version bump to reflect resourceless XML elements
Create a second Map from Object to its adjacencies

Before this change, queries with a wildcard for subject would not get
the O(log n) promised in the documentation, with the actual
implementation using multiple O(n) operations.

This patch changes the time/memory tradeoff towards memory, by creating
a secondary map from objects to their adjencies and hooking it up to
query'. This creates redundancy in triples storage (and thereby
increases memory usage), but delivers the promised O(log n)
complexity for queries with either subject or object non-wildcarded.
Update version in rdf4h.cabal to 1.2.3
Compile the library with -O2 flag
Merge pull request #7 from maertsen/update_cabal_version

Update version in rdf4h.cabal to 1.2.3
Merge pull request #8 from maertsen/use_O2

Compile the library with -O2 flag
Merge pull request #9 from maertsen/add_OPSMap_to_MGraph

Create a second Map from Object to its adjacencies
Remove a duplicate lookup in the hotpath of MGraph

The set membership test and find can be combined in one lookup call.
Switch MGraph from Map, Set to HashMap, HashSet

During use of RDF4h on a large dataset, it became apparent that a lot of
time was spent in the compare function of the Node type. Switching
MGraph over to HashMap and HashSet (i.e. using Hashable instead of Ord to
index the map) seems to be faster for heavier workloads.

Known issue: test suite does not pass for duplicate and select tests.
This is not of interest to my particular use of rdf4h, but should be
fixed if/before this change gets merged.
Sort triples before testing equality in 2 tests

Tests no_dupes and match_none compare lists of triples. Commit
2378635b5357aacecc14b6d0c0fa8b4dfd98ff76 introduces the HashMap
unordered container. So URIs are hashed prior to being added to an RDF
graph. A `triplesOf` call on the RDF graph will likely return the
triples in a different order to the list passed to `mkRdf`. The fix is
to sort triples in the two failing test cases with `sortTriples` before
testing the same triples lists for equality.
Merge pull request #11 from maertsen/Improve_MGraph_query_by_removing_duplicate_lookup

Remove a duplicate lookup in the hotpath of MGraph
Merge pull request #10 from maertsen/Switch_MGraph_to_HashMap_and_HashSet

Switch MGraph to HashMap and HashSet
Merge branch 'master' of github.com:robstewart57/rdf4h
Merge remote-tracking branch 'tmp-maersten/Switch_MGraph_to_HashMap_and_HashSet'
version bump to 1.2.4