lucy-query-engine: integrate relations and add more multi-target func…

…tionality

internal/query_engine.go

@@ -156,20 +156,12 @@ func (q *QueryEngine) Sync() error {
 
  break
  case SetTarget:
- if _, ok := q.cradle.deps[Where]; !ok {
- return Error(UnsatisfiedDependency, "missing: Where()")
- }
 
  cradle.Ops.Push(SetTarget)
  cradle.Out = qr.Output
  cradle.deps[SetTarget] = struct{}{}
  cradle.AllowEmptyResult = false
 
- break
- case MiscNodeName:
- cradle.Ops.Push(MiscNodeName)
- cradle.Exps.Push(qr.Params)
- cradle.deps[MiscNodeName] = struct{}{}
  break
  case Creation:
  cradle.Ops.Push(cradle.family)
@@ -241,6 +233,46 @@ func (q *QueryEngine) Sync() error {
  }
 
  cradle.Ops.Push(cradle.family)
+ break
+ case RelationX:
+ // nuke existing multi-target.
+ cradle.Out = nil
+
+ cradle.Ops.Push(cradle.family)
+ cradle.Exps.Push(qr.Params)
+ cradle.deps[RelationX] = struct{}{}
+ break
+ case RelationY:
+ if _, ok := cradle.deps[RelationX]; !ok {
+ return Error(UnsatisfiedDependency, "missing: Relate()")
+ }
+
+ cradle.Ops.Push(cradle.family)
+ cradle.Exps.Push(qr.Params)
+ cradle.deps[RelationY] = struct{}{}
+ break
+ case By:
+ if _, ok := cradle.deps[RelationY]; !ok {
+ return Error(UnsatisfiedDependency, "missing: To()")
+ }
+
+ cradle.Ops.Push(cradle.family)
+ cradle.Exps.Push(qr.Params)
+ break
+
+ case MTRelation:
+
+ // Use Relation() only after Find()
+ if q.cradle.Out == nil {
+ return Error(UnsatisfiedDependency, "missing: Find()")
+ }
+
+ cradle.Ops.Push(cradle.family)
+
+ exp := qr.Params.(Exp)
+ exp["out"] = cradle.Out
+ cradle.Exps.Push(exp)
+
  break
  }