[Lobster] optional scalars support

Author: aardappel

lobster/flatbuffers.lobster

@@ -257,6 +257,10 @@ class builder:
             f(x)
             Slot(o)
 
+    def PrependSlot(o:int, x, f):
+        f(x)
+        Slot(o)
+
     def PrependBoolSlot(o, x, d): PrependSlot(o, x, d): PrependBool(_)
     def PrependByteSlot(o, x, d): PrependSlot(o, x, d): PrependByte(_)
     def PrependUint8Slot(o, x, d): PrependSlot(o, x, d): PrependUint8(_)
@@ -270,6 +274,19 @@ class builder:
     def PrependFloat32Slot(o, x, d): PrependSlot(o, x, d): PrependFloat32(_)
     def PrependFloat64Slot(o, x, d): PrependSlot(o, x, d): PrependFloat64(_)
 
+    def PrependBoolSlot(o, x): PrependSlot(o, x): PrependBool(_)
+    def PrependByteSlot(o, x): PrependSlot(o, x): PrependByte(_)
+    def PrependUint8Slot(o, x): PrependSlot(o, x): PrependUint8(_)
+    def PrependUint16Slot(o, x): PrependSlot(o, x): PrependUint16(_)
+    def PrependUint32Slot(o, x): PrependSlot(o, x): PrependUint32(_)
+    def PrependUint64Slot(o, x): PrependSlot(o, x): PrependUint64(_)
+    def PrependInt8Slot(o, x): PrependSlot(o, x): PrependInt8(_)
+    def PrependInt16Slot(o, x): PrependSlot(o, x): PrependInt16(_)
+    def PrependInt32Slot(o, x): PrependSlot(o, x): PrependInt32(_)
+    def PrependInt64Slot(o, x): PrependSlot(o, x): PrependInt64(_)
+    def PrependFloat32Slot(o, x): PrependSlot(o, x): PrependFloat32(_)
+    def PrependFloat64Slot(o, x): PrependSlot(o, x): PrependFloat64(_)
+
     def PrependUOffsetTRelativeSlot(o:int, x:offset):
         if x.o:
             PrependUOffsetTRelative(x)

src/idl_gen_lobster.cpp

@@ -110,11 +110,14 @@ class LobsterGenerator : public BaseGenerator {
               offsets + ")";
 
       } else {
+        auto defval = field.nullable ? "0" : field.value.constant;
         acc = "buf_.flatbuffers_field_" + GenTypeName(field.value.type) +
-              "(pos_, " + offsets + ", " + field.value.constant + ")";
+              "(pos_, " + offsets + ", " + defval + ")";
       }
       if (field.value.type.enum_def)
         acc = NormalizedName(*field.value.type.enum_def) + "(" + acc + ")";
+      if (field.nullable)
+        acc += ", buf_.flatbuffers_field_present(pos_, " + offsets + ")";
       code += def + "():\n        return " + acc + "\n";
       return;
     }
@@ -198,7 +201,7 @@ class LobsterGenerator : public BaseGenerator {
               NormalizedName(field) + ":" + LobsterType(field.value.type) +
               "):\n        b_.Prepend" + GenMethod(field.value.type) + "Slot(" +
               NumToString(offset) + ", " + NormalizedName(field);
-      if (IsScalar(field.value.type.base_type))
+      if (IsScalar(field.value.type.base_type) && !field.nullable)
         code += ", " + field.value.constant;
       code += ")\n        return this\n";
     }

src/idl_parser.cpp

@@ -2258,7 +2258,8 @@ CheckedError Parser::CheckClash(std::vector<FieldDef *> &fields,
 
 
 bool Parser::SupportsNullableScalars() const {
-  return !(opts.lang_to_generate & ~(IDLOptions::kRust | IDLOptions::kSwift));
+  return !(opts.lang_to_generate &
+    ~(IDLOptions::kRust | IDLOptions::kSwift | IDLOptions::kLobster));
 }
 
 bool Parser::SupportsAdvancedUnionFeatures() const {

tests/generate_code.bat

@@ -54,7 +54,7 @@ set TEST_NOINCL_FLAGS=%TEST_BASE_FLAGS% --no-includes --no-fb-import
 ..\%buildtype%\flatc.exe --cpp %TEST_BASE_FLAGS% --cpp-ptr-type flatbuffers::unique_ptr native_type_test.fbs || goto FAIL
 
