Gremlin steps for tree traversal.

tree.groovy

// Taken from: https://gist.github.com/1170000
// Gremlin user-defined defined tree() steps
// inTree() and outTree()

// closure can't have the same name as the defined step
_tree = { vertices ->
  def results = []

  vertices.each() {
    results << it
    if (label)
      children = it."$direction"(label).toList()
    else
      children = it."$direction"().toList()
    if (children) 
      results << _tree(children)
  }

  results
}

inClosure = {final Object... params ->
  try { label = params[0] }
  catch(e){ label = null }
  direction = "in"
  _().transform{ _tree(it) }
}

outClosure = {final Object... params ->
  try { label = params[0] }
  catch(e){ label = null }
  direction = "out"
  _().transform{ _tree(it) }
}

Gremlin.defineStep("inTree", [Vertex,Pipe], inClosure)
Gremlin.defineStep("outTree", [Vertex,Pipe], outClosure)