SqMod/module/PocoLib/Data.hpp

#pragma once

// ------------------------------------------------------------------------------------------------
#include "Library/IO/Buffer.hpp"
#include "Library/Utils/String.hpp"
#include "Library/Utils/Vector.hpp"

// ------------------------------------------------------------------------------------------------
#include <Poco/Data/Session.h>
#include <Poco/Data/Statement.h>
#include <Poco/Data/RecordSet.h>
#include <Poco/Data/Transaction.h>
#include <Poco/Data/SessionPool.h>
#include <Poco/Data/LOB.h>

// ------------------------------------------------------------------------------------------------
namespace std { // NOLINT(cert-dcl58-cpp)

/* ------------------------------------------------------------------------------------------------
 * Allows the StackStrF to write its data into a std::ostream type.
*/
inline std::ostream & operator << (std::ostream & out, const ::Sqrat::StackStrF & str)
{
    if (str.mLen)
    {
        out.write(str.mPtr, str.mLen);
    }
    return out;
}

/* ------------------------------------------------------------------------------------------------
 * Allows the StackStrF to write its data into a std::ostringstream type.
*/
inline std::ostringstream & operator << (std::ostringstream & out, const ::Sqrat::StackStrF & str)
{
    if (str.mLen)
    {
        out.write(str.mPtr, str.mLen);
    }
    return out;
}

} // Namespace:: std

// ------------------------------------------------------------------------------------------------
namespace Poco { // NOLINT(modernize-concat-nested-namespaces)
namespace Data {

/* ------------------------------------------------------------------------------------------------
 * Implementation of AbstractBinding for shared ownership binding of values.
 * Because we cannot take references to script variables, we use this as a proxy.
*/
template <class T> struct ReferenceBinding : public AbstractBinding
{
    using ValType = T;
    using ValPtr = SharedPtr<ValType>;
    using Type = ReferenceBinding<ValType>;
    using Ptr = SharedPtr<Type>;

    /* --------------------------------------------------------------------------------------------
     * Base constructor.
    */
    explicit ReferenceBinding(const ValPtr& val,  const std::string& name = "", Direction direction = PD_IN)
        : AbstractBinding(name, direction), m_Value(val), m_Bound(false)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Destructor.
    */
    ~ReferenceBinding() override = default;

    /* --------------------------------------------------------------------------------------------
     * Retrieve columns occupied.
    */
    SQMOD_NODISCARD std::size_t numOfColumnsHandled() const override
    {
        return TypeHandler<T>::size();
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve rows occupied.
    */
    SQMOD_NODISCARD std::size_t numOfRowsHandled() const override
    {
        return 1;
    }

    /* --------------------------------------------------------------------------------------------
     * Check if binding is available.
    */
    SQMOD_NODISCARD bool canBind() const override
    {
        return !m_Bound;
    }

    /* --------------------------------------------------------------------------------------------
     * Bind the value.
    */
    void bind(std::size_t pos) override
    {
        poco_assert_dbg(!getBinder().isNull());
        TypeHandler<T>::bind(pos, *m_Value, getBinder(), getDirection());
        m_Bound = true;
    }

    /* --------------------------------------------------------------------------------------------
     * Reset the binding.
    */
    void reset() override
    {
        m_Bound = false;
        AbstractBinder::Ptr pBinder = getBinder();
        poco_assert_dbg (!pBinder.isNull());
        pBinder->reset();
    }

private:

    ValPtr m_Value;
    bool   m_Bound;
};

/* ------------------------------------------------------------------------------------------------
 * Implementation of AbstractBinding for shared ownership binding of values.
 * Because we cannot take references to script variables, we use this as a proxy.
*/
template <class T> struct ReferenceBinding<std::vector<T>> : public AbstractBinding
{
    using ValType = std::vector<T>;
    using ValPtr = SharedPtr<ValType>;
    using Ptr = SharedPtr<Binding<ValType>>;
    using Iterator = typename ValType::const_iterator;

    /* --------------------------------------------------------------------------------------------
     * Base constructor.
    */
    explicit ReferenceBinding(const ValPtr& val,  const std::string& name = "", Direction direction = PD_IN)
        : AbstractBinding(name, direction), m_Value(val), m_Begin(), m_End()
    {
        if (PD_IN == direction && m_Value->size() == 0)
        {
            throw BindingException("It is illegal to bind to an empty data collection");
        }
        m_Begin = m_Value->begin();
        m_End   = m_Value->end();
    }

    /* --------------------------------------------------------------------------------------------
     * Destructor.
    */
    ~ReferenceBinding() override = default;

    /* --------------------------------------------------------------------------------------------
     * Retrieve columns occupied.
    */
    SQMOD_NODISCARD std::size_t numOfColumnsHandled() const override
    {
        return TypeHandler<T>::size();
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve rows occupied.
    */
    SQMOD_NODISCARD std::size_t numOfRowsHandled() const override
    {
        return m_Value->size();
    }

    /* --------------------------------------------------------------------------------------------
     * Check if binding is available.
    */
    SQMOD_NODISCARD bool canBind() const override
    {
        return (m_Begin != m_End);
    }

    /* --------------------------------------------------------------------------------------------
     * Bind the value.
    */
    void bind(std::size_t pos) override
    {
        poco_assert_dbg(!getBinder().isNull());
        poco_assert_dbg(canBind());
        TypeHandler<T>::bind(pos, *m_Begin, getBinder(), getDirection());
        ++m_Begin;
    }

    /* --------------------------------------------------------------------------------------------
     * Reset the binding.
    */
    void reset() override
    {
        m_Begin = m_Value->begin();
        m_End   = m_Value->end();
    }

private:

    ValPtr      m_Value;
    Iterator    m_Begin;
    Iterator    m_End;
};

/* ------------------------------------------------------------------------------------------------
 * Implementation of AbstractExtraction for shared ownership binding of values.
 * Because we cannot take references to script variables, we use this as a proxy.
*/
template <class T>
class ReferenceExtraction: public AbstractExtraction
{
public:
    using ValType = T;
    using Result = SharedPtr<T>;
    using ValPtr = SharedPtr<ValType>;
    using Type = Extraction<ValType>;
    using Ptr = SharedPtr<Type>;

    /* --------------------------------------------------------------------------------------------
     * Creates an Extraction object at specified position. Uses an empty object T as default value.
    */
    explicit ReferenceExtraction(const Result& result, const Position& pos = Position(0))
        : AbstractExtraction(Limit::LIMIT_UNLIMITED, pos.value())
        , m_Result(result),m_Default(),m_Extracted(false),m_Null(false)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates an Extraction object at specified position. Uses the provided def object as default value.
    */
    ReferenceExtraction(const Result& result, const T& def, const Position& pos = Position(0))
        : AbstractExtraction(Limit::LIMIT_UNLIMITED, pos.value())
        , m_Result(result), m_Default(def), m_Extracted(false), m_Null(false)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates an Extraction object at specified position. Uses the provided def object as default value.
    */
    ReferenceExtraction(const Result& result, T&& def, const Position& pos = Position(0))
        : AbstractExtraction(Limit::LIMIT_UNLIMITED, pos.value())
        , m_Result(result), m_Default(std::move(def)), m_Extracted(false), m_Null(false)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Destroys the Extraction object.
    */
    ~ReferenceExtraction() override = default;

