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C++ Feature: Mutable union getters (#8852)

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* generate mutable union accessors

* add test

* Revert "add test"

This reverts commit 45e352b18f.

* update file

* formatter got in the way

* merge conflicts

* updated genned code

* manually fix code gen bc I can't figure out why this file won't code gen

---------

Co-authored-by: Wouter van Oortmerssen <aardappel@gmail.com>
This commit is contained in:
Justin Davis
2025-12-21 17:36:47 -05:00
committed by GitHub
parent b1e7868db6
commit 7cb0bcb212
11 changed files with 375 additions and 8 deletions
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44
src/idl_gen_cpp.cpp
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@@ -2685,14 +2685,18 @@ class CppGenerator : public BaseGenerator {
code_ += " }";
}
void GenTableUnionAsGetters(const FieldDef& field) {
void GenTableUnionAsGetters(const FieldDef& field, bool is_mutable) {
const auto& type = field.value.type;
auto u = type.enum_def;
code_.SetValue("MUTABLE_EXT", is_mutable ? "" : " const");
code_.SetValue("MUTABLE", is_mutable ? "mutable_" : "");
if (!type.enum_def->uses_multiple_type_instances)
code_ +=
" template<typename T> "
"const T *{{NULLABLE_EXT}}{{FIELD_NAME}}_as() const;";
" template<typename T>"
"{{MUTABLE_EXT}} T *{{MUTABLE}}{{NULLABLE_EXT}}{{FIELD_NAME}}_as()"
"{{MUTABLE_EXT}};";
for (auto u_it = u->Vals().begin(); u_it != u->Vals().end(); ++u_it) {
auto& ev = **u_it;
@@ -2706,15 +2710,19 @@ class CppGenerator : public BaseGenerator {
EscapeKeyword(Name(field) + UnionTypeFieldSuffix()));
code_.SetValue("U_ELEMENT_TYPE", WrapInNameSpace(u->defined_namespace,
GetEnumValUse(*u, ev)));
code_.SetValue("U_FIELD_TYPE", "const " + full_struct_name + " *");
code_.SetValue("U_FIELD_TYPE",
(is_mutable ? "" : "const ") + full_struct_name + " *");
code_.SetValue("U_FIELD_NAME", Name(field) + "_as_" + Name(ev));
code_.SetValue("U_NULLABLE", NullableExtension());
// `const Type *union_name_asType() const` accessor.
code_ += " {{U_FIELD_TYPE}}{{U_NULLABLE}}{{U_FIELD_NAME}}() const {";
// and `Type *mutable_union_name_asType()` accessor.
code_ +=
" {{U_FIELD_TYPE}}{{U_NULLABLE}}{{MUTABLE}}{{U_FIELD_NAME}}()"
"{{MUTABLE_EXT}} {";
code_ +=
" return {{U_GET_TYPE}}() == {{U_ELEMENT_TYPE}} ? "
"static_cast<{{U_FIELD_TYPE}}>({{FIELD_NAME}}()) "
"static_cast<{{U_FIELD_TYPE}}>({{MUTABLE}}{{FIELD_NAME}}()) "
": nullptr;";
code_ += " }";
}
@@ -2755,7 +2763,7 @@ class CppGenerator : public BaseGenerator {
code_.SetValue("FIELD_VALUE", GenUnderlyingCast(field, true, call));
code_.SetValue("NULLABLE_EXT", NullableExtension());
code_ += " {{FIELD_TYPE}}{{FIELD_NAME}}() const {";
if (IsVector(type) && field.value.constant == "[]") {
if (IsVector(type) && field.value.constant == "[]") {
const auto& vec_type = type.VectorType();
const std::string vtype_wire = GenTypeWire(
vec_type, "", VectorElementUserFacing(vec_type), field.offset64);
@@ -2799,7 +2807,7 @@ class CppGenerator : public BaseGenerator {
}
if (type.base_type == BASE_TYPE_UNION) {
GenTableUnionAsGetters(field);
GenTableUnionAsGetters(field, false);
}
}
@@ -2974,6 +2982,11 @@ class CppGenerator : public BaseGenerator {
auto wire_type = GenTypeGet(type, " ", "", postptr.c_str(), true);
code_.SetValue("FIELD_TYPE", wire_type);
// mutable union accessors
if (type.base_type == BASE_TYPE_UNION) {
GenTableUnionAsGetters(field, true);
}
if (IsVector(type) && field.value.constant == "[]") {
const auto& vec_type = type.VectorType();
const std::string vtype_wire = GenTypeWire(
@@ -3185,6 +3198,7 @@ class CppGenerator : public BaseGenerator {
code_.SetValue("U_FIELD_NAME", Name(*field) + "_as_" + Name(ev));
// `template<> const T *union_name_as<T>() const` accessor.
// and `template<> T *mutable_union_name_as<T>()` accessor.
code_ +=
"template<> "
"inline {{U_FIELD_TYPE}}{{STRUCT_NAME}}::{{FIELD_NAME}}_as"
@@ -3192,6 +3206,20 @@ class CppGenerator : public BaseGenerator {
code_ += " return {{U_FIELD_NAME}}();";
code_ += "}";
code_ += "";
if (opts_.mutable_buffer) {
code_.SetValue("U_FIELD_TYPE", full_struct_name + " *");
code_.SetValue("U_FIELD_NAME",
"mutable_" + Name(*field) + "_as_" + Name(ev));
code_ +=
"template<> "
"inline {{U_FIELD_TYPE}}"
"{{STRUCT_NAME}}::mutable_{{FIELD_NAME}}_as"
"<{{U_ELEMENT_NAME}}>() {";
code_ += " return {{U_FIELD_NAME}}();";
code_ += "}";
code_ += "";
}
}
}