cpp-common: add `bt2s::optional`, alias of `nonstd::optional`

[babeltrace.git] / src / cpp-common / bt2 / field-class.hpp

diff --git a/src/cpp-common/bt2/field-class.hpp b/src/cpp-common/bt2/field-class.hpp
index ae2c52a3711f58da6754e6ef82c32c849506e658..94cdb8e6de036f2cd94ece042011537d39ede863 100644 (file)
--- a/src/cpp-common/bt2/field-class.hpp
+++ b/src/cpp-common/bt2/field-class.hpp
@@ -13,11 +13,10 @@
 #include <babeltrace2/babeltrace.h>
 
 #include "common/assert.h"
-#include "cpp-common/optional.hpp"
-#include "cpp-common/string_view.hpp"
+#include "cpp-common/bt2s/optional.hpp"
 
+#include "borrowed-object-iterator.hpp"
 #include "borrowed-object.hpp"
-#include "common-iterator.hpp"
 #include "exc.hpp"
 #include "field-path.hpp"
 #include "integer-range-set.hpp"
@@ -172,9 +171,7 @@ protected:
 
 public:
     using Shared = SharedFieldClass<CommonFieldClass<LibObjT>, LibObjT>;
-
-    using UserAttributes =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstMapValue, MapValue>::type;
+    using UserAttributes = internal::DepUserAttrs<LibObjT>;
 
     explicit CommonFieldClass(const _LibObjPtr libObjPtr) noexcept : _ThisBorrowedObject {libObjPtr}
     {
@@ -186,12 +183,17 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonFieldClass& operator=(const CommonFieldClass<OtherLibObjT> fc) noexcept
+    CommonFieldClass operator=(const CommonFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisBorrowedObject::operator=(fc);
         return *this;
     }
 
+    CommonFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonFieldClass<const bt_field_class> {*this};
+    }
+
     FieldClassType type() const noexcept
     {
         return static_cast<FieldClassType>(bt_field_class_get_type(this->libObjPtr()));
@@ -400,7 +402,7 @@ public:
     template <typename LibValT>
     void userAttributes(const CommonMapValue<LibValT> userAttrs) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value, "Not available with `bt2::ConstFieldClass`.");
 
         bt_field_class_set_user_attributes(this->libObjPtr(), userAttrs.libObjPtr());
     }
@@ -469,13 +471,18 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonBitArrayFieldClass<LibObjT>&
+    CommonBitArrayFieldClass<LibObjT>
     operator=(const CommonBitArrayFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonBitArrayFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonBitArrayFieldClass<const bt_field_class> {*this};
+    }
+
     std::uint64_t length() const noexcept
     {
         return bt_field_class_bit_array_get_length(this->libObjPtr());
@@ -544,15 +551,21 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonIntegerFieldClass& operator=(const CommonIntegerFieldClass<OtherLibObjT> fc) noexcept
+    CommonIntegerFieldClass operator=(const CommonIntegerFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonIntegerFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonIntegerFieldClass<const bt_field_class> {*this};
+    }
+
     void fieldValueRange(const std::uint64_t n) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstIntegerFieldClass`.");
 
         bt_field_class_integer_set_field_value_range(this->libObjPtr(), n);
     }
@@ -564,7 +577,8 @@ public:
 
     void preferredDisplayBase(const DisplayBase base) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstIntegerFieldClass`.");
 
         bt_field_class_integer_set_preferred_display_base(
             this->libObjPtr(), static_cast<bt_field_class_integer_preferred_display_base>(base));
@@ -603,10 +617,6 @@ struct TypeDescr<ConstIntegerFieldClass> : public IntegerFieldClassTypeDescr
 {
 };
 
-} /* namespace internal */
-
-namespace internal {
-
 template <typename LibObjT>
 struct ConstEnumerationFieldClassMappingSpec;
 
@@ -671,7 +681,7 @@ public:
     {
     }
 
-    ConstEnumerationFieldClassMapping&
+    ConstEnumerationFieldClassMapping
     operator=(const ConstEnumerationFieldClassMapping& mapping) noexcept
     {
         _ThisBorrowedObject::operator=(mapping);
@@ -684,7 +694,7 @@ public:
             internal::ConstEnumerationFieldClassMappingSpec<LibObjT>::ranges(this->libObjPtr())};
     }
 
