Refactor Graph class in SwhUnidirectionalGraph and SwhBidirectionalGraph
This commit is a massive refactor of the project to apply a stronger
separation of concerns which will allow the project to be more
maintainable and extensible in the future.
The principal change is the switch from a single SwhGraph containing
everything SWH-specific to two new classes:
- SwhUnidirectionalGraph, an ImmutableGraph augmented with SWH-specific methods such as getSWHID(), getNodeType(), etc.
- SwhBidirectionalGraph, which leverages BidirectionalImmutableGraph to store two SwhUnidirectionnalGraph, one for each direction.
To share common behavior and storage between these two classes, such as
handling node types and node properties, another class has been created:
- SwhGraphProperties, which is designed to contain the graph properties that can apply on the graph whatever its direction is (node types, node properties, dataset version, etc.)
Finally, to allow users of this API to use the two classes
interchangeably when the direction(s) do not mattern, both classes
implement a new interface:
- SwhGraph, which is designed to hold the common SWH-specific behavior between SwhUnidirectionalGraph and SwhBidirectionalGraph.
┌──────────────┐ │ImmutableGraph◄────────┐ └────▲─────────┘ │extends │ │ │ ┌──────────┴────────────────┐ extends│ │BidirectionalImmutableGraph│ │ └────────────▲──────────────┘ │ │extends ┌──────────────┴───────┐ ┌──────┴──────────────┐ │SwhUnidirectionalGraph│◄────┤SwhBidirectionalGraph│ └──┬──────────────┬────┘ └────────┬───────────┬┘ │ │ contains x2 │ │ │ │ │ │ │ implements│ │implements │ │ ┌▼──────────┐ │ │ │ │SwhGraph(I)◄────────┘ │ contains │ └───────────┘ │contains │ │ │ ┌──────────────────┐ │ └────────────►SwhGraphProperties◄──────────────┘ └──────────────────┘
BidirectionalImmutableGraph is included in this pull-request, but is
intended to be merged upstream eventually:
This commit includes a (partial) documentation overhaul. Notably,
using cross-dependency compiling of java documentation allows us to
remove redundant method documentations when they are inherited from
webgraph classes. It also includes cross-dependency *linking*, which
allows users to click on external links to unimi.it libraries.
Finally, this commits introduces stub methods for optionally loading
*labelled* graphs, which will be useful to store edges properties such
as file names, etc. To avoid a combinatorial explosion of types
(SwhUnidirectionalLabelledGraph, SwhBidirectionalLabelledGraph, etc..),
this is only checked at runtime. Classes hold both the unlabelled and
labelled versions of the underlying graphs, with the labelled version
being equal to null when the labels have not been loaded.