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/*
* Copyright 2021 Google Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FLATBUFFERS_BFBS_GEN_H_
#define FLATBUFFERS_BFBS_GEN_H_
#include <cstdint>
#include "flatbuffers/code_generator.h"
#include "flatbuffers/reflection_generated.h"
namespace flatbuffers {
namespace {
static void ForAllEnums(
const flatbuffers::Vector<flatbuffers::Offset<reflection::Enum>> *enums,
std::function<void(const reflection::Enum *)> func) {
for (auto it = enums->cbegin(); it != enums->cend(); ++it) { func(*it); }
}
static void ForAllObjects(
const flatbuffers::Vector<flatbuffers::Offset<reflection::Object>> *objects,
std::function<void(const reflection::Object *)> func) {
for (auto it = objects->cbegin(); it != objects->cend(); ++it) { func(*it); }
}
static void ForAllEnumValues(
const reflection::Enum *enum_def,
std::function<void(const reflection::EnumVal *)> func) {
for (auto it = enum_def->values()->cbegin(); it != enum_def->values()->cend();
++it) {
func(*it);
}
}
static void ForAllDocumentation(
const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>
*documentation,
std::function<void(const flatbuffers::String *)> func) {
if (!documentation) { return; }
for (auto it = documentation->cbegin(); it != documentation->cend(); ++it) {
func(*it);
}
}
// Maps the field index into object->fields() to the field's ID (the ith element
// in the return vector).
static std::vector<uint32_t> FieldIdToIndex(const reflection::Object *object) {
std::vector<uint32_t> field_index_by_id;
field_index_by_id.resize(object->fields()->size());
// Create the mapping of field ID to the index into the vector.
for (uint32_t i = 0; i < object->fields()->size(); ++i) {
auto field = object->fields()->Get(i);
field_index_by_id[field->id()] = i;
}
return field_index_by_id;
}
static bool IsStructOrTable(const reflection::BaseType base_type) {
return base_type == reflection::Obj;
}
static bool IsFloatingPoint(const reflection::BaseType base_type) {
return base_type == reflection::Float || base_type == reflection::Double;
}
static bool IsBool(const reflection::BaseType base_type) {
return base_type == reflection::Bool;
}
static bool IsSingleByte(const reflection::BaseType base_type) {
return base_type >= reflection::UType && base_type <= reflection::UByte;
}
static bool IsVector(const reflection::BaseType base_type) {
return base_type == reflection::Vector;
}
} // namespace
// A concrete base Flatbuffer Generator that specific language generators can
// derive from.
class BaseBfbsGenerator : public CodeGenerator {
public:
virtual ~BaseBfbsGenerator() {}
BaseBfbsGenerator() : schema_(nullptr) {}
virtual Status GenerateFromSchema(const reflection::Schema *schema,
const CodeGenOptions &options) = 0;
virtual uint64_t SupportedAdvancedFeatures() const = 0;
// Override of the Generator::GenerateCode method that does the initial
// deserialization and verification steps.
Status GenerateCode(const uint8_t *buffer, int64_t length,
const CodeGenOptions &options) FLATBUFFERS_OVERRIDE {
flatbuffers::Verifier verifier(buffer, static_cast<size_t>(length));
if (!reflection::VerifySchemaBuffer(verifier)) {
return FAILED_VERIFICATION;
}
// Store the root schema since there are cases where leaf nodes refer to
// things in the root schema (e.g., indexing the objects).
schema_ = reflection::GetSchema(buffer);
const uint64_t advance_features = schema_->advanced_features();
if (advance_features > SupportedAdvancedFeatures()) {
return FAILED_VERIFICATION;
}
Status status = GenerateFromSchema(schema_, options);
schema_ = nullptr;
return status;
}
protected:
// GetObject returns the underlying object struct of the given type
// if element_type is true and GetObject is a list of objects then
// GetObject will correctly return the object struct of the vector's elements
const reflection::Object *GetObject(const reflection::Type *type,
bool element_type = false) const {
const reflection::BaseType base_type =
element_type ? type->element() : type->base_type();
if (type->index() >= 0 && IsStructOrTable(base_type)) {
return GetObjectByIndex(type->index());
}
return nullptr;
}
// GetEnum returns the underlying enum struct of the given type
// if element_type is true and GetEnum is a list of enums then
// GetEnum will correctly return the enum struct of the vector's elements
const reflection::Enum *GetEnum(const reflection::Type *type,
bool element_type = false) const {
const reflection::BaseType base_type =
element_type ? type->element() : type->base_type();
// TODO(derekbailey): it would be better to have a explicit list of allowed
// base types, instead of negating Obj types.
if (type->index() >= 0 && !IsStructOrTable(base_type)) {
return GetEnumByIndex(type->index());
}
return nullptr;
}
// Used to get a object that is reference by index. (e.g.
// reflection::Type::index). Returns nullptr if no object is available.
const reflection::Object *GetObjectByIndex(int32_t index) const {
if (!schema_ || index < 0 ||
index >= static_cast<int32_t>(schema_->objects()->size())) {
return nullptr;
}
return schema_->objects()->Get(index);
}
// Used to get a enum that is reference by index. (e.g.
// reflection::Type::index). Returns nullptr if no enum is available.
const reflection::Enum *GetEnumByIndex(int32_t index) const {
if (!schema_ || index < 0 ||
index >= static_cast<int32_t>(schema_->enums()->size())) {
return nullptr;
}
return schema_->enums()->Get(index);
}
void ForAllFields(const reflection::Object *object, bool reverse,
std::function<void(const reflection::Field *)> func) const {
const std::vector<uint32_t> field_to_id_map = FieldIdToIndex(object);
for (size_t i = 0; i < field_to_id_map.size(); ++i) {
func(object->fields()->Get(
field_to_id_map[reverse ? field_to_id_map.size() - (i + 1) : i]));
}
}
bool IsTable(const reflection::Type *type, bool use_element = false) const {
return !IsStruct(type, use_element);
}
bool IsStruct(const reflection::Type *type, bool use_element = false) const {
const reflection::BaseType base_type =
use_element ? type->element() : type->base_type();
return IsStructOrTable(base_type) &&
GetObjectByIndex(type->index())->is_struct();
}
const reflection::Schema *schema_;
};
} // namespace flatbuffers
#endif // FLATBUFFERS_BFBS_GEN_H_
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