-    bpstd::string_view label() const noexcept
+    const char *label() const noexcept
     {
         return internal::ConstEnumerationFieldClassMappingSpec<LibObjT>::label(this->libObjPtr());
     }
@@ -778,14 +788,19 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonBaseEnumerationFieldClass&
+    CommonBaseEnumerationFieldClass
     operator=(const CommonBaseEnumerationFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonIntegerFieldClass::operator=(fc);
         return *this;
     }
 
-    std::uint64_t size() const noexcept
+    CommonBaseEnumerationFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonBaseEnumerationFieldClass<const bt_field_class> {*this};
+    }
+
+    std::uint64_t length() const noexcept
     {
         return bt_field_class_enumeration_get_mapping_count(this->libObjPtr());
     }
@@ -802,11 +817,10 @@ class CommonEnumerationFieldClass final : public CommonBaseEnumerationFieldClass
 private:
     using typename CommonFieldClass<LibObjT>::_LibObjPtr;
     using typename CommonBaseEnumerationFieldClass<LibObjT>::_ThisCommonBaseEnumerationFieldClass;
-    using _ThisCommonEnumerationFieldClass = CommonEnumerationFieldClass<LibObjT, MappingT>;
 
 public:
-    using Shared = SharedFieldClass<_ThisCommonEnumerationFieldClass, LibObjT>;
-    using Iterator = CommonIterator<CommonEnumerationFieldClass, MappingT>;
+    using Shared = SharedFieldClass<CommonEnumerationFieldClass, LibObjT>;
+    using Iterator = BorrowedObjectIterator<CommonEnumerationFieldClass>;
     using Mapping = MappingT;
 
     explicit CommonEnumerationFieldClass(const _LibObjPtr libObjPtr) noexcept :
@@ -818,15 +832,15 @@ public:
     template <typename OtherLibObjT>
     CommonEnumerationFieldClass(
         const CommonEnumerationFieldClass<OtherLibObjT, MappingT> fc) noexcept :
-        _ThisCommonEnumerationFieldClass {fc}
+        CommonEnumerationFieldClass {fc}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonEnumerationFieldClass&
+    CommonEnumerationFieldClass
     operator=(const CommonEnumerationFieldClass<OtherLibObjT, MappingT> fc) noexcept
     {
-        _ThisCommonEnumerationFieldClass::operator=(fc);
+        CommonEnumerationFieldClass::operator=(fc);
         return *this;
     }
 
@@ -836,7 +850,7 @@ public:
             this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Mapping> operator[](const char * const label) const noexcept
+    bt2s::optional<Mapping> operator[](const char * const label) const noexcept
     {
         const auto libObjPtr = internal::CommonEnumerationFieldClassSpec<MappingT>::mappingByLabel(
             this->libObjPtr(), label);
@@ -845,10 +859,10 @@ public:
             return Mapping {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Mapping> operator[](const std::string& label) const noexcept
+    bt2s::optional<Mapping> operator[](const std::string& label) const noexcept
     {
         return (*this)[label.data()];
     }
@@ -875,7 +889,7 @@ public:
 
     Iterator end() const noexcept
     {
-        return Iterator {*this, this->size()};
+        return Iterator {*this, this->length()};
     }
 
     Shared shared() const noexcept
@@ -976,13 +990,10 @@ class CommonStructureFieldClassMember final : public BorrowedObject<LibObjT>
 private:
     using typename BorrowedObject<LibObjT>::_LibObjPtr;
     using typename BorrowedObject<LibObjT>::_ThisBorrowedObject;
-
-    using _FieldClass =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstFieldClass, FieldClass>::type;
+    using _FieldClass = internal::DepFc<LibObjT>;
 
 public:
-    using UserAttributes =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstMapValue, MapValue>::type;
+    using UserAttributes = internal::DepUserAttrs<LibObjT>;
 
     explicit CommonStructureFieldClassMember(const _LibObjPtr libObjPtr) noexcept :
         _ThisBorrowedObject {libObjPtr}
@@ -997,14 +1008,19 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonStructureFieldClassMember<LibObjT>&
+    CommonStructureFieldClassMember<LibObjT>
     operator=(const CommonStructureFieldClassMember<OtherLibObjT> fc) noexcept
     {
         _ThisBorrowedObject::operator=(fc);
         return *this;
     }
 
