function ForGroupBJ takes group whichGroup, code callback returns nothing
    // If the user wants the group destroyed, remember that fact and clear
    // the flag, in case it is used again in the callback.
    local boolean wantDestroy = bj_wantDestroyGroup
    set bj_wantDestroyGroup = false

    call ForGroup(whichGroup, callback)

    // If the user wants the group destroyed, do so now.
    if (wantDestroy) then
        call DestroyGroup(whichGroup)
    endif
endfunction

function GetUnitsInRangeOfLocMatching takes real radius, location whichLocation, boolexpr filter returns group
    local group g = CreateGroup()
    call GroupEnumUnitsInRangeOfLoc(g, whichLocation, radius, filter)
    call DestroyBoolExpr(filter)
    return g
endfunction

function GetUnitsInRectMatching takes rect r, boolexpr filter returns group
    local group g = CreateGroup()
    call GroupEnumUnitsInRect(g, r, filter)
    call DestroyBoolExpr(filter)
    return g
endfunction

function GetUnitsInRectOfPlayer takes rect r, player whichPlayer returns group
    local group g = CreateGroup()
    set bj_groupEnumOwningPlayer = whichPlayer
    call GroupEnumUnitsInRect(g, r, filterGetUnitsInRectOfPlayer)
    return g
endfunction

function GetUnitsOfPlayerAndTypeId takes player whichPlayer, integer unitid returns group
    local group g = CreateGroup()
    set bj_groupEnumTypeId = unitid
    call GroupEnumUnitsOfPlayer(g, whichPlayer, filterGetUnitsOfPlayerAndTypeId)
    return g
endfunction

function GetUnitsOfPlayerMatching takes player whichPlayer, boolexpr filter returns group
    local group g = CreateGroup()
    call GroupEnumUnitsOfPlayer(g, whichPlayer, filter)
    call DestroyBoolExpr(filter)
    return g
endfunction

function GetUnitsOfTypeIdAll takes integer unitid returns group
    local group   result = CreateGroup()
    local group   g      = CreateGroup()
    local integer index

    set index = 0
    loop
        set bj_groupEnumTypeId = unitid
        call GroupClear(g)
        call GroupEnumUnitsOfPlayer(g, Player(index), filterGetUnitsOfTypeIdAll)
        call GroupAddGroup(g, result)

        set index = index + 1
        exitwhen index == bj_MAX_PLAYER_SLOTS
    endloop
    call DestroyGroup(g)

    return result
endfunction

function GetUnitsSelectedAll takes player whichPlayer returns group
    local group g = CreateGroup()
    call SyncSelections()
    call GroupEnumUnitsSelected(g, whichPlayer, null)
    return g
endfunction