Ruopt enum (#6156)

* Rust support for optional enums

* make optional_scalars2 for languages that support optional enums

Co-authored-by: Casper Neo <cneo@google.com>

src/idl_gen_rust.cpp

@@ -673,6 +673,9 @@ class RustGenerator : public BaseGenerator {
       }
       case ftUnionKey:
       case ftEnumKey: {
+        if (field.optional) {
+            return "None";
+        }
         auto ev = field.value.type.enum_def->FindByValue(field.value.constant);
         assert(ev);
         return WrapInNameSpace(field.value.type.enum_def->defined_namespace,
@@ -724,7 +727,7 @@ class RustGenerator : public BaseGenerator {
       case ftEnumKey:
       case ftUnionKey: {
         const auto typname = WrapInNameSpace(*type.enum_def);
-        return typname;
+        return field.optional ? "Option<" + typname + ">" : typname;
       }
       case ftUnionValue: {
         return "Option<flatbuffers::WIPOffset<flatbuffers::UnionWIPOffset>>";
@@ -872,7 +875,9 @@ class RustGenerator : public BaseGenerator {
       case ftEnumKey:
       case ftUnionKey: {
         const auto underlying_typname = GetTypeBasic(type);
-        return "self.fbb_.push_slot::<" + underlying_typname + ">";
+        return (field.optional ?
+                   "self.fbb_.push_slot_always::<" :
+                   "self.fbb_.push_slot::<") + underlying_typname + ">";
       }
 
       case ftStruct: {
@@ -925,7 +930,7 @@ class RustGenerator : public BaseGenerator {
       case ftEnumKey:
       case ftUnionKey: {
         const auto typname = WrapInNameSpace(*type.enum_def);
-        return typname;
+        return field.optional ? "Option<" + typname + ">" : typname;
       }
 
       case ftUnionValue: {
@@ -1027,8 +1032,12 @@ class RustGenerator : public BaseGenerator {
         const auto underlying_typname = GetTypeBasic(type);  //<- never used
         const auto typname = WrapInNameSpace(*type.enum_def);
         const auto default_value = GetDefaultScalarValue(field);
-        return "self._tab.get::<" + typname + ">(" + offset_name + ", Some(" +
-               default_value + ")).unwrap()";
+        if (field.optional) {
+          return "self._tab.get::<" + typname + ">(" + offset_name + ", None)";
+        } else {
+          return "self._tab.get::<" + typname + ">(" + offset_name + ", Some(" +
+                 default_value + ")).unwrap()";
+        }
       }
       case ftString: {
         return AddUnwrapIfRequired(

tests/generate_code.sh

@@ -53,7 +53,8 @@ $TEST_NOINCL_FLAGS $TEST_CPP_FLAGS $TEST_CS_FLAGS $TEST_JS_TS_FLAGS -o namespace
 ../flatc --dart monster_extra.fbs
 
 # Generate optional scalar code for tests.
-../flatc --kotlin --rust --lobster optional_scalars.fbs
+../flatc --kotlin --lobster optional_scalars.fbs  # These ones have not added optional enum support.
+../flatc --rust optional_scalars2.fbs
 ../flatc $TEST_NOINCL_FLAGS $TEST_CPP_FLAGS --cpp optional_scalars.fbs
 
 # Generate the schema evolution tests

tests/optional_scalars2.fbs

@@ -0,0 +1,59 @@
+namespace optional_scalars;
+
+enum OptionalByte: byte {
+  None = 0,
+  One = 1,
+  Two = 2,
+}
+
+// This table tests optional scalars in tables. It should be integrated with
+// the main monster test once most languages support optional scalars.
+table ScalarStuff {
+  just_i8: int8;
+  maybe_i8: int8 = null;
+  default_i8: int8 = 42;
+  just_u8: uint8;
+  maybe_u8: uint8 = null;
+  default_u8: uint8 = 42;
+
+  just_i16: int16;
+  maybe_i16: int16 = null;
+  default_i16: int16 = 42;
+  just_u16: uint16;
+  maybe_u16: uint16 = null;
+  default_u16: uint16 = 42;
+
+  just_i32: int32;
+  maybe_i32: int32 = null;
+  default_i32: int32 = 42;
+  just_u32: uint32;
+  maybe_u32: uint32 = null;
+  default_u32: uint32 = 42;
+
+  just_i64: int64;
+  maybe_i64: int64 = null;
+  default_i64: int64 = 42;
+  just_u64: uint64;
+  maybe_u64: uint64 = null;
+  default_u64: uint64 = 42;
+
+  just_f32: float32;
+  maybe_f32: float32 = null;
+  default_f32: float32 = 42;
+  just_f64: float64;
+  maybe_f64: float64 = null;
+  default_f64: float64 = 42;
+
+  just_bool: bool;
+  maybe_bool: bool = null;
+  default_bool: bool = true;
+
+  just_enum: OptionalByte;
+  maybe_enum: OptionalByte = null;
+  default_enum: OptionalByte = One;
+}
+
+root_type ScalarStuff;
+
+file_identifier "NULL";
+file_extension "mon";