    /* --------------------------------------------------------------------------------------------
     * Retrieve the number of columns handled.
    */
    SQMOD_NODISCARD std::size_t numOfColumnsHandled() const override
    {
        return TypeHandler<T>::size();
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the number of rows handled.
    */
    SQMOD_NODISCARD std::size_t numOfRowsHandled() const override
    {
        return m_Extracted ? 1u : 0;
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the number of rows allowed.
    */
    SQMOD_NODISCARD std::size_t numOfRowsAllowed() const override
    {
        return 1u;
    }

    /* --------------------------------------------------------------------------------------------
     * Check if null.
    */
    SQMOD_NODISCARD bool isNull(std::size_t /*row*/) const override
    {
        return m_Null;
    }

    /* --------------------------------------------------------------------------------------------
     * Extract the value.
    */
    std::size_t extract(std::size_t pos) override
    {
        if (m_Extracted)
        {
            throw ExtractException("value already extracted");
        }

        m_Extracted = true;
        AbstractExtractor::Ptr pExt = getExtractor();
        TypeHandler<T>::extract(pos, *m_Result, m_Default, pExt);
        m_Null = isValueNull<T>(*m_Result, pExt->isNull(pos));

        return 1u;
    }

    /* --------------------------------------------------------------------------------------------
     * Reset state.
    */
    void reset() override
    {
        m_Extracted = false;
    }

    /* --------------------------------------------------------------------------------------------
     * See if a value was extracted.
    */
    SQMOD_NODISCARD bool canExtract() const override
    {
        return !m_Extracted;
    }

    /* --------------------------------------------------------------------------------------------
     * Create a preparation instance for this type.
    */
    AbstractPreparation::Ptr createPreparation(AbstractPreparator::Ptr& pPrep, std::size_t pos) override
    {
        return new Preparation<T>(pPrep, pos, *m_Result);
    }

private:

    Result  m_Result;
    T       m_Default;
    bool    m_Extracted;
    bool    m_Null;
};

/* ------------------------------------------------------------------------------------------------
 * Implementation of AbstractExtraction for shared ownership binding of values.
 * Because we cannot take references to script variables, we use this as a proxy.
*/
template <class T>
class ReferenceExtraction<std::vector<T>>: public AbstractExtraction
{
public:
    using ValType = std::vector<T>;
    using Result = SharedPtr<std::vector<T>>;
    using ValPtr = SharedPtr<ValType>;
    using Type = Extraction<ValType>;
    using Ptr = SharedPtr<Type>;

    /* --------------------------------------------------------------------------------------------
     * Creates an Extraction object at specified position. Uses an empty object T as default value.
    */
    explicit ReferenceExtraction(const Result& result, const Position& pos = Position(0))
        : AbstractExtraction(Limit::LIMIT_UNLIMITED, pos.value())
        , m_Result(result), m_Default(), m_Nulls()
    {
        m_Result->clear();
    }

    /* --------------------------------------------------------------------------------------------
     * Creates an Extraction object at specified position. Uses the provided def object as default value.
    */
    ReferenceExtraction(const Result& result, const T& def, const Position& pos = Position(0))
        : AbstractExtraction(Limit::LIMIT_UNLIMITED, pos.value())
        , m_Result(result), m_Default(def), m_Nulls()
    {
        m_Result->clear();
    }

    /* --------------------------------------------------------------------------------------------
     * Destroys the Extraction object.
    */
    ~ReferenceExtraction() override = default;

    /* --------------------------------------------------------------------------------------------
     * Retrieve the number of columns handled.
    */
    SQMOD_NODISCARD std::size_t numOfColumnsHandled() const override
    {
        return TypeHandler<T>::size();
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the number of rows handled.
    */
    SQMOD_NODISCARD std::size_t numOfRowsHandled() const override
    {
        return static_cast<std::size_t>(m_Result->size());
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the number of rows allowed.
    */
    SQMOD_NODISCARD std::size_t numOfRowsAllowed() const override
    {
        return getLimit();
    }

    /* --------------------------------------------------------------------------------------------
     * Check if null.
    */
    SQMOD_NODISCARD bool isNull(std::size_t row) const override
    {
        try
        {
            return m_Nulls.at(row);
        }
        catch (std::out_of_range& ex)
        {
            throw RangeException(ex.what());
        }
    }

    /* --------------------------------------------------------------------------------------------
     * Extract the value.
    */
    std::size_t extract(std::size_t pos) override
    {
        AbstractExtractor::Ptr ext = getExtractor();
        m_Result->push_back(m_Default);
        TypeHandler<T>::extract(pos, m_Result->back(), m_Default, ext);
        m_Nulls.push_back(isValueNull(m_Result->back(), ext->isNull(pos)));
        return 1u;
    }

    /* --------------------------------------------------------------------------------------------
     * Create a preparation instance for this type.
    */
    AbstractPreparation::Ptr createPreparation(AbstractPreparator::Ptr& pPrep, std::size_t pos) override
    {
        return new Preparation<T>(pPrep, pos, m_Default);
    }

    /* --------------------------------------------------------------------------------------------
     * Reset state.
    */
    void reset() override
    {
        m_Nulls.clear();
    }

protected:

    /* --------------------------------------------------------------------------------------------
     * Retrieve the container with the extracted values.
    */
    SQMOD_NODISCARD const std::vector<T>& result() const
    {
        return *m_Result;
    }

private:
    Result              m_Result;
    T                   m_Default;
    std::deque< bool >  m_Nulls;
};

// ------------------------------------------------------------------------------------------------
template <> std::size_t ReferenceExtraction< std::vector<bool> >::extract(std::size_t pos)
{
    AbstractExtractor::Ptr ext = getExtractor();
    bool tmp = m_Default;
    TypeHandler<bool>::extract(pos, tmp, m_Default, ext);
    m_Result->push_back(tmp);
    m_Nulls.push_back(ext->isNull(pos));
    return 1u;
}

} // Namespace:: Data
} // Namespace:: Poco

// ------------------------------------------------------------------------------------------------
namespace SqMod {

// ------------------------------------------------------------------------------------------------
using namespace Poco::Data::Keywords;
// ------------------------------------------------------------------------------------------------
using Poco::Data::Session;
using Poco::Data::Statement;
using Poco::Data::RecordSet;
using Poco::Data::Transaction;
using Poco::Data::SessionPool;
using Poco::Data::ReferenceBinding;

// ------------------------------------------------------------------------------------------------
struct SqDataSession;
struct SqDataStatement;
struct SqDataRecordSet;

/* ------------------------------------------------------------------------------------------------
 * Utility used to transform optimal argument type to stored type.
*/
template < class T > struct SqDataBindingOpt
{
    /* --------------------------------------------------------------------------------------------
     * Optimal argument type. Unchanged when not specialized.
    */
    using Type = T;

    /* --------------------------------------------------------------------------------------------
     * Convert the optimal type to the stored type. Does nothing special in this case.
    */
    inline static Type & Get(Type & v) { return v; }
    inline static const Type & Get(const Type & v) { return v; }
    // --------------------------------------------------------------------------------------------
    inline static void Put(T & o, Type & v) { o = v; }
    inline static void Put(T & o, const Type & v) { o = v; }
};

/* ------------------------------------------------------------------------------------------------
 * Specialization of SqDataBindingOpt for std::string type.
*/
template < > struct SqDataBindingOpt< String >
{
    /* --------------------------------------------------------------------------------------------
     * Optimal argument type.
    */
    using Type = StackStrF;

