enum representations

[skip ci]

openapi_type/Cargo.toml

@@ -19,4 +19,5 @@ serde_json = "1.0"
 
 [dev-dependencies]
 paste = "1.0"
+serde = "1.0"
 trybuild = "1.0"

openapi_type/tests/custom_types.rs

@@ -43,6 +43,15 @@ test_type!(SimpleStruct = {
 	"required": ["foo", "bar"]
 });
 
+#[derive(OpenapiType)]
+#[openapi(rename = "FooBar")]
+struct StructRename;
+test_type!(StructRename = {
+	"type": "object",
+	"title": "FooBar",
+	"additionalProperties": false
+});
+
 #[derive(OpenapiType)]
 enum EnumWithoutFields {
 	Success,
@@ -119,6 +128,7 @@ test_type!(EnumWithFields = {
 #[derive(OpenapiType)]
 enum EnumExternallyTagged {
 	Success { value: isize },
+	Empty,
 	Error
 }
 test_type!(EnumExternallyTagged = {
@@ -139,6 +149,101 @@ test_type!(EnumExternallyTagged = {
 		"required": ["Success"]
 	}, {
 		"type": "string",
-		"enum": ["Error"]
+		"enum": ["Empty", "Error"]
+	}]
+});
+
+#[derive(OpenapiType)]
+#[openapi(tag = "ty")]
+enum EnumInternallyTagged {
+	Success { value: isize },
+	Empty,
+	Error
+}
+test_type!(EnumInternallyTagged = {
+	"title": "EnumInternallyTagged",
+	"oneOf": [{
+		"type": "object",
+		"properties": {
+			"value": {
+				"type": "integer"
+			},
+			"ty": {
+				"type": "string",
+				"enum": ["Success"]
+			}
+		},
+		"required": ["value", "ty"]
+	}, {
+		"type": "object",
+		"properties": {
+			"ty": {
+				"type": "string",
+				"enum": ["Empty", "Error"]
+			}
+		},
+		"required": ["ty"]
+	}]
+});
+
+#[derive(OpenapiType)]
+#[openapi(tag = "ty", content = "ct")]
+enum EnumAdjacentlyTagged {
+	Success { value: isize },
+	Empty,
+	Error
+}
+test_type!(EnumAdjacentlyTagged = {
+	"title": "EnumAdjacentlyTagged",
+	"oneOf": [{
+		"type": "object",
+		"properties": {
+			"ty": {
+				"type": "string",
+				"enum": ["Success"]
+			},
+			"ct": {
+				"type": "object",
+				"properties": {
+					"value": {
+						"type": "integer"
+					}
+				},
+				"required": ["value"]
+			}
+		},
+		"required": ["ty", "ct"]
+	}, {
+		"type": "object",
+		"properties": {
+			"ty": {
+				"type": "string",
+				"enum": ["Empty", "Error"]
+			}
+		},
+		"required": ["ty"]
+	}]
+});
+
+#[derive(OpenapiType)]
+#[openapi(untagged)]
+enum EnumUntagged {
+	Success { value: isize },
+	Empty,
+	Error
+}
+test_type!(EnumUntagged = {
+	"title": "EnumUntagged",
+	"oneOf": [{
+		"type": "object",
+		"properties": {
+			"value": {
+				"type": "integer"
+			}
+		},
+		"required": ["value"]
+	}, {
+		"type": "object",
+		"additionalProperties": false
 	}]
 });

openapi_type_derive/src/lib.rs

@@ -17,16 +17,33 @@ mod parser;
 use parser::*;
 
