restruct_patch.jl

# function barrier for base_state
#
# WARN: This file can be removed if the implementations of `base_state` are removed from
# `QEDbase`.
#
# TL;DR: 
# The final state of the restructuing is, that QEDbase exports the symbol `base_state` and 
# QEDcore implements the concrete functions. However, currently, QEDbase provides both,
# the symbol and the implementation. Hiding this implementation in the QEDbase namespace 
# causes the usage of QEDbase.base_state implementation and not the QEDcore.base_state. 
# This is problematic, because the return type of `base_state` must be from `QEDcore`,
# which is not the case for `QEDbase.base_state`. Therefore, we need to recast the returns
# of `QEDbase.base_state` into types from `QEDcore`.
#
# This should not break if we update QEDbase by removing the concrete implementation of
# `base_state` in `QEDbase`, because `QEDcore` adds the implementations to the symbol 
# `QEDbase.base_state` anyway. 

function base_state(p::QEDbase.Fermion, d::QEDbase.Incoming, mom, spin)
    return BiSpinor(QEDbase.base_state(p, d, mom, spin))
end
function base_state(p::QEDbase.AntiFermion, d::QEDbase.Incoming, mom, spin)
    return AdjointBiSpinor(QEDbase.base_state(p, d, mom, spin))
end
function base_state(p::QEDbase.Fermion, d::QEDbase.Outgoing, mom, spin)
    return AdjointBiSpinor(QEDbase.base_state(p, d, mom, spin))
end
function base_state(p::QEDbase.AntiFermion, d::QEDbase.Outgoing, mom, spin)
    return BiSpinor(QEDbase.base_state(p, d, mom, spin))
end
function base_state(p::QEDbase.BosonLike, d::QEDbase.ParticleDirection, mom, spin)
    return SLorentzVector(QEDbase.base_state(p, d, mom, spin))
end

function base_state(p::QEDbase.Fermion, d::QEDbase.Incoming, mom, spin::QEDbase.AllSpin)
    return BiSpinor.(QEDbase.base_state(p, d, mom, spin))
end
function base_state(p::QEDbase.AntiFermion, d::QEDbase.Incoming, mom, spin::QEDbase.AllSpin)
    return AdjointBiSpinor.(QEDbase.base_state(p, d, mom, spin))
end
function base_state(p::QEDbase.Fermion, d::QEDbase.Outgoing, mom, spin::QEDbase.AllSpin)
    return AdjointBiSpinor.(QEDbase.base_state(p, d, mom, spin))
end
function base_state(p::QEDbase.AntiFermion, d::QEDbase.Outgoing, mom, spin::QEDbase.AllSpin)
    return BiSpinor.(QEDbase.base_state(p, d, mom, spin))
end
function base_state(
    p::QEDbase.BosonLike, d::QEDbase.ParticleDirection, mom, spin::QEDbase.AllPol
)
    return SLorentzVector.(QEDbase.base_state(p, d, mom, spin))
end