 @rem Generate the optional scalar code for tests.
-..\%buildtype%\flatc.exe --rust optional_scalars.fbs || goto FAIL
+..\%buildtype%\flatc.exe --rust --lobster optional_scalars.fbs || goto FAIL
 
 @rem Generate the schema evolution tests
 ..\%buildtype%\flatc.exe --cpp --scoped-enums %TEST_CPP_FLAGS% -o evolution_test ./evolution_test/evolution_v1.fbs ./evolution_test/evolution_v2.fbs || goto FAIL

tests/generate_code.sh

@@ -52,7 +52,7 @@ $TEST_NOINCL_FLAGS $TEST_CPP_FLAGS $TEST_CS_FLAGS -o namespace_test namespace_te
 ../flatc --dart monster_extra.fbs
 
 # Generate optional scalar code for tests.
-../flatc --rust optional_scalars.fbs
+../flatc --rust --lobster optional_scalars.fbs
 
 # Generate the schema evolution tests
 ../flatc --cpp --scoped-enums $TEST_CPP_FLAGS -o evolution_test ./evolution_test/evolution_v*.fbs

tests/lobstertest.lobster

@@ -14,6 +14,7 @@
 
 import from "../lobster/"
 import monster_test_generated
+import optional_scalars_generated
 
 def check_read_buffer(buf):
     // CheckReadBuffer checks that the given buffer is evaluated correctly as the example Monster.
@@ -108,6 +109,28 @@ def make_monster_from_generated_code():
 
     return b.SizedCopy()
 
+def test_optional_scalars():
+    def build(add_fields):
+        let b = flatbuffers_builder {}
+        let ss = optional_scalars_ScalarStuffBuilder { b }.start()
+        if add_fields:
+            ss.add_just_i8(1)
+            ss.add_maybe_i8(1)
+            ss.add_default_i8(1)
+        b.Finish(ss.end())
+        return optional_scalars_GetRootAsScalarStuff(b.SizedCopy())
+
+    var root = build(true)
+    assert root.just_i8() == 1 and root.default_i8() == 1
+    var maybe_val, maybe_present = root.maybe_i8()
+    assert maybe_val == 1 and maybe_present == true
+
+    root = build(false)
+    assert root.just_i8() == 0 and root.default_i8() == 42
+    maybe_val, maybe_present = root.maybe_i8()
+    assert maybe_val == 0 and maybe_present == false
+
+
 // Verify that the canonical flatbuffer file (produced by the C++ implementation)
 // is readable by the generated Lobster code.
 let fb2 = read_file("monsterdata_test.mon")
@@ -134,4 +157,7 @@ assert not err2
 // Check the resulting binary again (full roundtrip test):
 check_read_buffer(fb3)
 
-print "Lobster test succesful!"
+// Additional tests.
+test_optional_scalars()
+
+print "Lobster test succesful!"