 /// The derive macro for [OpenapiType][openapi_type::OpenapiType].
-#[proc_macro_derive(OpenapiType)]
+#[proc_macro_derive(OpenapiType, attributes(openapi))]
 pub fn derive_openapi_type(input: TokenStream) -> TokenStream {
 	let input = parse_macro_input!(input);
 	expand_openapi_type(input).unwrap_or_else(|err| err.to_compile_error()).into()
 }
 
 fn expand_openapi_type(mut input: DeriveInput) -> syn::Result<TokenStream2> {
+	// parse #[serde] and #[openapi] attributes
+	let mut attrs = ContainerAttributes::default();
+	for attr in &input.attrs {
+		if attr.path.is_ident("serde") {
+			parse_container_attrs(attr, &mut attrs, false)?;
+		}
+	}
+	for attr in &input.attrs {
+		if attr.path.is_ident("openapi") {
+			parse_container_attrs(attr, &mut attrs, true)?;
+		}
+	}
+
+	// prepare impl block for codegen
 	let ident = &input.ident;
 	let name = ident.to_string();
-	let name = LitStr::new(&name, ident.span());
+	let mut name = LitStr::new(&name, ident.span());
+	if let Some(rename) = &attrs.rename {
+		name = rename.clone();
+	}
 
 	// prepare the generics - all impl generics will get `OpenapiType` requirement
 	let (impl_generics, ty_generics, where_clause) = {
@@ -46,7 +63,7 @@ fn expand_openapi_type(mut input: DeriveInput) -> syn::Result<TokenStream2> {
 	// parse the input data
 	let parsed = match &input.data {
 		Data::Struct(strukt) => parse_struct(strukt)?,
-		Data::Enum(inum) => parse_enum(inum)?,
+		Data::Enum(inum) => parse_enum(inum, &attrs)?,
 		Data::Union(union) => parse_union(union)?
 	};
 

openapi_type_derive/src/parser.rs

@@ -1,5 +1,9 @@
-use crate::util::ToLitStr;
-use syn::{spanned::Spanned as _, DataEnum, DataStruct, DataUnion, Fields, FieldsNamed, LitStr, Type};
+use crate::util::{ExpectLit, ToLitStr};
+use proc_macro2::Span;
+use syn::{
+	punctuated::Punctuated, spanned::Spanned as _, Attribute, DataEnum, DataStruct, DataUnion, Fields, FieldsNamed, LitStr,
+	Meta, Token, Type
+};
 
 pub(super) enum ParseDataType {
 	Type(Type),
@@ -36,7 +40,7 @@ pub(super) fn parse_struct(strukt: &DataStruct) -> syn::Result<ParseData> {
 	}
 }
 
-pub(super) fn parse_enum(inum: &DataEnum) -> syn::Result<ParseData> {
+pub(super) fn parse_enum(inum: &DataEnum, attrs: &ContainerAttributes) -> syn::Result<ParseData> {
 	let mut strings: Vec<LitStr> = Vec::new();
 	let mut types: Vec<(LitStr, ParseData)> = Vec::new();
 
@@ -54,19 +58,59 @@ pub(super) fn parse_enum(inum: &DataEnum) -> syn::Result<ParseData> {
 	let data_strings = if strings.is_empty() {
 		None
 	} else {
-		Some(ParseData::Enum(strings))
+		match (&attrs.tag, &attrs.content, attrs.untagged) {
+			// externally tagged (default)
+			(None, None, false) => Some(ParseData::Enum(strings)),
+			// internally tagged or adjacently tagged
+			(Some(tag), _, false) => Some(ParseData::Struct(vec![(
+				tag.clone(),
+				ParseDataType::Inline(ParseData::Enum(strings))
+			)])),
+			// untagged
+			(None, None, true) => Some(ParseData::Unit),
+			// unknown
+			_ => return Err(syn::Error::new(Span::call_site(), "Unknown enum representation"))
+		}
 	};
 
