Pascal and Tomas,
Thanks for both of your assistance. I've found the slicer example Pascal
referred me to and think I understand the query examples. A couple more
questions:
Which approach is preferred? It seems like the query interface might result
in code that is easier to understand at a high level, but maybe I haven't
understood the slicer deeply enough yet. I note that the query interface is
advertised as being marginally faster.
Is there an example anywhere putting together the bits required to use the
query interface?
Here's what I have so far:
//Loading repos
Collection<IMetadataRepository> metadataReposList = new
LinkedList<IMetadataRepository>();
metadataReposList.add(metadataManager.loadRepository(new URI(P2SITE),
monitor));
metadataReposList.add(metadataManager.loadRepository(new URI(SECOND_P2SITE),
monitor));
metadataReposList.add(metadataManager.loadRepository(new URI(THIRD_P2SITE),
monitor));
//Querying
IQueryable<IInstallableUnit> allMetadataRepos =
QueryUtil.compoundQueryable(metadataReposList);
Set<IInstallableUnit> toInstallOrUpdate = allMetadataRepos.query(
QueryUtil.createIUAnyQuery(), monitor).toUnmodifiableSet();
Now suppose I've got two Features I want to use as a root to search from. I
know I need a traverse query, and I can see how to run a query against an
IQueryable, but I'm not sure how to pass my two root Features in as
arguments. Or am I asking the wrong question?
Thanks in advance,
Dave
On Fri, Dec 10, 2010 at 8:35 AM, Thomas Hallgren <[email protected]> wrote:
> On 2010-12-09 23:21, David Orme wrote:
>
> Hi all,
>
> I'm trying to execute a P2 query that can chase down all IUs resulting
> from starting with several features and traversing the tree of IUs and
> included features until all dependencies are satisfied.
>
> I found the example of how to construct such a query at
> wiki.eclipse.org/Query_Language_for_p2, but can't work out how to run it
> against a set of inputs.
>
> It seems that I need an IQueryable to execute against and some way to
> specify the set of Features to use as roots.
>
> I've got an IQueryable, (and can successfully createIUAnyQuery() against
> it), but haven't been able to work out how to extend this to query for the
> subset that is reachable from a set of Features that are being treated as
> roots and are available via the IQueryable.
>
> Any pointers to code snippets or anything else would be welcome.
>
> The simplest query from the wiki looks like this:
>
> $0.traverse(parent | parent.requirements.collect(rc | select(iu | iu ~=
> rc)).flatten())
>
> It expects a collection (i.e. your set of roots) as it's first argument.
> You then apply it to your IQueryable.
>
> In the expression, 'parent' is the variable holding each item from the
> roots. The expression compares all iu's from your IQueryable with the
> requirements of the 'parent' and this results in new instances that will
> become 'parent' as the query traverses recursively.
>
> HTH,
> Thomas Hallgren
>
>
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>
>
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