reflective-rapidjson/generator/binaryserializationcodegenerator.cpp

#include "./binaryserializationcodegenerator.h"

#include "../lib/binary/serializable.h"

#include <clang/AST/DeclCXX.h>
#include <clang/AST/DeclFriend.h>
#include <clang/AST/DeclTemplate.h>

#include <iostream>

using namespace std;
using namespace CppUtilities;

namespace ReflectiveRapidJSON {

/*!
 * \brief Initializes the CLI arguments which are specific to the BinarySerializationCodeGenerator.
 * \todo Find a more general approach to pass CLI arguments from main() to the particular code generators.
 */
BinarySerializationCodeGenerator::Options::Options()
    : additionalClassesArg("binary-classes", '\0', "specifies additional classes to consider for binary (de)serialization", { "class-name" })
    , visibilityArg("binary-visibility", '\0', "specifies the \"visibility attribute\" for generated functions", { "attribute" })
{
    additionalClassesArg.setRequiredValueCount(Argument::varValueCount);
    additionalClassesArg.setValueCompletionBehavior(ValueCompletionBehavior::None);
    visibilityArg.setPreDefinedCompletionValues("CPP_UTILITIES_GENERIC_LIB_EXPORT");
}

BinarySerializationCodeGenerator::BinarySerializationCodeGenerator(CodeFactory &factory, const Options &options)
    : SerializationCodeGenerator(factory)
    , m_options(options)
{
    m_qualifiedNameOfRecords = BinarySerializable<void>::qualifiedName;
    m_qualifiedNameOfAdaptionRecords = AdaptedBinarySerializable<void>::qualifiedName;
}

/*!
 * \brief Returns the qualified name of the specified \a record if it is considered relevant.
 */
string BinarySerializationCodeGenerator::qualifiedNameIfRelevant(clang::CXXRecordDecl *record) const
{
    const string qualifiedName(record->getQualifiedNameAsString());
    switch (isQualifiedNameIfRelevant(record, qualifiedName)) {
    case IsRelevant::Yes:
        return qualifiedName;
    case IsRelevant::No:
        return string();
    default:;
    }

    // consider all classes specified via "--additional-classes" argument relevant
    if (!m_options.additionalClassesArg.isPresent()) {
        return string();
    }
    for (const char *className : m_options.additionalClassesArg.values()) {
        if (className == qualifiedName) {
            return qualifiedName;
        }
    }

    return string();
}

/*!
 * \brief Generates pull() and push() helper functions in the ReflectiveRapidJSON::BinaryReflector namespace for the relevant classes.
 */
void BinarySerializationCodeGenerator::generate(ostream &os) const
{
    // initialize source manager to make use of isOnlyIncluded() for skipping records which are only included
    lazyInitializeSourceManager();

    // find relevant classes
    const auto relevantClasses = findRelevantClasses();
    if (relevantClasses.empty()) {
        return; // nothing to generate
    }

    // put everything into namespace ReflectiveRapidJSON::BinaryReflector
    os << "namespace ReflectiveRapidJSON {\n"
          "namespace BinaryReflector {\n\n";

    // determine visibility attribute
    const char *visibility = m_options.visibilityArg.firstValue();
    if (!visibility) {
        visibility = "";
    }

    // add push and pull functions for each class, for an example of the resulting
    // output, see ../lib/tests/binaryserializable.cpp
    for (const RelevantClass &relevantClass : relevantClasses) {
        // determine whether private members should be pushed/pulled as well: check whether friend declarations for push/pull present
        // note: the friend declarations we are looking for are expanded from the REFLECTIVE_RAPIDJSON_ENABLE_PRIVATE_MEMBERS macro
        bool writePrivateMembers = false, readPrivateMembers = false;
        for (const clang::FriendDecl *const friendDecl : relevantClass.record->friends()) {
            // get the actual declaration which must be a function
            const clang::NamedDecl *const actualFriendDecl = friendDecl->getFriendDecl();
            if (!actualFriendDecl || actualFriendDecl->getKind() != clang::Decl::Kind::Function) {
                continue;
            }
            // check whether the friend function matches the push/pull helper function
            const string friendName(actualFriendDecl->getQualifiedNameAsString());
            if (friendName == "ReflectiveRapidJSON::BinaryReflector::writeCustomType") {
                writePrivateMembers = true;
            }
            if (friendName == "ReflectiveRapidJSON::BinaryReflector::readCustomType") {
                readPrivateMembers = true;
            }
            if (writePrivateMembers && readPrivateMembers) {
                break;
            }
        }

        // find relevant base classes
        const vector<const RelevantClass *> relevantBases = findRelevantBaseClasses(relevantClass, relevantClasses);

        // print comment
        os << "// define code for (de)serializing " << relevantClass.qualifiedName << " objects\n";

        // print writeCustomType method
        os << "template <> " << visibility << " void writeCustomType<::" << relevantClass.qualifiedName
           << ">(BinarySerializer &serializer, const ::" << relevantClass.qualifiedName
           << " &customObject)\n{\n"
              "    // write base classes\n";
        for (const RelevantClass *baseClass : relevantBases) {
            os << "    serializer.write(static_cast<const ::" << baseClass->qualifiedName << " &>(customObject));\n";
        }
        os << "    // write members\n";
        auto membersWritten = false;
        for (const clang::FieldDecl *field : relevantClass.record->fields()) {
            if (writePrivateMembers || field->getAccess() == clang::AS_public) {
                os << "    serializer.write(customObject." << field->getName() << ");\n";
                membersWritten = true;
            }
        }
        if (relevantBases.empty() && !membersWritten) {
            os << "    (void)serializer;\n    (void)customObject;\n";
        }
        os << "}\n";

        // skip printing the readCustomType method for classes without default constructor because deserializing those is currently not supported
        if (!relevantClass.record->hasDefaultConstructor()) {
            continue;
        }

        // print readCustomType method
        os << "template <> " << visibility << " void readCustomType<::" << relevantClass.qualifiedName
           << ">(BinaryDeserializer &deserializer, ::" << relevantClass.qualifiedName
           << " &customObject)\n{\n"
              "    // read base classes\n";
        for (const RelevantClass *baseClass : relevantBases) {
            os << "    deserializer.read(static_cast<::" << baseClass->qualifiedName << " &>(customObject));\n";
        }
        os << "    // read members\n";
        auto membersRead = false;
        for (const clang::FieldDecl *field : relevantClass.record->fields()) {
            // skip const members
            if (field->getType().isConstant(field->getASTContext())) {
                continue;
            }
            if (readPrivateMembers || field->getAccess() == clang::AS_public) {
                os << "    deserializer.read(customObject." << field->getName() << ");\n";
                membersRead = true;
            }
        }
        if (relevantBases.empty() && !membersRead) {
            os << "    (void)deserializer;\n    (void)customObject;\n";
        }
        os << "}\n\n";
    }

    // close namespace ReflectiveRapidJSON::BinaryReflector
    os << "} // namespace BinaryReflector\n"
          "} // namespace ReflectiveRapidJSON\n";
}

} // namespace ReflectiveRapidJSON