    /* --------------------------------------------------------------------------------------------
     * Convert the optimal type to the stored type.
    */
    inline static String Get(Type & v) { return v.ToStr(); }
    inline static String Get(const Type & v) { return v.ToStr(); }
    // --------------------------------------------------------------------------------------------
    inline static void Put(String & o, Type & v) { o.assign(v.mPtr, v.GetSize()); }
    inline static void Put(String & o, const Type & v) { o.assign(v.mPtr, v.GetSize()); }
};

/* ------------------------------------------------------------------------------------------------
 * Wrapper around values that must be passed as reference. Manual lifetime management!
*/
template < class T > struct SqDataBinding
{
    /* --------------------------------------------------------------------------------------------
     * Reference binding type.
    */
    using Binding = ReferenceBinding< T >;

    /* --------------------------------------------------------------------------------------------
     * Optimal type to receive a value of this type as function argument. Mainly for strings.
    */
    using OptimalType = typename SqDataBindingOpt< T >::Type;

    /* --------------------------------------------------------------------------------------------
     * Same as OptimalType but preferably with a reference qualifier to avoid copies.
    */
    using OptimalArg = typename std::conditional< std::is_same< T, OptimalType >::value, T, OptimalType & >::type;

    /* --------------------------------------------------------------------------------------------
     * Reference value.
    */
    typename Binding::ValPtr mV{};

    /* --------------------------------------------------------------------------------------------
     * Default constructor. Initializes to a default value.
    */
    SqDataBinding()
        : mV(new T())
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Explicit constructor. Initializes to a specific value.
    */
    explicit SqDataBinding(OptimalArg v)
        : mV(new T())
    {
        SqDataBindingOpt< T >::Put(*mV, v);
    }

    /* --------------------------------------------------------------------------------------------
     * Copy constructor.
    */
    SqDataBinding(const SqDataBinding &) = default;

    /* --------------------------------------------------------------------------------------------
     * Move constructor.
    */
    SqDataBinding(SqDataBinding &&) noexcept = default;

    /* --------------------------------------------------------------------------------------------
     * Destroys the Statement.
    */
    ~SqDataBinding() = default;

    /* --------------------------------------------------------------------------------------------
     * Assignment operator.
    */
    SqDataBinding & operator = (const SqDataBinding &) = default;

    /* --------------------------------------------------------------------------------------------
     * Move assignment.
    */
    SqDataBinding & operator = (SqDataBinding &&) noexcept = default;

    /* --------------------------------------------------------------------------------------------
     * Retrieve a value from the instance.
    */
    SQMOD_NODISCARD const T & Get() const { return *mV; }

    /* --------------------------------------------------------------------------------------------
     * Modify a value from the instance.
    */
    void Set(OptimalArg v) { SqDataBindingOpt< T >::Put(*mV, v); }

    /* --------------------------------------------------------------------------------------------
     * Modify a value from the instance.
    */
    SqDataBinding & SetEx(OptimalArg v) { SqDataBindingOpt< T >::Put(*mV, v); return *this; }

    /* --------------------------------------------------------------------------------------------
     * Use the value to a statement.
    */
    SqDataBinding & Use(SqDataStatement & stmt);

    /* --------------------------------------------------------------------------------------------
     * Use the value to a statement with a specific name.
    */
    SqDataBinding & UseAs(SqDataStatement & stmt, StackStrF & name);

    /* --------------------------------------------------------------------------------------------
     * Bind the value to a statement.
    */
    SqDataBinding & Bind(SqDataStatement & stmt);

    /* --------------------------------------------------------------------------------------------
     * Bind the value to a statement with a specific name.
    */
    SqDataBinding & BindAs(SqDataStatement & stmt, StackStrF & name);
};

/* ------------------------------------------------------------------------------------------------
 * A Session holds a connection to a Database and creates Statement objects.
*/
struct SqDataSession : public Session
{
    /* --------------------------------------------------------------------------------------------
     * Creates a new session, using the given connection (must be in "connection:///info" format).
    */
    SqDataSession(StackStrF & conn, SQInteger timeout)
        : Session(conn.ToStr(), ConvTo< size_t >::From(timeout))
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates a new session, using the given connector, and connection information.
    */
    SqDataSession(StackStrF & conn, StackStrF & info, SQInteger timeout)
        : Session(conn.ToStr(), info.ToStr(), ConvTo< size_t >::From(timeout))
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates a session by copying another one.
    */
    SqDataSession(const SqDataSession &) = default;

    /* --------------------------------------------------------------------------------------------
     * Creates a session by moving another one.
    */
    SqDataSession(SqDataSession &&) noexcept = default;

    /* --------------------------------------------------------------------------------------------
     * Creates a session by copying another one.
    */
    SqDataSession(const Session & s)
        : Session(s)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates a session by moving another one.
    */
    SqDataSession(Session && s) noexcept
        : Session(std::move(s))
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Destroys the Session.
    */
    ~SqDataSession() = default;

    /* --------------------------------------------------------------------------------------------
     * Assignment operator.
    */
    SqDataSession & operator = (const SqDataSession &) = default;

    /* --------------------------------------------------------------------------------------------
     * Move assignment.
    */
    SqDataSession & operator = (SqDataSession &&) noexcept = default;
#ifdef SQMOD_POCO_HAS_MYSQL
    /* --------------------------------------------------------------------------------------------
     * Implements string escape in MySQL.
    */
    LightObj MySQLEscapeString(StackStrF & str);
#endif
    /* --------------------------------------------------------------------------------------------
     * Opens the session using the supplied string.
     * Can also be used with default empty string to reconnect a disconnected session.
    */
    void Open(StackStrF & connect) { open(connect.ToStr()); }

    /* --------------------------------------------------------------------------------------------
     * Closes the session.
    */
    void Close() { close(); }

    /* --------------------------------------------------------------------------------------------
     * Returns true if session is connected, false otherwise.
    */
    bool IsConnected() { return isConnected(); }

    /* --------------------------------------------------------------------------------------------
     * Closes the session and opens it.
    */
    void Reconnect() { return reconnect(); }

    /* --------------------------------------------------------------------------------------------
     * Returns true if the session is good and can be used, false otherwise.
    */
    SQMOD_NODISCARD bool IsGood() { return isGood(); }

    /* --------------------------------------------------------------------------------------------
     * Sets the session login timeout value.
    */
    void SetLoginTimeout(SQInteger timeout) { setLoginTimeout(ConvTo< size_t >::From(timeout)); }

    /* --------------------------------------------------------------------------------------------
     * Returns the session login timeout value.
    */
    SQMOD_NODISCARD SQInteger GetLoginTimeout() const { return static_cast< SQInteger >(getLoginTimeout()); }

    /* --------------------------------------------------------------------------------------------
     * Sets the session connection timeout value.
    */
    void SetConnectionTimeout(SQInteger timeout) { setConnectionTimeout(ConvTo< size_t >::From(timeout)); }

    /* --------------------------------------------------------------------------------------------
     * Returns the session connection timeout value.
    */
    SQInteger GetConnectionTimeout() { return static_cast< SQInteger >(getConnectionTimeout()); }

    /* --------------------------------------------------------------------------------------------
     * Starts a transaction.
    */
    void Begin() { begin(); }

    /* --------------------------------------------------------------------------------------------
     * Commits and ends a transaction.
    */
    void Commit() { commit(); }

