func writeWays(file *os.File, ways []way) error {
if len(ways) == 0 {
return nil
}
for wayGroupIndex := 0; wayGroupIndex < (len(ways)/8000)+1; wayGroupIndex++ {
beg := (wayGroupIndex + 0) * 8000
end := (wayGroupIndex + 1) * 8000
if len(ways) < end {
end = len(ways)
}
wayGroup := ways[beg:end]
stringTable := make([][]byte, 1, 1000)
stringTableIndexes := make(map[string]uint32, 0)
for _, way := range wayGroup {
for _, s := range way.keys {
idx := stringTableIndexes[s]
if idx == 0 {
stringTableIndexes[s] = uint32(len(stringTable))
stringTable = append(stringTable, []byte(s))
}
}
for _, s := range way.values {
idx := stringTableIndexes[s]
if idx == 0 {
stringTableIndexes[s] = uint32(len(stringTable))
stringTable = append(stringTable, []byte(s))
}
}
}
osmWays := make([]*OSMPBF.Way, len(wayGroup))
for idx, way := range wayGroup {
osmWay := &OSMPBF.Way{}
var wayId int64 = way.id
osmWay.Id = &wayId
// delta-encode the node ids
nodeRefs := make([]int64, len(way.nodeIds))
var prevNodeId int64 = 0
for i, nodeId := range way.nodeIds {
nodeIdDelta := nodeId - prevNodeId
prevNodeId = nodeId
nodeRefs[i] = nodeIdDelta
}
osmWay.Refs = nodeRefs
osmWay.Keys = make([]uint32, len(way.keys))
for i, s := range way.keys {
osmWay.Keys[i] = stringTableIndexes[s]
}
osmWay.Vals = make([]uint32, len(way.values))
for i, s := range way.values {
osmWay.Vals[i] = stringTableIndexes[s]
}
osmWays[idx] = osmWay
}
group := OSMPBF.PrimitiveGroup{}
group.Ways = osmWays
block := OSMPBF.PrimitiveBlock{}
block.Stringtable = &OSMPBF.StringTable{stringTable, nil}
block.Primitivegroup = []*OSMPBF.PrimitiveGroup{&group}
err := WriteBlock(file, &block, "OSMData")
if err != nil {
return err
}
}
return nil
}