tests/optional_scalars_generated.lobster

@@ -0,0 +1,184 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+import flatbuffers
+
+namespace optional_scalars
+
+class ScalarStuff
+
+class ScalarStuff : flatbuffers_handle
+    def just_i8():
+        return buf_.flatbuffers_field_int8(pos_, 4, 0)
+    def maybe_i8():
+        return buf_.flatbuffers_field_int8(pos_, 6, 0), buf_.flatbuffers_field_present(pos_, 6)
+    def default_i8():
+        return buf_.flatbuffers_field_int8(pos_, 8, 42)
+    def just_u8():
+        return buf_.flatbuffers_field_int8(pos_, 10, 0)
+    def maybe_u8():
+        return buf_.flatbuffers_field_int8(pos_, 12, 0), buf_.flatbuffers_field_present(pos_, 12)
+    def default_u8():
+        return buf_.flatbuffers_field_int8(pos_, 14, 42)
+    def just_i16():
+        return buf_.flatbuffers_field_int16(pos_, 16, 0)
+    def maybe_i16():
+        return buf_.flatbuffers_field_int16(pos_, 18, 0), buf_.flatbuffers_field_present(pos_, 18)
+    def default_i16():
+        return buf_.flatbuffers_field_int16(pos_, 20, 42)
+    def just_u16():
+        return buf_.flatbuffers_field_int16(pos_, 22, 0)
+    def maybe_u16():
+        return buf_.flatbuffers_field_int16(pos_, 24, 0), buf_.flatbuffers_field_present(pos_, 24)
+    def default_u16():
+        return buf_.flatbuffers_field_int16(pos_, 26, 42)
+    def just_i32():
+        return buf_.flatbuffers_field_int32(pos_, 28, 0)
+    def maybe_i32():
+        return buf_.flatbuffers_field_int32(pos_, 30, 0), buf_.flatbuffers_field_present(pos_, 30)
+    def default_i32():
+        return buf_.flatbuffers_field_int32(pos_, 32, 42)
+    def just_u32():
+        return buf_.flatbuffers_field_int32(pos_, 34, 0)
+    def maybe_u32():
+        return buf_.flatbuffers_field_int32(pos_, 36, 0), buf_.flatbuffers_field_present(pos_, 36)
+    def default_u32():
+        return buf_.flatbuffers_field_int32(pos_, 38, 42)
+    def just_i64():
+        return buf_.flatbuffers_field_int64(pos_, 40, 0)
+    def maybe_i64():
+        return buf_.flatbuffers_field_int64(pos_, 42, 0), buf_.flatbuffers_field_present(pos_, 42)
+    def default_i64():
+        return buf_.flatbuffers_field_int64(pos_, 44, 42)
+    def just_u64():
+        return buf_.flatbuffers_field_int64(pos_, 46, 0)
+    def maybe_u64():
+        return buf_.flatbuffers_field_int64(pos_, 48, 0), buf_.flatbuffers_field_present(pos_, 48)
+    def default_u64():
+        return buf_.flatbuffers_field_int64(pos_, 50, 42)
+    def just_f32():
+        return buf_.flatbuffers_field_float32(pos_, 52, 0.0)
+    def maybe_f32():
+        return buf_.flatbuffers_field_float32(pos_, 54, 0), buf_.flatbuffers_field_present(pos_, 54)
+    def default_f32():
+        return buf_.flatbuffers_field_float32(pos_, 56, 42.0)
+    def just_f64():
+        return buf_.flatbuffers_field_float64(pos_, 58, 0.0)
+    def maybe_f64():
+        return buf_.flatbuffers_field_float64(pos_, 60, 0), buf_.flatbuffers_field_present(pos_, 60)
+    def default_f64():
+        return buf_.flatbuffers_field_float64(pos_, 62, 42.0)
+    def just_bool():
+        return buf_.flatbuffers_field_int8(pos_, 64, 0)
+    def maybe_bool():
+        return buf_.flatbuffers_field_int8(pos_, 66, 0), buf_.flatbuffers_field_present(pos_, 66)
+    def default_bool():
+        return buf_.flatbuffers_field_int8(pos_, 68, 1)
+
+def GetRootAsScalarStuff(buf:string): return ScalarStuff { buf, buf.flatbuffers_indirect(0) }
+
+struct ScalarStuffBuilder:
+    b_:flatbuffers_builder
+    def start():
+        b_.StartObject(33)
+        return this
