // impl later
@@ -132,6 +132,21 @@ macro_rules! methods {
     }
   };
 
+  (@method $name:ident, $variant:ident(Span, Option<(String, Span)>)) => {
+    pub fn $name(&self) -> Option<Option<&(String, Span)>> {
+      self.attrs
+        .iter()
+        .filter_map(|a| match &a.1 {
+          BindgenAttr::$variant(_, s) => {
+            a.0.set(true);
+            Some(s.as_ref())
+          }
+          _ => None,
+        })
+        .next()
+    }
+  };
+
   (@method $name:ident, $variant:ident(Span, Option<bool>), $default_value:literal) => {
     pub fn $name(&self) -> bool {
       self.attrs
@@ -396,6 +411,21 @@ impl Parse for BindgenAttr {
           return Ok(BindgenAttr::$variant(attr_span, val, span))
         });
 
+        (@parser $variant:ident(Span, Option<(String, Span)>)) => ({
+          if let Ok(_) = input.parse::<Token![=]>() {
+            let val = match input.parse::<syn::LitStr>() {
+              Ok(str) => Some((str.value(), str.span())),
+              Err(_) => {
+                let ident = input.parse::<AnyIdent>()?.0;
+                Some((ident.to_string(), ident.span()))
+              }
+            };
+            return Ok(BindgenAttr::$variant(attr_span, val))
+          } else {
+            return Ok(BindgenAttr::$variant(attr_span, None))
+          }
+        });
+
         (@parser $variant:ident(Span, Option<bool>), $default_value:literal) => ({
           if let Ok(_) = input.parse::<Token![=]>() {
             let (val, _) = match input.parse::<syn::LitBool>() {

crates/macro/src/parser/mod.rs

@@ -1062,26 +1062,48 @@ impl ConvertToAST for syn::ItemEnum {
       .map_or_else(|| self.ident.to_string(), |(s, _)| s.to_string());
 
     let variants = match opts.string_enum() {
-      Some(_) => self
-        .variants
-        .iter()
-        .map(|v| {
-          if !matches!(v.fields, syn::Fields::Unit) {
-            bail_span!(v.fields, "Structured enum is not supported in #[napi]")
+      Some(case) => {
+        let case = case.map(|c| Ok::<Case, Diagnostic>(match c.0.as_str() {
+          "lowercase" => Case::Flat,
+          "UPPERCASE" => Case::UpperFlat,
+          "PascalCase" => Case::Pascal,
+          "camelCase" => Case::Camel,
+          "snake_case" => Case::Snake,
+          "SCREAMING_SNAKE_CASE" => Case::UpperSnake,
+          "kebab-case" => Case::Kebab,
+          "SCREAMING-KEBAB-CASE" => Case::UpperKebab,
+          _ => {
+            bail_span!(self, "Unknown string enum case. Possible values are \"lowercase\", \"UPPERCASE\", \"PascalCase\", \"camelCase\", \"snake_case\", \"SCREAMING_SNAKE_CASE\", \"kebab-case\", or \"SCREAMING-KEBAB-CASE\"")
           }
-          if matches!(&v.discriminant, Some((_, _))) {
-            bail_span!(
-              v.fields,
-              "Literal values are not supported with string enum in #[napi]"
-            )
-          }
-          Ok(NapiEnumVariant {
-            name: v.ident.clone(),
-            val: NapiEnumValue::String(v.ident.to_string()),
-            comments: extract_doc_comments(&v.attrs),
+        })).transpose()?;
+
+        self
+          .variants
+          .iter()
+          .map(|v| {
+            if !matches!(v.fields, syn::Fields::Unit) {
+              bail_span!(v.fields, "Structured enum is not supported in #[napi]")
+            }
+            if matches!(&v.discriminant, Some((_, _))) {
+              bail_span!(
+                v.fields,
+                "Literal values are not supported with string enum in #[napi]"
+              )
+            }
+
+            let mut val = v.ident.to_string();
+            if let Some(case) = case {
+              val = val.to_case(case)
+            };
+
+            Ok(NapiEnumVariant {
+              name: v.ident.clone(),
+              val: NapiEnumValue::String(val),
+              comments: extract_doc_comments(&v.attrs),
+            })
           })
-        })
-        .collect::<BindgenResult<Vec<NapiEnumVariant>>>()?,
+          .collect::<BindgenResult<Vec<NapiEnumVariant>>>()?
+      }
       None => {
         let mut last_variant_val: i32 = -1;
 

examples/napi/__tests__/__snapshots__/typegen.spec.ts.md

@@ -617,6 +617,12 @@ Generated by [AVA](https://avajs.dev).
       name: string␊
     }␊
     ␊
+    export const enum StringEnum {␊
+      VariantOne = 'variantone',␊
+      VariantTwo = 'varianttwo',␊
+      VariantThree = 'variantthree'␊
+    }␊
+    ␊
     export function sumBtreeMapping(nums: Record<string, number>): number␊
     ␊
     export function sumIndexMapping(nums: Record<string, number>): number␊

examples/napi/index.cjs

@@ -509,6 +509,7 @@ module.exports.roundtripStr = nativeBinding.roundtripStr
 module.exports.runScript = nativeBinding.runScript
 module.exports.setSymbolInObj = nativeBinding.setSymbolInObj
 module.exports.Status = nativeBinding.Status
+module.exports.StringEnum = nativeBinding.StringEnum
 module.exports.sumBtreeMapping = nativeBinding.sumBtreeMapping
 module.exports.sumIndexMapping = nativeBinding.sumIndexMapping
 module.exports.sumMapping = nativeBinding.sumMapping

examples/napi/index.d.cts

@@ -607,6 +607,12 @@ export interface StrictObject {
   name: string
 }
 
+export const enum StringEnum {
+  VariantOne = 'variantone',
+  VariantTwo = 'varianttwo',
+  VariantThree = 'variantthree'
+}
+
 export function sumBtreeMapping(nums: Record<string, number>): number
 
 export function sumIndexMapping(nums: Record<string, number>): number

examples/napi/src/enum.rs

@@ -19,6 +19,13 @@ pub enum Status {
   Ready,
 }
 
+#[napi(string_enum = "lowercase")]
+pub enum StringEnum {
+  VariantOne,
+  VariantTwo,
+  VariantThree,
+}
+
 /// You could break the step and for an new continuous value.
 #[napi]
 pub enum CustomNumEnum {