-	let data_types = if types.is_empty() {
-		None
-	} else {
-		Some(ParseData::Alternatives(
-			types
-				.into_iter()
-				.map(|(name, data)| ParseData::Struct(vec![(name, ParseDataType::Inline(data))]))
-				.collect()
-		))
-	};
+	let data_types =
+		if types.is_empty() {
+			None
+		} else {
+			Some(ParseData::Alternatives(
+				types
+					.into_iter()
+					.map(|(name, mut data)| {
+						Ok(match (&attrs.tag, &attrs.content, attrs.untagged) {
+							// externally tagged (default)
+							(None, None, false) => ParseData::Struct(vec![(name, ParseDataType::Inline(data))]),
+							// internally tagged
+							(Some(tag), None, false) => {
+								match &mut data {
+									ParseData::Struct(fields) => {
+										fields.push((tag.clone(), ParseDataType::Inline(ParseData::Enum(vec![name]))))
+									},
+									_ => return Err(syn::Error::new(
+										tag.span(),
+										"#[derive(OpenapiType)] does not support tuple variants on internally tagged enums"
+									))
+								};
+								data
+							},
+							// adjacently tagged
+							(Some(tag), Some(content), false) => ParseData::Struct(vec![
+								(tag.clone(), ParseDataType::Inline(ParseData::Enum(vec![name]))),
+								(content.clone(), ParseDataType::Inline(data)),
+							]),
+							// untagged
+							(None, None, true) => data,
+							// unknown
+							_ => return Err(syn::Error::new(Span::call_site(), "Unknown enum representation"))
+						})
+					})
+					.collect::<syn::Result<Vec<_>>>()?
+			))
+		};
 
 	match (data_strings, data_types) {
 		// only variants without fields
@@ -96,3 +140,49 @@ pub(super) fn parse_union(union: &DataUnion) -> syn::Result<ParseData> {
 		"#[derive(OpenapiType)] cannot be used on unions"
 	))
 }
+
+#[derive(Default)]
+pub(super) struct ContainerAttributes {
+	pub(super) rename: Option<LitStr>,
+	pub(super) rename_all: Option<LitStr>,
+	pub(super) tag: Option<LitStr>,
+	pub(super) content: Option<LitStr>,
+	pub(super) untagged: bool
+}
+
+pub(super) fn parse_container_attrs(
+	input: &Attribute,
+	attrs: &mut ContainerAttributes,
+	error_on_unknown: bool
+) -> syn::Result<()> {
+	let tokens: Punctuated<Meta, Token![,]> = input.parse_args_with(Punctuated::parse_terminated)?;
+	for token in tokens {
+		match token {
+			Meta::NameValue(kv) if kv.path.is_ident("rename") => {
+				attrs.rename = Some(kv.lit.expect_str()?);
+			},
+
+			Meta::NameValue(kv) if kv.path.is_ident("rename_all") => {
+				attrs.rename_all = Some(kv.lit.expect_str()?);
+			},
+
+			Meta::NameValue(kv) if kv.path.is_ident("tag") => {
+				attrs.tag = Some(kv.lit.expect_str()?);
+			},
+
+			Meta::NameValue(kv) if kv.path.is_ident("content") => {
+				attrs.content = Some(kv.lit.expect_str()?);
+			},
+
+			Meta::Path(path) if path.is_ident("untagged") => {
+				attrs.untagged = true;
+			},
+
+			Meta::Path(path) if error_on_unknown => return Err(syn::Error::new(path.span(), "Unexpected token")),
+			Meta::List(list) if error_on_unknown => return Err(syn::Error::new(list.span(), "Unexpected token")),
+			Meta::NameValue(kv) if error_on_unknown => return Err(syn::Error::new(kv.path.span(), "Unexpected token")),
+			_ => {}
+		}
+	}
+	Ok(())
+}

openapi_type_derive/src/util.rs

@@ -1,5 +1,5 @@
 use proc_macro2::Ident;
-use syn::LitStr;
+use syn::{Lit, LitStr};
 
 /// Convert any literal path into a [syn::Path].
 macro_rules! path {
@@ -36,3 +36,17 @@ impl ToLitStr for Ident {
 		LitStr::new(&self.to_string(), self.span())
 	}
 }
+
+/// Convert a [Lit] to one specific literal type.
+pub(crate) trait ExpectLit {
+	fn expect_str(self) -> syn::Result<LitStr>;
+}
+
+impl ExpectLit for Lit {
+	fn expect_str(self) -> syn::Result<LitStr> {
+		match self {
+			Self::Str(str) => Ok(str),
+			_ => Err(syn::Error::new(self.span(), "Expected string literal"))
+		}
+	}
+}