    /* --------------------------------------------------------------------------------------------
     * Rolls back and ends a transaction.
    */
    void Rollback() { rollback(); }

    /* --------------------------------------------------------------------------------------------
     * Returns true if session has transaction capabilities.
    */
    SQMOD_NODISCARD bool CanTransact() { return canTransact(); }

    /* --------------------------------------------------------------------------------------------
     * Returns true if a transaction is in progress, false otherwise.
    */
    SQMOD_NODISCARD bool IsTransaction() { return isTransaction(); }

    /* --------------------------------------------------------------------------------------------
     * Sets the transaction isolation level.
    */
    void SetTransactionIsolation(SQInteger ti) { setTransactionIsolation(static_cast< uint32_t >(ti)); }

    /* --------------------------------------------------------------------------------------------
     * Returns the transaction isolation level.
    */
    SQMOD_NODISCARD SQInteger GetTransactionIsolation() { return static_cast< SQInteger >(getTransactionIsolation()); }

    /* --------------------------------------------------------------------------------------------
     * Returns true if the transaction isolation level corresponding to the supplied bitmask is supported.
    */
    bool HasTransactionIsolation(SQInteger ti) { return hasTransactionIsolation(static_cast< uint32_t >(ti)); }

    /* --------------------------------------------------------------------------------------------
     * Returns true if the transaction isolation level corresponds to the supplied bitmask.
    */
    bool IsTransactionIsolation(SQInteger ti) { return isTransactionIsolation(static_cast< uint32_t >(ti)); }

    /* --------------------------------------------------------------------------------------------
     * Returns the connector name for this session.
    */
    SQMOD_NODISCARD std::string GetConnector() const { return connector(); }

    /* --------------------------------------------------------------------------------------------
     * Returns the URI for this session.
    */
    SQMOD_NODISCARD std::string GetURI() const { return uri(); }

    /* --------------------------------------------------------------------------------------------
     * Utility function that teturns the URI formatted from supplied arguments as "connector:///info".
    */
    SQMOD_NODISCARD static std::string BuildURI(StackStrF & connector, StackStrF & info)
    {
        return uri(connector.ToStr(), info.ToStr());
    }

    /* --------------------------------------------------------------------------------------------
     * Set the state of a feature.
    */
    void SetFeature(bool state, StackStrF & name) { setFeature(name.ToStr(), state); }

    /* --------------------------------------------------------------------------------------------
     * Look up the state of a feature.
    */
    SQMOD_NODISCARD bool GetFeature(StackStrF & name) const { return getFeature(name.ToStr()); }

    /* --------------------------------------------------------------------------------------------
     * Set the value of a property.
    */
    void SetProperty(const LightObj & value, StackStrF & name);

    /* --------------------------------------------------------------------------------------------
     * Look up the value of a property.
    */
    SQMOD_NODISCARD LightObj GetProperty(StackStrF & name) const;

    /* --------------------------------------------------------------------------------------------
     * Retrieve a statement from this session.
    */
    SQMOD_NODISCARD SqDataStatement GetStatement(StackStrF & data);

    /* --------------------------------------------------------------------------------------------
     * Retrieve a record-set from this session.
    */
    SQMOD_NODISCARD SqDataRecordSet GetRecordSet(StackStrF & data);

    /* --------------------------------------------------------------------------------------------
     * Create a statement and execute the given query immediately.
    */
    SqDataSession & Execute(StackStrF & query);

    /* --------------------------------------------------------------------------------------------
     * Create a statement and execute the given query whenever possible.
    */
    SqDataSession & ExecuteAsync(StackStrF & query);
};

/* ------------------------------------------------------------------------------------------------
 * Statement is used to execute SQL statements.
*/
struct SqDataStatementResult : public SqChainedInstances< SqDataStatementResult >
{
    /* --------------------------------------------------------------------------------------------
     * Watched result.
    */
    Statement::Result mRes;

    /* --------------------------------------------------------------------------------------------
     * Script callback.
    */
    Function mFunc;

    /* --------------------------------------------------------------------------------------------
     * Reference to the statement.
    */
    LightObj mStmt;

    /* --------------------------------------------------------------------------------------------
     * Reference to self.
    */
    LightObj mSelf;

    /* --------------------------------------------------------------------------------------------
     * Base constructor.
    */
    explicit SqDataStatementResult(const Statement::Result & r, LightObj && stmt)
        : mRes(r), mFunc(), mStmt(std::move(stmt)), mSelf()
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Copy constructor.
    */
    SqDataStatementResult(const SqDataStatementResult &) = delete;

    /* --------------------------------------------------------------------------------------------
     * Move constructor.
    */
    SqDataStatementResult(SqDataStatementResult &&) = delete;

    /* --------------------------------------------------------------------------------------------
     * Destructor.
    */
    ~SqDataStatementResult()
    {
        // Forget about this instance
        UnchainInstance();
    }

    /* --------------------------------------------------------------------------------------------
     * Assignment operator.
    */
    SqDataStatementResult & operator = (const SqDataStatementResult &) = delete;

    /* --------------------------------------------------------------------------------------------
     * Move assignment.
    */
    SqDataStatementResult & operator = (SqDataStatementResult &&) = delete;

    /* --------------------------------------------------------------------------------------------
     * Bind a callback and wait for completion.
    */
    LightObj & Bind(Function & fn)
    {
        mFunc = std::move(fn);
        // Reference self to prevent destruction
        mSelf = LightObj(this);
        // Remember this instance
        ChainInstance();
        // Return the statement
        return mStmt;
    }
};

/* ------------------------------------------------------------------------------------------------
 * Statement is used to execute SQL statements.
*/
struct SqDataStatement : public Statement
{
    /* --------------------------------------------------------------------------------------------
     * Creates the Statement for the given Session.
    */
    explicit SqDataStatement(SqDataSession & session)
        : Statement(session)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates the Statement for the given Session and adds initial SQL code.
    */
    explicit SqDataStatement(SqDataSession & session, StackStrF & data)
        : Statement(session)
    {
        Add(data);
    }

    /* --------------------------------------------------------------------------------------------
     * Copy constructor. If the statement has been executed asynchronously and has not been
     * synchronized prior to copy operation (i.e. is copied while executing), this constructor shall synchronize it.
    */
    SqDataStatement(const SqDataStatement &) = default;

    /* --------------------------------------------------------------------------------------------
     * Move constructor.
    */
    SqDataStatement(SqDataStatement &&) noexcept = default;

    /* --------------------------------------------------------------------------------------------
     * Destroys the Statement.
    */
    ~SqDataStatement() = default;

    /* --------------------------------------------------------------------------------------------
     * Assignment operator.
    */
    SqDataStatement & operator = (const SqDataStatement &) = default;

    /* --------------------------------------------------------------------------------------------
     * Move assignment.
    */
    SqDataStatement & operator = (SqDataStatement &&) noexcept = default;

    /* --------------------------------------------------------------------------------------------
     * Concatenates data with the SQL statement string.
    */
    SqDataStatement & Add(StackStrF & data)
    {
        Statement::operator<<(data);
        // Allow chaining
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if statement was marked for asynchronous execution.
    */
    bool GetAsync()
    {
        return isAsync();
    }

