Add @optional support to rosidl_generator_cpp

rosidl_generator_cpp/resource/idl__struct.hpp.em

@@ -30,6 +30,7 @@ include_directives = set()
 #include <array>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 

rosidl_generator_cpp/resource/msg__struct.hpp.em

@@ -4,6 +4,7 @@ from rosidl_generator_cpp import create_init_alloc_and_member_lists
 from rosidl_generator_cpp import escape_string
 from rosidl_generator_cpp import escape_wstring
 from rosidl_generator_cpp import msg_type_to_cpp
+from rosidl_generator_cpp import member_to_cpp
 from rosidl_generator_cpp import MSG_TYPE_TO_CPP
 from rosidl_generator_cpp import generate_zero_string
 from rosidl_generator_cpp import generate_default_string
@@ -207,15 +208,15 @@ non_defaulted_zero_initialized_members = [
   // field types and members
 @[for member in message.structure.members]@
   using _@(member.name)_type =
-    @(msg_type_to_cpp(member.type));
+    @(member_to_cpp(member));
   _@(member.name)_type @(member.name);
 @[end for]@
 
 @[if len(message.structure.members) != 1 or message.structure.members[0].name != EMPTY_STRUCTURE_REQUIRED_MEMBER_NAME]@
   // setters for named parameter idiom
 @[  for member in message.structure.members]@
   Type & set__@(member.name)(
-    const @(msg_type_to_cpp(member.type)) & _arg)
+    const @(member_to_cpp(member)) & _arg)
   {
     this->@(member.name) = _arg;
     return *this;

rosidl_generator_cpp/resource/msg__traits.hpp.em

@@ -1,5 +1,6 @@
 @# Included from rosidl_generator_cpp/resource/idl__traits.hpp.em
 @{
+from rosidl_generator_cpp import msg_type_to_cpp
 from rosidl_parser.definition import ACTION_FEEDBACK_SUFFIX
 from rosidl_parser.definition import ACTION_GOAL_SUFFIX
 from rosidl_parser.definition import ACTION_RESULT_SUFFIX
@@ -13,6 +14,7 @@ from rosidl_parser.definition import EMPTY_STRUCTURE_REQUIRED_MEMBER_NAME
 from rosidl_parser.definition import NamespacedType
 from rosidl_parser.definition import AbstractSequence
 from rosidl_parser.definition import UnboundedSequence
+from rosidl_parser.definition import OPTIONAL_ANNOTATION
 
 message_namespace = '::'.join(message.structure.namespaced_type.namespaces)
 message_typename = '::'.join(message.structure.namespaced_type.namespaced_name())
@@ -90,27 +92,39 @@ inline void to_flow_style_yaml(
 
 @[    end if]@
   // member: @(member.name)
-  {
+  do {
+@[    if member.has_annotation(OPTIONAL_ANNOTATION)]@
+    auto value = msg.@(member.name).value();
+    if (msg.@(member.name) == std::nullopt) {
+      out << "@(member.name): null";
+@[    if i < len(message.structure.members) - 1]@
+      out << ", ";
+@[    end if]@
+      break;
+    }
+@[    else]@
+    auto value = msg.@(member.name);
+@[    end if]@
 @[    if isinstance(member.type, BasicType)]@
     out << "@(member.name): ";
 @[      if member.type.typename in ('octet', 'char', 'wchar')]@
-    rosidl_generator_traits::character_value_to_yaml(msg.@(member.name), out);
+    rosidl_generator_traits::character_value_to_yaml(value, out);
 @[      else]@
-    rosidl_generator_traits::value_to_yaml(msg.@(member.name), out);
+    rosidl_generator_traits::value_to_yaml(value, out);
 @[      end if]@
 @[    elif isinstance(member.type, AbstractGenericString)]@
     out << "@(member.name): ";
-    rosidl_generator_traits::value_to_yaml(msg.@(member.name), out);
+    rosidl_generator_traits::value_to_yaml(value, out);
 @[    elif isinstance(member.type, NamespacedType)]@
     out << "@(member.name): ";
-    to_flow_style_yaml(msg.@(member.name), out);
+    to_flow_style_yaml(value, out);
 @[    elif isinstance(member.type, (AbstractSequence, Array))]@
-    if (msg.@(member.name).size() == 0) {
+    if (value.size() == 0) {
       out << "@(member.name): []";
     } else {
       out << "@(member.name): [";
-      size_t pending_items = msg.@(member.name).size();
-      for (auto item : msg.@(member.name)) {
+      size_t pending_items = value.size();
+      for (auto item : value) {
 @[      if isinstance(member.type.value_type, BasicType)]@
 @[        if member.type.value_type.typename in ('octet', 'char', 'wchar')]@
         rosidl_generator_traits::character_value_to_yaml(item, out);
@@ -132,7 +146,7 @@ inline void to_flow_style_yaml(
 @[    if i < len(message.structure.members) - 1]@
     out << ", ";
 @[    end if]@
-  }
+  } while (false);
 @[  end for]@
   out << "}";
 @[end if]@
@@ -152,31 +166,40 @@ inline void to_block_style_yaml(
 
