rippled/include/xrpl/protocol/STExchange.h

//------------------------------------------------------------------------------
/*
    This file is part of rippled: https://github.com/ripple/rippled
    Copyright (c) 2012, 2013 Ripple Labs Inc.

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

#ifndef RIPPLE_PROTOCOL_STEXCHANGE_H_INCLUDED
#define RIPPLE_PROTOCOL_STEXCHANGE_H_INCLUDED

#include <xrpl/basics/Blob.h>
#include <xrpl/basics/Buffer.h>
#include <xrpl/basics/Slice.h>
#include <xrpl/basics/contract.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STBlob.h>
#include <xrpl/protocol/STInteger.h>
#include <xrpl/protocol/STObject.h>

#include <memory>
#include <optional>
#include <stdexcept>
#include <type_traits>
#include <utility>

namespace ripple {

/** Convert between serialized type U and C++ type T. */
template <class U, class T>
struct STExchange;

template <class U, class T>
struct STExchange<STInteger<U>, T>
{
    explicit STExchange() = default;

    using value_type = U;

    static void
    get(std::optional<T>& t, STInteger<U> const& u)
    {
        t = u.value();
    }

    static std::unique_ptr<STInteger<U>>
    set(SField const& f, T const& t)
    {
        return std::make_unique<STInteger<U>>(f, t);
    }
};

template <>
struct STExchange<STBlob, Slice>
{
    explicit STExchange() = default;

    using value_type = Slice;

    static void
    get(std::optional<value_type>& t, STBlob const& u)
    {
        t.emplace(u.data(), u.size());
    }

    static std::unique_ptr<STBlob>
    set(TypedField<STBlob> const& f, Slice const& t)
    {
        return std::make_unique<STBlob>(f, t.data(), t.size());
    }
};

template <>
struct STExchange<STBlob, Buffer>
{
    explicit STExchange() = default;

    using value_type = Buffer;

    static void
    get(std::optional<Buffer>& t, STBlob const& u)
    {
        t.emplace(u.data(), u.size());
    }

    static std::unique_ptr<STBlob>
    set(TypedField<STBlob> const& f, Buffer const& t)
    {
        return std::make_unique<STBlob>(f, t.data(), t.size());
    }

    static std::unique_ptr<STBlob>
    set(TypedField<STBlob> const& f, Buffer&& t)
    {
        return std::make_unique<STBlob>(f, std::move(t));
    }
};

//------------------------------------------------------------------------------

/** Return the value of a field in an STObject as a given type. */
/** @{ */
template <class T, class U>
std::optional<T>
get(STObject const& st, TypedField<U> const& f)
{
    std::optional<T> t;
    STBase const* const b = st.peekAtPField(f);
    if (!b)
        return t;
    auto const id = b->getSType();
    if (id == STI_NOTPRESENT)
        return t;
    auto const u = dynamic_cast<U const*>(b);
    // This should never happen
    if (!u)
        Throw<std::runtime_error>("Wrong field type");
    STExchange<U, T>::get(t, *u);
    return t;
}

template <class U>
std::optional<typename STExchange<U, typename U::value_type>::value_type>
get(STObject const& st, TypedField<U> const& f)
{
    return get<typename U::value_type>(st, f);
}
/** @} */

/** Set a field value in an STObject. */
template <class U, class T>
void
set(STObject& st, TypedField<U> const& f, T&& t)
{
    st.set(STExchange<U, typename std::decay<T>::type>::set(
        f, std::forward<T>(t)));
}

/** Set a blob field using an init function. */
template <class Init>
void
set(STObject& st, TypedField<STBlob> const& f, std::size_t size, Init&& init)
{
    st.set(std::make_unique<STBlob>(f, size, init));
}

/** Set a blob field from data. */
template <class = void>
void
set(STObject& st,
    TypedField<STBlob> const& f,
    void const* data,
    std::size_t size)
{
    st.set(std::make_unique<STBlob>(f, data, size));
}

/** Remove a field in an STObject. */
template <class U>
void
erase(STObject& st, TypedField<U> const& f)
{
    st.makeFieldAbsent(f);
}

}  // namespace ripple

#endif