!  GeAllocTree.f90
!
!  Allocates one tree and sets up the pointers.
!  Returns actual size.
!
!  Detlef Irmscher, Thomas Ullrich, Uni Heidelberg, September 1993
!  Last update: 17.3.95 tu
!
integer function GeAllocTree (parentindex, part_name)
    use genesis_m, self=>GeAllocTree
    use mom_m
    implicit none
    integer, intent(in)             :: parentindex
    character(len=*), intent(in)    :: part_name
    type(tree), pointer             :: new_tree
    integer                         :: indexp, i

    ! get appropriate particle type from particle list
    indexp = GeParticleIndex (part_name)
    if (indexp == -1) return

    call GeAppendTree                                ! increases lasttree
    new_tree => treeList(lasttree)

    ! set the pointers to decay and child to zero; set decay flag to false
    nullify (new_tree%decaytype)

    do i = 1, 3
        new_tree%child(i) = 0
    enddo
    new_tree%decayed = .false.

    ! set stability to false
    new_tree%isStable = .false.

    ! set pointer to parent and parttype
    new_tree%parent = parentindex
    new_tree%parttype => particleList(indexp)

    ! set 4-momentum to 0
    new_tree%p4 = mom4(0., mom3(0., 0., 0.))

    ! setup return index
    GeAllocTree = lasttree
end function GeAllocTree