 @[    end if]@
   // member: @(member.name)
-  {
+  do {
     if (indentation > 0) {
       out << std::string(indentation, ' ');
     }
+@[    if member.has_annotation(OPTIONAL_ANNOTATION)]@
+    auto value = msg.@(member.name).value();
+    if (msg.@(member.name) == std::nullopt) {
+      out << "@(member.name): null\n";
+      break;
+    }
+@[    else]@
+    auto value = msg.@(member.name);
+@[    end if]@
 @[    if isinstance(member.type, BasicType)]@
     out << "@(member.name): ";
 @[      if member.type.typename in ('octet', 'char', 'wchar')]@
-    rosidl_generator_traits::character_value_to_yaml(msg.@(member.name), out);
+    rosidl_generator_traits::character_value_to_yaml(value, out);
 @[      else]@
-    rosidl_generator_traits::value_to_yaml(msg.@(member.name), out);
+    rosidl_generator_traits::value_to_yaml(value, out);
 @[      end if]@
     out << "\n";
 @[    elif isinstance(member.type, AbstractGenericString)]@
     out << "@(member.name): ";
-    rosidl_generator_traits::value_to_yaml(msg.@(member.name), out);
+    rosidl_generator_traits::value_to_yaml(value, out);
     out << "\n";
 @[    elif isinstance(member.type, NamespacedType)]@
     out << "@(member.name):\n";
-    to_block_style_yaml(msg.@(member.name), out, indentation + 2);
+    to_block_style_yaml(value, out, indentation + 2);
 @[    elif isinstance(member.type, (AbstractSequence, Array))]@
-    if (msg.@(member.name).size() == 0) {
+    if (value.size() == 0) {
       out << "@(member.name): []\n";
     } else {
       out << "@(member.name):\n";
-      for (auto item : msg.@(member.name)) {
+      for (auto item : value) {
         if (indentation > 0) {
           out << std::string(indentation, ' ');
         }
@@ -199,7 +222,7 @@ inline void to_block_style_yaml(
       }
     }
 @[    end if]@
-  }
+  } while(false);
 @[  end for]@
 @[end if]@
 }  // NOLINT(readability/fn_size)

rosidl_generator_cpp/rosidl_generator_cpp/__init__.py

@@ -14,17 +14,23 @@
 
 from ast import literal_eval
 from typing import List
+from typing import Optional
+from typing import Union
 
 from rosidl_parser.definition import AbstractGenericString
 from rosidl_parser.definition import AbstractNestedType
 from rosidl_parser.definition import AbstractSequence
 from rosidl_parser.definition import AbstractString
+from rosidl_parser.definition import AbstractType
 from rosidl_parser.definition import AbstractWString
 from rosidl_parser.definition import Array
 from rosidl_parser.definition import BasicType
 from rosidl_parser.definition import BoundedSequence
 from rosidl_parser.definition import FLOATING_POINT_TYPES
+from rosidl_parser.definition import Member
+from rosidl_parser.definition import Message
 from rosidl_parser.definition import NamespacedType
+from rosidl_parser.definition import OPTIONAL_ANNOTATION
 from rosidl_parser.definition import UnboundedSequence
 from rosidl_pycommon import generate_files
 
@@ -76,7 +82,7 @@ def prefix_with_bom_if_necessary(content: str) -> str:
 }
 
 
-def msg_type_only_to_cpp(type_):
+def msg_type_only_to_cpp(type_: AbstractType) -> str:
     """
     Convert a message type into the C++ declaration, ignoring array types.
 
@@ -103,7 +109,7 @@ def msg_type_only_to_cpp(type_):
     return cpp_type
 
 
-def msg_type_to_cpp(type_):
+def msg_type_to_cpp(type_: AbstractType) -> str:
     """
     Convert a message type into the C++ declaration, along with the array type.
 
@@ -134,7 +140,16 @@ def msg_type_to_cpp(type_):
         return cpp_type
 
 
-def value_to_cpp(type_, value):
+def member_to_cpp(member: Member) -> str:
+    """Convert a member into the C++ declaration. This exists to add optional support."""
+    cpp_type = msg_type_to_cpp(member.type)
+
+    if member.has_annotation(OPTIONAL_ANNOTATION):
+        return f'std::optional<{cpp_type}>'
+    return cpp_type
+
+
+def value_to_cpp(type_: AbstractType, value) -> str:
     """
     Convert a python value into a string representing that value in C++.
 
@@ -149,7 +164,9 @@ def value_to_cpp(type_, value):
     """
     assert not isinstance(type_, NamespacedType), \
         "Could not convert non-primitive type '%s' to CPP" % (type_)
-    assert value is not None, "Value for type '%s' must not be None" % (type_)
+
+    if value is None:
+        return 'std::nullopt'
 
     if not isinstance(type_, AbstractNestedType):
         return primitive_value_to_cpp(type_, value)
@@ -171,7 +188,7 @@ def value_to_cpp(type_, value):
     return cpp_value
 
 
-def primitive_value_to_cpp(type_, value):
+def primitive_value_to_cpp(type_: Union[BasicType, AbstractGenericString], value) -> str:
     """
     Convert a python value into a string representing that value in C++.
 
