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Add compare operator to code generated for c++ (#4940)

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* Add operator== for c++ genated code

New "--gen-compare" option for flatc to generate compare operators. The operators are defined based on object based api types.

Inspired by issue #263.

* Improve compare operator for c++.
Thanks for the code review.

- Improve robustness against future schema extensions
- Code style
- Fix --rust generation in generate_code.sh
This commit is contained in:
Thomas
2018-09-22 01:53:59 +02:00
committed by Wouter van Oortmerssen
parent 873a60b0d8
commit 33791dc7b0
11 changed files with 384 additions and 11 deletions
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96
src/idl_gen_cpp.cpp
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@@ -226,14 +226,30 @@ class CppGenerator : public BaseGenerator {
if (!struct_def.generated) {
SetNameSpace(struct_def.defined_namespace);
code_ += "struct " + Name(struct_def) + ";";
if (parser_.opts.generate_object_based_api && !struct_def.fixed) {
code_ += "struct " +
NativeName(Name(struct_def), &struct_def, parser_.opts) +
";";
if (parser_.opts.generate_object_based_api) {
auto nativeName = NativeName(Name(struct_def), &struct_def, parser_.opts);
if (!struct_def.fixed) {
code_ += "struct " + nativeName + ";";
}
}
code_ += "";
}
}
// Generate forward declarations for all equal operators
if (parser_.opts.generate_object_based_api && parser_.opts.gen_compare) {
for (auto it = parser_.structs_.vec.begin();
it != parser_.structs_.vec.end(); ++it) {
const auto &struct_def = **it;
if (!struct_def.generated) {
SetNameSpace(struct_def.defined_namespace);
auto nativeName = NativeName(Name(struct_def), &struct_def, parser_.opts);
code_ += "bool operator==(const " + nativeName + " &lhs, const " + nativeName + " &rhs);";
}
}
code_ += "";
}
// Generate preablmle code for mini reflection.
if (parser_.opts.mini_reflect != IDLOptions::kNone) {
// To break cyclic dependencies, first pre-declare all tables/structs.
@@ -1096,6 +1112,38 @@ class CppGenerator : public BaseGenerator {
}
code_ += "};";
code_ += "";
if (parser_.opts.gen_compare) {
code_ += "";
code_ += "inline bool operator==(const {{NAME}}Union &lhs, const {{NAME}}Union &rhs) {";
code_ += " if (lhs.type != rhs.type) return false;";
code_ += " switch (lhs.type) {";
for (auto it = enum_def.vals.vec.begin(); it != enum_def.vals.vec.end();
++it) {
const auto &ev = **it;
code_.SetValue("NATIVE_ID", GetEnumValUse(enum_def, ev));
if (ev.value) {
const auto native_type =
NativeName(GetUnionElement(ev, true, true, true),
ev.union_type.struct_def, parser_.opts);
code_.SetValue("NATIVE_TYPE", native_type);
code_ += " case {{NATIVE_ID}}: {";
code_ += " return *(reinterpret_cast<const {{NATIVE_TYPE}} *>(lhs.value)) ==";
code_ += " *(reinterpret_cast<const {{NATIVE_TYPE}} *>(rhs.value));";
code_ += " }";
} else {
code_ += " case {{NATIVE_ID}}: {";
code_ += " return true;"; // "NONE" enum value.
code_ += " }";
}
}
code_ += " default: {";
code_ += " return false;";
code_ += " }";
code_ += " }";
code_ += "}";
}
}
if (enum_def.is_union) {
@@ -1456,6 +1504,44 @@ class CppGenerator : public BaseGenerator {
code_ += " }";
}
void GenCompareOperator(const StructDef &struct_def, std::string accessSuffix = "") {
std::string compare_op;
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
const auto &field = **it;
if (!field.deprecated && // Deprecated fields won't be accessible.
field.value.type.base_type != BASE_TYPE_UTYPE &&
(field.value.type.base_type != BASE_TYPE_VECTOR ||
field.value.type.element != BASE_TYPE_UTYPE)) {
if (!compare_op.empty()) {
compare_op += " &&\n ";
}
auto accessor = Name(field) + accessSuffix;
compare_op += "(lhs." + accessor + " == rhs." + accessor + ")";
}
}
std::string cmp_lhs;
std::string cmp_rhs;
if (compare_op.empty()) {
cmp_lhs = "";
cmp_rhs = "";
compare_op = " return true;";
} else {
cmp_lhs = "lhs";
cmp_rhs = "rhs";
compare_op = " return\n " + compare_op + ";";
}
code_.SetValue("CMP_OP", compare_op);
code_.SetValue("CMP_LHS", cmp_lhs);
code_.SetValue("CMP_RHS", cmp_rhs);
code_ += "";
code_ += "inline bool operator==(const {{NATIVE_NAME}} &{{CMP_LHS}}, const {{NATIVE_NAME}} &{{CMP_RHS}}) {";
code_ += "{{CMP_OP}}";
code_ += "}";
}
void GenOperatorNewDelete(const StructDef &struct_def) {
if (auto native_custom_alloc =
struct_def.attributes.Lookup("native_custom_alloc")) {
@@ -1488,6 +1574,7 @@ class CppGenerator : public BaseGenerator {
GenOperatorNewDelete(struct_def);
GenDefaultConstructor(struct_def);
code_ += "};";
if (parser_.opts.gen_compare) GenCompareOperator(struct_def);
code_ += "";
}
@@ -2600,6 +2687,7 @@ class CppGenerator : public BaseGenerator {
code_.SetValue("STRUCT_BYTE_SIZE", NumToString(struct_def.bytesize));
code_ += "FLATBUFFERS_STRUCT_END({{STRUCT_NAME}}, {{STRUCT_BYTE_SIZE}});";
if (parser_.opts.gen_compare) GenCompareOperator(struct_def, "()");
code_ += "";
}