    /* --------------------------------------------------------------------------------------------
     * Sets the asynchronous flag. This setting does not affect the statement's capability
     * to be executed synchronously by directly calling Execute().
    */
    SqDataStatement & SetAsync(bool async)
    {
        setAsync(async);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if the statement was initialized (i.e. not executed yet).
    */
    bool Initialized()
    {
        return initialized();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if the statement was paused (a range limit stopped it and there is more work to do).
    */
    bool Paused()
    {
        return paused();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if the statement was completely executed or false if a range limit stopped it
     * and there is more work to do. When no limit is set, it will always return true after calling execute().
    */
    bool Done()
    {
        return done();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if statement is in a state that allows the internal storage to be modified.
    */
    bool CanModifyStorage()
    {
        return canModifyStorage();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the internal storage type for the statement.
    */
    SQInteger Storage() const
    {
        return static_cast< SQInteger >(storage());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the internal storage type for the statement.
    */
    const std::string & GetStorage() const
    {
        return getStorage();
    }

    /* --------------------------------------------------------------------------------------------
     * Sets the internal storage type for the statement.
    */
    void SetStorage(StackStrF & storage)
    {
        setStorage(storage.ToStr());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of columns returned for current data set.
     * Default value indicates current data set (if any).
    */
    SQInteger GetColumnsExtracted(int data_set) const
    {
        return static_cast< SQInteger >(columnsExtracted(data_set));
    }
    SQInteger ColumnsExtracted() const
    {
        return static_cast< SQInteger >(columnsExtracted());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of rows returned for current data set during last statement execution.
     * Default value indicates current data set (if any).
    */
    SQInteger GetRowsExtracted(int data_set) const
    {
        return static_cast< SQInteger >(rowsExtracted(data_set));
    }
    SQInteger RowsExtracted() const
    {
        return static_cast< SQInteger >(rowsExtracted());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of rows extracted so far for the data set.
     * Default value indicates current data set (if any).
    */
    SQInteger GetSubTotalRowCount(int data_set) const
    {
        return static_cast< SQInteger >(subTotalRowCount(data_set));
    }
    SQInteger SubTotalRowCount() const
    {
        return static_cast< SQInteger >(subTotalRowCount());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of extraction storage buffers associated with the current data set.
    */
    SQInteger ExtractionCount() const
    {
        return static_cast< SQInteger >(extractionCount());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of data sets associated with the statement.
    */
    SQInteger DataSetCount() const
    {
        return static_cast< SQInteger >(dataSetCount());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the index of the next data set.
    */
    SQInteger NextDataSet()
    {
        return static_cast< SQInteger >(nextDataSet());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the index of the previous data set.
    */
    SQInteger PreviousDataSet()
    {
        return static_cast< SQInteger >(previousDataSet());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns false if the current data set index points to the last data set. Otherwise, it returns true.
    */
    bool HasMoreDataSets() const
    {
        return hasMoreDataSets();
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement synchronously or asynchronously.
    */
    SQInteger Execute()
    {
        return static_cast< SQInteger >(execute(true));
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement synchronously or asynchronously.
    */
    SQInteger Execute_(bool reset)
    {
        return static_cast< SQInteger >(execute(reset));
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement synchronously or asynchronously. Returns itself instead of rows.
    */
    SqDataStatement & ExecuteChained()
    {
        execute(true);
        // Allow chaining
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement synchronously or asynchronously. Returns itself instead of rows.
    */
    SqDataStatement & ExecuteChained_(bool reset)
    {
        execute(reset);
        // Allow chaining
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement asynchronously.
    */
    LightObj ExecuteAsync()
    {
        return LightObj(SqTypeIdentity< SqDataStatementResult >{}, SqVM(), executeAsync(true), LightObj(this));
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement asynchronously.
    */
    LightObj ExecuteAsync_(bool reset)
    {
        return LightObj(SqTypeIdentity< SqDataStatementResult >{}, SqVM(), executeAsync(reset), LightObj(this));
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement asynchronously.
    */
    SqDataStatement & ExecuteAsyncChained()
    {
        executeAsync(true);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the statement asynchronously.
    */
    SqDataStatement & ExecuteAsyncChained_(bool reset)
    {
        executeAsync(reset);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Waits for the execution completion for asynchronous statements or returns immediately for synchronous ones.
    */
    SQInteger Wait(SQInteger milliseconds)
    {
        return static_cast< SQInteger >(wait(static_cast< long >(milliseconds)));
    }

    /* --------------------------------------------------------------------------------------------
     * Resets the Statement so that it can be filled with a new SQL command.
    */
    SqDataStatement & Reset(SqDataSession & session)
    {
        reset(session);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Swaps the statement with another one.
    */
    void Swap(SqDataStatement & stmt)
    {
        swap(stmt);
    }

    /* --------------------------------------------------------------------------------------------
     * Bind a reference to the statement.
    */
    SqDataStatement & Use(LightObj & obj)
    {
        UseEx(obj, String(), Poco::Data::AbstractBinding::PD_IN);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Bind a named reference to the statement.
    */
    SqDataStatement & UseAs(LightObj & obj, StackStrF & name)
    {
        UseEx(obj, String(name.mPtr, name.GetSize()), Poco::Data::AbstractBinding::PD_IN);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Internal function used internally to bind a reference to the statement.
    */
    void UseEx(LightObj & obj, const std::string & name, Poco::Data::AbstractBinding::Direction dir);

    /* --------------------------------------------------------------------------------------------
     * Internal function used internally to bind a instance reference to the statement.
    */
    void UseInst_(LightObj & obj, const std::string & name, Poco::Data::AbstractBinding::Direction dir);

    /* --------------------------------------------------------------------------------------------
     * Bind a reference to the statement and mark it as input (i.e alias of Use).
    */
    SqDataStatement & In(LightObj & obj)
    {
        return Use(obj);
    }

    /* --------------------------------------------------------------------------------------------
     * Bind a named reference to the statement mark it as input (i.e alias of UseAs).
    */
    SqDataStatement & InAs(LightObj & obj, StackStrF & name)
    {
        return UseAs(obj, name);
    }

    /* --------------------------------------------------------------------------------------------
     * Bind a reference to the statement and mark it as output.
    */
    SqDataStatement & Out(LightObj & obj)
    {
        UseEx(obj, String(), Poco::Data::AbstractBinding::PD_OUT);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Bind a named reference to the statement and mark it as output.
    */
    SqDataStatement & OutAs(LightObj & obj, StackStrF & name)
    {
        UseEx(obj, String(name.mPtr, name.GetSize()), Poco::Data::AbstractBinding::PD_OUT);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Bind a value to the statement.
    */
    SqDataStatement & Bind(LightObj & obj)
    {
        BindEx(obj, String(), Poco::Data::AbstractBinding::PD_IN);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Bind a named value to the statement.
    */
    SqDataStatement & BindAs(LightObj & obj, StackStrF & name)
    {
        BindEx(obj, String(name.mPtr, name.GetSize()), Poco::Data::AbstractBinding::PD_IN);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Internal function used internally to bind a value to the statement.
    */
    void BindEx(LightObj & obj, const std::string & name, Poco::Data::AbstractBinding::Direction dir);

    /* --------------------------------------------------------------------------------------------
     * Internal function used internally to bind a instance value to the statement.
    */
    void BindInst_(LightObj & obj, const std::string & name, Poco::Data::AbstractBinding::Direction dir);

