[osmosis-dev] API 0.6 and unique keys

[marcus.wolschon at googlemail.com]

On Wed, 28 Jan 2009 21:09:26 +1100, Brett Henderson <brett at bretth.com>
wrote:
> marcus.wolschon at googlemail.com wrote:
>> I just learned on OSM-dev that in 0.6 you can no longer
>> have more then one value for any key on an entity.
>>
>> Any chance we can use this to replace the Tag-class with
>> a simple read-only Hashtable in the v0_6.Entity -class?
>> It should simplify a lot of code and be much faster for
>> accessing key-values for known keys.
>> e.g. looking up the "highway"-attribute of a large number
>> of ways now requires you to iterate over all attributes of
>> all these ways in O(m+n) time whereas we can reduce this
>> to O(m) -time and even end up with much simpler code.
>>   
> Yeah, makes sense.

A TreeMap may prove usefull here. It is a SortedMap.

BTW: The Entity-classes could well use usefull toString()
-methods. ;)


> Out of curiosity, what were the main changes that took the time?

Way.addNode()
Entity.addTag()
Relation.addMember()

I usually filled them after creating all entities, sometimes in loops
and had to completely reorder the code.
Also handling relations in the LevelOfDetail-DataSet (combining
and simplifying very, very long ways) had to be rewritten as
I was often modifying the member-list of relations while
recursively handling the case that an existing relation is detected
while collecting the ways belonging to a long street/coastline/... .

Marcus