tests/optional_scalars2_generated.rs

@@ -23,11 +23,12 @@ pub mod optional_scalars {
 pub enum OptionalByte {
   None = 0,
   One = 1,
+  Two = 2,
 
 }
 
 pub const ENUM_MIN_OPTIONAL_BYTE: i8 = 0;
-pub const ENUM_MAX_OPTIONAL_BYTE: i8 = 1;
+pub const ENUM_MAX_OPTIONAL_BYTE: i8 = 2;
 
 impl<'a> flatbuffers::Follow<'a> for OptionalByte {
   type Inner = Self;
@@ -61,15 +62,17 @@ impl flatbuffers::Push for OptionalByte {
 }
 
 #[allow(non_camel_case_types)]
-pub const ENUM_VALUES_OPTIONAL_BYTE: [OptionalByte; 2] = [
+pub const ENUM_VALUES_OPTIONAL_BYTE: [OptionalByte; 3] = [
   OptionalByte::None,
-  OptionalByte::One
+  OptionalByte::One,
+  OptionalByte::Two
 ];
 
 #[allow(non_camel_case_types)]
-pub const ENUM_NAMES_OPTIONAL_BYTE: [&str; 2] = [
+pub const ENUM_NAMES_OPTIONAL_BYTE: [&str; 3] = [
     "None",
-    "One"
+    "One",
+    "Two"
 ];
 
 pub fn enum_name_optional_byte(e: OptionalByte) -> &'static str {
@@ -129,6 +132,7 @@ impl<'a> ScalarStuff<'a> {
       if let Some(x) = args.maybe_i16 { builder.add_maybe_i16(x); }
       builder.add_just_i16(args.just_i16);
       builder.add_default_enum(args.default_enum);
+      if let Some(x) = args.maybe_enum { builder.add_maybe_enum(x); }
       builder.add_just_enum(args.just_enum);
       builder.add_default_bool(args.default_bool);
       if let Some(x) = args.maybe_bool { builder.add_maybe_bool(x); }
@@ -176,7 +180,8 @@ impl<'a> ScalarStuff<'a> {
     pub const VT_MAYBE_BOOL: flatbuffers::VOffsetT = 66;
     pub const VT_DEFAULT_BOOL: flatbuffers::VOffsetT = 68;
     pub const VT_JUST_ENUM: flatbuffers::VOffsetT = 70;
-    pub const VT_DEFAULT_ENUM: flatbuffers::VOffsetT = 72;
+    pub const VT_MAYBE_ENUM: flatbuffers::VOffsetT = 72;
+    pub const VT_DEFAULT_ENUM: flatbuffers::VOffsetT = 74;
 
