====== Graph queries in XL ======

===== Description =====

Queries are used to query existing graphs for specific features. They are used to analyse the actual graph and search for a specific pattern.

===== XL syntax =====

Queries are enclosed in asterisked parenthesis: ''(* *)''

The elements are given in their expected order. For example, ''(* Internode Internode Apex *)'' searches for a subgraph which consists of a sequence of nodes of the types ''Internode Internode Apex'', connected by successor edges.

===== Examples =====

  * Find all ''Internode'' nodes, and print them out:
''println( (* Internode *) )''
  * Find all newly created ''Internode'' nodes (with age 0):
''(* i:Internode, (i[age] == 0) *)''
  * Search for all ''Internode'' nodes with diameter greater than 0.01:
''(* i:Internode, (i[diameter] > 0.01) *)''
  * Find all pairs of segments ''F'' with distance smaller than 1:
''(* f:F, g:F, ( (f != g) && (distance(f, g) < 1) ) *)''
  * Find all ''Internode'' nodes, connected to a ''Leaf'' node with a branching edge:
''(* Internode +> Leaf *)''