Add Set\Vertices and move Vertex::getFirst() and Vertex::getAll()
Use Set\Vertices for accessing Graph's Vertices
Additional helpers for Set\Vertices
Each getVertices*() method should return a Set\Vertices instance
Each getVertices*() method returns a Set\Vertices instance
Add Set\VerticesAggregate Interface + implementation
Add Set\VerticesMap implementation for faster access
Remove unneeded methods getVerticesIds() and getVerticesId()
Add Set\Vertices::getVertexLast() helper
Fix missing imports
Move getting ordering function to helper getCallback()
Add Vertices::getSumCallback() helper
Remove unneeded imports
Throw OutOfBoundsException in Set\Vertices::getIndexVertex()
Remove NO-OP Set\Vertices::ORDER_FIFO
Do not use limited SplPriorityQueue for sorting
Add tests for Set\Vertices with 100% coverage
Do not re-declare abstract method getVertices()
Work around for PHP < 5.3.9 (#43200)
Move unneeded Vertices definitions in Set to Walk
Simplify Walk::getVertices() and remove Walk::getVerticesSequence*()