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Improved union copy constructor.

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It now at least works in simple cases.

Change-Id: I3af0738e676e62166b69accaa6bd19f531fbe5ee
Tested: on Linux.
This commit is contained in:
Wouter van Oortmerssen
2017-04-17 17:27:20 -07:00
parent 728bb64fed
commit e093f72d00
4 changed files with 116 additions and 10 deletions
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50
src/idl_gen_cpp.cpp
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@@ -687,8 +687,9 @@ class CppGenerator : public BaseGenerator {
code_ += " {{NAME}}Union({{NAME}}Union&& u) FLATBUFFERS_NOEXCEPT :";
code_ += " type({{NONE}}), value(nullptr)";
code_ += " { std::swap(type, u.type); std::swap(value, u.value); }";
code_ += " {{NAME}}Union(const {{NAME}}Union &) { assert(false); }";
code_ += " {{NAME}}Union &operator=(const {{NAME}}Union &) { assert(false); return *this; }";
code_ += " {{NAME}}Union(const {{NAME}}Union &) FLATBUFFERS_NOEXCEPT;";
code_ += " {{NAME}}Union &operator=({{NAME}}Union u) FLATBUFFERS_NOEXCEPT";
code_ += " { std::swap(type, u.type); std::swap(value, u.value); return *this; }";
code_ += " {{NAME}}Union &operator=({{NAME}}Union &&u) FLATBUFFERS_NOEXCEPT";
code_ += " { std::swap(type, u.type); std::swap(value, u.value); return *this; }";
code_ += " ~{{NAME}}Union() { Reset(); }";
@@ -865,6 +866,49 @@ class CppGenerator : public BaseGenerator {
code_ += "}";
code_ += "";
// Union copy constructor
code_ += "inline {{ENUM_NAME}}Union::{{ENUM_NAME}}Union(const "
"{{ENUM_NAME}}Union &u) FLATBUFFERS_NOEXCEPT : type(u.type), "
"value(nullptr) {";
code_ += " switch (type) {";
for (auto it = enum_def.vals.vec.begin(); it != enum_def.vals.vec.end();
++it) {
const auto &ev = **it;
if (!ev.value) {
continue;
}
code_.SetValue("LABEL", GetEnumValUse(enum_def, ev));
code_.SetValue("TYPE", NativeName(GetUnionElement(ev, true, true, true),
ev.union_type.struct_def));
code_ += " case {{LABEL}}: {";
bool copyable = true;
if (ev.union_type.base_type == BASE_TYPE_STRUCT) {
// Don't generate code to copy if table is not copyable.
// TODO(wvo): make tables copyable instead.
for (auto fit = ev.union_type.struct_def->fields.vec.begin();
fit != ev.union_type.struct_def->fields.vec.end(); ++fit) {
const auto &field = **fit;
if (!field.deprecated && field.value.type.struct_def) {
copyable = false;
break;
}
}
}
if (copyable) {
code_ += " value = new {{TYPE}}(*reinterpret_cast<{{TYPE}} *>"
"(u.value));";
} else {
code_ += " assert(false); // {{TYPE}} not copyable.";
}
code_ += " break;";
code_ += " }";
}
code_ += " default:";
code_ += " break;";
code_ += " }";
code_ += "}";
code_ += "";
// Union Reset() function.
code_.SetValue("NONE",
GetEnumValUse(enum_def, *enum_def.vals.Lookup("NONE")));
@@ -877,11 +921,9 @@ class CppGenerator : public BaseGenerator {
if (!ev.value) {
continue;
}
code_.SetValue("LABEL", GetEnumValUse(enum_def, ev));
code_.SetValue("TYPE", NativeName(GetUnionElement(ev, true, true, true),
ev.union_type.struct_def));
code_ += " case {{LABEL}}: {";
code_ += " auto ptr = reinterpret_cast<{{TYPE}} *>(value);";
code_ += " delete ptr;";