structure.dot

// Useful links:
// https://stackoverflow.com/questions/7115870/creating-straight-edges-in-graphviz

digraph {
  rankdir=LR
  splines=ortho
  ranksep=0.3
  nodesep=0.3
  node [shape=none margin=0 width=0.75 height=0.2]
  { rank=same; input [label="input value"]; program [label="jq program"]; }
  output [label="output values & errors"]

  node [shape=box margin=0.1 width=0 height=0]
  subgraph cluster_syntax {
    label="Syntax"
    hir [label="HIR"]
    mir [label="MIR"]
  }
  subgraph cluster_semantics {
    label = "Semantics"
    { rank=same; above_eval [width=0 shape=point label=""]; eval [label="Evaluation"] }
    { rank=same; update_eval [label="Update evaluation"]; value_ops [label="Value operations"] }
  }

  edge [arrowsize=0.5]
  program -> hir
  hir -> mir
  mir -> eval
  input -> above_eval [arrowhead=none]
  above_eval -> eval [tailport=center]
  eval -> output

  edge [style=dashed]
  eval -> update_eval [dir=both]
  eval -> value_ops
  update_eval -> value_ops
}