-    bpstd::string_view name() const noexcept
+    CommonStructureFieldClassMember<const bt_field_class_structure_member> asConst() const noexcept
+    {
+        return CommonStructureFieldClassMember<const bt_field_class_structure_member> {*this};
+    }
+
+    const char *name() const noexcept
     {
         return bt_field_class_structure_member_get_name(this->libObjPtr());
     }
@@ -1018,7 +1034,8 @@ public:
     template <typename LibValT>
     void userAttributes(const CommonMapValue<LibValT> userAttrs) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstStructureFieldClassMember`.");
 
         bt_field_class_structure_member_set_user_attributes(this->libObjPtr(),
                                                             userAttrs.libObjPtr());
@@ -1103,11 +1120,10 @@ private:
 
 public:
     using Shared = SharedFieldClass<CommonStructureFieldClass<LibObjT>, LibObjT>;
-    using Member =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstStructureFieldClassMember,
-                                  StructureFieldClassMember>::type;
+    using Iterator = BorrowedObjectIterator<CommonStructureFieldClass<LibObjT>>;
 
-    using Iterator = CommonIterator<CommonStructureFieldClass<LibObjT>, Member>;
+    using Member =
+        internal::DepType<LibObjT, StructureFieldClassMember, ConstStructureFieldClassMember>;
 
     explicit CommonStructureFieldClass(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonFieldClass {libObjPtr}
@@ -1122,15 +1138,21 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonStructureFieldClass& operator=(const CommonStructureFieldClass<OtherLibObjT> fc) noexcept
+    CommonStructureFieldClass operator=(const CommonStructureFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonStructureFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonStructureFieldClass<const bt_field_class> {*this};
+    }
+
     void appendMember(const char * const name, const FieldClass fc) const
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstStructureFieldClass`.");
 
         const auto status =
             bt_field_class_structure_append_member(this->libObjPtr(), name, fc.libObjPtr());
@@ -1145,7 +1167,7 @@ public:
         this->appendMember(name.data(), fc);
     }
 
-    std::uint64_t size() const noexcept
+    std::uint64_t length() const noexcept
     {
         return bt_field_class_structure_get_member_count(this->libObjPtr());
     }
@@ -1157,7 +1179,7 @@ public:
 
     Iterator end() const noexcept
     {
-        return Iterator {*this, this->size()};
+        return Iterator {*this, this->length()};
     }
 
     Member operator[](const std::uint64_t index) const noexcept
@@ -1166,7 +1188,7 @@ public:
             this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Member> operator[](const char * const name) const noexcept
+    bt2s::optional<Member> operator[](const char * const name) const noexcept
     {
         const auto libObjPtr =
             internal::CommonStructureFieldClassSpec<LibObjT>::memberByName(this->libObjPtr(), name);
@@ -1175,10 +1197,10 @@ public:
             return Member {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Member> operator[](const std::string& name) const noexcept
+    bt2s::optional<Member> operator[](const std::string& name) const noexcept
     {
         return (*this)[name.data()];
     }
@@ -1240,9 +1262,7 @@ class CommonArrayFieldClass : public CommonFieldClass<LibObjT>
 {
 private:
     using typename CommonFieldClass<LibObjT>::_ThisCommonFieldClass;
-
-    using _FieldClass =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstFieldClass, FieldClass>::type;
+    using _FieldClass = internal::DepFc<LibObjT>;
 
 protected:
     using typename CommonFieldClass<LibObjT>::_LibObjPtr;
@@ -1264,12 +1284,17 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonArrayFieldClass& operator=(const CommonArrayFieldClass<OtherLibObjT> fc) noexcept
+    CommonArrayFieldClass operator=(const CommonArrayFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonArrayFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonArrayFieldClass<const bt_field_class> {*this};
+    }
+
     _FieldClass elementFieldClass() const noexcept
     {
         return _FieldClass {
@@ -1328,13 +1353,18 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonStaticArrayFieldClass&
+    CommonStaticArrayFieldClass
     operator=(const CommonStaticArrayFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonArrayFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonStaticArrayFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonStaticArrayFieldClass<const bt_field_class> {*this};
+    }
+
     std::uint64_t length() const noexcept
     {
         return bt_field_class_array_static_get_length(this->libObjPtr());
@@ -1393,13 +1423,18 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonDynamicArrayWithLengthFieldClass&
+    CommonDynamicArrayWithLengthFieldClass
     operator=(const CommonDynamicArrayWithLengthFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonArrayFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonDynamicArrayWithLengthFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonDynamicArrayWithLengthFieldClass<const bt_field_class> {*this};
+    }
+
     ConstFieldPath lengthFieldPath() const noexcept
     {
         return ConstFieldPath {
@@ -1468,9 +1503,7 @@ class CommonOptionFieldClass : public CommonFieldClass<LibObjT>
 {
 private:
     using typename CommonFieldClass<LibObjT>::_ThisCommonFieldClass;
-
-    using _FieldClass =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstFieldClass, FieldClass>::type;
+    using _FieldClass = internal::DepFc<LibObjT>;
 
