// Opens a closed way (i.e. a way where the last node has the
// same id as the first one) at the node with the given id. A
// new node is inserted where the way is open. This new node
// will be the end of the current way -> the first node will
// not necessarily stay the first node
func (w *Way) OpenAt(id int64) (nn *node.Node, err error) {
if !w.Closed() {
return nil, errors.New("Cannot open non-closed way")
}
var i int
var nd *node.Node
last := len(w.Nodes_) - 1
for i, nd = range w.Nodes_ {
if nd.Id_ != id {
continue
}
w.modified = true
nn = node.New(nd.Position_)
nn.Tags_ = nd.Tags_
if i == 0 {
w.Nodes_[last] = nn
return nn, nil
}
nb, nl := w.Nodes_[:i], w.Nodes_[i:]
nl = append(nl, nb...)
w.Nodes_ = append(nl, nn)
return nn, nil
}
return nil, errors.New(fmt.Sprintf("Node #%d not a member of way #%d", id, w.Id()))
}
// Splits a way and returns all resulting ways. For a closed way at least two
// node ids must be given. A resulting way must contain at least two nodes.
func (w *Way) Split(ids ...int64) (ws []*Way, err error) {
var orig []*node.Node
for _, n := range w.Nodes_ {
orig = append(orig, n)
}
if w.Closed() {
if len(ids) < 2 {
err = errors.New("Not enough arguments to split a closed way")
return
}
var id0 int64
id0, ids = ids[0], ids[1:]
_, err = w.OpenAt(id0)
if err != nil {
w.Nodes_ = orig
return
}
}
min_len := 2*len(ids) + 1
if min_len > len(w.Nodes_) {
w.Nodes_ = orig
err = errors.New("Way has too few nodes to split")
return
}
ws = []*Way{w}
cur_w := w
for _, id := range ids {
// the node with the id "id" will be the last node of the current
// way, a new node with the same position is inserted at the
// beginning of the new way
var nid int64
nid, err = cur_w.NextNodeId(id)
if err != nil {
w.Nodes_ = orig
ws = EmptyWays()
err = errors.New(fmt.Sprintf("Node #%d not a member of way #%d", nid, w.Id()))
return
}
for i, n := range cur_w.Nodes_ {
if n.Id_ == nid {
if i == 0 || i == len(cur_w.Nodes_)-1 {
w.Nodes_ = orig
ws = EmptyWays()
err = errors.New("Cannot split way at first or last node")
return
}
if i == 1 {
w.Nodes_ = orig
ws = EmptyWays()
err = errors.New("Cannot split into a way with one node")
return
}
nn := node.New(n.Position_)
nn.Tags_ = n.Tags_
nl := []*node.Node{nn}
for _, nd := range cur_w.Nodes_[i:] {
nl = append(nl, nd)
}
cur_w.Nodes_ = cur_w.Nodes_[0:i]
var new_w *Way
new_w, err = New(nl)
if err != nil {
w.Nodes_ = orig
ws = EmptyWays()
return
}
new_w.Tags_ = cur_w.Tags_
ws = append(ws, new_w)
cur_w = new_w
}
}
}
w.modified = true
return ws, nil
}