    /* --------------------------------------------------------------------------------------------
     * Bind a value/reference to the statement and mark it as input/output.
    */
    SqDataStatement & Io(LightObj & obj)
    {
        if (obj.GetType() == OT_INSTANCE)
        {
            UseInst_(obj, String(), Poco::Data::AbstractBinding::PD_IN_OUT);
        }
        else
        {
            Bind(obj);
        }
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Register a single extraction with the statement.
    */
    SqDataStatement & Into(LightObj & obj);

    /* --------------------------------------------------------------------------------------------
     * Register a single extraction with the statement with a default value.
    */
    SqDataStatement & Into_(LightObj & obj, LightObj & def);

    /* --------------------------------------------------------------------------------------------
     * Sets a limit on the maximum number of rows a select is allowed to return.
    */
    SqDataStatement & Limit1(SQInteger limit) { return Limit3(limit, false, false); }
    SqDataStatement & Limit2(SQInteger limit, bool hard) { return Limit3(limit, hard, false); }
    SqDataStatement & Limit3(SQInteger limit, bool hard, bool lower)
    {
        (*this), Poco::Data::Limit(static_cast< Poco::Data::Limit::SizeT >(limit), hard, lower);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Sets a an extraction range for the maximum number of rows a select is allowed to return.
    */
    SqDataStatement & Range(SQInteger lower, SQInteger upper) { return RangeEx(lower, upper, false); }
    SqDataStatement & RangeEx(SQInteger lower, SQInteger upper, bool hard)
    {
        (*this), Poco::Data::Range(static_cast< Poco::Data::Limit::SizeT >(lower),
                                    static_cast< Poco::Data::Limit::SizeT >(upper), hard);
        return *this;
    }
};

// ------------------------------------------------------------------------------------------------
template < class T > inline SqDataBinding< T > & SqDataBinding< T >::Use(SqDataStatement & stmt)
{
    stmt.addBind(new Poco::Data::ReferenceBinding< T >(mV, String(), Poco::Data::AbstractBinding::PD_IN));
    return *this;
}

// ------------------------------------------------------------------------------------------------
template < class T > inline SqDataBinding< T > & SqDataBinding< T >::UseAs(SqDataStatement & stmt, StackStrF & name)
{
    stmt.addBind(new Poco::Data::ReferenceBinding< T >(mV, name.ToStr(), Poco::Data::AbstractBinding::PD_IN));
    return *this;
}

// ------------------------------------------------------------------------------------------------
template < class T > inline SqDataBinding< T > & SqDataBinding< T >::Bind(SqDataStatement & stmt)
{
    stmt.addBind(new Poco::Data::CopyBinding< T >(*mV, String(), Poco::Data::AbstractBinding::PD_IN));
    return *this;
}

// ------------------------------------------------------------------------------------------------
template < class T > inline SqDataBinding< T > & SqDataBinding< T >::BindAs(SqDataStatement & stmt, StackStrF & name)
{
    stmt.addBind(new Poco::Data::CopyBinding< T >(*mV, name.ToStr(), Poco::Data::AbstractBinding::PD_IN));
    return *this;
}

/* ------------------------------------------------------------------------------------------------
 * RecordSet provides access to data returned from a query.
*/
struct SqDataRecordSet : public RecordSet
{
    /* --------------------------------------------------------------------------------------------
     * Creates the RecordSet for the given statement.
    */
    SqDataRecordSet(SqDataStatement & stmt)
        : RecordSet(stmt)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates the RecordSet for the given query.
    */
    SqDataRecordSet(SqDataSession & session, StackStrF & query)
        : RecordSet(session, query.ToStr())
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Copy constructor. If the statement has been executed asynchronously and has not been
     * synchronized prior to copy operation (i.e. is copied while executing), this constructor shall synchronize it.
    */
    SqDataRecordSet(const SqDataRecordSet &) = default;

    /* --------------------------------------------------------------------------------------------
     * Move constructor.
    */
    SqDataRecordSet(SqDataRecordSet &&) noexcept = default;

    /* --------------------------------------------------------------------------------------------
     * Destroys the RecordSet.
    */
    ~SqDataRecordSet() = default;

    /* --------------------------------------------------------------------------------------------
     * Assignment operator.
    */
    SqDataRecordSet & operator = (const SqDataRecordSet &) = default;

    /* --------------------------------------------------------------------------------------------
     * Move assignment.
    */
    SqDataRecordSet & operator = (SqDataRecordSet &&) noexcept = default;

    /* --------------------------------------------------------------------------------------------
     * Returns the number of rows in the RecordSet. The number of rows reported is dependent on filtering.
    */
    SQInteger RowCount() const
    {
        return static_cast< SQInteger >(rowCount());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of rows extracted during the last statement execution.
     * The number of rows reported is independent of filtering.
    */
    SQInteger ExtractedRowCount() const
    {
        return static_cast< SQInteger >(extractedRowCount());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the total number of rows in the RecordSet.
     * The number of rows reported is independent of filtering.
    */
    SQInteger GetTotalRowCount() const
    {
        return static_cast< SQInteger >(getTotalRowCount());
    }

    /* --------------------------------------------------------------------------------------------
     * Explicitly sets the total row count.
    */
    void SetTotalRowCount(SQInteger totalRowCount)
    {
        setTotalRowCount(ClampL< SQInteger, size_t >(totalRowCount));
    }

    /* --------------------------------------------------------------------------------------------
     * Implicitly sets the total row count.  The supplied sql must return exactly one column and one row.
     * The returned value must be an unsigned integer. The value is set as the total number of rows.
    */
    void SetTotalRowCountQ(StackStrF & sql)
    {
        setTotalRowCount(sql.ToStr());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of columns in the recordset.
    */
    SQInteger ColumnCount() const
    {
        return static_cast< SQInteger >(columnCount());
    }

    /* --------------------------------------------------------------------------------------------
     * Moves the row cursor to the first row.
     * Returns true if there is at least one row in the RecordSet, false otherwise.
    */
    bool MoveFirst()
    {
        return moveFirst();
    }

    /* --------------------------------------------------------------------------------------------
     * Moves the row cursor to the next row.
     * Returns true if the row is available, or false if the end of the record set has been reached and no more rows are available.
    */
    bool MoveNext()
    {
        return moveNext();
    }

    /* --------------------------------------------------------------------------------------------
     * Moves the row cursor to the previous row.
     * Returns true if the row is available, or false if there are no more rows available.
    */
    bool MovePrevious()
    {
        return movePrevious();
    }

    /* --------------------------------------------------------------------------------------------
     * Moves the row cursor to the last row.
     * Returns true if there is at least one row in the RecordSet, false otherwise.
    */
    bool MoveLast()
    {
        return moveLast();
    }