 protected:
     using typename CommonFieldClass<LibObjT>::_LibObjPtr;
@@ -1492,12 +1525,17 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonOptionFieldClass& operator=(const CommonOptionFieldClass<OtherLibObjT> fc) noexcept
+    CommonOptionFieldClass operator=(const CommonOptionFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonOptionFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonOptionFieldClass<const bt_field_class> {*this};
+    }
+
     _FieldClass fieldClass() const noexcept
     {
         return _FieldClass {
@@ -1560,13 +1598,18 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonOptionWithSelectorFieldClass&
+    CommonOptionWithSelectorFieldClass
     operator=(const CommonOptionWithSelectorFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonOptionFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonOptionWithSelectorFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonOptionWithSelectorFieldClass<const bt_field_class> {*this};
+    }
+
     ConstFieldPath selectorFieldPath() const noexcept
     {
         return ConstFieldPath {
@@ -1629,13 +1672,18 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonOptionWithBoolSelectorFieldClass&
+    CommonOptionWithBoolSelectorFieldClass
     operator=(const CommonOptionWithBoolSelectorFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonOptionWithSelectorFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonOptionWithBoolSelectorFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonOptionWithBoolSelectorFieldClass<const bt_field_class> {*this};
+    }
+
     bool selectorIsReversed() const noexcept
     {
         return bt_field_class_option_with_selector_field_bool_selector_is_reversed(
@@ -1711,12 +1759,8 @@ private:
     using typename CommonOptionWithSelectorFieldClass<
         LibObjT>::_ThisCommonOptionWithSelectorFieldClass;
 
-    using _ThisCommonOptionWithIntegerSelectorFieldClass =
-        CommonOptionWithIntegerSelectorFieldClass<LibObjT, RangeSetT>;
-
 public:
-    using Shared = SharedFieldClass<_ThisCommonOptionWithIntegerSelectorFieldClass, LibObjT>;
-
+    using Shared = SharedFieldClass<CommonOptionWithIntegerSelectorFieldClass, LibObjT>;
     using RangeSet = RangeSetT;
 
     explicit CommonOptionWithIntegerSelectorFieldClass(const _LibObjPtr libObjPtr) noexcept :
@@ -1733,7 +1777,7 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonOptionWithIntegerSelectorFieldClass&
+    CommonOptionWithIntegerSelectorFieldClass
     operator=(const CommonOptionWithIntegerSelectorFieldClass<OtherLibObjT, RangeSetT> fc) noexcept
     {
         _ThisCommonOptionWithSelectorFieldClass::operator=(fc);
@@ -1845,13 +1889,10 @@ class CommonVariantFieldClassOption : public BorrowedObject<LibObjT>
 private:
     using typename BorrowedObject<LibObjT>::_ThisBorrowedObject;
     using typename BorrowedObject<LibObjT>::_LibObjPtr;
-
-    using _FieldClass =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstFieldClass, FieldClass>::type;
+    using _FieldClass = internal::DepFc<LibObjT>;
 
 public:
-    using UserAttributes =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstMapValue, MapValue>::type;
+    using UserAttributes = internal::DepUserAttrs<LibObjT>;
 
     explicit CommonVariantFieldClassOption(const _LibObjPtr libObjPtr) noexcept :
         _ThisBorrowedObject {libObjPtr}
@@ -1865,22 +1906,21 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonVariantFieldClassOption&
+    CommonVariantFieldClassOption
     operator=(const CommonVariantFieldClassOption<OtherLibObjT> fc) noexcept
     {
         _ThisBorrowedObject::operator=(fc);
         return *this;
     }
 
