Add value.SameValue(otherValue) function (rogchap#162)

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Support for calling constructors functions with NewInstance on Function
 - Build v8 with i18n support
 - Access "this" from function callback
+- value.SameValue(otherValue) function to compare values for sameness
 
 ### Changed
 - Removed error return value from Context.Isolate() which never fails

function_template.go

@@ -83,7 +83,7 @@ func goFunctionCallback(ctxref int, cbref int, thisAndArgs *C.ValuePtr, argsCoun
 		args: make([]*Value, argsCount),
 	}
 
-	argv := (*[1 << 30]C.ValuePtr)(unsafe.Pointer(thisAndArgs))[1:argsCount + 1:argsCount + 1]
+	argv := (*[1 << 30]C.ValuePtr)(unsafe.Pointer(thisAndArgs))[1 : argsCount+1 : argsCount+1]
 	for i, v := range argv {
 		val := &Value{ptr: v, ctx: ctx}
 		info.args[i] = val

v8go.cc

@@ -708,6 +708,17 @@ ValuePtr ValueToObject(ValuePtr ptr) {
   return tracked_value(ctx, new_val);
 }
 
+int ValueSameValue(ValuePtr ptr, ValuePtr otherPtr) {
+  m_value* val1 = static_cast<m_value*>(ptr);
+  m_value* val2 = static_cast<m_value*>(otherPtr);
+
+  ISOLATE_SCOPE(val1->iso);
+  Local<Value> value1 = val1->ptr.Get(iso);
+  Local<Value> value2 = val2->ptr.Get(iso);
+
+  return value1->SameValue(value2);
+}
+
 int ValueIsUndefined(ValuePtr ptr) {
   LOCAL_VALUE(ptr);
   return value->IsUndefined();

v8go.h

@@ -105,6 +105,7 @@ const char* ValueToDetailString(ValuePtr ptr);
 uint32_t ValueToUint32(ValuePtr ptr);
 extern ValueBigInt ValueToBigInt(ValuePtr ptr);
 extern ValuePtr ValueToObject(ValuePtr ptr);
+int ValueSameValue(ValuePtr ptr, ValuePtr otherPtr);
 int ValueIsUndefined(ValuePtr ptr);
 int ValueIsNull(ValuePtr ptr);
 int ValueIsNullOrUndefined(ValuePtr ptr);

value.go

@@ -224,6 +224,12 @@ func (v *Value) Uint32() uint32 {
 	return uint32(C.ValueToUint32(v.ptr))
 }
 
+// SameValue returns true if the other value is the same value.
+// This is equivalent to `Object.is(v, other)` in JS.
+func (v *Value) SameValue(other *Value) bool {
+	return C.ValueSameValue(v.ptr, other.ptr) != 0
+}
+
 // IsUndefined returns true if this value is the undefined value. See ECMA-262 4.3.10.
 func (v *Value) IsUndefined() bool {
 	return C.ValueIsUndefined(v.ptr) != 0

value_test.go

@@ -443,6 +443,27 @@ func TestValueFunction(t *testing.T) {
 
 }
 
+func TestValueSameValue(t *testing.T) {
+	t.Parallel()
+	iso, _ := v8go.NewIsolate()
+	defer iso.Dispose()
+	ctx, _ := v8go.NewContext(iso)
+	defer ctx.Close()
+
+	objTempl := v8go.NewObjectTemplate(iso)
+	obj1, err := objTempl.NewInstance(ctx)
+	failIf(t, err)
+	obj2, err := objTempl.NewInstance(ctx)
+	failIf(t, err)
+
+	if obj1.Value.SameValue(obj2.Value) != false {
+		t.Errorf("SameValue on two different values didn't return false")
+	}
+	if obj1.Value.SameValue(obj1.Value) != true {
+		t.Errorf("SameValue on two of the same value didn't return true")
+	}
+}
+
 func TestValueIsXXX(t *testing.T) {
 	t.Parallel()
 	iso, _ := v8go.NewIsolate()