[Go] generator does not support dimensionType as a group parameter.

[sergiu128]

Take the following group:

<group name="NoOrderIDEntries" id="37705" description="Number of OrderID entries" blockLength="24" dimensionType="groupSize8Byte">
    <field name="OrderID" id="37" type="uInt64" description="Unique Order ID" offset="0" semanticType="int"/>
    <field name="MDOrderPriority" id="37707" type="uInt64NULL" description="Order priority for execution on the order book" offset="8" semanticType="int"/>
    <field name="MDDisplayQty" id="37706" type="Int32NULL" description="Visible qty of order" offset="16" semanticType="Qty"/>
    <field name="ReferenceID" id="9633" type="uInt8NULL" description="Reference to corresponding Price and Security ID, sequence of MD entry in the message" offset="20" semanticType="int"/>
    <field name="OrderUpdateAction" id="37708" type="OrderUpdateAction" description="Order book update action to be applied to the order referenced by OrderID" offset="21" semanticType="int"/>
</group>

where groupSize8Byte is:

<composite name="groupSize8Byte" description="8 Byte aligned repeating group dimensions" semanticType="NumInGroup">
    <type name="blockLength" description="Length" primitiveType="uint16"/>
    <type name="numInGroup" description="NumInGroup" offset="7" primitiveType="uint8"/>
</composite>

The go generator does not take into account the dimensionType. The C++ generator does, which leads to correct decoding.

This is what the Go generator does right now:

if m.NoOrderIDEntriesInActingVersion(actingVersion) {
    var NoOrderIDEntriesBlockLength uint16
    if err := _m.ReadUint16(_r, &NoOrderIDEntriesBlockLength); err != nil {
        return err
    }
    var NoOrderIDEntriesNumInGroup uint8
    if err := _m.ReadUint8(_r, &NoOrderIDEntriesNumInGroup); err != nil {
        return err
    }
    if cap(m.NoOrderIDEntries) < int(NoOrderIDEntriesNumInGroup) {
        m.NoOrderIDEntries = make([]MDIncrementalRefreshBook46NoOrderIDEntries, NoOrderIDEntriesNumInGroup)
    }
    m.NoOrderIDEntries = m.NoOrderIDEntries[:NoOrderIDEntriesNumInGroup]
    for i := range m.NoOrderIDEntries {
        if err := m.NoOrderIDEntries[i].Decode(_m, _r, actingVersion, uint(NoOrderIDEntriesBlockLength)); err != nil {
            return err
        }
    }
}

This is what the Go generator should do:

if m.NoOrderIDEntriesInActingVersion(actingVersion) {
    groupSize := &GroupSize8Byte{}
    if err := groupSize.Decode(_m, _r, actingVersion); err != nil {
        return err
    }

    if cap(m.NoOrderIDEntries) < int(groupSize.NumInGroup) {
        m.NoOrderIDEntries = make([]MDIncrementalRefreshBook46NoOrderIDEntries, groupSize.NumInGroup)
    }
    m.NoOrderIDEntries = m.NoOrderIDEntries[:groupSize.NumInGroup]
    for i := range m.NoOrderIDEntries {
        if err := m.NoOrderIDEntries[i].Decode(_m, _r, actingVersion, uint(groupSize.BlockLength)); err != nil {
            return err
        }
    }
}

This is what the C++ generator does:

inline void wrapForDecode(
    char *buffer,
    std::uint64_t *pos,
    const std::uint64_t actingVersion,
    const std::uint64_t bufferLength,
) {
    GroupSize8Byte dimensions(buffer, *pos, bufferLength, actingVersion);
    m_buffer = buffer;
    m_bufferLength = bufferLength;
    m_blockLength = dimensions.blockLength();
    m_count = dimensions.numInGroup();
    m_index = 0;
    m_actingVersion = actingVersion;
    m_initialPosition = *pos;
    m_positionPtr = pos;
    *m_positionPtr = *m_positionPtr + 8;
}

You can run the example above here.

CC @theodosiosandreou