-    nonstd::optional<bpstd::string_view> name() const noexcept
+    CommonVariantFieldClassOption<const bt_field_class_variant_option> asConst() const noexcept
     {
-        const auto name = bt_field_class_variant_option_get_name(this->libObjPtr());
-
-        if (name) {
-            return name;
-        }
+        return CommonVariantFieldClassOption<const bt_field_class_variant_option> {*this};
+    }
 
-        return nonstd::nullopt;
+    const char *name() const noexcept
+    {
+        return bt_field_class_variant_option_get_name(this->libObjPtr());
     }
 
     _FieldClass fieldClass() const noexcept
@@ -1892,7 +1932,8 @@ public:
     template <typename LibValT>
     void userAttributes(const CommonMapValue<LibValT> userAttrs) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstVariantFieldClassOption`.");
 
         bt_field_class_variant_option_set_user_attributes(this->libObjPtr(), userAttrs.libObjPtr());
     }
@@ -2006,7 +2047,7 @@ public:
     }
 
     template <typename OtherLibObjT>
-    ConstVariantWithIntegerSelectorFieldClassOption&
+    ConstVariantWithIntegerSelectorFieldClassOption
     operator=(const ConstVariantWithIntegerSelectorFieldClassOption<OtherLibObjT> fc) noexcept
     {
         _ThisBorrowedObject::operator=(fc);
@@ -2018,7 +2059,7 @@ public:
         return ConstVariantFieldClassOption {_Spec::asBaseOption(this->libObjPtr())};
     }
 
-    nonstd::optional<bpstd::string_view> name() const noexcept
+    const char *name() const noexcept
     {
         return this->asBaseOption().name();
     }
@@ -2095,12 +2136,10 @@ protected:
 
 public:
     using Shared = SharedFieldClass<CommonVariantFieldClass<LibObjT>, LibObjT>;
+    using Iterator = BorrowedObjectIterator<CommonVariantFieldClass>;
 
     using Option =
-        typename std::conditional<std::is_const<LibObjT>::value, ConstVariantFieldClassOption,
-                                  VariantFieldClassOption>::type;
-
-    using Iterator = CommonIterator<CommonVariantFieldClass, Option>;
+        internal::DepType<LibObjT, VariantFieldClassOption, ConstVariantFieldClassOption>;
 
     explicit CommonVariantFieldClass(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonFieldClass {libObjPtr}
@@ -2115,13 +2154,18 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonVariantFieldClass& operator=(const CommonVariantFieldClass<OtherLibObjT> fc) noexcept
+    CommonVariantFieldClass operator=(const CommonVariantFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonFieldClass::operator=(fc);
         return *this;
     }
 
-    std::uint64_t size() const noexcept
+    CommonVariantFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonVariantFieldClass<const bt_field_class> {*this};
+    }
+
+    std::uint64_t length() const noexcept
     {
         return bt_field_class_variant_get_option_count(this->libObjPtr());
     }
@@ -2133,7 +2177,7 @@ public:
 
     Iterator end() const noexcept
     {
-        return Iterator {*this, this->size()};
+        return Iterator {*this, this->length()};
     }
 
     Option operator[](const std::uint64_t index) const noexcept
@@ -2142,7 +2186,7 @@ public:
             this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Option> operator[](const char * const name) const noexcept
+    bt2s::optional<Option> operator[](const char * const name) const noexcept
     {
         const auto libObjPtr =
             internal::CommonVariantFieldClassSpec<LibObjT>::optionByName(this->libObjPtr(), name);
@@ -2151,10 +2195,10 @@ public:
             return Option {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Option> operator[](const std::string& name) const noexcept
+    bt2s::optional<Option> operator[](const std::string& name) const noexcept
     {
         return (*this)[name.data()];
     }
@@ -2212,16 +2256,22 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonVariantWithoutSelectorFieldClass&
+    CommonVariantWithoutSelectorFieldClass
     operator=(const CommonVariantWithoutSelectorFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonVariantFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonVariantWithoutSelectorFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonVariantWithoutSelectorFieldClass<const bt_field_class> {*this};
+    }
+
     void appendOption(const char * const name, const FieldClass fc) const
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstVariantWithoutSelectorFieldClass`.");
 
         const auto status = bt_field_class_variant_without_selector_append_option(
             this->libObjPtr(), name, fc.libObjPtr());
@@ -2232,7 +2282,7 @@ public:
         }
     }
 