@@ -246,30 +263,30 @@ def default_value_from_type(type_):
     return 0
 
 
-def escape_string(s):
+def escape_string(s: str) -> str:
     s = s.replace('\\', '\\\\')
     s = s.replace('"', '\\"')
     return s
 
 
-def escape_wstring(s):
+def escape_wstring(s: str) -> str:
     return escape_string(s)
 
 
-def create_init_alloc_and_member_lists(message):
+def create_init_alloc_and_member_lists(message: Message):
     # A Member object represents the information we need to know to initialize
     # a single member of the class.
     class Member:
 
-        def __init__(self, name):
+        def __init__(self, name: str):
             self.name = name
-            self.default_value = None
-            self.zero_value = None
+            self.default_value: Optional[str] = None
+            self.zero_value: Optional[str] = None
             self.zero_need_array_override = False
-            self.type = None
+            self.type: Optional[AbstractType] = None
             self.num_prealloc = 0
 
-        def same_default_and_zero_value(self, other):
+        def same_default_and_zero_value(self, other) -> bool:
             return self.default_value == other.default_value and \
                 self.zero_value == other.zero_value
 
@@ -280,10 +297,10 @@ def same_default_and_zero_value(self, other):
     # value).
     class CommonMemberSet:
 
-        def __init__(self):
-            self.members = []
+        def __init__(self) -> None:
+            self.members: list[Member] = []
 
-        def add_member(self, member):
+        def add_member(self, member: Member) -> bool:
             if not self.members or self.members[-1].same_default_and_zero_value(member):
                 self.members.append(member)
                 return True
@@ -296,12 +313,13 @@ def add_member(self, member):
     #                initializion in the allocator constructor
     #   member_list - The list of members that we will generate initialization code
     #                 for in the body of the constructors
-    init_list = []
-    alloc_list = []
-    member_list = []
+    init_list: list[str] = []
+    alloc_list: list[str] = []
+    member_list: list[CommonMemberSet] = []
     for field in message.structure.members:
         member = Member(field.name)
         member.type = field.type
+
         if isinstance(field.type, Array):
             alloc_list.append(field.name + '(_alloc)')
             if isinstance(field.type.value_type, BasicType) or \
@@ -346,6 +364,10 @@ def add_member(self, member):
                 commonset.add_member(member)
                 member_list.append(commonset)
 
+        # Override zero_value if optional
+        if field.has_annotation(OPTIONAL_ANNOTATION):
+            member.zero_value = value_to_cpp(field.type, None)
+
     return init_list, alloc_list, member_list
 
 

rosidl_generator_tests/CMakeLists.txt

@@ -35,6 +35,7 @@ if(BUILD_TESTING)
     ${test_interface_files_MSG_FILES}
     ${test_interface_files_SRV_FILES}
     msg/BasicIdl.idl
+    msg/Optional.msg
     msg/SmallConstant.msg
     ADD_LINTER_TESTS
     SKIP_INSTALL

rosidl_generator_tests/msg/Optional.msg

@@ -0,0 +1,11 @@
+@optional
+float32 optional_float
+
+@optional
+float32 default_optional_float 32.0
+
+# @optional
+# string optional_string
+
+# @optional
+# short optional_short_array[3]

rosidl_generator_tests/test/rosidl_generator_cpp/test_msg_builder.cpp

@@ -14,11 +14,14 @@
 
 #include <gtest/gtest.h>
 
+#include <optional>
+
 #include "rosidl_generator_tests/msg/detail/arrays__builder.hpp"
 #include "rosidl_generator_tests/msg/detail/basic_types__builder.hpp"
 #include "rosidl_generator_tests/msg/detail/empty__builder.hpp"
 #include "rosidl_generator_tests/msg/detail/multi_nested__builder.hpp"
 #include "rosidl_generator_tests/msg/detail/nested__builder.hpp"
+#include "rosidl_generator_tests/msg/detail/optional_idl__builder.hpp"
 
 TEST(Test_msg_initialization, build) {
   ::rosidl_generator_tests::msg::BasicTypes basic =
@@ -200,4 +203,16 @@ TEST(Test_msg_initialization, build) {
   rosidl_generator_tests::msg::Empty empty =
     rosidl_generator_tests::build<rosidl_generator_tests::msg::Empty>();
   ASSERT_EQ(0, empty.structure_needs_at_least_one_member);
+
+  rosidl_generator_tests::msg::OptionalIdl optional =
+    rosidl_generator_tests::build<rosidl_generator_tests::msg::OptionalIdl>()
+    .optional_float(0.1f)
+    .default_optional_float(2.0);
+    // .optional_short_array({{-100, -200, -100}});
+    // .optional_string("init");
+
+  ASSERT_EQ(0.1f, optional.optional_float);
+  ASSERT_EQ(2.0, optional.default_optional_float);
+  // ASSERT_EQ({-100, -200, -100}, optional.default_optional_float);
+  // ASSERT_EQ("init", optional.optional_string)
 }