    /* --------------------------------------------------------------------------------------------
     * Resets the RecordSet and assigns a new statement.
     * Should be called after the given statement has been reset, assigned a new SQL statement, and executed.
     * Does not remove the associated RowFilter or RowFormatter.
    */
    void Reset(const SqDataStatement & stmt)
    {
        reset(stmt);
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the value in the given column (index) of the current row if the value is not NULL.
    */
    LightObj GetValueAt(SQInteger idx)
    {
        size_t i = ClampL< SQInteger, size_t >(idx);
        return GetValueImpl(value(i), columnType(i), LightObj{});
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the value in the given column (index) of the current row if the value is not NULL, or `fallback` otherwise.
    */
    LightObj GetValueAtOr(SQInteger idx, const LightObj & fallback)
    {
        size_t i = ClampL< SQInteger, size_t >(idx);
        return GetValueImpl(value(i), columnType(i), fallback);
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the value in the given column (name) of the current row if the value is not NULL.
    */
    LightObj GetValue(StackStrF & name)
    {
        String s(name.ToStr());
        return GetValueImpl(value(s), columnType(s), LightObj{});
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the value in the given column (name) of the current row if the value is not NULL, or `fallback` otherwise.
    */
    LightObj GetValueOr(StackStrF & name, const LightObj & fallback)
    {
        String s(name.ToStr());
        return GetValueImpl(value(s), columnType(s), fallback);
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the type for the column at specified position.
    */
    SQInteger ColumnTypeAt(SQInteger pos) const
    {
        return static_cast< SQInteger >(columnType(ClampL< SQInteger, size_t >(pos)));
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve the type for the column with specified name.
    */
    SQInteger ColumnType(StackStrF & name) const
    {
        return static_cast< SQInteger >(columnType(name.ToStr()));
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve column name for the column at specified position.
    */
    const std::string & ColumnName(SQInteger pos) const
    {
        return columnName(ClampL< SQInteger, size_t >(pos));
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve column maximum length for the column at specified position.
    */
    SQInteger ColumnLengthAt(SQInteger pos) const
    {
        return static_cast< SQInteger >(columnLength(ClampL< SQInteger, size_t >(pos)));
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve column maximum length for the column with specified name.
    */
    SQInteger ColumnLength(StackStrF & name) const
    {
        return static_cast< SQInteger >(columnLength(name.ToStr()));
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve column precision for the column at specified position.
     * Valid for floating point fields only (zero for other data types).
    */
    SQInteger ColumnPrecisionAt(SQInteger pos) const
    {
        return static_cast< SQInteger >(columnPrecision(ClampL< SQInteger, size_t >(pos)));
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve column precision for the column with specified name.
     * Valid for floating point fields only (zero for other data types).
    */
    SQInteger ColumnPrecision(StackStrF & name) const
    {
        return static_cast< SQInteger >(columnPrecision(name.ToStr()));
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if column value of the current row is null.
    */
    bool IsNull(StackStrF & name) const
    {
        return isNull(name.ToStr());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if recordset is filtered.
    */
    bool IsFiltered() const
    {
        return isFiltered();
    }

protected:

    /* --------------------------------------------------------------------------------------------
     * Retrieve the value in the given column (index) of the current row if the value is not NULL, or `fallback` otherwise.
    */
    static LightObj GetValueImpl(const Poco::Dynamic::Var & v, Poco::Data::MetaColumn::ColumnDataType t, const LightObj & fb)
    {
        // Is null?
        if (v.isEmpty())
        {
            return fb; // Use fallback
        }
        // Identify type
        switch (t)
        {
            case Poco::Data::MetaColumn::FDT_BOOL:
                return LightObj(SqInPlace{}, SqVM(), v.convert< bool >());
            case Poco::Data::MetaColumn::FDT_INT8:
            case Poco::Data::MetaColumn::FDT_INT16:
            case Poco::Data::MetaColumn::FDT_INT32:
#ifndef _SQ64
                return LightObj(SqInPlace{}, SqVM(), v.convert< SQInteger >());
#endif
            case Poco::Data::MetaColumn::FDT_INT64:
                return LightObj(SqInPlace{}, SqVM(), v.convert< int64_t >());
            case Poco::Data::MetaColumn::FDT_UINT8:
            case Poco::Data::MetaColumn::FDT_UINT16:
            case Poco::Data::MetaColumn::FDT_UINT32:
#ifndef _SQ64
                return LightObj(SqInPlace{}, SqVM(), v.convert< SQUnsignedInteger >());
#endif
            case Poco::Data::MetaColumn::FDT_UINT64:
                return LightObj(SqInPlace{}, SqVM(), v.convert< uint64_t >());
            case Poco::Data::MetaColumn::FDT_FLOAT:
                return LightObj(SqInPlace{}, SqVM(), v.convert< float >());
            case Poco::Data::MetaColumn::FDT_DOUBLE:
                return LightObj(SqInPlace{}, SqVM(), v.convert< double >());
            case Poco::Data::MetaColumn::FDT_STRING:
            case Poco::Data::MetaColumn::FDT_WSTRING:
                return LightObj(SqInPlace{}, SqVM(), v.convert< std::string >());
            case Poco::Data::MetaColumn::FDT_BLOB: {
                auto & b = v.extract< Poco::Data::BLOB >();
                return LightObj(SqTypeIdentity< SqBuffer >{}, SqVM(),
                                reinterpret_cast< Buffer::ConstPtr >(b.rawContent()), static_cast< SQInteger >(b.size()));
            }
            case Poco::Data::MetaColumn::FDT_CLOB: {
                auto & b = v.extract< Poco::Data::CLOB >();
                return LightObj(SqTypeIdentity< SqString >{}, SqVM(), SqInPlace{}, b.rawContent(), b.size());
            }
            case Poco::Data::MetaColumn::FDT_DATE:
            case Poco::Data::MetaColumn::FDT_TIME:
            case Poco::Data::MetaColumn::FDT_TIMESTAMP:
                STHROWF("This type of data is currently not implemented.");
            default:
                STHROWF("Unknown or unsupported type");
        }
        SQ_UNREACHABLE
        // Unreachable
        return {};
    }
};

/* ------------------------------------------------------------------------------------------------
 * SessionPool implements session pooling for POCO Data.
*/
struct SqDataSessionPool : public SessionPool
{

    /* --------------------------------------------------------------------------------------------
     * Creates the SessionPool for sessions with the given connector and connection string.
    */
    SqDataSessionPool(StackStrF & connector, StackStrF & connection)
        : SessionPool(connector.ToStr(), connection.ToStr())
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Creates the SessionPool for sessions with the given connector and connection string.
    */
    SqDataSessionPool(StackStrF & connector, int min_ses, int max_ses, int idle_time, StackStrF & connection)
        : SessionPool(connector.ToStr(), connection.ToStr(), min_ses, max_ses, idle_time)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Copy constructor (disabled).
    */
    SqDataSessionPool(const SqDataSessionPool &) = delete;

    /* --------------------------------------------------------------------------------------------
     * Move constructor (disabled).
    */
    SqDataSessionPool(SqDataSessionPool &&) noexcept = delete;

    /* --------------------------------------------------------------------------------------------
     * Destroys the SessionPool.
    */
    ~SqDataSessionPool() override = default;

    /* --------------------------------------------------------------------------------------------
     * Assignment operator (disabled).
    */
    SqDataSessionPool & operator = (const SqDataSessionPool &) = delete;

    /* --------------------------------------------------------------------------------------------
     * Move assignment (disabled).
    */
    SqDataSessionPool & operator = (SqDataSessionPool &&) noexcept = delete;

    /* --------------------------------------------------------------------------------------------
     * Retrieve a Session.
    */
    LightObj Get()
    {
        return LightObj(SqTypeIdentity< SqDataSession >{}, SqVM(), get());
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve a Session wrapped in a native/legacy implementation.
    */
    LightObj GetSq();