-    void appendOption(const nonstd::optional<std::string>& name, const FieldClass fc) const
+    void appendOption(const bt2s::optional<std::string>& name, const FieldClass fc) const
     {
         this->appendOption(name ? name->data() : nullptr, fc);
     }
@@ -2359,13 +2409,18 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonVariantWithSelectorFieldClass&
+    CommonVariantWithSelectorFieldClass
     operator=(const CommonVariantWithSelectorFieldClass<OtherLibObjT> fc) noexcept
     {
         _ThisCommonVariantFieldClass::operator=(fc);
         return *this;
     }
 
+    CommonVariantWithSelectorFieldClass<const bt_field_class> asConst() const noexcept
+    {
+        return CommonVariantWithSelectorFieldClass<const bt_field_class> {*this};
+    }
+
     ConstFieldPath selectorFieldPath() const noexcept
     {
         return ConstFieldPath {
@@ -2391,17 +2446,15 @@ private:
     using typename CommonVariantWithSelectorFieldClass<
         LibObjT>::_ThisCommonVariantWithSelectorFieldClass;
     using typename CommonFieldClass<LibObjT>::_LibObjPtr;
-    using _ThisCommonVariantWithIntegerSelectorFieldClass =
-        CommonVariantWithIntegerSelectorFieldClass<LibObjT, OptionT>;
 
     using _Spec = internal::CommonVariantWithIntegerSelectorFieldClassSpec<OptionT>;
 
 public:
-    using Shared = SharedFieldClass<_ThisCommonVariantWithIntegerSelectorFieldClass, LibObjT>;
-
+    using Shared = SharedFieldClass<CommonVariantWithIntegerSelectorFieldClass, LibObjT>;
     using Option = OptionT;
+
     using Iterator =
-        CommonIterator<CommonVariantWithIntegerSelectorFieldClass<LibObjT, Option>, Option>;
+        BorrowedObjectIterator<CommonVariantWithIntegerSelectorFieldClass<LibObjT, Option>>;
 
     explicit CommonVariantWithIntegerSelectorFieldClass(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonVariantWithSelectorFieldClass {libObjPtr}
@@ -2417,7 +2470,7 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonVariantWithIntegerSelectorFieldClass&
+    CommonVariantWithIntegerSelectorFieldClass
     operator=(const CommonVariantWithIntegerSelectorFieldClass<OtherLibObjT, OptionT> fc) noexcept
     {
         _ThisCommonVariantWithSelectorFieldClass::operator=(fc);
@@ -2429,7 +2482,7 @@ public:
         return Option {_Spec::optionByIndex(this->libObjPtr(), index)};
     }
 
-    nonstd::optional<Option> operator[](const char * const name) const noexcept
+    bt2s::optional<Option> operator[](const char * const name) const noexcept
     {
         const auto libObjPtr = _Spec::optionByName(this->libObjPtr(), name);
 
@@ -2437,10 +2490,10 @@ public:
             return Option {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
-    nonstd::optional<Option> operator[](const std::string& name) const noexcept
+    bt2s::optional<Option> operator[](const std::string& name) const noexcept
     {
         return (*this)[name.data()];
     }
@@ -2448,7 +2501,9 @@ public:
     void appendOption(const char * const name, const FieldClass fc,
                       const typename Option::RangeSet ranges) const
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(
+            !std::is_const<LibObjT>::value,
+            "Not available with `bt2::ConstVariantWithUnsignedIntegerSelectorFieldClass`.");
 
         const auto status =
             _Spec::appendOption(this->libObjPtr(), name, fc.libObjPtr(), ranges.libObjPtr());
@@ -2459,7 +2514,7 @@ public:
         }
     }
 
-    void appendOption(const nonstd::optional<std::string>& name, const FieldClass fc,
+    void appendOption(const bt2s::optional<std::string>& name, const FieldClass fc,
                       const typename Option::RangeSet ranges) const
     {
         this->appendOption(name ? name->data() : nullptr, fc, ranges);
@@ -2472,7 +2527,7 @@ public:
 
     Iterator end() const noexcept
     {
-        return Iterator {*this, this->size()};
+        return Iterator {*this, this->length()};
     }
 
     Shared shared() const noexcept