   #[inline]
   pub fn just_i8(&self) -> i8 {
@@ -315,6 +320,10 @@ impl<'a> ScalarStuff<'a> {
     self._tab.get::<OptionalByte>(ScalarStuff::VT_JUST_ENUM, Some(OptionalByte::None)).unwrap()
   }
   #[inline]
+  pub fn maybe_enum(&self) -> Option<OptionalByte> {
+    self._tab.get::<OptionalByte>(ScalarStuff::VT_MAYBE_ENUM, None)
+  }
+  #[inline]
   pub fn default_enum(&self) -> OptionalByte {
     self._tab.get::<OptionalByte>(ScalarStuff::VT_DEFAULT_ENUM, Some(OptionalByte::One)).unwrap()
   }
@@ -355,6 +364,7 @@ pub struct ScalarStuffArgs {
     pub maybe_bool: Option<bool>,
     pub default_bool: bool,
     pub just_enum: OptionalByte,
+    pub maybe_enum: Option<OptionalByte>,
     pub default_enum: OptionalByte,
 }
 impl<'a> Default for ScalarStuffArgs {
@@ -395,6 +405,7 @@ impl<'a> Default for ScalarStuffArgs {
             maybe_bool: None,
             default_bool: true,
             just_enum: OptionalByte::None,
+            maybe_enum: None,
             default_enum: OptionalByte::One,
         }
     }
@@ -541,6 +552,10 @@ impl<'a: 'b, 'b> ScalarStuffBuilder<'a, 'b> {
     self.fbb_.push_slot::<OptionalByte>(ScalarStuff::VT_JUST_ENUM, just_enum, OptionalByte::None);
   }
   #[inline]
+  pub fn add_maybe_enum(&mut self, maybe_enum: OptionalByte) {
+    self.fbb_.push_slot_always::<OptionalByte>(ScalarStuff::VT_MAYBE_ENUM, maybe_enum);
+  }
+  #[inline]
   pub fn add_default_enum(&mut self, default_enum: OptionalByte) {
     self.fbb_.push_slot::<OptionalByte>(ScalarStuff::VT_DEFAULT_ENUM, default_enum, OptionalByte::One);
   }

tests/rust_usage_test/tests/integration_test.rs

@@ -43,7 +43,7 @@ mod monster_test_generated;
 pub use monster_test_generated::my_game;
 
 #[allow(dead_code, unused_imports)]
-#[path = "../../optional_scalars_generated.rs"]
+#[path = "../../optional_scalars2_generated.rs"]
 mod optional_scalars_generated;
 
 #[rustfmt::skip] // TODO: Use standard rust formatting and remove dead code.

tests/rust_usage_test/tests/optional_scalars_test.rs

@@ -1,5 +1,5 @@
 #[allow(dead_code, unused_imports)]
-#[path = "../../optional_scalars_generated.rs"]
+#[path = "../../optional_scalars2_generated.rs"]
 mod optional_scalars_generated;
 use crate::optional_scalars_generated::optional_scalars::*;
 
@@ -16,12 +16,15 @@ macro_rules! make_test {
         fn $test_name() {
             let mut builder = flatbuffers::FlatBufferBuilder::new();
             // Test five makes sense when specified.
-            let ss = ScalarStuff::create(&mut builder, &ScalarStuffArgs {
-                $just: $five,
-                $default: $five,
-                $maybe: Some($five),
-                ..Default::default()
-            });
+            let ss = ScalarStuff::create(
+                &mut builder,
+                &ScalarStuffArgs {
+                    $just: $five,
+                    $default: $five,
+                    $maybe: Some($five),
+                    ..Default::default()
+                },
+            );
             builder.finish(ss, None);
 
             let s = flatbuffers::get_root::<ScalarStuff>(builder.finished_data());
@@ -35,7 +38,6 @@ macro_rules! make_test {
             assert_eq!(s.$default(), $fortytwo);
             assert_eq!(s.$maybe(), None);
         }
-
     };
 }
 
@@ -47,6 +49,39 @@ make_test!(optional_i32, just_i32, default_i32, maybe_i32, 5, 0, 42);
 make_test!(optional_u32, just_u32, default_u32, maybe_u32, 5, 0, 42);
 make_test!(optional_i64, just_i64, default_i64, maybe_i64, 5, 0, 42);
 make_test!(optional_u64, just_u64, default_u64, maybe_u64, 5, 0, 42);
-make_test!(optional_f32, just_f32, default_f32, maybe_f32, 5.0, 0.0, 42.0);
-make_test!(optional_f64, just_f64, default_f64, maybe_f64, 5.0, 0.0, 42.0);
-make_test!(optional_bool, just_bool, default_bool, maybe_bool, true, false, true);
+make_test!(
+    optional_f32,
+    just_f32,
+    default_f32,
+    maybe_f32,
+    5.0,
+    0.0,
+    42.0
+);
+make_test!(
+    optional_f64,
+    just_f64,
+    default_f64,
+    maybe_f64,
+    5.0,
+    0.0,
+    42.0
+);
+make_test!(
+    optional_bool,
+    just_bool,
+    default_bool,
+    maybe_bool,
+    true,
+    false,
+    true
+);
+make_test!(
+     optional_enum,
+     just_enum,
+     default_enum,
+     maybe_enum,
+     OptionalByte::Two,
+     OptionalByte::None,
+     OptionalByte::One
+);