+    def add_just_i8(just_i8:int):
+        b_.PrependInt8Slot(0, just_i8, 0)
+        return this
+    def add_maybe_i8(maybe_i8:int):
+        b_.PrependInt8Slot(1, maybe_i8)
+        return this
+    def add_default_i8(default_i8:int):
+        b_.PrependInt8Slot(2, default_i8, 42)
+        return this
+    def add_just_u8(just_u8:int):
+        b_.PrependUint8Slot(3, just_u8, 0)
+        return this
+    def add_maybe_u8(maybe_u8:int):
+        b_.PrependUint8Slot(4, maybe_u8)
+        return this
+    def add_default_u8(default_u8:int):
+        b_.PrependUint8Slot(5, default_u8, 42)
+        return this
+    def add_just_i16(just_i16:int):
+        b_.PrependInt16Slot(6, just_i16, 0)
+        return this
+    def add_maybe_i16(maybe_i16:int):
+        b_.PrependInt16Slot(7, maybe_i16)
+        return this
+    def add_default_i16(default_i16:int):
+        b_.PrependInt16Slot(8, default_i16, 42)
+        return this
+    def add_just_u16(just_u16:int):
+        b_.PrependUint16Slot(9, just_u16, 0)
+        return this
+    def add_maybe_u16(maybe_u16:int):
+        b_.PrependUint16Slot(10, maybe_u16)
+        return this
+    def add_default_u16(default_u16:int):
+        b_.PrependUint16Slot(11, default_u16, 42)
+        return this
+    def add_just_i32(just_i32:int):
+        b_.PrependInt32Slot(12, just_i32, 0)
+        return this
+    def add_maybe_i32(maybe_i32:int):
+        b_.PrependInt32Slot(13, maybe_i32)
+        return this
+    def add_default_i32(default_i32:int):
+        b_.PrependInt32Slot(14, default_i32, 42)
+        return this
+    def add_just_u32(just_u32:int):
+        b_.PrependUint32Slot(15, just_u32, 0)
+        return this
+    def add_maybe_u32(maybe_u32:int):
+        b_.PrependUint32Slot(16, maybe_u32)
+        return this
+    def add_default_u32(default_u32:int):
+        b_.PrependUint32Slot(17, default_u32, 42)
+        return this
+    def add_just_i64(just_i64:int):
+        b_.PrependInt64Slot(18, just_i64, 0)
+        return this
+    def add_maybe_i64(maybe_i64:int):
+        b_.PrependInt64Slot(19, maybe_i64)
+        return this
+    def add_default_i64(default_i64:int):
+        b_.PrependInt64Slot(20, default_i64, 42)
+        return this
+    def add_just_u64(just_u64:int):
+        b_.PrependUint64Slot(21, just_u64, 0)
+        return this
+    def add_maybe_u64(maybe_u64:int):
+        b_.PrependUint64Slot(22, maybe_u64)
+        return this
+    def add_default_u64(default_u64:int):
+        b_.PrependUint64Slot(23, default_u64, 42)
+        return this
+    def add_just_f32(just_f32:float):
+        b_.PrependFloat32Slot(24, just_f32, 0.0)
+        return this
+    def add_maybe_f32(maybe_f32:float):
+        b_.PrependFloat32Slot(25, maybe_f32)
+        return this
+    def add_default_f32(default_f32:float):
+        b_.PrependFloat32Slot(26, default_f32, 42.0)
+        return this
+    def add_just_f64(just_f64:float):
+        b_.PrependFloat64Slot(27, just_f64, 0.0)
+        return this
+    def add_maybe_f64(maybe_f64:float):
+        b_.PrependFloat64Slot(28, maybe_f64)
+        return this
+    def add_default_f64(default_f64:float):
+        b_.PrependFloat64Slot(29, default_f64, 42.0)
+        return this
+    def add_just_bool(just_bool:int):
+        b_.PrependBoolSlot(30, just_bool, 0)
+        return this
+    def add_maybe_bool(maybe_bool:int):
+        b_.PrependBoolSlot(31, maybe_bool)
+        return this
+    def add_default_bool(default_bool:int):
+        b_.PrependBoolSlot(32, default_bool, 1)
+        return this
+    def end():
+        return b_.EndObject()
+