scxml as a JavaScript builder

scxml-builder.js

//------------------------------------------------------------------------------
// examples from:
//   State Chart XML (SCXML): State Machine Notation for Control Abstraction
//   http://www.w3.org/TR/scxml/
//   http://www.w3.org/TR/2014/WD-scxml-20140529/ (latest version)
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
// <state id=s">
//    <transition event="e" cond="x==1" target="s1"/>
//    <transition event="e" target="s2"/>
//    <transition event="*" target="s3"/>
// </state>
//------------------------------------------------------------------------------

sc = state( {id:"s"} , function() {
  transition( {event:"e", target:"s1", cond:"x==1"} )
  transition( {event:"e", target:"s2"} )
  transition( {event:"*", target:"s3"} )
})

console.log(JSON.stringify(sc,null,4))

// prints:
// {
//   "el": "state",
//   "id": "s",
//   "children": [
//   {
//     "el": "transition",
//     "event": "e",
//     "target": "s1",
//     "cond": "x==1"
//   },
//   {
//     "el": "transition",
//     "event": "e",
//     "target": "s2"
//   },
//   {
//     "el": "transition",
//     "event": "*",
//     "target": "s3"
//   }
//   ]
// }

//------------------------------------------------------------------------------
// <parallel id="p">
//
//   <transition event="done.state.p" target="someOtherState"/>
//
//   <state id="S1" initial="S11">
//     <state id="S11">
//       <transition event="e4" target="S12"/>
//     </state>
//     <state id="S12">
//       <transition event="e1" target="S1Final"/>
//     </state>
//     <final id="S1Final"/>
//   </state>
//
//   <state id="S2" initial="S21">
//     <state id=S21">
//       <transition event="e1" target="S22"/>
//     </state>
//     <state id="S22">
//       <transition event="e2" target="S2Final/>
//     </state>
//     <final id="S2Final"/>
//   </state>
//
// </parallel>
//------------------------------------------------------------------------------

sc = parallel( {id:"p"}, function() {

  transition( {event:"done.state.p", target:"someOtherState"} )

  state( {id:"S1", initial:"S11"}, function() {
    state( {id:"S11"}, function() {
      transition( {event:"e4", target:"S12"} )
    })
    state( {id:"S12"}, function() {
      transition( {event:"e1", target:"S1Final"} )
    })
    final( {id:"S1Final"} )
  })

  state( {id:"S2", initial:"S21"}, function() {
    state( {id:"S21"}, function() {
      transition( {event:"e1", target:"S22"} )
    })
    state( {id:"S22"}, function() {
      transition( {event:"e2", target:"S2Final"} )
    })
    final( {id:"S2Final"} )
  })
})

console.log(JSON.stringify(sc,null,4))

//------------------------------------------------------------------------------
// impl
//------------------------------------------------------------------------------
function parallel(   attrs, children ) { return genNode("parallel",   attrs, children) }
function state(      attrs, children ) { return genNode("state",      attrs, children) }
function transition( attrs, children ) { return genNode("transition", attrs, children) }
function final(      attrs, children ) { return genNode("final",      attrs, children) }

//------------------------------------------------------------------------------
var NodeParent

function genNode(name, attrs, children) {

  // create new node with el as first property
  var node = { el: name }

  // copy in rest of attrs
  for (var key in attrs) {
    node[key] = attrs[key]
  }

  // set parentage
  node.children = []
  if (NodeParent) NodeParent.children.push(node)

  // assign children
  var prevNodeParent = NodeParent

  NodeParent = node

  if (children) children()

  NodeParent = prevNodeParent

  return node
}