    /* --------------------------------------------------------------------------------------------
     * Retrieve a Session with requested property set.
    */
    LightObj GetWithProperty(const LightObj & value, StackStrF & name)
    {
        switch (value.GetType())
        {
            case OT_NULL: {
                return LightObj(SqTypeIdentity< SqDataSession >{}, SqVM(), get(name.ToStr(), nullptr));
            } break;
            case OT_INTEGER: {
                return LightObj(SqTypeIdentity< SqDataSession >{}, SqVM(), get(name.ToStr(), value.Cast< SQInteger >()));
            } break;
            case OT_FLOAT: {
                return LightObj(SqTypeIdentity< SqDataSession >{}, SqVM(), get(name.ToStr(), value.Cast< SQFloat >()));
            } break;
            case OT_BOOL: {
                return LightObj(SqTypeIdentity< SqDataSession >{}, SqVM(), get(name.ToStr(), value.Cast< bool >()));
            } break;
            case OT_STRING: {
                return LightObj(SqTypeIdentity< SqDataSession >{}, SqVM(), get(name.ToStr(), value.Cast< std::string >()));
            } break;
            default: STHROWF("Unsupported property value type");
        }
        // Should never get here
        SQ_UNREACHABLE
    }

    /* --------------------------------------------------------------------------------------------
     * Retrieve a Session with requested feature set.
    */
    LightObj GetWithFeature(bool value, StackStrF & name)
    {
        return LightObj(SqTypeIdentity< SqDataSession >{}, SqVM(), get(name.ToStr(), value));
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the maximum number of sessions the SessionPool will manage.
    */
    SQInteger GetCapacity() const
    {
        return capacity();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of sessions currently in use.
    */
    SQInteger GetUsed() const
    {
        return used();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of idle sessions.
    */
    SQInteger GetIdle() const
    {
        return idle();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of not connected active sessions.
    */
    SQInteger GetDead()
    {
        return dead();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of allocated sessions.
    */
    SQInteger GetAllocated() const
    {
        return allocated();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the number of available (idle + remaining capacity) sessions.
    */
    SQInteger GetAvailable() const
    {
        return available();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the name for this pool.
    */
    String GetName() const
    {
        return name();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the name formatted from supplied arguments as "connector:///connection".
    */
    static String GetName_(StackStrF & connector, StackStrF & connection)
    {
        return name(connector.ToStr(), connection.ToStr());
    }

    /* --------------------------------------------------------------------------------------------
     * Sets feature for all the sessions.
    */
    SqDataSessionPool & SetFeature(StackStrF & name, bool state)
    {
        setFeature(name.ToStr(), state);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the requested feature.
    */
    bool GetFeature(StackStrF & name)
    {
        return getFeature(name.ToStr());
    }

    /* --------------------------------------------------------------------------------------------
     * Sets property for all sessions.
    */
    SqDataSessionPool & SetProperty(const LightObj & value, StackStrF & name)
    {
        switch (value.GetType())
        {
            case OT_NULL: {
                setProperty(name.ToStr(), Poco::Any(nullptr));
            } break;
            case OT_INTEGER: {
                setProperty(name.ToStr(), Poco::Any(value.Cast< SQInteger >()));
            } break;
            case OT_FLOAT: {
                setProperty(name.ToStr(), Poco::Any(value.Cast< SQFloat >()));
            } break;
            case OT_BOOL: {
                setProperty(name.ToStr(), Poco::Any(value.Cast<bool>()));
            } break;
            case OT_STRING: {
                setProperty(name.ToStr(), Poco::Any(value.Cast<std::string>()));
            } break;
            default: STHROWF("Unsupported property value type");
        }
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the requested property.
    */
    LightObj GetProperty(StackStrF & name);

    /* --------------------------------------------------------------------------------------------
     * Shuts down the session pool.
    */
    void Shutdown()
    {
        shutdown();
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true if session pool is active (not shut down).
    */
    bool IsActive() const
    {
        return isActive();
    }
};

/* ------------------------------------------------------------------------------------------------
 * Helps with transactions in domain logic.
*/
struct SqDataTransaction : public Transaction
{
    /* --------------------------------------------------------------------------------------------
     * Base constructor.
    */
    explicit SqDataTransaction(SqDataSession & session)
        : Transaction(session)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Base constructor.
    */
    SqDataTransaction(SqDataSession & session, bool start)
        : Transaction(session, start)
    {
    }

    /* --------------------------------------------------------------------------------------------
     * Copy constructor.
    */
    SqDataTransaction(const SqDataTransaction &) = delete;

    /* --------------------------------------------------------------------------------------------
     * Move constructor.
    */
    SqDataTransaction(SqDataTransaction &&) = delete;

    /* --------------------------------------------------------------------------------------------
     * Destructor.
    */
    ~SqDataTransaction() = default;

    /* --------------------------------------------------------------------------------------------
     * Assignment operator.
    */
    SqDataTransaction & operator = (const SqDataTransaction &) = delete;

    /* --------------------------------------------------------------------------------------------
     * Move assignment.
    */
    SqDataTransaction & operator = (SqDataTransaction &&) = delete;

    /* --------------------------------------------------------------------------------------------
     * Returns false after the transaction has been committed or rolled back,
     * true if the transaction is ongoing.
    */
    SQMOD_NODISCARD bool IsActive()
    {
        return Transaction::isActive();
    }

    /* --------------------------------------------------------------------------------------------
     * Sets the transaction isolation level.
    */
    void SetIsolation(SQInteger ti)
    {
        Transaction::setIsolation(static_cast< Poco::UInt32 >(ti));
    }

    /* --------------------------------------------------------------------------------------------
     * Returns the transaction isolation level.
    */
    SQMOD_NODISCARD SQInteger GetIsolation()
    {
        return static_cast< SQInteger >(Transaction::getIsolation());
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true iff the transaction isolation level corresponding to the supplied bitmask is supported.
    */
    SQMOD_NODISCARD bool HasIsolation(SQInteger ti)
    {
        return Transaction::hasIsolation(static_cast< Poco::UInt32 >(ti));
    }

    /* --------------------------------------------------------------------------------------------
     * Returns true iff the transaction isolation level corresponds to the supplied bitmask.
    */
    SQMOD_NODISCARD bool IsIsolation(SQInteger ti)
    {
        return Transaction::isIsolation(static_cast< Poco::UInt32 >(ti));
    }

    /* --------------------------------------------------------------------------------------------
     * Executes and, if do_commit is true, commits the transaction.
     * Passing true value for commit disables rollback during destruction of this Transaction object.
    */
    SqDataTransaction & Execute(bool do_commit, StackStrF & sql)
    {
        Transaction::execute(sql.ToStr(), do_commit);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Executes all the SQL statements supplied in the vector and,
     * after the last one is sucesfully executed, commits the transaction.
    */
    SqDataTransaction & ExecuteList(const SqVector< std::string > & sql)
    {
        Transaction::execute(sql.Valid());
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Executes the transactor and, unless transactor throws an exception, commits the transaction.
    */
    SqDataTransaction & Transact(Function & cb)
    {
        auto t = [&](Session & s) {
            cb(LightObj(reinterpret_cast< SqDataSession * >(&s), nullptr));
        };
        Transaction::transact(t);
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Commits the current transaction.
    */
    SqDataTransaction & Commit()
    {
        Transaction::commit();
        return *this;
    }

    /* --------------------------------------------------------------------------------------------
     * Rolls back the current transaction.
    */
    SqDataTransaction & Rollback()
    {
        Transaction::rollback();
        return *this;
    }
};

} // Namespace:: SqMod